Monday, December 10, 2007
MMIC PBL 1
Sex: Male
Age: 37 years old
Type of Specimen: Wound swab
Clinical diagnosis
Symptoms: Fever, swelling around operation wound
Diagnosis: Wound infection
Approach for the diagnosis of wound infection [1]
- A wound swab was obtained
- The specimen is gram-stained. The shape, size, arrangement and whether they are gram-positive or gram-negative should be observed.
- The specimen is cultured on appropriate media, to obtain ‘pure culture’. Plates should be incubated in aerobic or anaerobic environment.
- Identification of the organism by means of biochemical tests.
- Perform antibiotic susceptibility tests.
Note: Wound infection could be due to multiple organisms, so it’s important to culture the specimen on several different media under different atmospheric conditions e.g. aerobic or anaerobic. Gram staining provides useful information about the range of possible causative agents. [1]
Gram-positive cocci:
1) Streptococci Species (Facultative anaerobes)
- Enterococcus faecalis
- Streptococcus pyogenes
2) Staphylococcus aureus (Facultative anaerobes)
Gram-positive rod:
1) Bacillus anthracis (Strict aerobes; spore formation)
2) Clostridium perfringens (Stric anaerobes; spore formation)
Gram-negative rod:
1) Pseudomonas aeruginosa (Strict aerobes)
2) Enterobacteriaceae species (Facultative anaerobes)
- Escherichia coli
- Enterobacter cloacae
- Serratia marcescens
- Proteus mirabilis
- Klebsiella pneumoniae
Differential diagnosis for gram-positive cocci:
Streptococci Species
1] Enterococcus faecalis
2] Streptococcus pyogenes
Sheep blood agar:[1]
- Beta-hemolytic colonies: Streptococcus pyogenes
- Gamma-hemolytic or lack of change in the medium around colonies: Enterococcus faecalis
Catalase test: Both Negative [2]
This test differentiates Streptococci Species and Staphylococcus aureus.
- A drop of hydrogen peroxide is added to a sample from the bacterial colony
- Presence of catalase converts hydrogen peroxide into water and oxygen
- Results in the production of visible bubbles
Bile-esculi agar: [2]
- Positive: E. faecalis
- Negative: Strep. Pyogenes
E. faecalis hydrolyse esculin, which results in black discoloration of the agar.
Hypertonic (6.5%) NaCl solution:
- E. faecalis grows, while Strep. Pyogenes doesn’t
Antibody Susceptibility: [1]
1] Enterococcus faecalis:
- Penicillin
- Erythromycin
- Bacitracin
- Tetracycline
2] Streptococcus pyogenes:
- Penicillin
- Erythromycin
- Bacitracin
- Tetracycline
Staphylococcus aureus [1]
Sheep blood agar:
- Beta-hemolytic colonies indicate Staphylococcus aureus
Catalase test: Positive
Coagulase test: Positive
Coagulase test differentiates S. aureus, from other staphylococcus species such as S. epidermidis present in the normal flora.
Mannitol Salt Agar: Yellow colonies
Differential test for mannitol fermentors and non-fermentators; S. aureus ferments mannitol.
Antibody susceptiblity:
- Vancomycin
- Gentamicin
- Nafcillin
- Methicillin
Picture 1: Beta-hemolysis represented by beta sign and gamma-hemolysis represented by gamma sign
Picture: micrsweb>lab3grampostitive>lab3introtomethods.html/">rsweb>lab3grampostitive>lab3introtomethods.html/">http://www3.umdnj.edu>micrsweb>lab3grampostitive>lab3introtomethods.html
Picture 2: Catalase positive reaction indicating S. aureus infection
Picture:html>stitch.phps=72880656991974&id=39006255044608/">html>stitch.phps=72880656991974&id=39006255044608/">html>stitch.phps=72880656991974&id=39006255044608/">html>stitch.phps=72880656991974&id=39006255044608/">http://www.cfkeep.org>html>stitch.phps=72880656991974&id=39006255044608
Differential diagnosis for spore forming gram-positive rods:
Bacillus anthracis: [1, 2]
Blood agar (Culture aerobically): Gamma-hemolytic ;large and irregular colonies
Egg yolk agar: Lecithinase negative
In addition, it can be diagnosed by means of antigen and molecular tests.
Antibody susceptibility: [1]
- Ciprofloxacin
- Doxycycline
Clostridium perfringens: [2]
Blood agar (Culture anaerobically): Double zone of beta-hemolysis
Egg yolk agar: Lecithinase positive
Antibody susceptibility: [1]
- Penicillin
Picture 3: Left plate: Positive test for lecithinase; Right plate: Negative for lecithinase
Picture: kkiser>lecithpn.jpg/">kkiser>lecithpn.jpg/">kkiser>lecithpn.jpg/">http://users.stlcc.edu>kkiser>Lecithpn.jpg
Differential diagnosis for gram-negative rods:[1]
MacConkey agar: selective agar used for the isolation and differentiation of lactose-fermenting and non-fermenting gram-negative rods. Alternatively, Eosin Methylene Blue Agar (EMB) can be used.
Lactose fermenters: Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae; form red to pink colonies.
Non-fermenters: Proteus mirabilis, Pseudomonas aeruginosa and Serratia marcescens; form colourless colonies
Oxidase test: [1]
- Positive: Pseudomonas aeruginosa
- Negative: Enterobacteriaceae species
This test determines the presence of oxidase enzyme. An oxidase paper is touched onto colony, in the presence of oxidase, paper changes to purple (Pseudomonas aeruginosa).
Triple sugar iron agar: [1]
Biochemcial tests: Indole test, Methyl red test, Voges-Proskauer reaction test and Citrate utilization test (IMViC test)
Pseudomonas aeruginosa: [1]
- Colonies: Fluoresce under ultraviolet light; give fruity odor and grow at 42° C
- Indole test: Negative
- Methyl red test: Positive
- Voges-Proskauer reaction test: Negative
- Citrate utilization test: Positive
- Urease test: Negative
Antibody susceptibility: [1]
- Penicillin e.g. ticarcillin or piperacillin
- Aminoglyoside e.g. gentamicin or amikacin
Enterobacteriaceae species:
1] Escherichia coli [1]
- Motile
- Indole test: Negative
- Methyl red test: Positive
- Voges-Proskauer reaction test: Negative
- Citrate utilization test: Negative
- Urease test: Negative
Antibody susceptibility: [1]
- Cefotaxime
- Gentamicin
- Ampicillin
- Loperamide
2] Enterobacter cloacae [1]
- Indole test:Negative
- Methyl red test: Negative
- Voges-Proskauer reaction test: Positive
- Citrate utilization test: Positive
- Urease test: Negative
Antibody susceptibility: [1]
- Imipenem
- Gentamicin
- Cefotaxime
3] Serratia marcescens [1]
- Indole test: Positive
- Methyl red test: Negative
- Voges-Proskauer reaction test: Positive
- Citrate utilization test: Positive
- Urease test: Negative
Antibody susceptibility: [1]
- Imipenem
- Gentamicin
- Cefotaxime
4] Proteus mirabilis [1]
- Indole test: Positive
- Methyl red test: Positive
- Voges-Proskauer reaction test: Negative
- Citrate utilization test: Positive
- Urease test: Positive
Antibody susceptibility: [1]
- Ampicillin
- Cefotaxime
5] Klebsiella pneumoniae [1]
- Indole test: Positive
- Methyl red test: Positive
- Voges-Proskauer reaction test: Positive
- Citrate utilization test: Positive
- Urease test: Positive
Antibody susceptibility: [1]
- Imipenem
- Gentamicin
- Cefotaxime
Refereneces:
1)Levinson, W. (2006). Review of Medical Microbiology and Immunology. San Francisco,California: Lange Medical Books/ McGraw-Hill Medical Publishing Division
2)www.textbookofbacteriology.net>search
Foo Yong Yang
TG02
0503196H
Sunday, December 9, 2007
Principles of Test used by the team
MacConkey agar
MacConkey agar is a selective, differential platingmedium. It selects enterobacteriaceae and other gram-negative bacteria and differentiates them into lactose fermenters and non-lactose fermenters. The presence of bile salts and crystal violet will inhibit the growth of gram-positive microorganism. The incorporation of lactose serves as the sole carbohydrate source. Gram-negative bacilli which ferments lactose produces a dark red to pink colonies while non-lactose fermenting gram negative bacilli produces colourless or transparent colonies
http://www.yahoo.com/> Image search> MacConkey agar
Eosin-Methylene Blue Agar
Eosin-methylene blue agar is a selective, differential medium used for the isolation and identification of gram-negative bacteria. Eosin Y and methylene blue dyes inhibit the growth of gram-positive bacteria and allows the growth of gram-negative bacteria. Lactose and sucrose are incorporated to allow differentiation of isolates based on lactose fermentation. Fermentation is detected by colour changes and precipitation of dye such as pH drops. Sucrose is incorporated as it serves as another alternative source of carbohydrates for slow lactose fermenters.
http://www.yahoo.com/> Image search> Eosin-methylene blue agar
Blood Agar
Blood agar is used to cultivate a wide variety of fastidious bacterium. An infusion agar of tryptic soy agar base can be enriched by the addition of 5-10% of sheep’s, rabbit’s blood. The incorporation of blood not only provides enrichment for growth but also allows the detection and characterization of haemolytic patterns
micrsweb>lab3grampostitive>lab3introtomethods.html/">http://www3.umdnj.edu>micrsweb>lab3grampostitive>lab3introtomethods.html/
-alpha-hemolysis represented by alpha sign
alpha-hemolysis is the partial clearing of the blood around the colony that results in a green discoloration pf the medium
-Beta-hemolysis represented by beta sign
Beta-hemolysis is the complete clearing of blood around the bacterial colonies. This is due to the complete haemolysis of the surrounding RBCs
-Gamma-hemolysis represented by gamma sign
Gamma-hemolysis occurs when the RBCs surrounding the colonies are unaffected and there is no change in the colour of the bacterial colonies
Mannitol Salt Agar
Differential test for mannitol fermentors and non-fermentators; S. aureus ferments mannitol producing yellow colonies.
Left: Non- fermented mannitol Right: Fermented mannitol (S. aureus)
http://www.cfkeep.org>html>stitch.php?s=72880656991974&id=39006255044608
Triple Sugar Iron Agar Test
TSI contains glucose, lactose and sucrose as well as a pH-sensitive color indicator. It also contains an iron ingredient for detecting hydrogen sulfide production, which blackens the medium if it occurs. Fermentation of the sugars by the test organism is interpreted by color changes in the butt
and the slant of the mediums.
Interpretation
Acid (yellow) butt – alkaline (pink) slant (K/A)
- glucose fermented
- sucrose or lactose not fermented
acid butt - acid slant (A/A)
- glucose fermented
- lactose and/or sucrose fermented
alkaline butt - alkaline slant (K/K)
- neither glucose, lactose or sucrose fermented
- organism probably not an enteric bacillus
Gas production - indicated by bubbles in the butt. With large amounts of gas production, the agar may be broken or pushed upward.
Hydrogen sulfide production - indicated by any amount of blackening in the butt.
TSI agar
http://www.yahoo.com/ > http://biology.uwsp.edu > faculty>TBarta > fermentation > TSI agar
Indole test
Bacteria that possess the enzyme tryptophanase are capable of hydrolyzing and deaminating tryptophan with the production of indole, pyruvic acid and ammonia. Indole production is an important characteristic in the identification of many species of microorganisms being particularly useful in separating E. coli (positive) from members of the Klebsiella-Enterobacter-Hafnia-Serratia group (mostly negative)
www.yahoo.com > http://www.mc.maricopa.edu >johnson >labtools >biochem
Interpretation Positive test: bright pink colour at the interface between the broth and the reagent Negative test: No colour change or a slight yellow ring
Methyl Red test
Methyl red is an acid sensitive dye that is yellow at pH above 4.5 and red at pH below 4.5. This test is used to indicate whether glucose has been broken down completely to highly acidic end products or only partially to less acidic end products.
www.yahoo.com > http://www.mc.maricopa.edu >johnson >labtools >biochemInterpretation
Positive - bright red color, indicates pH of 4.5 or less
Negative - yellow or orange color, indicates pH of above 4.5
Voges Proskauer
The Voges-Proskauer test is used to detect the presence of acetylmethylcarbinol, one of the end products of glucose metabolism.
www.yahoo.com > http://www.mc.maricopa.edu >johnson >labtools >biochem
Interpretation
Positive - strong red color will develop
Negative - no color change
Citrate test
Organisms that are capable of utilizing citrate as their sole carbon source also utilize ammonium salts as their sole nitrogen source. This results in an alkaline environment that turns the indicator bromothymol blue to an intense blue when pH is above 7.6. This characteristic can used to differentiate members of the family Enterobacteriaceae and other gram-negative rods.
www.yahoo.com > http://www.mc.maricopa.edu >johnson >labtools >biochemRight tube- negative results; Left tube- positive results
Urease Test
Detects the enzyme urease, which breaks down urea into ammonia. Ammonia is a base and thus will raise the pH of the media if it is present. This change in pH is indicated by a pH indicator called phenol red which is present in the media.
InterpretationPositive test: A color change from yellow to bright pinkish-redNegative test: No colour change
Oxidation-Fermentation Test
The oxidative-fermentative approach permits the separation of bacteria by a simple method that differentiates anaerobic and aerobic degradation of carbohydrates in an environment responsive to weak production of acids. Agar is added to give a semisolid consistency so that acids that form on the surface of the agar may permeate throughout the medium, making interpretation off the pH shift of the indicator bromothymol blue easier to visualize.
Interpretation
Positive test: medium becomes yellow at the top indicating acid productionNegative test: medium remains green if no acid formed
Catalase Test
The catalase test is used to differentiate between bacterial species in the lab. The test is done by placing a drop of hydrogen peroxide on a microscope slide. Using an applicator stick, the colony is smeared into the hydrogen peroxide drop. If bubbles or froth form, the organism is said to be catalase-positive; if not, the organism is catalase-negative
Catalase positive reaction indicating S. aureus infection
http://www.cfkeep.org>html>stitch.php?s=72880656991974&id=39006255044608
Oxidase Test
Use to determine the presence of oxidase enzymes. An oxidase paper is touched onto colony, in the presence of oxidase, paper changes to purple indicating Pseudomonas aeruginosa. The absence of oxidase result in no colour change, and is indicative of Enterobacteriaceae family
Coagulase Test
Coagualse test is performed to test the ability of the microorganism to clot plasma by the action of coagulase
Rabbit plasma is incubated with staphylococcus colony If staphylococci isolated from infection are able to clot blood, then they are coagulase positive S. aureus.
Coagulase test differentiates S. aureus, from other staphylococcus species such as S. epidermidis and S. saprophyticus present in the normal flora.
Right: Coagulase negative; Left: Coagulase positive
micrsweb>lab3grampostitive>lab3introtomethods.html/">micrsweb>lab3grampostitive>lab3introtomethods.html/">http://www3.umdnj.edu>micrsweb>lab3grampostitive>lab3introtomethods.html/Bile esculin Test
The medium contains esculin and peptone that is to provide nutrition to the microorganism while bile inhibits Gram-postivie bacteria other than Group D streptococci and enterococci, and sodium azide to inhibit the Gram-negative bacteria. Ferric citrate is added as a color indicator.
Interpretation
Positive test: An agar slant that is more than half darkened after incubation.
Negative test: Less than half the slant has darkened.
Optochin Test
Optochin (ethylhydrocupreine hydrochloride), a quinine derivative, has a detergent-like action and causes selective lysis of pneumococci. A sterile disk impregnated with optochin is placed on the first sector of an isolation plate before incubation. A zone of inhibition (area with no growth) of 14 mm. or more in diameter will be seen around the disk after incubation if the organism is Streptococcus pneumoniae. Other alpha-hemolytic streptococci are resistant to (not killed by) optochin. Their colonies will thus grow right up to the disk of optochin or have zones of inhibition less than 14 mm. in diameter.
Bile Solubility Test
Bile will selectively lyse colonies of Streptococcus pneumoniae while other strep are immune to bile's activity. When a bile salt such as desoxycholate is added directly to Streptococcus pneumoniae growing on an agar plate or in a broth culture the bacteria will lyse and the area become clear. Other alpha-hemolytic streptococci are resistant to (not lysed by) bile and will stay visible or turbid (cloudy).
Bile-esculi agar
Bile-esculi agar is a selective, differential agar used to isolate and identify group D streptococci and enterococci. Bile salts is a selective component and esculin is the differential ingredient. All group D streptococci and enterococci hydrolyzes esculin. The products of esculin hydrolysis react with ferric citrate in the medium to produce insoluble iron slats. This results in the blackening of the agar.
micrsweb>lab3grampostitive>lab3introtomethods.html/">micrsweb>lab3grampostitive>lab3introtomethods.html/">http://www3.umdnj.edu>micrsweb>lab3grampostitive>lab3introtomethods.html/
6.5% NaCl Test
NaCl is sued to differentiate those gram-positive cocci that will grow in 6.5% NaCl from those that are inhibited by this salt concentration. Enterococcus species can withstand higher salt concentration than other gram-positive cocci
Egg Yolk Agar
Egg yolk agar is a differential medium used in the detection of lecithinase, lipase and protease activity. The egg emulsion in the agar provides the lecithin, lipase and proteins to be degraded by these enzymes. A given microorganism may produce one or all of the above enzymes.
Left plate: Positive test for lecithinase
Right plate: Negative for lecithinase
http://users.stlcc.edu>kkiser>Lecithpn.jpg
DNase Test
Extacellular DNases are only present in a few bacterial species such as Serratia marcescens, Pseudomonas aerugionsa. The biochemical and morphology of other Enterbacteriaceae are similar especially in Klebsiella-Enterobacter supp. The only difference which separates S. marcescens from Klebsiella-Enterobacter supp is the DNases that is produced.
8% sodium chloride broth
Test is done to differentiate vibrio cholerae and vibrio parahaemolyticus.
Unlike vibrio parahaemolyticus, vibrio cholerae cannot grow at 8% sodium chloride broth.
Spore stain (Bartholomew and mitters)
In spore stain test, hot malachite green is used to stain spores, while the safranin is used as a counterstain. In this test, spores would be stain green and the rest of the cell appear pink/red
References
http://www.mc.maricopa.edu/~johnson/labtools.html> Optochin sensitivity & bile solubility
http://en.wikipedia.org/wiki/Main_Page > search > catalase
http://en.wikipedia.org/wiki/Main_Page > search > oxidase
Mahon C. R. and Manuselis G, Jr (1995). Textbook of Diagnostic Microbiology. W.B. Saunders Company
MacFaddin J. F. (2000). Biochemical Test for Indentification of Medical Bacteria. Lippincott Williams & Wilkins
search>pseudomonas/">www.textbookofbacteriology.net>search>pseudomonas
Levinson, W. (2006). Review of Medical Microbiology and Immunology. San Francisco,California: Lange Medical Books/ McGraw-Hill Medical Publishing Division
http://www.yahoo.com/ > http://www2.umdnj.edu >labpix > E.coli > biochemical test
http://www.yahoo.com/ > http://people.uis.edu > Labs > Enterobacteriaceae > biochemical test
search>staph./">search>staph./">www.textbookofbacteriology.net>search>staph
Student attachment materials
Mmic Case 3
Patient : Maisy Hong
Age : 67
Urine Specimen 3
Diagnosis: UTI, indwelling catheter
E.coli on blood plate
E.coli on MacConkey plate - lactose fermentors
Serratia on blood plate - colonies appear as 'buff' coloured
Proteus on blood plate- swarmingAll pictures obtained from:
http://www.microbelibrary.org/asmonly/details.asp?id=2038
Antibiotics
1. S. epidermidis
Highly resistant to antibiotics.
· Novobiocin
· Vancomycin+rifampin/aminoglycoside
2. Enterococci
· Ampicillin
· Nitrofurantoin
3. E.coli
· Ampicillin
· Aminoglycosides
· Cephalosporin
· SXT (Trimethoprim-sulfamethaxazole)
4. Proteus
· Penicillin-derivatives
· Aminoglycosides
· Cephalosporin
· Quinolones
5. Serratia
Mulit-drug resistant
· Third generation Cephalosporin
6. P. aeruginosa
Highly mulit-drug resistant therefore combination of antibiotics is necessary.
· Penicillin derivatives + aminoglycosides
· Third generation Cephalosporin
· Quinolones e.g. ciprofloxacin
· Monbactams e.g. aztreonam
· Carbepenam e.g. imipenam
7. Acinetobacter
· Aminoglycosides
· Cephalosporin
phuiyuen
Name: Ong Fei Fei
Sex: Female
Age: 37 years old
IC NO: S210334X
Location: Clinic T (Outpatient)
Clinical Diagnosis: Urinary Tract Infection (UTI)
Antibiotic Treatment: Nil
Signs and Symptoms: Fever, pain during urination, virginal discharge
Specimen type: Vaginal Discharge
Urinary Tract Infection
Bacteria first travel to the urethra. An infection occurs when the bacteria multiply. When infection is limited only to the urethra, the infection is known as urethritis. If bacteria move to the lower urinary tract (bladder), an infection, called cystitis, results. If the infection is not treated promptly, bacteria may spread to the upper tract and multiply. This infects the kidneys causing infection known as pyelonephritis.
From the clinical diagnosis and symptoms, these are the possible causative agents:
Bacteria
Escherichia coli
Gram negative rod; Facultative anaerobe
Habitat is the human colon (fecal flora); it colonizes the vagina and urethra.
From the urethra it ascends and causes UTI.
Laboratory Diagnosis
Gram stained smear and culture on blood agar
Lactose fermenting colonies (pink) on EMB or MacConkey’s agar.
Green sheen on EMB agar
TSI agar show acid slant and acid butt with gas but no H2S
Motile
Indole +
Methyl red +
Voges- Proskauer reaction -
Citrate utilization -
Serologic tests for antibodies in patient’s serum not useful
Treatment
Ampicillin
Sulfonamides
Cephalosporin
Aminoglycosides
www.google.com > EMB E.coli
http://www.microbelibrary.org/microbelibrary/files/ccImages/Articleimages/Atlas_EMB/E.coli_EMB_fig1.jpg
Gram positive cocci in clusters; Facultative Anaerobe
Inhabits the skin surrounding the genitourinary tract
Community acquired
Laboratory Diagnosis
Coagulase negative
Catalase Positive
Resistant to the antibiotic novobiocin
Treatment
Quinolone (norfloxacin)
Trimethoprim- Sulfamethoxazole
Psuedomonas aeruginosa
Gram negative rods; Obligate Aerobes
Produce water soluble pigments
Transmission via fecal contamination
Laboratory Diagnosis
Gram stain smear
Culture: Non Lactose fermenting colonies on MAC or EMB (colorless)
Blue green pigment on ordinary nutrient agar
TSI show alkaline slant and an alkaline butt
Oxidase +
Pyocyanin +
Fluorescein +
Citrate +
Urease +/-
Indole –
Serological test not useful
Treatment
Highly multidrug resistant
Combination therapy
Anit-pseudomonal penicillin and aminoglycoside are often used
Picture 2: Blue Green Pigment on Ordinary Nutrient agar
www.google.com > Pseudomonas aeruginosa nutrient agar
http://www.bmb.leeds.ac.uk/mbiology/ug/ugteach/icu8/images/uti/pyocyanin.jpg
Enterococcus faecalis
Gram positive cocci in chains; Facultative anaerobe
Habitat is the human colon; urethra and female genital tract can be colonized
Hospital acquired UTI
Laboratory Diagnosis
Gram stained smear and culture
Alpha-, Beta-, or non-hemolytic colonies on blood agar
Catalase negative
Coagulase negative
Grows in 6.5% NaCl and hydrolyzes esculin in the presence of 40% bile
Serological test not useful
Treatment
Combination Therapy
Penicillin or vancomycin plus an aminoglycoide such as gentamicin
Proteus-Providencia-Morganella Family
Community and hosipital acquired
Gram negative rod; Facultative anaerobe
Presence in colon and vigorous motility contribute to their ability to invade the urinary tract
Laboratory Diagnosis
Highly motile and produce a swarming overgrowth on blood agar
Growth on blood agar containing phenylethyl alcohol inhibits swarming, thus allowing isolated colonies of Proteus and other organisms to be obtained.
Produce non-lactose fermenting colonies on MacConkey or EMB agar
Urease producing
TSI agar shows an alkaline slant and acid butt with H2S
Indole +
Treatment
Trimethoprim-sulfamethoxazole
Ampicillin
3rd generation cephalosporin
Enterobacter-Klebsiella-Serrtia Family
Gram negative rod with large polysaccharide capsule; Facultative anaerobe
Transmitted to the urinary tract by ascending spread of fecal flora
Endotoxin causes fever
Laboratory Diagnosis
Gram stained smear and culture
Characteristic mucoid colonies are a consequence of the organism’s abundant polysaccharide capsule
Lactose fermenting colonies on MacConkey’s agar
Voges Prooskauer +
Serratia marcescens: Red-pigmented colonies
Treatment
Cephalosporins alone or with aminoglycosides, but antibiotic sensitivity testing must be done
Picture 3: Serratia marcescens: Red-pigmented colonies
http://www.google.com/ > Serratia Marcescens agar
http://microvet.arizona.edu/Courses/JC-MIC205/S08/Images/pour_Serratia.jpg
Mycoplasma genitalium
Small, wall-less organism
Reproduce by budding, fragmentation or binary fission
Normal flora of the genitourinary tract
Laboratory Diagnosis
Serologic testing
Cold agglutinin titre of 1:128 or higher indicate recent infection
4 fold rise in antibody titre in complement fixation test
Treatment
Resolves spontaneously
Penicillins and cephalosporins are inactive due to lack of cell wall
Macrolide ( Erythromycin/ Tetracycline)
Ureaplasma urealyticum
Small, wall-less organism
Reproduce by budding, fragmentation or binary fission
Normal flora of the genitourinary tract
Laboratory Diagnosis
Serologic testing
Cold agglutinin titre of 1:128 or higher indicate recent infection
4 fold rise in antibody titre in complement fixation test
Urease producing
Treatment
Resolves spontaneously
Penicillins and cephalosporins are inactive due to lack of cell wall
Macrolide ( Erythromycin/ Tetracycline)
Gardnerella vaginalis
Facultative gram variable rod associated with bacterial viginosis
Characterized by a malodorous vaginal discharge and clue cells, which hare vaginal epithelial cells covered with bacteria
Laboratory Diagnosis
“Whiff” test – consists of treating the vavginal discharge with 10% KOH and smelling a pungent, fishy odor is usually positive.
Trichomoniasis can also cause a positive whiff test and must be ruled out before a diagnosis of bacterial vaginosis can be made
Mobiluncus an anaerobic rod is often found in this disease as well
Treatment
Metronidazole
Parasite
Chlamydia trachomatis
Obligate intracellular parasites; Gram negative bacteria, possess rigid cell wall
Habitat is the human genital tract and is transmitted by sexual contact
Laboratory Diagnosis
Cytoplasmic inclusions seen on Giemsa-stained or fluorescent-antibody-stained smear
Glycogen-filled cytoplasmic inclusions can be visualized with iodine
PCR based assay and an ELISA using patient’s urine
Grown in cell cultures treated with cycloheximide, which inhibits host cell but not Chlamydia protein synthesis
Serologic test rarely helpful in diagnosis
Treatment
Tetracycline (Doxycycline)
Macrolide (Azithromycin)
Protozoa
Trichomonas vaginalis
Urogenital protozoan
Pear shape, flagellated trophozoites
No cysts or other forms
Transmitted sexually – attach to wall of vagina and cause inflammation and discharge
Laboratory Diagnosis
Visible in secretions
Wet mount - Motile
Treatment
Metronidazole
Fungi (Yeast)
Candida albicans
Oval yeast with a single bud
Part of normal flora of the female genital tracts
Laboratory Diagnosis
Microscopic examination reveals yeasts and pseudohyphae
Gram positive and can be visualized using calcofluor- white staining
Forms colonies of yeasts on Sabouraud’s agar
Germ tube formation and production of chlamydospores distinguish Candida albicans from other species of Candida
Serologic tests not useful
Treatment
Oral or topical antifungal agents such as nystatin or miconazole
Amphotericin B
Ketoconazole
Virus
Herpes Simplex Virus Type 2
Enveloped virus with icosahedral nucleocapsid and linear double stranded DNA
No virion polymerase
No herpes group specific antigen
Transmitted through sexual contact
Laboratory Diagnosis
Causes cytopathic effect in cell culture
Identify by antibody neutralization or fluorescent- antibody test
Rise in antibody titre can be used to diagnose a primary infection
Treatment
Acyclovir
Picture 4: Cytopathic Effect
http://www.google.com/ >cytopathic effect
http://pathmicro.med.sc.edu/lecture/images/multinuc.jpg
Identification of Bacteria
Identification of other Causative Agents
References
Loh Mun Jo-anne
TG02
0503324F
MMIC Case Study 4 Post 2
Patient Name: Tong Wei Hong
Sex: Male
Age: 68 years old
Complaints: Fever, chills, excessive phlegm, breathing problems
Diagnosis: Bronchitis
Bronchitis can also be caused by viruses such as Influenza virus, adenoviruses and rhinoviruses. The bacteria that have been shortlisted are:
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Haemophilus influenzae
- Moraxella catarrhalis
- Bordetella pertussis
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
Pictures to help for diagnosis of bacteria:
Haemophilus influenzae on blood agarPicture taken from: http://en.wikipedia.org/ > search > Haemophilus Influenzae
Gram stain of Haemophilus influenzaePicture taken from: http://www.textbookofbacteriology.net > search> Haemophilus Influenzae
Klebsiella pneumoniae on MacConkey’s agar (Pink)
Bile solubility test for Streptococcus pneumoniae (Right)Picture taken from http://www.mc.maricopa.edu/~johnson/labtools/Dbiochem/opto.html
Optochin test for Streptococcus pneumoniae (Left)Picture taken from http://www.mc.maricopa.edu/~johnson/labtools/Dbiochem/opto.html
Martin Ng TG02
Blog 2
MMIC: Case 2
Name: Kwan Siew Yan
Sex: Female
I/C No: S000123X
HRN: OPD001
Age:29 years
Ward/Clinic: Clinic X
Clinical Diagnosis
Complaints: Diarrhea
Diagnosis: Enterocolitis
Antibotic Treatment (if any): Nil
Enterocolitis
Enterocolitis is the inflammation of the large and small intestines. The most common symptom of enterocolitis is diarrhea.
Causative Agents
The most common way a person can get enterocolitis is by infection. Infection includes Bacteria, Virus and Parasites. Below are the identified causative agents that can cause enterocolitis.
Bacteria
Campylobacter jejuni
Salmonella species
Shigella species
Escherichia coli
Vibrio cholerae
Vibrio parahaemolyticus
Clostridium perfringens
Clostridium difficile
Virus
Rotavirus
Norovirus
Parasites
Giardia lamblia/ Giardia intestinalis
Biochemical Tests
Since this PBL is on bacterial pathology I’ll only be discussing the biochemical properties of the microorganisms from the bacteria group.
Campylobacter jejuni
Domestic animals such as cattle, chickens and dogs serve as a source of the organisms for humans. Food and water contamination with infected animal feces is the major source of human infection.
· Laboratory Diagnosis
o Gram Negative Rod
o Motile
o Non-lactose fermenter
o Microaerophilic
o Incubation at 42°c
o Oxidase positive
o Catalase positive
o Hippurate positive
o TSI shows no H2S production
o Urease negative
o Culture on Charcoal based selective medium
o Methylene blue stain of a fecal sample
· Antibiotic Treatment
o Erythromycin
o Ciprofloxacin
Salmonella species
Humans and animals serve as reservoirs for the bacteria.
The ingestion of food and water contaminated by human and animal waste is the main mode of transmission.
· Laboratory Diagnosis
o Gram Negative Rods
o Non-Lactose Fermenting colonies on MacConkey’s agar or EMB agar
o Motile
o Facultative Anaerobe
o TSI shows alkaline slunt but acid butt with both gas and H2S produced
o Catalase positive
o Oxidase negative
o Urease negative
o Indole test negative
o Methyl Red Positive
o Voges-proskauer negative
o Citrate positive
o Lysine decarboxylase positive
o Ornithine decarboxylase positive
o Slide agglutination Test
o Commonly grown on Xylose Lysine Deoxycholate (XLD) agar
o Serological test such as widal test can be used
o Methylene Blue stain of fecal sample
· Antibiotic Treatment
o Antibiotic treatment is usually not prescribed, as salmonella is a self limiting disease that resolves without treatment
http://www.bact.wisc.edu> the microbial world> salmonellaEnterocolitis caused by Shigella species is usually called bacillary dysentery. Shigellaosis is a human only disease and has no animal reservoir. Transmission is most common via the fecal-oral route
· Laboratory Diagnosis
o Gram Negative Rods
o Non-Lactose Fermenting colonies formed on MacConkey’s and EMB agar
o Non-motile
o Facultative Anaerobe
o Urease negative
o Lysine decarboxylase negative
o Indole negative
o Methyl red positive
o Voges-proskauer negative
o Citrate negative
o TSI shows alkaline slant and an acid butt, with no gas and no H2S produced
o Methylene Blue stain of fecal sample
o Commonly grown on Xylose Lysine Deoxycholate (XLD) agar
· Antibiotic Treatment
o In mild cases no antibiotics are prescribed, only fluid and electrolyte replacements
o In severe cases ciprofloxacin and Trimethoprim-sulfamethoxazole can be presribed
Escherichia coli
Escherichia Coli is frequently associated with traveler’s diarrhea. The reservoir of E.Coli includes both humans and animals. The source of the E.Coli that causes traveler’s diarrhea is by ingestion of food or water contaminated with human feces.
· Laboratory Diagnosis
o Gram Negative Rod
o Lactose Fermenting
o Motile
o Facultative anaerobe
o Indole positive
o Methyl-red positive
o Voges-proskauer negative
o Citrate negative
o Culture on blood agar plate followed by a differential medium either EMB or MacConkey’s agar
o Form lactose fermenting colonies on MacConkey’s agar
o A Characteristic green sheen is observed on EMB agar
o TSI shows acid slant and butt with gas produced and no H2S
o Methylene Blue on fecal smear to observe for neutrophils
· Antibiotic Treatment
o Trimethoprim-sulfamethoxazole
o Loperamide (Imodium)
www.yahoo.com> escherichia coli on blood agar> http://www.visualsunlimited.com/browse/vu303/vu303820.html
www.yahoo.com> escherichia coli on MacConkey's agar> http://www.visualsunlimited.com/browse/vu416/vu416843.html
Vibrio cholerae
Vibrio Cholerae is transmitted by fecal contamination of water and food, primarily from human sources.
· Laboratory Diagnosis
o Gram Negative Rod
o Motile
o Non lactose fermenting colonies form on MacConkey’s agar
o Facultative anaerobe
o Urease negative
o Oxidase Positive
o Lysine decarboxylase positive
o Ornithine decarboxylase positive
o Methyl Red positive/negative (depending on strain)
o Voges-proskauer positive/negative (depending on strain)
o TSI shows acid slant and acid butt without gas or H2S
o A retrospective diagnosis can be made serologically by detecting a rise in antibody titer in acute and convalescent-phase sera.
· Antibiotic Treatment
o Antibiotics are not necessary, as treatment usually consists of replacement of water and electrolytes.
o Antibiotics such as tetracyclines shorten the duration of symptoms and reduce the time of excretion of the organisms.
Vibrio parahaemolyticus
· Laboratory Diagnosis
o Gram Negative Rod
o Motile
o Beta-hemolysis colonies observed when cultured on blood agar plates
o Non-lactose fermenting colonies form on MacConkey’s agar
o Facultative anaerobe
o Urease negative
o Oxidase Positive
o Lysine decarboxylase positive
o Ornithine decarboxylase positive
o Methyl red negative
o Voges-proskauer negative
o TSI shows acid slant and acid butt without gas or H2S
o A retrospective diagnosis can be made serologically by detecting a rise in antibody titer in acute and convalescent-phase sera.
o Differentiated from V.Cholerae on the basis of growth in Sodium Chloride V.Parahaemolyticus grows in 8% sodium chloride while V.Cholerae does not
· Antibiotic Treatment
o Antibiotics are not necessary, as treatment usually consists of replacement of water and electrolytes.
o Antibiotics such as tetracyclines shorten the duration of symptoms and reduce the time of excretion of the organisms.
Clostridium perfringens
Spores located in soil can contaminate food. The heat resistant spores survive cooking and germinate. The organisms grow to large numbers in reheated food, especially meat dishes.
· Laboratory Diagnosis
o Gram Positive Rod
o Endospore-forming
o Anaerobic
o Spore staining positive ( Bartholomew and Mittwer)
o Nagler test
· Antibiotic Treatment
o Self-limiting disease
o Symptomatic treatment is given, no antimicrobial drugs are administered
Clostridim difficile
Normal flora in the intestines, that can become opportunistic pathogens in patients treated with broad-spectrum antibiotics such as penicillin and cephalosporin. The most common nosocomial cause of diarrhea.
· Laboratory Diagnosis
o Gram positive Rod
o Motile
o Anaerobic
o Endospore forming
o Spore staining positive (Bartholomew and Mittwer’s)
o ELISA testing
o Cytotoxicity testing
· Antibiotic Treatment
o Causative antibiotic should be withdrawn
o Metronidazole
o Vancomycin
Identification of Microorganism
Culture on Blood agar in anaerobic conditions
Microorganisms that grow in anaerobic conditions: Salmonella species, Shigella species, , Escherichia coli, Vibrio cholerae, Vibrio parahaemolyticus, Clostridium perfringens, Clostridium difficile
Microorganisms that do not grow in anaerobic conditions: Campylobacter jejuni,(microaerophilic)
Anaerobic Microorganisms
Perform Gram stain and observe under microscope: to differentiate gram positive and gram negative bacteria
Gram Negative Microorganisms: Salmonella species, Shigella species, Escherichia coli, Vibrio cholerae, Vibrio parahaemolyticus
Gram Positive Microorganisms: Clostridium perfringens, Clostridium difficile
Gram Negative Microorganism
Perform Wet mount: To differentiate motile and non-motile organisms
Motile: Salmonella species, Escherichia coli, Vibrio cholerae
Vibrio parahaemolyticus
Non-Motile: Shigella species
Motile Microrganisms
Culture on MacConkey's/ Eosin-Methylene Blue (EMB) agar:
To differentiate between lactose and non-lactose fermenting microorganisms
Lactose Fermenters: Escherichia coli
Non-Lactose Fermenters: Salmonella species, Vibrio cholerae
Vibrio parahaemolyticus
Non-Lactose Fermenting Microorganisms
Perform Oxidase Test: To differentiate between microorganisms containing the enzyme cytochrome oxidase and microorganisms that do not contain the enzyme.
Oxidase Positive: Vibrio cholerae, Vibrio parahaemolyticus
Oxidase Negative: Salmonella species
To differentiate between Vibrio cholerae and Vibrio parahaemolyticus, culture the microorganism into a 8% sodium choloride broth. Vibrio Parahaemolyticus can grow in 8% sodium chloride but Vibrio Cholerae cannot.
Gram Positive Microorganisms
Since the patient is not on any antibiotic treatment, we can rule out Clostridium difficile, as it is a nosocomial cause of diarrhea. Therefore if the microorganism is observed to be gram positive, a spore stain can be done to confirm that it is Clostridium perfringen
Randall
TG02
0503272G
References:
www.medicinenet.com>search> Diarrhea
www.wrongdiagnosis.com > search > Enterocolitis
http://www.cfsan.fda.gov/~mow/chap4.html
Levinson, W. (2006). Review of Medical Microbiology and Immunology. San Francisco,California: Lange Medical Books/ McGraw-Hill Medical Publishing Division
Bauman, R,W. (2004). Microbiology. San Francisco, California: Pearson Education inc/
Pearson Benjamin Cummings
Saturday, December 8, 2007
Medical Microbiology [Case 1--Blog 2]
Sex : Female
Age: 27 years old
Specimen: Urine [specimen 1]
Clinical Diagnosis
Complaints: Fever, Chills, Dysuria
Diagnosis: Urinary Tract Infection (UTI)
Interpretation of clinical diagnosis (complaints)
Fever [1]
Fever a common manifestation of infection and inflammation [such as influenza, urinary tract infection, bowel disease]. Fever can be caused by many bacterial products, most notably, endotoxin of gram-negative bacteria. Endotoxin would result in the release of endogenus pyrogen, which derived from monocytes and macrophages. Other substances that can cause fever are interlukin 1 and interferons.
Chills [2]
The word ‘chill’ refers to an episode of shivering, accompanied by paleness and feeling cold. Chills may occur at the beginning of an infection, and is usually associated with fever. Chills are caused by rapid muscle contraction and relaxation, and are the body's way of generating heat when the body feels that it is cold. Causes of chills includes exposure to cold environment and virus and bacterial infections [such as meningitis, urinary tract infection, pneumonia]
Dysuria [3]
Dysuria is a condition whereby there is discomfort/pain during urination. Causes of dysuria includes urinary tract infection, cystitis, prostatitis and urethritis
Although UTIs occur in both men and women, women tend to suffer more from it because of the anatomical difference. Women's urethra tube is shorter than men's, and the opening is just a short distance away from the vaginal tract and the rectal openings. Because of this, there is a higher risk of bacteria from these adjacent areas to scuttle up the tube into the bladder. [5]
Microorganism that causes urinary tract infection[4,6]
1) Bacteria [6]
E. coli http:///www.yahoo.com > Image> Search > Escherichia colib) Staphylococcus saprophyticus [About 5% of community acquired UTI and 1% of hospital acquired UTI are caused by S. saprophyticus]
S. saprophyticus http:///www.yahoo.com > Image> Search > Staphylococcus saprophyticusc) Proteus mirabilis [About 3% of community acquired UTI and 10% of hospital acquired UTI are caused by P. mirabilis]
P. mirabilis http:///www.yahoo.com > Image> Search > Proteus mirabilisd) Pseudomonas aeruginosa [About 1% of community acquired UTI and 5% of hospital acquired UTI are caused by P. aerginosa]
P. aeruginosa http:///www.yahoo.com > Image> Search > Pseudomonas aerugionsae) Enterobacter faecalis [About 5% of community acquired UTI and 8% of hospital acquired UTI are caused by E. faecalis]
E. faecalis http:///www.yahoo.com > Image> Search> Enterobacter faecalis f) Staphylococcus epidermidis [About 2% of community acquired UTI and 3% of hospital acquired UTI are caused by S. epidermidis]
S. epidermidis http:///www.yahoo.com > Image> Search> Staphylococcus epidermidis g) Other coliforms [About 5% of community acquired UTI and 25% of hospital acquired UTI are caused by other Enterobacteriaceae such as Klebsiella pneumonia, Serratia marcescens]
K. pneumonia http:///www.yahoo.com > Image> Search> Klebsiella pneumonia 
S. marcescen http:///www.yahoo.com > Image> Search> Serrtia marcescenIn addition, Acinetobacter sp. causes nosocomial UTI. Other less common microorganism that causes UTI include Mycobacterium tuberculosis. [7]
2) Viruses [6]
a) Adenovirus
b) Human polyoma virus
a) Trichomonas vaginalis
b) Schistoma haematobium
In this PBL, only bacteria is being dealt with thus viruses, parasites and fungus are eliminated.
1) Escherichia coli [4,6,8]
a) Facultative Anaerobe, gram negative bacilli
b) Confirmatory test bi)Microscopy and gram staining shows motile gram-negative rod
bii) Cultures shows dark pink to red, dry flat lactose-fermenting colonies on MacConkey agar, and blue black colonies w/wo green metallic sheen on eosin methylene blue (EMB) agar
biii) Biochemical test to be done/results for E. coli biii[a]) Citrate, H2S, Urea and Voges-Proskauer (VP) negative
biii[b]) Indole, Methyl-red positive
biii[c]) Ferments both glucose and lactose with gas and no H2S
Escherichia coli is the most common cause of UTI. It is a normal flora in the intestine and colon that enters and invades the urethra causing an infection.
2) Staphylococcus saprophyticus [4,6,8]
a) Facultative Anaerobe, gram positive cocci
b) Confirmatory test
bi) Microscopy and gram staining shows gram-positive cocci
bii) Absence of hemolysis on blood agar
biii)Biochemical test to be done/results for S. saprophyticus
biii[a]) Catalase positive
biii[b]) Oxidase, Coagulase, Mannitol fermentation negative
bv) Resistant: Bacitracin, Novobiocin
a) Facultative Anaerobe, motile, non-spore fermenting gram-negative rod
b) Confirmatory test
bi) Microscopy and gram staining shows motile gram-negative rod
bii) Pale colonies on MacConkey’s agar and colourless/light purple colonies on EMB agar
biii) Biochemical test to be done/results for P. mirabilis
biii[a]) Oxidase negative
biii[b]) H2S, Urea and Indole positive
biii[c]) Voges-Proskauer (VP) negative/positive biii[d]) Non-lactose fermenting
4) Pseudomonas aeruginosa [4,6,8]
a) Facultative Anaerobe, gram-negative rod
b) Confirmatory test
bi) Microscopy and gram staining shows motile gram-negative rod
bii) Flat and green pigmentation on MacConkey’s agar and , colourless/light purple colonies on EMB agar
biii) Biochemical test to be done/results for P. aerginosa
biii[a]) Citrate, Oxidase positive
biii[b]) Non-lactose fermenting
biii[c]) Indole negative
biv) Treatment: Ciprofloacin, Imipenam, Carbenicillin, Ticarcillin
Pseudomonas aeruginosa is the most frequent colonizers of medical catheters. Since patient is not using such devices,Pseudomonas aeruginosa may not be the microorganism isolated
a) Facultative Anaerobe, non-motile, gram-negative rod
b) Confirmatory test
bi) Microscopy and gram staining shows non-motile gram-negative rod
bii) Dark pink to red Mucoid colonies observed on MacConkey agar and blue black colonies w/wo green metallic sheen on eosin methylene blue (EMB) agar
biii)Biochemical test to be done/ results for K. pneumonia
biii[a]) Ferments both lactose and glucose with gas and no H2S
biii[b]) Urease, Voges-Proskauer, Citrate positive
biii[c]) Indole, methyl-red negative
The chances of identifying Klebsiella pneumonia increases with the length of hospital stay. Since the patient is an out-patient, in this case, the bacteria would most probably not be the cause of UTI.
a) Obligate Anaerobe, Gram-positive cocci
b) Confirmatory test
bi) Microscopy and gram staining shows cluster of gram-positive cocci
bii) Non-hemolytic colonies observed on sheep’s blood agar
biii) Biochemical test to be done/ results for S. epidermidis
biii[a]) Catalase, urease positive
biii[b]) Coagulase, mannitol fermentation negative
Staphylococcus epidermidis found in hospitalized patient older than 50 years of age with urinary tract complication.
7) Enterococcus faecalis [4,6,8]
a) Facultative Anaerobe, Non-motile, gram-positive Streptococci
b) Confirmatory test
bi) Microscopy and gram staining shows a gram-positive cocci
bii) Alpha, beta or no hemolysis on blood agar
biii) Biochemical test to be done/ results for E. faecalis
biii[a]) Bile esculin, 6.5% NaCl positive
biii[b]) Catalase negative
Enterococcus faecalis identification is usually associated with the usage of catheters. It is more commonly found in hospitalized patient. Since the patient is not required for any observation in the hospital [meaning that she is an out-patient], Enterococcus faecalis may not be the bacteria that is to be identified.
a) Facultative Anaerobe, motile, Gram negative bacilli
b) Confirmatory test
bi) Microscopy and gram staining shows a gram-negative bacilli
bii) Slight pink colonies on MacConkey Agar, colourless/light purple colonies on EMB agar
biii) Biochemical test to be done/ results for S. marcescens
biii[a]) Ferments both glucose and lactose and no H2S
biii[b]) Indole, methyl-red negative
biii[c]) Voges-Proskauer, Citrate positive
biii[d]) DNAse positive
The identification of Serratia marcescens increases with the length of hospital stay. In this case, since the patient is an out-patient, the bacteria would most probably not be the cause of UTI.
Mycobacterium tuberculosis is a rare bacteria that is being isolated in UTI cases, thus eliminated
Acinetobacter sp. is involved in hospital-acquired infection and commonly infect immunocomprised individuals.
Though either Escherichia coli or Staphylococcus saprophyticus may be the most probable microorganism isolated in this case, the microorganism above would be identified by a series of test
-E.coli
-S. saprophyticus
-P. mirabilis
-P. aeruginosa
-E. faecelis
-S. marcescens
-K. pneumonia
Obligate Anaerobe
-S. epidermis
1) Culture on blood agar, in aerobic conditions
Organisms that can grow on blood agar in aerobic conditions:
-E.coli
-S. saprophyticus
-P. mirabilis
-P. aeruginosa
-E. faecelis
-S. marcescen
-K. pneumonia
Organisms that cannot grow on blood agar in aerobic conditions:
-S. epidermis
2) Perform Gram Stain
Gram negative organisms: Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Klebsiella pneumonia, Serratia marcescens
Gram positive organisms: Enterococcus faecalis, Staphylococcus saprophyticus
3) Gram negative organisms
3a) Perform Wet Mount
Motile organisms: Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Serratia marcescens
Non-motile organisms: Klebsiella pneumonia
3b) Culture on MacConkey
Microorganisms that form lactose fermenting colonies on MacConkey: Escherichia coli
E. coli(left) and P. mirabilis (right) on MacConkey agar http://www.yahoo.com/ > Image> Search> E. coli
Microorganisms that do not form lactose fermenting colonies on MacConkey: Proteus mirabilis,Pseudomonas aeruginosa, Serratia marcescens
3c) Oxidase Test
Oxidase positive organisms: Pseudomonas aeruginosa
Oxidase negative organisms: Proteus mirabilis, Serratia marcescens
3d) Perform TSI
H2S producing microorganisms: Proteus mirabilis
Non-H2S producing microorganisms: Serratia marcescens
4) Gram positive organisms
4a) Catalase test
Catalase positive organisms: Staphylococcus saprophyticus
Catalase negative organisms: Enterococcus faecalis
The image below show how the microorganism is being identified [flowchart]
References[1] Coico, R., Sunshine, G. and Benjamini, E. (2003) Immunology: A Short Course. John Wiley & Sons, Inc., Hoboken, New Jersey.
[2] Medical Encyclopedia. (2007). Chills. Retrieved 31st November, 2007 from
http://www.nlm.nih.gov/ Search NLM Web Site> Chills
[3] Medicine Net. (2007). Dysuria. Retrieved 31st November, 2007 from
http://www.medterms.com/> MedTerms Dictionary> Dysuria> Medical Dictionary> Dysuria
[4] Spicer W. J. (2000). Clinical Bacteriology, Mycology and Parasitology: An illustrated colour text. Churchchill Livingstone
[5] Juicing for Health.com (20007). Urinary Tract Infection. Retrieved 31st November, 2007
http://www.juicing-for-health.com/> Google Search> www.juicing-for-health.com >Urinary Tract Infections
[6] Elliott, T., Hastings, M. and Desselberger, U. (1997). Lecture Notes on Medical Microbiology. Blackwell Science Ltd.
[7] Phage Therapy Center. (2005). Chronic and Acute Urinary Tract Infection. Retrieved 31st
http://www.phagetherapycenter.com/ >>Clinics>What we treat> Chronic and Acute Urinary Tract Infections (UTI) and Cystitis
[8] Mahon C. R. and Manuselis G, Jr (1995). Textbook of Diagnostic Microbiology. W.B. Saunders Company
Eugene Wong
TG02
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