MMIC laboratory diagnosis

Patient particulars:

Name: Wong Fei Hong

Sex: Male

Age: 37 years

Complaints: fever sewlling around operation wound

Diagnosis: wound infection

List of possible organism	Test required	Expected results	treatment
Corynebacterium diphtheriae	1) Gram stain 2) Methylene blue 3) Culture (Loffler medium followed by tellurite plate) 4) PCR assay	1) gram-positive, highly pleomorphic organisms with no particular arrangement 2) Demostrate the presence of metachromatic granules 3) If C. diphtheriae is presence, tellurium in the medium will be reduced to elemental tellurium by the organism, showing a grap-black color of tellurium in the colony 4) Identify the toxin gene presence in the organism isolated form the patient	Antitoxin penicillinG Erythromycin
Pseudomonas aeruginosa	1) Gram stain 2) Culture (EMB or MacConkey’s agar) 3) TSI medium 4) Biochemical test (catalase, oxidase, nitrase, lipase)	1) Gram negative rod with no particular arrangement 2) Culture of patient specimen on MacConkey’s agar produce colourless colonies as the organism does not ferment lactose 3) Alkaline slant and an alkaline butt as the organism does not ferment lactose 4) Catalase, Oxidase, Nitrase and Lipase positive	Antipseudomonal penicillin Aminoglycoside
staphylococcuss aureus	1) Gram stain 2) culture (Mannitol salt agar) 3) coagulase test 4)biochemical test (catalase test)	1) Gram positive cocci in grapelike clusters 2) Golden yellow colonies 3) coagulase positive 4)catalase positive	Mupirocin Beta-lactamose resistant penicillins such as nafcillin, cloxacillin, cephalosporins or vancomycin
Proteus mirabilis	1) Gram stain 2) culture (EMB or MacConkey’s agar)3) TSI agar 4) biochemical test (indole test	1) Gram negative rod 2) Non-lactose fermenting colonies on EMB or MacConkey’s agar 3) alkaline slant and acid butt. 4) indole negative	Ampicillin Tetracycline
group A streptococcus bacterium	1) Gram stain 2) Culture (blood culture) 3) Biochemical test (indole test)	1) Gram positive cocci in chain 2) Beta hemolytic colonies 3) Indole test negative	Penicillin G
Bacteroides fragilis	1) Gram stain 2) Anaerobic Culture blood agar plates containing kanamycin and vaomyycin 3) TSI agar	1) Gram negative rod 2) Colonies should be able to grow on the BAP containing the anitbiotic 3) Red stunt yellow butt	Penicillin G Cephalosporins Aminoglycosises Metronidazole
Pasteurella Multocida	1) Gram stain 2) Culture (blood agr or chocolate agar) 3) oxidase test 4) catalase test	1) Encapsulated gram negative rod 2) positive 3) positive 4)positive	Penicillin G
Aeromonas Hydrophila	1) Gram stain 2) Culture (Sheep blood agar with ampicillin) 3) catalse test 4) oxidase test	1) Gram negative rod 2) Aeromonas Hydrophila is able to grow on the agar plate while the ampicillin will inhibit the grow of other competing organism 3) positive 4) positive	chloramphenicol
Clostridium perfringens	1) Gram stain 2) Culture ( blood agar)	1) Large gram postitive rods 2) Exhibit a double zone of hemolysis	Penicillin G

Types of wound infection and their causative agents:

-Skin infection at the site of preexisting skin leison: Corynebacterium diphtheriae

-Burn wound infection: Pseudomonas aeruginosa

-Wound infection in diabetic patients: Staphylococcuss aureus

-Surgical wound infection: Staphylococcuss aureus

-Abcess infection of brain, lung or abdominal: Bacteroides fragilis

-Wound infection caused by cats or dog bite: Pasteurella multocida

-Traumatic open wound infection: Aeromonas hydrophila

-Gas gangrene wound infection: Clostridium perfringens

Reference:

1) Levinson, W. (2006). Review Of Medical Microbiology and Immunology. (9th ed.). US: The McGraw-Hill Company

Wing Fat

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