Sunday, December 09, 2007

Medical Microbiology- dPBL- Case 1 to 6-
Microorganisms Identifications

Case 1 (Suat Fang, 0503328G)

Particulars of patient

Name: Khong Fay Seah Sex: Female
HRN: OPD 009 IC No. : S00055X
Date of birth : 1/12/80 Age : 27 years
Ward/Clinic : Clinic M Bed No : -------

Clinical diagnosis

: Fever, chills and dysuria
Diagnosis: Urinary Tract Infection
Specimen: Urine

Suspected Microorganisms Identifications


Case 2
(Sharifah, 0503189C)
Particulars of patient

: Kwan Siew Yan Sex : Female
HRN : OPD001 IC No. : S000123X
Date of birth : 16/6/78 Age : 23 years
Ward/Clinic : Clinic X Bed No : -------

Clinical diagnosis

Complaints: Diarrhea
Diagnosis: Enterocolitis
Specimen: Stool

Suspected Microorganisms Identifications

References>wiki> Salmonella>wiki> Escherichia_coli>wiki> Campylobacter>wiki> Vibrio>wiki> Yersinia
Levinson, W. (2004). Review of Medical Microbiology and Immunology. 9th edition. McGraw-Hill.

Case 3 (Royston, 0503289A)
Particulars of patient

Name : Maisy Hong Sex : Female
HRN : 006789T IC No. : S000111Y
Date of birth : 1/12/40 Age : 67 years
Ward/Clinic : AB2 Bed No : -------
(Patient is in-patient, thus more susceptible to nosocomial infection)

Clinical diagnosis

Complaints: Fever, chills, bladder distension (stretching); on indwelling catheter
Diagnosis: Urinary Tract Infection
Specimen: Urine

Suspected Microorganisms Identifications


Case 4 (Najib, 0503217B), (Charmaine, 0503186I)

Particulars of patient

Name : Tong Wei Hong Sex : Male
HRN : OPD 004 IC No. : S000444X
Date of birth : 1/12/39 Age : 68 years
Ward/Clinic : Clinic M Bed No : -------

Clinical diagnosis

Complaints: Fever, chills, excessive phlegm, breathing problems
Diagnosis: Bronchitis
Specimen: Sputum

Suspected Microorganisms Identifications


Case 5 (Jeremy, 0503168G)
Particulars of patient

Name : Wong Fei Hong Sex : Male
HRN : OPD 0010 IC No. : S210444X
Date of birth : 1/12/70 Age : 37 years
Ward/Clinic : Clinic S Bed No : -------

Clinical diagnosis

Complaints: Fever, swelling around operation wound
Diagnosis: Wound infection
Specimen: Wound swab

Suspected Microorganisms

Warren Levinson. Review of medical microbiology and immunology (9thed).

Case 6
(Natalie, 0503275J)
Particulars of patient

Name : Ong Fei Fei Sex : Female
HRN : OPD 0013 IC No. : S210334X
Date of birth: 1/12/70 Age: 37 years
Ward/Clinic: Clinic T Bed No: -------

Clinical diagnosis

Complaints: Fever, pain during urination, virginal discharge
Diagnosis: UTI
Specimen: Virginal Discharge

Suspected Microorganisms Identifications

Escherichia coli (E.coli)

Test: Gram-Stain
Biochemical Tests: Lactose fermentation test, Indole test, Lysine test
Treatment: Antibiotics which may be used to treat E. coli infection include (but are not limited to) amoxicillin as well as other semi-synthetic penicillins, many cephalosporins, carbapenems, aztreonam, trimethoprim-sulfamethoxazole, ciprofloxacin, nitrofurantoin and the aminoglycosides


Test: Gram-Stain/DNA-based test
Identification: Chlamydia species are readily identified and distinguished from other chlamydial species using DNA-based tests. Most strains of C. trachomatis are recognized by monoclonal antibodies (mAbs) to epitopes in the VS4 region of MOMP
Treatment: It may be treated with any of several antibiotics such as azithromycin, erythromycin or doxycycline/tetracycline.

Klebsiella pneumoniae

Test: Gram Stain
Biochemical Tests: Indole test, citrate test, urease test, motility test, malonate test, Phenylalanine slant test
Treatment: carbenicillin, ampicillin, quinolones, and ceftazidime

Pseudomonas aeruginosa

Test: Gram Stain
Biochemical Tests: Triple Ion Sugar (TSI), Oxidase test, Indole test, Citrate test
Treatment: Aminoglycosides, Quinolones, Cephalosporins, Ureidopenicillins

Followings are the additional microorganisms of other causative agents of UTI:

Candida albicans (yeast)
Candida albicans is a diploid fungus (a form of yeast), which is capable of mating but not of meiosis, and a causal agent of opportunistic oral and genital infections in humans. C. albicans is among the gut flora, the many organisms which live in the human mouth and gastrointestinal tract. Under normal circumstances, C. albicans lives in 80% of the human population with no harmful effects, although overgrowth results in candidiasis.

Test: Calcofluor- white Gram Stain followed by direct microscopy, Culturing
Treatment: Amphotericin B, Ketoconazole

Trichomonas vaginalis (protozoan)
Trichomonas vaginalis, an anaerobic, parasitic flagellated protozoan, is the causative agent of trichomoniasis, and is the most common pathogenic protozoan infection of humans in industrialized countries.

Test: Pap smear, Culturing
Treatment: Metronidazole/ Tinidazole

Gardnerella vaginalis
Gardnerella is a genus of gram-variable bacteria of which Gardnerella vaginalis is the only species. Gardnerella vaginalis can cause bacterial vaginosis in some women.

G. vaginalis is an aerobic, non-motile, slow growing coccobacillus. It grows as small, circular, convex, gray colonies on chocolate agar; it will also grow on HBT agar. A selective medium for G. vaginalis is colistin-oxolinic acid blood agar

Test: Microscopy of Clue cells, Amine test
Treatment: metronidazole

Illustrations for the types of Biochemical tests used and their results

1. Citrate Utilisation Test: The citrate tube is used to determine if an organism is capable of utilizing citrate.

2. Urease test: The urea agar slant allows detection of urease activity of both rapidly urease pos organisms as well as enterobacteriaceae family.

3. Motility Test: Used to detect the motility of organisms in a semi-solid gelatin medium.

4. Indole Test: Can be detected by its ability to combine with certain aldehyde to form a coloured compound.

5. Phenylalanine Slant Test: Determine the ability of an organism to deaminate phenylalanine to phenylpyruvic acid enzymatically with resulting acidity.

6. Malonate Broth Test: Determine the ability of an organism to use sodium molante as the sole carbon with resulting alkanity and it is used to differentiate enterobact family.

Triple Sugar Iron (TSI) Test: Used to differentiate enterics based on the ability to reduce sulfur and ferment carbohydrates.

All pictures extracted from: >kkiser>biochem

Laboratory Investigations (Bacteria Identification)

The specimen (virginal discharge) will be cultured so as to isolate the microorganisms short listed above. Next, a series of biochemical tests will be carried out and incubated for a day before verifying the results for the final identification of the specific microorganism. Lastly, antibiotic susceptibility testing is performed to achieve a cure for the infection.

1) Gram-staining followed by microscopy examination (of unknown bacteria)
i.e. Gram Negative: E. Coli, P. Aeruginosa, and Enterobacter-Klebsiella-Serrtia Family

2) Culturing of bacteria
MacConkey’s Agar: To check for Lactose Fermenters
Positive: E.Coli and Enterobacter-Klebsiella-Serrtia Family
Negative: P. Aeruginosa
Nutrient Agar: To observe for P. Aeruginosa
Eosin- methylene blue Agar: E. Coli

3) For gram-neg bacteria, biochemical tests are carried out (i.e. different tests + F12). F12 is of antimicrobial agents such as penicillin, it tells us the sensitiveness and susceptibility of the bacteria towards different types of antibodies.

Example of Biochemical Tests:

  1. Simmons citrate

  2. Urease

  3. Motility (& OF) test

  4. Indole

  5. Phenylalanine slant

  6. Malonate test

References>wiki>Escherichia_coli>wiki>Chlamydia_trachomatis>wiki>Pseudomonas_aeruginosa>wiki>Klebsiella_pneumoniae>wiki>Trichomonas_vaginalis>wiki>Gardnerella>wiki>Candida_albicans>Kudiseases>pubs>utiadult/>techinfo>proc_bacto_biochem>Gardnerella Vaginalis>Symptoms

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