Sunday, December 2, 2007

MMIC Blog Post 1

Case One

Patient: Khong Fay Seah, Female, 27, outpatient

Complaints: Fever, chills, dysuria

Diagnosis: Urinary Tract Infection (UTI)

The urinary tract includes the kidneys, ureters, bladder and urethra. As compared to men and children, women are of greater risk in acquiring urinary tract infection due to the shorter urethra and close proximity between the anus, urethra and vagina.

UTI is a common infection that occurs when bacteria enter the opening of the urethra and multiply in the urinary tract. Possible source of infections include the transfer of natural flora in fasces from the anus to urethra due to poor hygiene practices and the travelling of enteric tract organism (e.g. E.coli) to the urethra colonization. UTI can also be sexually transmitted.

There are two classifications of UTI, mainly lower and upper. While lower UTI involves the bladder and urethra, upper UTI implicates the ureters and kidneys. The common symptoms of lower UTI includes back pain, blood in the urine (hematuria), cloudy urine, fever, polyuria, general discomfort (malaise) and painful urination (dysuria). As for upper UTI, it involves high fever, shaking chills, nausea and may or may not include symptoms of lower UTI.

Common Causative Organisms

Supporting reason(s)



Escherichia Coli

(Gram-negative bacillus)

Occurs in more than 70% of UTI cases

Present in human colon as nature flora and is present in feces

-Blood Agar

-EMB Agar (Green sheen colonies)

-MacConkey’s Agar (Pink colonies)

Staphylococcus saprophyticus and aureus

(Gram-positive cocci)

Causes community-acquired urinary tract infection in young woman

-Mannitol-salt Agar (Yellowish-gold colonies)

Enterococcus faecalis

(Gram-positive cocci)

Present in human colon as nature flora and is present in feces

Largely involved in lower UTI

-EMB Agar (Coloured colonies)

MacConkey’s Agar (Coloured colonies)

Proteus mirabilis

(Gram-negative bacillus)

Vigorously motile contributing to their ability to invade urinary tract

Present as normal flora in colon

-Phenylethyl alcohol containing blood agar (inhibit swarming)

-EMB (Colourless colonies)

-MacConkey’s agar

Klebsiella pneumoniae

(Gram negative bacillus)

Involves in nosocomial infections especially UTI

Common causative agent of patients with catheter

-EMB Agar (Coloured colonies)

MacConkey’s Agar (Coloured colonies)

Enterobacter spp.

(Gram-negative bacillus).

Frequently found in large intestine

EMB Agar (Coloured colonies)

-MacConkey’s Agar (Coloured colonies)

Pseudomonas aeruginosa

(Gram-negative bacillus)

Opportunistic pathogen

10% of human carry it as nature flora of colon

EMB Agar (Colourless colonies)

MacConkey’s Agar


Candida albicans

Frequently infects people who have an impaired immune system or a bladder catheter in place.

Sabouraud’s Agar


Herpes Simplex Virus Type 2 (HSV-2)

Common causative agent of genital lesions

Proliferates in female genital tract

Identify by immunological tests


Trichomonas vaginalis

Transmitted via sexual activities

Causes yellow-green vaginal discharge with a strong odor

Wet mount examined for trichomonads

Fig 1.1 On the left shows the non-lactose
culture (colourless) and on the right lactose-fermenter (metallic green sheen) on EMB agar

(Taken from > images > search >E.coli on EMB)

Fig1.2 Lactosing Fermenting organism forming pink
colonies on MacMonkey Agar

(Taken from > images > search >E.coli on MacConkey)

Fig 1.3
Staphylococcus saprophycius on Mannitol-salt Agar

(Taken from > images > search >Staphylococcus on Mannitol-salt Agar)

Though Trichomonas vaginalis and Herpes Simplex Virus Type 2 (HSV-2) lead to UTI, it mainly causes vaginitis instead which leads to vaginal discharge. These symptoms is not observed for Ms Khong Fay Seah Also, candidal urethritis is in healthy women unless catheter is in placed and thus we rule out Candida albicans infection.

Done by: Jiaxin

Case 2

Patient: Kwan Siew Yan, Female, 29, outpatient

Complaints: Diarrhea

Diagnosis: Enterocolitis

Enterocolitis is the inflammation of both the small and large intestines. Most of the time however, it is categorized as either of the following:

  1. Enteritis: which is the inflammation of the small intestine

  2. Colitis: which is the inflammation of the large intestine, especially the co

A few types of enterocolitis can occur and these include:

  • Pseudomembranous enterocolitis
    • Thought to be caused by a toxin-producing strain of Clostridium difficile

    • Necrotic mucosa is replaced by a pseudomembrane filled with staphylococci, leukocytes, mucus, fibrin, and inflammatory cells

    • Has occurred postoperatively in debilitated patients who has undergone abdominal surgery and in patients treated with broad-spectrum antibiotics (Ampicillin, clindamycin, and cephalosporins are suspected as causative factors)

    • Immunocompromised patients are at increased risk for this disease

  • Salmonella enterocolitis
    • An infection in the lining of the small intestine caused by Salmonella

    • It occurs when food or water that is contaminated with Salmonella are ingested

  • Enterocolitis caused by parasites

  • Enterocolitis caused by medications

  • Necrotizing enterocolitis (NEC)
    • Usually occurs in premature neonates (less than 34 weeks’ gestation) and those of low birth weight (less than 5 lb [2.3 kg]). NEC is occurring in more neonates, possibly because of the higher incidence and survival of premature and low-birth-weight neonates

    • Since it is most commonly seen in neonates and premature and low-birth-weight neonates, the patient is probably not suffering from this type of enterocolitis

Symptoms include pain, swelling, cramping or tenderness of the abdominal area, diarrhoea, nausea, vomiting, fever, chills rectal bleeding, sluggishness, and muscle pain

Stool(faecal) sample

Screening of faeces should be routine for Salmonella, Shigella, Compylobacter and Vibrio spp. The role of Aeromonas and Plesiomonas spp. in causing diarrhoea is controversial and these are reported only when found in pure and heavy growth. On occasions, enteropathogenic E. coli (EPEC) cause problems in neonatal outbreaks and like other diarrhoegenic E. coli (ETEC, EIEC and EAEC), they are not readily detected by current reagents and media. Where indicated, Yersinia spp., enterohaemorrhagic E. coli and C. difficile (cause of hospital-associated or antibiotic-associated diarrhoea) may be cultured.

Common Causative Organisms

Supporting reasons


Salmonella spp. (Gram-negative)

- Certain strains of Salmonella can infect the lining of the small intestine causing Salmonella enterocolitis

Culture on:
- Salmonella-
Shigella (SS) plate
- Campylobacter Selective Medium
- Thiosulphate-citrate bile sucrose agar (TCBS)
- Selenite F broth
- Alkaline Peptone Water (APW)
- Enterococcosel Agar with 6ug/mL of vancomycin
- Sorbitol MAC for enterohaemorrhagic E. coli

All are grown under aerobic conditions except for Campylobacter selective medium which requires anaerobic incubation

- Gram stain
- Wet mount
- Parasite
- Stool ova & cyst
Shigella spp. (Gram-negative)

- Causes dysentery (severe diarrhoea) that result in the destruction of the epithelial cells of the intestinal mucosa in the cecum and rectum

- Symptoms include diarrhea, fever, nausea, vomiting, stomach cramps and the stool may contain blood, mucus, or pus

Campylobacter spp. (Gram-negative)

- Causes campylobacteriosis, an inflammatory, sometimes bloody, diarrhea or dysentery syndrome, mostly including cramps, fever and pain

Clostridium difficile (Gram-positive)

- Toxins produced by this organism are thought to cause Pseudomembranous enterocolitis

Vibrio spp (Gram-negative)- Commonly found in seafood and may cause gastroenteritis (diarrhoea)

- Enteropathogenic Escherichia coli [EPEC](Gram-negative)

- Enterohaemorrhagic E. coli

- Diarrhoegenic E. coli [ETEC, EIEC and EAEC]

- Yersinia spp. (Gram-negative)

- These organisms are possible causative agents of enterocolitis

Parasites- The presence of parasites may cause irritation and inflammation of the intestines and thus causing diarrhoea

Done by: Azhar

Case 3

Patient: Maisy Hong, Female, 67, inpatient

Complaints: Fever, chills, bladder distension, on indwelling catheter

Diagnosis: UTI

As the patient is suffering from bladder distension, a condition in which she is unable to urinate by herself, an indwelling catheter is used. The use of the indwelling catheter is an important predisposing risk factor for UTI as bacteria from the anus can be easily passed up the urethra because of the location of the insertion. Furthermore, presence of bacteria within the catheter can occur if it is not sanitised properly. As the patient is hospitalised, this is probably a nosocomial (hospital-acquired) infection.

The patient might be suffering from lower UTI as the symptoms (fever and chills) are often observed in lower UTI. In upper UTI, the symptoms are usually more serious (high fever and shaking chills). However, infections associated with catheters usually do not have symptoms such as dysuria, increased frequency and urgency to urinate, suprarubic and back pain so it is difficult to confirm the diagnosis.

As the patient is on indwelling catheter, it can be assumed that the urine sample is collected through the catheter.

Common Causative Organisms

Supporting reasons


Escherichia coli (Gram-negative)

- Predominant causative agent of UTI

- Most frequent cause of nosocomial UTI and are associated with the use of indwelling catheters

Culture on:

  • BAP

  • EMB agar

  • MAC

  • Ordinary nutrient agar

  • Triple Sugar Iron (TSI) agar

All are grown under anaerobic conditions except for P. aeruginosa as it is a strict aerobe


  • Gram stain

  • Fungal stain

Pseudomonas aeruginosa (Gram-negative)

- Causes infection in almost anywhere in the body but main infections include UTI

- Infections occur primarily in patients who are immunocompromised and are associated with the use of indwelling catheters

Enterococcus faecalis (Gram-positive)

- Causes UTI especially in hospitalized patients

- Use of indwelling catheter is an important predisposing factor

Klebsiella pneumoniae (Gram-negative)

- Emerging as an important nosocomial pathogen

- Causes UTI that are catheter-associated but most infections are lungs-associated

Enterobacter cloacae (Gram-negative)

- Important nosocomial pathogens that cause a variety of infections including UTI

- Especially in patients of extreme ages and associated with the use of indwelling catheter

Serratia marcescens (Gram-negative)

- Causes UTI in hospitalized patients associated with the use of catheter

Proteus mirabilis (Gram-negative)

- Once attached to the urinary tract, it infects the kidney more commonly than E. coli.

- Its vigorous motility contributes to its ability to invade the urinary tract

Staphylococcus saprophyticus, Candida albicans, Adenovirus
also causes UTI. UTI caused by S. saprophyticus is particularly in sexually active young woman so it is not possible in this case. Candida albicans might not be the causative agent in this case because the patient does not have symptoms such as itching and vaginal discharge that are seen in vaginitis (infection by Candida). Adenovirus (Types 11 and 21) causes hemorrhagic cystitis. It is also not a possible causative agent because prominent symptoms such as hematuria and dysuria are not observed in the patient.

Done by: Ming Boon

Case 4

Name: Tong Wei Hong, Male, 68, outpatient

Complaints: Fever, chills, excessive phlegm, breathing problems

Diagnosis: Bronchitis

Bronchitis is an inflammation of the bronchial tubes, or bronchi, that bring air into the lungs. It can either be acute or chronic. In acute bronchitis, it usually begins with symptoms of cold such as runny nose, slight fever and dry cough. If remain unhealed, it could slowly progress to chronic bronchitis in which the person will have difficulties in breathing, coughing with phlegm. If the disease advances, wheezing will occur and is accompanied with shortness of breath. Bronchitis is mostly due to viruses such as influenza A and B and those who have chronic medical problems may experience shortness of breath while having the flu. Bronchitis due to viral infections can be complicated with bacterial infections and this can be observed in the colour of the phlegm. With viral bronchitis, small amounts of white mucus are often coughed up. When the coughed-up mucus changes from white to green or yellow, the condition might be complicated by a bacterial infection.

Mycoplasma pneumoniae and Chlamydia pneumoniae often cause bacterial bronchitis in young adults. Among middle-aged and older people, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis are the most common organisms causing bacterial bronchitis. Bordetella pertussis could also be another possible causative agent for bronchitis as it is responsible for pertussis, commonly known as whopping cough, which is an acute tracheobronchitis. However, pertussis is considered as a pediatric disease and is typically uncommon in adults.

A person often has a combination of bacterial and viral bronchitis. Hence the possible pathogenic bacteria responsible for bronchitis of this patient are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.

Possible causative agents.
(Types of microorganisms)
Supporting reasonsPreliminary lab investigations
Streptococcus pneumoniaeThese are the most common microorganisms that caused bacterial bronchitis in middle-aged and older people. Symptoms of bronchitis will be seen.Gram staining test and identify colony characteristics under a light microscope.
Biochemical identification test to detect the presence of catalase.
Identify type of haemolysis on blood agar.
Antibiotic susceptibility test using penicillin, erythromycin and vancomycin.
Haemophilus influenzaGram staining test and identify colony characteristics under a light microscope.
Biochemical identification test to detect the presence of oxidase.
Antibiotic susceptibility test using
Ceftriaxone, trimethoprim-sulfamethoxazole.
Identify microorganism on heated blood agar enriched with factor X( a heme compound) and factor Y (NAD).
Moraxella catarrhalisGram staining test and identify colony characteristics under a light microscope.
Biochemical identification test to detect the presence of oxidase.
Antibiotic susceptibility test using erythromycin and tetracycline.
Mycoplasma pneumoniaeMycoplasma pneumoniae and Chlamydia pneumoniae often cause bacterial bronchitis in young adults (5-15years old). Symptoms of bronchitis will be seen. For Mycoplasma pneumoniae, it will cause primary atypical pneumonia in which the body will responds with a persistent unproductive cough in an attempt to clear lungs. For Chlamydia pneumoniae, it causes 5% of cases of bronchitis and it usually cause atypical pneumonia.Serologic testing using antibodies.
Chlamydia pneumoniaeGiemsa stain or by immunofluorescence identify colony characteristics.
Perform cell cultures treated with cycloheximide. Antibiotic susceptibility test using tetracycline such as doxycycline and macrolides such as erythromycin can be conducted.
Bordetella pertussisIt is responsible for the disease (pertussis) commonly known as whooping cough which is a type of bronchitis. Symptoms include cough and excessive production of mucus.Gram staining test and identify colony characteristics under a light microscope.
Biochemical identification test to detect the presence of oxidase.
Perform cell culture in Bordet-Gengou medium.
Serologic testing using antibodies.

Done by: Michelle

Case 5

Patient: Wong Fei Hong, Male, 37, outpatient

Complaints: Fever, swelling around the operation wound

Diagnosis: Wound infection

As the given information stated that it was an operation wound, the likelihood of the patient suffering from surgical-wound infection would be higher, rather than infection caused by injury.

Common Causative Organisms

Supporting reasons


Staphylococcus aureus (Gram-positive)

- Most common microorganism present in surgical-wound infection

- A major cause of nosocomial infection of surgical wounds and infections associated with indwelling medical devices

- The localized host response to staphylococcal infection is inflammation, characterized by fever and swelling

Culture on: anaerobic condition

  • BAP

  • MAC

  • Mannitol-salt agar


  • Gram stain

Pseudomonas aeruginosa (Gram-negative)

- Cause infections in the body, primarily wound infection due to burns

- An opportunistic pathogen that causes infections in hospitalized patients (immunocompromised)

Bacteriodes fragilis (Gram-negative)

- Causes a variety of infections

- Predisposing factor such as surgery play an important role in pathogenesis

Clostridium perfringens (Gram-positive)

- Common in open-wound infections

- Edema occurs in the wound area

Other causative agents that cause wound infection, such as Pasturella multocida which are transmitted by animals and Wuchereria bancrofti, transmitted by mosquitoes primarily in Africa, were ruled out in this investigation.

Done by: Yvonne

Case 6

Patient: Ong Fei Fei, Female, 37, outpatient

Complaints: Fever, pain during urination, vaginal discharge

Diagnosis: UTI

Common causative agents

Supporting reasons


Eschericia coli

(gram-neg bacteria)

Normal flora of anterior

urethra as well as vagina Common agent in UTI

Culture on:



-Fungal stain

-Wet mount

-Gram stain

Candida albicans


- Opportunistic pathogen which exist as normal flora in the vagina of some women

- Causes infection when normal flora of the genital tract is disrupted

- Usually seen in patients with indwelling catheter or on antibiotic treatment

Staphylococcus aureus

(gram-positive cocci)

- Found on mucosal lining of vagina

- Overgrowth may lead to infection of the urethra

Proteus mirabilis

(gram-neg bacteria)

- Found as normal flora in the genital tract

- Possible agent of UTI

Staphylococcus saprophyticus

(gram-positive cocci)

- 2nd most common UTI agent in sexually active women

Trichomonas vaginalis


-Causes trichomoniasis

-Greenish vaginal discharge is watery, foul-smelling.

Chlamydia trachomatis


- Obligate intracellular bacterium

- Cause urethritis in both male and female

Klebsiella pneumoniae


- Non-motile

- Causes UTI among other diseases

- Ubiquitous in the enviroment

Pseudomonas aeruoginosa

(gram-neg rod)

- Aerobic bacterium

- Motile

Serratia marcesens

(gram-neg rod)

- Facultative anaerobe

- Causes UTI

Gardnerella vaginalis

(gram- variable rod)

- Agent in bacterial vaginosis

- Vaginal discharge is pungent, fishy-odour

Mobiluncus sp.

(gram- +ve rod)

- Causative agent in bacterial vaginosis

- Anaerobic bacterium

Enterococcus faecalis

(gram- +ve cocci)

- Found in the colon

- Alpha-hemolytic

The above are the possible causative agents of UTI in this patient. Other possible agents like Ureaplasma ureatylticum and Mycoplasma genitalium are excluded as they cause urethritis in men only.

Done by: Shahirah


1.>urinary tract infection>page 3
2.>urinary tract infection
4.>salmonella enterocolitis
6.>bladder distension
7.>overcoming bladder disease
8.>guideline for prevention of catheter-associated urinary tract infections
9. Levinson W. 2006. Review of Medical Microbiology and Immunology, 9th edition. McGraw Hill Companies
12.>the microbial world>normal flora
13.>urinary tract infections
14.>urinary tract infections
15.>proteus mirabilis
16.>urinary tract infection
Brooks, Geo F, Butel J & Morse S. 2004. Jawetz, Melnick, and Adelberg's Medical Microbiology, 23rd edition

Sorry for the tables! Did my best already!

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