Microbe of the WeekMycobacterium marinum

• The aquarium or fish tank disease,first reported in 1962

• Rare but important if not treated

• Living example-Karen Bahr the Biology Department Administrative Assistant

Mycobacterium marinum Infection

• Commonly found in aquariums and infected fish, reptiles or amphibians

• Never transmitted from an infected human to another human

How do I get the Infection?

• ･ when in contact with water from an aquarium or fish tank

• when handling, cleaning, or processing fish

• while swimming or working in fresh or salt water.

Mycobacterium marinuminfection

• Contracted when small cuts or abrasions exposed to aquarium water or fish amphibians etc

• Usually results in superficial nodulars or ulcerated lesions on hands and fingers in the case of aquarium transmission

• Swimming pool transmission same symptoms on elbows, knees and feet.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Mycobacterium marinumInfection

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Mycobacterium marinumDiagnosis

• Hardest part is the diagnosis. Difficult to culture using normal diagnostic media and incubation temperature and often goes undiagnosed for long periods

• Culture on Mycobacterium medium called Lowenstein-Jensen or LJ at 32C. Will not grow at 37C

• It is photochromogenic which means it produces a pigment when exposed to light thus this is diagnostic

Mycobacterium marinumDiagnosis

• After culturing do an acid fast stain and then antibiotic susceptibility

Mycobacterium marinumTreatment

• Surgical aspiration often done• Antibiotic treatment often for 2-12

months. • Minocycline combined with

rifampin(rifamicin). Most potent rifamycins +clarithromycin

• Wound dressing often silver based with collagen

Mycobacterium marinumPrognosis

• Excellent recovery if treated with antibiotics and surgery

• If untreated can lead to death

MICROBE OF THE WEEK

• Infection usually results because of antibiotic therapy which disturbs normal bacterial flora of colon.

• Cause- C. difficile releases 2 toxins, A and B. A is an enterotoxin and B is a cytotoxin. Both bind to receptors on the intestinal mucal cells compromising fluid absorption + retention

MICROBE OF THE WEEKClostridium difficile

• Disposition to: Hospitalization, antibiotic therapy, Age (elderly). Most common antibiotics implicated are chephalosorins, ampicillin/amoxicillin and clindamycin

• Mechanism: Spores of bacteria prevalent in hospitals. Ingestion or surgical contamination of patient. Spores germinate in colon and colonize producing toxins.

MICROBE OF THE WEEK

• Symptoms. Mild to moderate watery diarrhea(rarely bloody)

cramping, anorexia, fever, dehydration, abdominal tenderness.

Diagnosis. Conclusive diagnosis depends on detection of toxin in stool. Fibroblast tissue culture-24-48h(94-100%). Commercial enzyme immunoassay kits (69-87%). Less sensitive but very quick (hours)

MICROBE OF THE WEEK

• Treatment. Usually Vancomycin or Metronidazole. Organism is very susceptible to vancomycin. It is resistant to cephalosporins, ampicillin/amoxicillin, and clindamycin and aminoglycosides.

• Support therapy. Hydration.

MICROBE OF THE WEEK

HELICOBACTER PYLORI AND PEPTIC ULCERS

95% of peptic ulcers and gastritis

Also correlation between infection and gastric cancer

Helicobacter pylori

Gram negative spirocheteColonizes gastric mucous secreting cells

•Grown best under microaerophilic conditions

•Causes disease via urease, proteases and phospholipase combined with a cell mediated immune response

•50% of world population infected

Helicobacter pylori

Gram negative spirocheteColonizes gastric mucous secreting cells

•Grown best under microaerophilic conditions

•Causes disease via urease, proteases and phospholipase combined with a cell mediated immune response

•50% of world population infected

Helicobacter pylori

Gram negative spirocheteColonizes gastric mucous secreting cells

•Grown best under microaerophilic conditions

•Causes disease via urease, proteases and phospholipase combined with a cell mediated immune response

•50% of world population infected

Helicobacter pylori

Identification • a biopsy with subsequent culture • breath test for urea • stool antigen assays •urease detection in biopsy

Helicobacter Pylori

Treatment •PeptoBismol combined with metronidazole and tetracycline or amoxicillin

Helicobacter pylori