Microbe of the Week Mycobacterium marinum

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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

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Mycobacterium marinum Infection

• Commonly found in aquariums and infected fish,
  reptiles or amphibians
• Never transmitted from an infected human to
  another human

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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.

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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.

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Mycobacterium marinum Infection
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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

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Mycobacterium marinumDiagnosis

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

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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

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Mycobacterium marinumPrognosis

• Excellent recovery if treated with antibiotics
  and surgery
• If untreated can lead to death

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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

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MICROBE OF THE WEEKClostridium difficile

• Disposition to Hospitalization, antibiotic
  therapy, Age (elderly). Most common antibiotics
  implicated are chephalosorins, ampicillin/amoxicil
  lin and clindamycin
• Mechanism Spores of bacteria prevalent in
  hospitals. Ingestion or surgical contamination
  of patient. Spores germinate in colon and
  colonize producing toxins.

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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)

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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.

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MICROBE OF THE WEEK
HELICOBACTER PYLORI AND PEPTIC ULCERS
95 of peptic ulcers and gastritis
Also correlation between infection and gastric
cancer
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Helicobacter pylori
Gram negative spirochete
Colonizes 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
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Helicobacter pylori
Gram negative spirochete
Colonizes 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
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Helicobacter pylori
Gram negative spirochete
Colonizes 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
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Helicobacter pylori
Identification a biopsy with subsequent
culture breath test for urea stool
antigen assays urease detection in biopsy
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Helicobacter Pylori
Treatment PeptoBismol combined with
metronidazole and tetracycline or amoxicillin
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Helicobacter pylori