Aquatic infections

• What are the common features of aquatic injury infections?

  Gram negative polymicrobial infections with marine bacteria
• What is the characteristic resistance pattern of marine bacteria?

  Most are resistant to 1st and 2nd generation penicillin and cephalosporins
• What is the structure of Aeromonas?

  Gram negative bacilli
• What is produced by Aeromonas?

  Enterotoxins and haemolysins
• What is the clinical presentation of Aeromonas?

  Acute haemorrhagic diarrhoea or cellulitis like picture
• Where is Aeromonas found in the environment?

  Soil, fresh and brackish water
• To which drugs are Aeromonas susceptible?

  Fluoroquinolones, tetracyclines, aminoglycosides, carbapenems, 3rd and 4th generation cephalosporins
• What is the structure of Chromobacterium violacium?

  Aerobic Gram negative bacillus
• Where is Chromobacterium found?

  Saphrophyte, in soil & water in subtropics
• What is the usual mode of entry of Chromobacterium violacium?

  Usually via skin from laceration/ fish bite
• What is the clinical picture of Chromobacterium violacium?

  Haematogenous dissemination within days, abscesses in bone, liver, lung and spleen
• What is Chromobacterium violacium resistant to?

  Most penicillins and cephalosporins
• What its the structure of Edwardsellia tarda?

  Gram negative rod
• What is the most common infection caused by Edwardsellia tarda?

  Intraintestinal
• What is the more serious complication of Edwardsellia tarda?

  Myonecrosis and fatal septic shock- seen in immunocompromised, especially chronic liver disease
• Which antimicrobials are used to manage Edwardsellia tarda?

  Gram negative coverage- ampicillin, cephalosporins, aminoglycosides, fluoroquinolones
• What is the structure of Shewanella?

  Gram negative
• What is the appearance of Shewanella on plating?

  Brown mucus colonies that emit hydrogen sulfide on culture
• How does Shewanella infection present?

  Deep ulcers with haemorrhagic bullae usually on lower extremities, otitis externa, otitis media, biliary tract infection and bacteraemia
• How is Shewanella infection acquired?

  Ingestion of raw seafood, minor trauma, lacerations in marine environment, and pre- existing lower limb ulcers
• What is the management of Shewanella?

  3rd/ 4th generation cephalosporin, carbapenems and fluoroquinolones
• What is the structure of Vibrio vulnificus?

  Halophilic Gram negative curved rod
• Where is the environment for Vibrio vulnificus?

  >18 degrees and marine areas with low- moderate salinities
• What are the 3 patterns of infection with Vibrio vulnificus?

  Acute gastroenteritis, invasive sepsis (both from shellfish) and necrotising wound infections (marine injuries)
• Why do men get Vibrio vulnificus more?

  Occupation, recreation, serum iron, alcohol, liver disease, lower oestrogen
• Which non sex risk factors for Vibrio vulnificus exist?

  Haematological conditions which increase iron (e.g. haemochromatosis, thalassaemia), chronic liver disease, liver transplant, DM, steroids, splenectomy, ESRF
• Which environmental factors increase risk of Vibrio vulnificus?

  Exposure to raw seafood and seawater, also seen more in summer
• How is Vibrio vulnificus managed?

  Immediate antibiotics- ceftazidime and doxycycline
• What is the initial presentation of Erysipelothrix rhusiopathiae?

  Manifests 1-2 days after skin injuries while preparing or handling fish; localised cutaneous (erysipeloid) or generalised cutaneous; both intensely pruritic lesions
• What is Erysipelothrix rhusiopathiae usually resistant to?

  Vancomycin, sulfonamides and aminoglycosides
• What is the major complication of Erysipelopthrix rhusiopathiae?

  Infective endocarditis (involves aortic valve commonly, 40% fatality rate)
• What is Erysipelothrix rhusiopathiae sensitive to?

  Penicillins, carbapenems, cephalosporins, fluoroquinolones, daptomycin and clindamycin
• Which mycobacterium is most commonly associated with aquatic injuries?

  Mycobacterium marinum
• What is the presentation of mycobacterium marinum?

  Red- violet verrucous/ crusted plaques at innoculation sites, followed by granulomatous nodules with yellowish discharge
• Which aquatic mycobacteria are more rapid presenting?

  Mycobacterium abscessus and Mycobacterium fortuitum (often in marine injuries and Tsunamis)
• How can mycobacterium be spread in cities?

  Footbaths, pedicures and 'doctor fish'
• How is mycobacterium marinum managed?

  Macrolides- clarithromycin, sulfonamides, co- trimoxazole, ethambutol and rifampicin
• How is Mycobacterium fortunitum managed?

  Quinolones, newer macrolides (azithromycin/ clarithromycin), sulfonamides, doxycycline and amikacin; at least 2 agents for 4 months