Journal of the Louisiana State Medical Society
Comamonas species could be human gastrointestinal tract commensals. 10 In seven cases, there were no predisposing factors, with the exception of one case following a tiger bite. 10 Comamonas peritonitis occurred in eight cases, endocarditis in two cases, and one in an intravenous drug abuser. 10 Smith and Gradon reported a case of Comamonas sepsis in a previously healthy 89-year-old man who slept next to a tropical fish tank in which fish had started to die rapidly, turning the tank water opaque and malodorous. 10 The pa- tient presentedwith sore throat, myalgia, fever, and had two sequential positive blood cultures for Comamonas species sensitive to all antibiotics tested. 10 The patient was treated with levofloxacin, and his condition rapidly stabilized without sequelae. 10 Since the patient denied any physical contact with his son’s fish tank, the authors concluded that the most likely source of infection was by inhalation and recommended that Comamonas bacteremia be considered in the differential diagnosis of sepsis in patients who are tropical fish tank enthusiasts. 10 Shewanella species Shewanella species are saprophytic gram-negative bac- teria that are distributed in temperate regions worldwide and are part of the normal microflora of the marine environ- ment like Aeromonas hydrophila , Erysipelothrix rhusiopathiae , and Vibrio vulnificus . 11-13 There are more than 50 species of Shewanella , all of which produce yellowish-brown mucoid colonies that emit hydrogen sulfide in culture. 11-13 Several Shewanella species have been recently recognized as emerg- ing causes of soft tissue and invasive infections after seawa- ter exposures, including S. algae , S. haliotis , S. putrefaciens , and S. xiamenensis . 13 The most common clinical manifesta- tions of Shewanella infections are deep ulcers associated with hemorrhagic bullae, usually on the lower extremities, otitis externa, otitis media, and bacteremia. 11-13 Non-healing ulcers have resulted in necrotizing fasciitis, compartment syndromes requiring decompressive fasciotomies, and osteomyelitis (Figure 1). 11-13 Shewanella septicemia has been associated with endocarditis and meningitis. 11-13 Shewanella pneumonia, cholecystitis, and peritonitis have been reported following aspiration or ingestion of seawater. 12 Besides sea- water exposure and ingestion of raw seafood, other common risk factors for Shewanella infections have included minor trauma or lacerations in marine environments, pre-existing lower extremity ulcers, and immunocompromise. 13 Wagner and colleagues reported a case of S. algae -infected chronic leg ulcers in a 52-year-old female with autoimmune vascu- litis and myasthenia gravis seven months after returning from a Mediterranean vacation during which she reported frequently bathing in the surf. 11 Poovorawan and colleagues reported another recent case of severe S. haliotis soft tissue infection in the left lower leg with compartment syndrome in a 52-year-old female from Bangkok who had undergone orthotopic liver transplantation six months previously and reported frequent handling of fresh saltwater fish in a seafood market (Figure 1). 13 In a descriptive analysis of
Gulf of Mexico region not touch the animal, keep all pets away from the animal, and notify the NOAA immediately at 1-877-942-5343. 5 All persons who handle strandedmarine mammals or who participate in autopsies on their carcasses should be educated as to the potential risks of marine mam- mal brucellosis and use personal protective equipment, including respirators. 1,5 Chromobacterium violaceum Chromobacterium violaceum is an aerobic, gram-negative bacillus, and a saprophyte found in soil andwater in tropical and subtropical regions worldwide. 6 The organism grows rapidly on ordinary culture media and is typically first identified by the violet-color of its colonies. 6 Non-pigmented strains of C. violaceum are less commonly found than pig- mented strains, but do co-exist with pigmented strains and can causemixed infections. 7 Althoughwidely distributed, C. violaceum is a low-grade pathogen and causes few infections, withmost reported from the southeastern US with high case fatality rates, especially in the immunocompromised. 8 In 1982, Macher and colleagues reported 12 cases of C. viola- ceum infections in the United States in patients with chronic granulomatous disease - seven of whom died of invasive septicemia 7 days to 15 months after initial infections. 9 The portal of entry for C. violaceum is typically a break in the skin from an insect bite, laceration, or fish bite, followed by exposure to brackish or stagnant water. An ulcerated skin lesionwith a bluish purulent discharge develops at the initial injury site with regional swelling usually on an extremity. Within days, invasive septicemia may occur, especially in the immunocompromised, with high fevers and dissemi- nated macular skin lesions that progress to abscesses. Ab- scesses may also occur in bone and in the liver. The organism is susceptible to aminoglycosides, quinolones, tetracyclines, imipenem, and trimethoprim-sulfamethoxazole but resistant to penicillins and cephalosporins. 8 Due to high case fatality rates, treatment of suspected C. violaceum infections should begin immediately with drainage of all purulent abscess collections and combined intravenous antibiotic therapy. A high index of suspicion for C. violaceum infections should be maintained in all cases with a rapid progression from an ul- cerated lesion in a soil- or water-contaminatedminor wound followed by sepsis, widespread cutaneous involvement, and liver abscesses. Rapidly growing violet-pigmented colonies on blood or MacConkey agar are diagnostic of the pigmented strains of C. violaceum . Comamonas species Comamonas species are flagellated, gram-negative, rod- shaped bacteria that form characteristic pink-pigmented colonies on ordinary culture media. 10 Like C. violaceum , Comamonas species are widely distributed in nature in soil and water but rarely cause human infections, with 24 cases reported to date and a case fatality rate of 12.5%. 10 Of the 24 reported human cases, eight cases were associated with appendicitis or perforated appendix, suggesting that
106 J La State Med Soc VOL 166 May/June 2014
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