Bacteremia due to Comamonas species possibly associated with exposure to tropical fish.

Abstract: Comamonas species are environmental Gram-negative rods that grow forming pink-pigmented colonies. Despite their common occurrence in nature, they rarely cause human infection. We present a case of Comamonas bacteremia that we think may have been related to tropical fish exposure. The patient was treated successfully with levofloxacin.

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Key Points

* Cryptogenic infeetion due to Comamonas species may be related to tropical fish tank exposure.

* Comamonas isolates are generally susceptible to a variety of antibiotics, with fluoroquinolones always being active.

* A frequent endogenous source of Comamonas infection is the gastrointestinal tract (eg, appendicitis).

Case Report

An 89-year-old, previously healthy man presented with sore throat, myalgia, and fever. Initial clinical and laboratory evaluation failed to reveal any obvious source of infection. Further questioning indicated that he lived with his son who had kept tropical fish for more than 20 years and had been successful in keeping his fish alive for long periods. During the past 2 months, however, the fish had started to die rapidly, and the water had turned opaque and malodorous. The patient slept on a couch next to the fish tank in his son's house. He did not personally care for the fish or change the water in the tank, nor did he have any "outdoor" or gardening hobbies. Because of his advanced age, an extensive evaluation was begun rapidly. Abdominal and pelvic computed tomographic scans were unremarkable, and results of pharyngeal, sputum, and urine cultures were negative. Thoracic computed tomographic scan showed an infiltrate in the left lung base. Empiric antimicrobial therapy with levofloxacin was begun, and the patient's condition stabilized rapidly. By the second hospital day, both admission blood cultures were growing Gram-variable bacilli that produced pink-pigmented colonies on blood agar. The isolates were referred to the Mayo Clinic and were identified as Comamonas species. Antimicrobial susceptibility testing performed at the Mayo Clinic indicated that the isolate was sensitive to all agents tested. These included ceftazidime, ciprofloxacin, levofloxacin, imipenem, trimethoprim-sulfamethoxazole, amikacin, gentamicin, chloramphenicol, cefepime, and piperacillin-tazobactam. An echocardiogram did not reveal any vegetations, and the patient was discharged home to complete a 14-day course of oral levofloxacin therapy.

Discussion

In 1987, Tamaoka et al (1) proposed that Pseudomonas acidovorans and P. testosteroni be placed in the genus Comamonas along with the species C. terrigena. All are motile by way of a polar tuft of up to six flagella, with the distinctive feature of having a long wavelength. These organisms are ubiquitous in soil and water. However, despite their common occurrence in nature, they only rarely cause human infection. The reported cases are summarized in Table 1. (2-8)

In general, the species C. testosteroni and C. terrigena are more antibiotic sensitive than are isolates of C. acidovorans, which tend to be aminoglycoside resistant. In vitro data indicate that all Comamonas species are sensitive to piperacillin, cefoxitin, cefotaxime, imipenem, and ciprofloxacin. (9) Duration of therapy would appear to be the same as for other causes of "Gram-negative infection," with 10 to 14 days of therapy for bacteremia seeming to be appropriate.

Sites of isolation include cerebrospinal fluid, sputum, urine, the pharynx, and traumatic wounds. In addition, Comamonas species have been reported in a case of a feline bite, (2) as a component of polymicrobial pneumonia in acquired immunodeficiency syndrome patients, (3) as a cause of bacterial endocarditis, (4) and as a cause of bacteremia in a child with non-Hodgkin's lymphoma. (4) C. acidovorans has also been isolated in a case of corneal ulceration and bacteremia. (10) Barbaro et al (7) suggested that infection with C. testosteroni is associated with anatomic abnormalities in the gastrointestinal tract such as appendicitis.

No cases associated with aquatic exposures have been reported to date. Although Comamonas species are found in many environmental settings, no cases of infection through inhalation have been reported. In a MEDLINE search using the key words Comamonas bacteremia and/or inhalation, we found no reported cases of infection by inhalation.

On the basis of the history and presentation of infection in our patient, we propose that he may have acquired Comamonas bacteremia from the infected water in his son's tropical fish tank. The most likely route of infection would have been by inhalation, because the patient categorically denied any physical contact with the fish tank or its contents. Although this hypothesis cannot be proved, it is consistent with temporal development of the infection that killed the tropical fish and the patient's close physical proximity to the fish tank. We thus propose that Comamonas bacteremia be considered in the differential diagnosis of sepsis in patients who are tropical fish tank enthusiasts.

Table 1. Summary of reported cases of infection due to Comamonas
species (a)

                              Age                       Site of
Series (ref. no.)             (yr)/sex                  infection

Sonnenwirth, 1970 (6)         71/F                      Endocarditis
Barbaro et al, 1987 (7)       31/M                      Abdominal
                                                          abscess
                              24/F                      Cerebrospinal
                                                          fluid
                              59/F                      Peritoneum
                              11/M                      Peritoneum
                              12/F                      Peritoneum
                              21/F                      Peritoneum
                              Stillborn                 Cord blood
                              84/F                      Urine
                              24/M                      Peritoneum
                              Newborn/F                 Blood
                              17/F                      Peritoneum
                              59/M                      NR
                              66/M                      Peritoneum
                              14/M                      Appendix
                              15/M                      Peritoneum
                              4/M                       Blood
                              28/F                      Blood
Horowitz et al, 1990 (4)      42/F                      Tricuspid valve
Franzetti et al, 1992 (3)     Unknown                   Lung/pneumonia
Castagnola et al, 1994 (5)    9/M                       Central venous
                                                          catheter
Ender et al, 1996 (8)         4/F                       Indwelling
                                                          catheter
Isotalo et al, 2000 (2)       35/M                      Animal bite
Present case                  89/M                      Blood

                                    Predisposing
Series (ref. no.)                     factors

Sonnenwirth, 1970 (6)         Preexisting heart disease
Barbaro et al, 1987 (7)       Perforated appendix
                              Intravenous drug abuse
                              Alcoholic cirrhosis
                              Perforated appendix
                              Perforated appendix
                              Pregnancy, perforated
                                appendix
                              Maternal intravenous
                                drug abuse
                              Congestive heart failure
                              Perforated appendix
                              Maternal intravenous
                                drug abuse
                              Appendicitis
                              NR
                              NR
                              Appendicitis
                              NR
                              NR
                              NR
Horowitz et al, 1990 (4)      Intravenous drug abuse
Franzetti et al, 1992 (3)     AIDS-related complex
Castagnola et al, 1994 (5)    Non-Hodgkin's
                                lymphoma
Ender et al, 1996 (8)         Neutropenia, metastatic
                                neuroblastoma
Isotalo et al, 2000 (2)       Zoonotic infection
Present case                  Environmental exposure

Series (ref. no.)             Treatment

Sonnenwirth, 1970 (6)         Penicillin
Barbaro et al, 1987 (7)       Cefoxitin; drainage then
                                ampicillin, gentamicin,
                                clindamycin
                              Moxalactam, nafcillin
                              Cefoxitin
                              Ampicillin, clindamycin,
                                tobramycin
                              Cefoxitin
                              Cefoxitin
                              None
                              Ampicillin
                              Cefoxitin
                              Ampicillin
                              NR
                              NR
                              NR
                              NR
                              NR
                              NR
Horowitz et al, 1990 (4)      Ciprofloxacin, ceftazidime
Franzetti et al, 1992 (3)     Ceftazidime
Castagnola et al, 1994 (5)    Ceftazidime, vancomycin,
                                amikacin
Ender et al, 1996 (8)         Ceftazidime, ciprofloxacin
Isotalo et al, 2000 (2)       Cefazolin, gentamicin
Present case                  Lovofloxacin

Series (ref. no.)             Outcome

Sonnenwirth, 1970 (6)         Cured
Barbaro et al, 1987 (7)       Cured
                              Cured
                              Cured
                              Cured
                              Cured
                              Cured
                              Died
                              Cured
                              Cured
                              Died within
                                24 h
                              NR
                              NR
                              NR
                              NR
                              NR
                              NR
                              NR
Horowitz et al, 1990 (4)      Cured
Franzetti et al, 1992 (3)     Died
Castagnola et al, 1994 (5)    Cured
Ender et al, 1996 (8)         Cured
Isotalo et al, 2000 (2)       Cured
Present case                  Cured

Series (ref. no.)             Pathogens

Sonnenwirth, 1970 (6)         C. terrigena
Barbaro et al, 1987 (7)       Pseudomonas
                                testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosteroni
                              P. testosleroni
                              P. testosteroni
Horowitz et al, 1990 (4)      C. acidovoran
Franzetti et al, 1992 (3)     C. acidovoran,
                                C. testosteroni
Castagnola et al, 1994 (5)    C. acidovoran
Ender et al, 1996 (8)         C. acidovoran
Isotalo et al, 2000 (2)       Comamonas
                                species
Present case                  Comamonas
                                species

(a) AIDS, acquired immunodeficiency syndrome; NR, not reported.

References

(1.) Tamaoka J, Ha DM, Komagata K. Reclassification of Pseudomonas acidovorans den Dooren de Jong 1926 and Pseudomonas testosteroni Marcus and Talahay 1956 as Comamonas acidovorans comb. nov. and Comamonas testosteroni comb. nov. with an emended description of the genus Comamonas. Int J Syst Bacteriol 1987;37:52-59.

(2.) Isotalo PA, Edgar D, Toye B. Polymicrobial tenosynovitis with Pasteurella multocida and other gram negative bacilli after a Siberian tiger bite. J Clin Pathol 2000;53:871-872.

(3.) Franzetti F, Cernuschi M, Esposito R, Moroni M. Pseudomonas infections in patients with AIDS and AIDS-related complex. J Intern Med 1992;231:437 443.

(4.) Horowitz H, Gilroy S, Feinstein S, Gilardi G. Endocarditis associated with Comamonas acidovorans. J Clin Microbiol 1990;28:143-145.

(5.) Castagnola E, Tasso L, Conte M, Nantron M, Barretta A, Giacchino R. Central venous catheter-related infection due to Comamonas acidovorans in a child with non-Hodgkin's lymphoma. Clin Infect Dis 1994;19:559-560 (letter).

(6.) Sonnenwirth AC. Bacteremia with and without meningitis due to Yersinia enterocolitica, Edwardsiella tarda, Comamonas terrigena, and Pseudomonas maltophilia. Ann N Y Acad Sci 1970; 174:488 -502.

(7.) Barbaro DJ, Mackowiak PA, Barth SS, Southern PM Jr. Pseudomonas testosteroni infections: Eighteen recent cases and a review of the literature. Rev Infect Dis 1987;9:124-129.

(8.) Ender PT, Dooley DP, Moore RH. Vascular catheter-related Comamonas acidovorans bacteremia managed with preservation of the catheter. Pediatr Infect Dis J 1996;15:918-920.

(9.) Fass RJ, Barnishan J. In vitro susceptibilities of nonfermentative gram-negative bacilli other than Pseudomonas aeruginosa to 32 antimicrobial agents. Rev Inject Dis 1980;2:841-853.

(10.) Stonecipher KG, Jensen HG, Kastl PR, Faulkner A, Rowsey JJ. Ocular infections associated with Comamonas acidovorans. Am J Ophthalmol 1991;112:46-49.

From the Department of Medicine, Sinai Hospital of Baltimore, Baltimore, MD.

Reprint requests to Jeremy D. Gradon, MD, Department of Medicine, Sinai Hospital of Baltimore, 2401 W. Belvedere Avenue, Baltimore, MD 21215. Email: [e-mail]

Accepted November 14, 2002.