| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Case Report |
1 Department of Medical Microbiology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
2 Department of Medicine, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
Correspondence
I.-C. Sam
jicsam{at}um.edu.my
Received July 10, 2008
Accepted September 21, 2008
A 17-year-old man with acute lymphoblastic leukaemia had fever and diarrhoea during a febrile neutropenic episode. A spiral-shaped, Gram-negative anaerobic bacterium was isolated from blood, and confirmed as Anaerobiospirillum succiniciproducens by 16S rRNA sequencing. The patient responded to imipenem.
Introduction
The species Anaerobiospirillum was described for the first time by Davis et al. (1976), and comprises a group of spiral-shaped, Gram-negative anaerobic bacteria. They are motile, with bipolar tufts of flagella, and are present in the faeces of healthy cats and dogs (Rossi et al., 2008). Anaerobiospirillum succiniciproducens has been reported as a rare cause of bacteraemia, particularly in immunocompromised hosts (Tee et al., 1998; Pienaar et al., 2003), and diarrhoeal illness (Malnick et al., 1990). As gastrointestinal symptoms are the most common accompanying symptoms of bacteraemia, the gastrointestinal tract is believed to be the portal of entry (McNeil et al., 1987). We describe a case of A. succiniciproducens bacteraemia in a 17-year-old Chinese man with acute lymphoblastic leukaemia.
Case report
The patient, who was on chemotherapy, presented with generalized weakness and an erythematous rash over his arms. His blood count showed pancytopenia, with a total white count of <0.1x109 l–1. On the third day of his admission, he developed a fever of 38.8 °C and diarrhoea, and was empirically treated with piperacillin–tazobactam. Three sets of blood cultures (BACTEC 9240; Becton Dickinson), but no stool sample, were collected.
A spiral-shaped, Gram-negative bacillus was grown from a single anaerobic bottle, drawn from the white lumen of an intravascular catheter (Fig. 1
). The isolate only grew after 48 h under anaerobic conditions at 37 °C on 5 % sheep blood agar and fastidious anaerobic agar (Oxoid). Colonies were translucent and non-haemolytic, with a feathery swarming appearance. There was no growth on Skirrow supplemented plates (Oxoid) incubated under microaerophilic conditions for Campylobacter. Antibiotic susceptibility testing of anaerobes is not routinely performed in our laboratory due to lack of suitable media, but the metronidazole disc used to screen for anaerobes showed no zone of inhibition. The isolate was negative for oxidase and catalase. Rapid ID 32A (bioMérieux) identified the isolate as A. succiniciproducens.
|
Discussion
Two species of Anaerobiospirillum, A. succiniciproducens and A. thomasii, are known to infect humans and are associated with diarrhoea (Malnick, 1997). Anaerobiospirillum species are part of the normal intestinal flora of cats and dogs, but apparently not of humans (Malnick et al., 1990; Rossi et al., 2008). It has been suggested that Anaerobiospirillum species are zoonotic bacteria transmitted to humans from animals, and that they are underdiagnosed because human stool samples are not routinely screened for these organisms (Malnick et al., 1990). The patient had no direct contact with animals, although he reported that his neighbour had a cat.
A. succiniciproducens is also rarely associated with bacteraemia, with about 30 case reports from USA, Europe, Africa and Asia, suggesting a global distribution. Almost all reported bacteraemia cases have occurred in patients with underlying medical conditions such as alcoholic liver disease, atherosclerosis, recent surgery and malignancies (McNeil et al., 1987; Goddard et al., 1998; Pienaar et al., 2003).
Screening of the isolate in this case with a metronidazole disc suggested resistance to this drug. Other studies have found that A. succiniciproducens is often resistant to metronidazole and erythromycin (McNeil et al., 1987; Yuen et al., 1989; Tee et al., 1998; Pienaar et al., 2003), antibiotics that are empirically used for suspected infections with anaerobes and Campylobacter species, respectively. Thus, it is important for diagnostic laboratories to identify A. succiniciproducens, and especially to distinguish it from Campylobacter species, which have a similar Gram stain and colony appearance, but are oxidase and catalase positive. Isolation on Skirrow media is not specific for Campylobacter species, as some strains of A. succiniciproducens may grow (Malnick et al., 1990). Commercial identification systems using biochemical tests may help, and 16S rRNA sequencing is definitive.
The optimal treatment for A. succiniciproducens is not yet known, with some reported patients dying despite treatment with antibiotics to which the bacteria showed in vitro susceptibility, and some recovering without specific treatment (McNeil et al., 1987; Tee et al., 1998). Our patient did not respond to piperacillin–tazobactam, but did respond to imipenem, to which A. succiniciproducens has shown in vitro susceptibility in the few studies that have tested for it (Tee et al., 1998; Pienaar et al., 2003).
In conclusion, we have described what is believed to be the second Asian case of A. succiniciproducens bacteraemia. Improved awareness and diagnosis of this rarely encountered organism will help further understanding of its epidemiology and treatment.
References
Davis, C. P., Cleven, D., Brown, J. & Balish, E. (1976). Anaerobiospirillum, a new genus of spiral-shaped bacteria. Int J Syst Bacteriol 26, 498–504.
Goddard, W. W., Bennett, S. A. & Parkinson, C. (1998). Anaerobiospirillum succiniciproducens septicaemia: important aspects of diagnosis and management. J Infect 37, 68–70.[CrossRef][Medline]
Malnick, H. (1997). Anaerobiospirillum thomasii sp. nov., an anaerobic spiral bacterium isolated from the feces of cats and dogs and from diarrheal feces of humans, and emendation of the genus Anaerobiospirillum. Int J Syst Bacteriol 47, 381–384.
Malnick, H., Williams, K., Phil-Ebosie, J. & Levy, A. S. (1990). Description of a medium for isolating Anaerobiospirillum spp., a possible cause of zoonotic disease, from diarrheal feces and blood of humans and use of the medium in a survey of human, canine, and feline feces. J Clin Microbiol 28, 1380–1384.
McNeil, M. M., Martone, W. J. & Dowell, V. R., Jr (1987). Bacteremia with Anaerobiospirillum succiniciproducens. Rev Infect Dis 9, 737–742.[Medline]
Misbah, S., Hassan, H., Yusof, M. Y., Hanifah, Y. A. & AbuBakar, S. (2005). Genomic species identification of Acinetobacter of clinical isolates by 16S rDNA sequencing. Singapore Med J 46, 461–464.[Medline]
Pienaar, C., Kruger, A. J., Venter, E. C. & Pitout, J. D. D. (2003). Anaerobiospirillum succiniciproducens bacteraemia. J Clin Pathol 56, 316–318.
Rossi, M., Hänninen, M. L., Revez, J., Hannula, M. & Zanoni, R. G. (2008). Occurrence and species level diagnostics of Campylobacter spp., enteric Helicobacter spp. and Anaerobiospirillum spp. in healthy and diarrheic dogs and cats. Vet Microbiol 129, 304–314.[CrossRef][Medline]
Tee, W., Korman, T. M., Waters, M. J., MacPhee, A., Jenney, A., Joyce, L. & Dyall-Smith, M. L. (1998). Three cases of Anaerobiospirillum succiniciproducens bacteremia confirmed by 16S rRNA gene sequencing. J Clin Microbiol 36, 1209–1213.
Yuen, K. Y., Yung, W. H. & Seto, W. H. (1989). A case report of Anaerobiospirillum causing septicemia. J Infect Dis 159, 153–154.[Medline]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | J MED MICROBIOL | MICROBIOLOGY | J GEN VIROL | ALL SGM JOURNALS |
