Chrysobacterium meningosepticum

Abstract & Commentary

Synopsis: Host factors are the major determinants of the outcomes of C. meningosepticum infections.

Source: Lin PY, et al. Clinical and Microbiological Analysis of Bloodstream Infections Caused by Chryseobacterium meningosepticum in Nonneonatal Patients. J Clin Microbiol. 2004;42:3353-3355.

Lin and colleagues describe 9 adults (40-82 years of age) and 2 children (0.5 and 1.5 years of age) seen at 2 hospitals in Taiwan from 2001 to 2002 with bacteremia due to Chrysobacterium meningosepticum. Six of the infections were community acquired. The mean duration of hospitalization, prior to infection in the 5 patients with nosocomial acquisition, was 32 days (range, 13 to 99 days). All the adults had significant underlying disease.

Each isolate represented a distinct genotype. All 11 isolates were resistant in vitro to all beta lactam antibiotics tested including piperacillin, ceftazidime, cefepime, and imipenem. The majority of the isolates produced at least 2 beta-lactamases, including an extended spectrum beta-lactamase and a metallo-beta-lactamase.

All isolates were also resistant to vancomycin, and most isolates were also resistant to gentamicin, chloramphenicol, and azithromycin. The most active antibiotics in vitro were minocycline, trimethoprim-sulfamethoxazole, and rifampin.

Fever and infection resolved in the 2 children (both without underlying disease) in the absence of any antibiotic therapy, and infection also resolved in 4 adults in the absence of appropriate antibiotic administration.

Comment by Stan Deresinski, MD, FACP

C. meningosepticum (formerly Flavobacterium meningosepticum), is present in soil and water. Its ability to survive in chlorinated water allows it to colonize hospital sinks and water taps, which have served as sources for nosocomial outbreaks of infection due to this organism. Most such infections have occurred in neonates and immunocompromised adults.

A recent report from the SENTRY Antimicrobial Surveillance Program examined the in vitro susceptibility of 24 isolates of C. meningosepticum from throughout the world, with results largely consistent with those reported by Lin et al. Gatifloxacin and garenoxacin were each active in vitro against 100% of the isolates; levofloxacin inhibited 96% and ciprofloxacin 71%. In contrast to the current report, the SENTRY study found that 62% were susceptible to piperacillin and 71% to piperacillin-tazobactam. Fewer than 10% of isolates were susceptible to other beta-lactams tested, except for cefepime (38% susceptible). Seventy-nine percent were susceptible to trimethoprim-sulfamethoxazole and 88% were susceptible to rifampin. Fewer than 10% were susceptible to aminoglycosides, vacnomcyin, or rifampin.

The remarkable resistance of C. meningosepticum to beta-lactam antibiotics is the consequence of the frequent presence of multiple beta-lactamases, especially Ambler class A extended spectrum enzymes and chromosomal metallo-beta-lactamases. In fact, some isolates have been detected that contained multiple versions of the latter.

The Sanford guide recommends vancomycin with or without rifampin as the first choice for treatment of infections due to C. meningosepticum, with either levofloxacin or ciprofloxacin as alternative choices. Although there is a question regarding the therapeutic predictive value of in vitro susceptibility results with this organism, the usefulness of vancomycin has been called into question, both because of these results and because of clinical failure. To the extent that the in vitro susceptibility data is of value, it would suggest that the most active antibiotics are newer fluoroquinolones, such as gatifloxacin, desfluoroquinolone, and the investigational garenoxacin.

While the reported mortality associated with systemic C. meningosepticum infection has been high, that was not the case in the report from Taiwan. In fact, 2 children had "occult bacteremia" that resolved in the absence of antibiotic therapy and infection resolved in 4 adults in the absence of appropriate therapy. This is consistent with an organism of limited virulence, likely to cause death only in significantly compromised patients.

Stan Deresinski, MD, FACP, Clinical Professor of Medicine, Stanford; Associate Chief of Infectious Diseases, Santa Clara Valley Medical Center, is Editor of Infectious Disease Alert.