Clostridium
difficile has been a
familiar nosocomial pathogen for decades, but its well-known disease
patterns are changing: Studies are finding unusual frequency and
severity of hospital-acquired disease and unexpected cases of
community-acquired disease. Is a new strain responsible?
Researchers
studied 187 isolates of C. difficile collected from patients
at eight healthcare facilities in six states where outbreaks of C.
difficile-associated disease (CDAD) had occurred. About half of
the isolates proved to be the strain associated with recent hospital
outbreaks. This strain has a unique toxin profile thought to
represent increased virulence and also has more extensive quinolone
resistance than most other strains.
Canadian
researchers studied a CDAD epidemic involving 1719 episodes of
infection in 12 Montreal-area hospitals. A case-control analysis
confirmed that prior use of cephalosporins and quinolones were
independent risk factors for CDAD, but clindamycin use was not. Of
157 isolates, 132 were similar or identical to the epidemic strain
described above, and severe illness was more common in patients with
this strain than in others.
In
2005, Pennsylvania health authorities identified two cases of severe
community-based CDAD. A 31-year-old woman pregnant with twins
developed severe colitis that evolved into toxic megacolon; both the
patient and the fetuses died. The patient's only antibiotic exposure
was to trimethoprim-sulfamethoxazole, prescribed for a urinary tract
infection about 3 months before the illness. A 10-year-old girl with
no antibiotic exposure developed severe CDAD requiring
hospitalization. She might have been infected by a younger brother,
who had a febrile diarrheal illness that resolved without treatment;
he also had no recent antibiotic exposure. Ten additional reports of
peripartum CDAD and 23 of community-acquired CDAD were obtained from
nearby states. Eight of the 33 patients reported no antibiotic use
within 3 months of illness. Two isolates available for analysis had
some of the virulence features identified in the epidemic hospital
strain described above.
These
reports read like the rumble of distant thunder, announcing trouble
ahead. More surveillance is needed to characterize the prevalence and
virulence of this new strain of C. difficile and to determine
if person-to-person transmission is now occurring in the community as
well as in hospitals. The only remedy at this point is what
editorialists concisely describe as "antibiotic stewardship,"
especially in limiting unnecessary use of quinolones, which are a
specific risk factor for this new strain.
Reference:
1.
McDonald LC et al. An epidemic, toxin gene-variant strain of Clostridium
difficile. N Engl J Med 2005 Dec 8; 353:2433-41.
2.
Loo VG et al. A predominantly clonal multi-institutional outbreak of Clostridium
difficile-associated diarrhea with high morbidity and mortality. N
Engl J Med 2005 Dec 8; 353:2442-9.
3.
Centers for Disease Control and Prevention. Severe Clostridium difficile-associated
disease in populations previously at low risk — Four states, 2005. MMWR
Morb Mortal Wkly Rep 2005 Dec 2; 54:1201-5.
4. Bartlett JG and Perl TM. The new Clostridium difficile — What does it mean? N Engl J Med 2005 Dec 8; 353:2503-5.