Widespread distribution of urinary tract infections caused by a multidrug-resistant Escherichia coli clonal group.
BACKGROUND
The management of urinary tract infections is complicated by the increasing prevalence of antibiotic-resistant strains of Escherichia coli. We studied the clonal composition of E. coli isolates that were resistant to trimethoprim-sulfamethoxazole from women with community-acquired urinary tract infections.


METHODS
Prospectively collected E. coli isolates from women with urinary tract infections in a university community in California were evaluated for antibiotic susceptibility, O:H serotype, DNA fingerprinting, pulsed-field gel electrophoretic pattern, and virulence factors. The prevalence and characteristics of an antibiotic-resistant clone were evaluated in this group of isolates and in those from comparison cohorts in Michigan and Minnesota.


RESULTS
Fifty-five of the 255 E. coli isolates (22 percent) from the California cohort were resistant to trimethoprim-sulfamethoxazole as well as other antibiotics. There was a common pattern of DNA fingerprinting, suggesting that the isolates belonged to the same clonal group (clonal group A), in 28 of 55 isolates with trimethoprim-sulfamethoxazole resistance (51 percent) and in 2 of 50 randomly selected isolates that were susceptible to trimethoprim-sulfamethoxazole (4 percent, P<0.001). In addition, 11 of 29 resistant isolates (38 percent) from the Michigan cohort and 7 of 18 (39 percent) from the Minnesota cohort belonged to clonal group A. Most of the clonal group A isolates were serotype O11:H(nt) or O77:H(nt), with similar patterns of virulence factors, antibiotic susceptibility, and electrophoretic features.


CONCLUSIONS
In three geographically diverse communities, a single clonal group accounted for nearly half of community-acquired urinary tract infections in women that were caused by E. coli strains with resistance to trimethoprim-sulfamethoxazole. The widespread distribution and high prevalence of E. coli clonal group A has major public health implications.
Manges
A R
AR
Division of Epidemiology and Public Health Biology, School of Public Health, University of California at Berkeley, 94720, USA.
Johnson
J R
JR
Foxman
B
B
O'Bryan
T T
TT
Fullerton
K E
KE
Riley
L W
LW
D000293:Adolescent; D000328:Adult; D000368:Aged; D000892:Anti-Infective Agents, Urinary / Q000494:pharmacology / Q000627:therapeutic use; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology; D016172:DNA Fingerprinting; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006801:Humans; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D015995:Prevalence; D012703:Serotyping; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology / Q000627:therapeutic use; D014552:Urinary Tract Infections / Q000453:epidemiology / Q000382:microbiology*; D014774:Virulence / Q000235:genetics
D000892:Anti-Infective Agents, Urinary; D015662:Trimethoprim, Sulfamethoxazole Drug Combination