A nosocomial outbreak of fluoroquinolone-resistant Streptococcus pneumoniae.
Over the course of a 20-month period, in a hospital respiratory ward in which ciprofloxacin was often used as empirical antimicrobial therapy for lower respiratory tract infections (LRTIs), 16 patients with chronic bronchitis developed nosocomial LRTIs caused by penicillin- and ciprofloxacin-resistant Streptococcus pneumoniae (serotype 23 F). The minimum inhibitory concentration (MIC) of ciprofloxacin for all isolates from the first 9 patients was 4 microg/mL, in association with a parC mutation. Isolates from the subsequent 7 patients all had a ciprofloxacin MIC of 16 microg/mL, in association with an additional mutation in gyrA. The MICs for this isolate were 8 microg/mL of levofloxacin (resistant), 2 microg/mL of moxifloxacin and gatifloxacin (intermediately resistant), and 0.12 microg/mL of gemifloxacin. This outbreak demonstrates the ability of S. pneumoniae to acquire multiple mutations that result in increasing levels of resistance to the fluoroquinolones and to be transmitted from person to person.
Weiss
K
K
Department of Microbiology and Infectious Diseases, Hôpital Maisonneuve-Rosemont, University of Montreal, 5415 L'Assomption, Montreal, Quebec, Canada, H1T 2M4. weisscan@aol.com
Restieri
C
C
Gauthier
R
R
Laverdière
M
M
McGeer
A
A
Davidson
R J
RJ
Kilburn
L
L
Bast
D J
DJ
de Azavedo
J
J
Low
D E
DE
D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000494:pharmacology*; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D004352:Drug Resistance, Microbial; D018432:Drug Resistance, Multiple; D005260:Female; D024841:Fluoroquinolones; D005838:Genotype; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010641:Phenotype; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D024841:Fluoroquinolones