A multicenter study of the prevalence and susceptibility patterns of isolates of Streptococcus pneumoniae with reduced susceptibility to penicillin G in Louisiana.
Because of increasing reports of multiple-antibiotic-resistant strains of Streptococcus pneumoniae and associated clinical failures, this study was performed to determine the prevalence of multiresistance among strains from nine Louisiana medical centers. Using a National Committee for Laboratory Standards broth microdilution method, 481 strains were tested. Of these, 70% were penicillin-susceptible (PS), 23% had intermediate minimum inhibitory concentration values to penicillin (I), and 7% were fully resistant to penicillin (PR). The isolation rates (15% to 40% for I strains and 0% to 33% for PR strains) at the various medical centers varied appreciably. The prevalence of penicillin resistance was highest among upper respiratory isolates, while cross-resistance to other antimicrobials varied. The least cross-resistance was noted among PS strains. However, strains with reduced penicillin susceptibility had high levels of cross-resistance. Among I strains, the prevalence of cross-resistance (%) was noted for amoxicillin/clavulanate (6%), cefuroxime (71%), cefaclor (91%), ceftriaxone (13%), cefotaxime (34%), erythromycin (67%), azithromycin (32%), and clarithromycin (32%). For PR strains, the prevalence of cross-resistance was 97% for amoxicillin/clavulanate, cefuroxime, and cefaclor; 67% for ceftriaxone and erythromycin; 89% for cefotaxime; and 69% for azithromycin and clarithromycin. These data emphasize the high prevalence of multiple-antimicrobial-resistance among strains of S pneumoniae with reduced penicillin susceptibility in this geographic area.
Aldridge
K E
KE
Department of Medicine, Louisiana State University Medical Center, New Orleans 70112, USA.
Ashcraft
D S
DS
O'Cain
P
P
Sanders
C V
CV
Janney
A
A
Brown
W
W
Silberman
R
R
Pankey
G K
GK
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D006801:Humans; D007753:Laboratories / Q000592:standards; D008145:Louisiana / Q000453:epidemiology; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D010400:Penicillin G / Q000627:therapeutic use*; D010403:Penicillin Resistance; D015995:Prevalence; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D010400:Penicillin G