Presence of ROB-1 beta-lactamase correlates with cefaclor resistance among recent isolates of Haemophilus influenzae.
beta-Lactamase production in Canadian isolates of Haemophilus influenzae has remained relatively constant (25-35%) over the last decade despite increasing cefaclor resistance (MIC >/= 32 mg/L). TEM (294/324, 90.7%) and ROB-1 (30/324, 9.3%) prevalence rates among 324 isolates of H. influenzae obtained from across Canada in 1997-1998 were similar (P > 0.05) to previously published reports. However, 66. 7% (26/39) of cefaclor-resistant isolates were ROB-1-positive (P < 0. 001) and the remaining four ROB-1-positive isolates were cefaclor-intermediate (MIC 16 mg/L). Susceptibilities to loracarbef (P < 0.001) and cefprozil were also reduced in the presence of ROB-1 while the activities of cefuroxime, cefotaxime, cefixime and imipenem were similar in both TEM- and ROB-1-positive solates.
Karlowsky
J A
JA
Department of Medical Microbiology and Faculty of Pharmacy, University of Manitoba, Winnipeg, Manitoba, Canada. jkarlowsky@hsc.mb.ca
Verma
G
G
Zhanel
G G
GG
Hoban
D J
DJ
D002170:Canada / Q000453:epidemiology; D002433:Cefaclor / Q000494:pharmacology*; D018550:Cephalosporin Resistance; D002511:Cephalosporins / Q000494:pharmacology*; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D006801:Humans; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014481:United States / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*
D002511:Cephalosporins; D002433:Cefaclor; C071165:beta-lactamse ROB-1; D001618:beta-Lactamases