title: In vitro susceptibilities of 180 clinical isolates of Haemophilus influenzae to ampicillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, clarithromycin, and azithromycin.
abstract: One hundred eighty consecutive, unduplicate isolates of Haemophilus influenzae from clinical specimens collected from November 1994 through February 1995 in nine general hospitals throughout Belgium were examined for beta-lactamase production using a nitrocefin-based test, and for their in vitro susceptibilities to ampicillin, amoxycillin/clavulanate, cefaclor, cefuroxime, cefotaxime, clarithromycin and azithromycin by means of the NCCLS agar dilution test. The isolates were all from respiratory tract specimens. The prevalence of capsular type b was 1.1%, and the overall rate of beta-lactamase production 16.7%. Rates of beta-lactamase production were higher in isolates from children (22.0%) than in those from adults (15.3%), and in isolates from upper respiratory tract specimens (22.0%) than in those from the lower respiratory tract (15.1%). Beta-lactamase-negative ampicillin resistance amounted to 1.1%. Cefotaxime had the highest activity on a weight basis [MIC (minimal inhibitory concentration) for 50% of the isolates tested (MIC50) < or = 0.06 microgram/ml], followed by ampicillin (MIC50 of 0.25 microgram/ml), amoxycillin/clavulanate and cefuroxime (MIC50 of 0.5 microgram/ml), azithromycin (MIC50 of 2 micrograms/ml), cefaclor (MIC50 of 4 micrograms/ml), and clarithromycin (MIC50 of 8 micrograms/ml). Cefotaxime was also the most active drug in terms of susceptibility rates of the isolates (100.0%), followed by amoxycillin/clavulanate and azithromycin (98.9%), cefuroxime (97.2%), cefaclor (89.4%), clarithromycin (82.8%), and ampicillin (82.2%). In conclusion, amoxycillin/clavulanate and cefuroxime retain an excellent activity against H. influenzae, while cefaclor lost some of its activity. The rate of susceptibility to azithromycin was markedly higher than that to clarithromycin; however, its ability to accumulate intracellularly while concentrations in serum and interstitial fluid remain low, should be considered, as it may represent a major drawback to its use in H. influenzae infections.
authors.affiliation: UCL, Unité de Microbiologie, Bruxelles.
authors.forename: M
authors.initials: M
authors.lastname: Delmée
authors.forename: M
authors.initials: M
authors.lastname: Carpentier
authors.forename: Y
authors.initials: Y
authors.lastname: Glupczynski
authors.forename: B
authors.initials: B
authors.lastname: Gordts
authors.forename: K
authors.initials: K
authors.lastname: Magerman
authors.forename: A
authors.initials: A
authors.lastname: Simon
authors.forename: I
authors.initials: I
authors.lastname: Surmont
authors.forename: M
authors.initials: M
authors.lastname: Van de Vyvere
authors.forename: H
authors.initials: H
authors.lastname: Van Landuyt
authors.forename: L
authors.initials: L
authors.lastname: Van Nimmen
authors.forename: R
authors.initials: R
authors.lastname: Van Noyen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000658:Amoxicillin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017963:Azithromycin / Q000494:pharmacology; D002433:Cefaclor / Q000494:pharmacology; D002439:Cefotaxime / Q000494:pharmacology; D002444:Cefuroxime / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D017291:Clarithromycin / Q000494:pharmacology; D002969:Clavulanic Acids / Q000494:pharmacology; D003428:Cross Infection / Q000382:microbiology; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D008826:Microbial Sensitivity Tests; D008875:Middle Aged
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D002433:Cefaclor; D000658:Amoxicillin; D017963:Azithromycin; D017291:Clarithromycin; D002439:Cefotaxime; D002444:Cefuroxime