title: Canadian beta-lactamase-negative Haemophilus influenzae isolates showing decreased susceptibility toward ampicillin have significant penicillin binding protein 3 mutations.
abstract: Nineteen beta-lactamase-negative ampicillin-resistant (BLNAR) and 2 beta-lactamase-positive amoxicillin-clavulanic acid-resistant Canadian Haemophilus influenzae strains were characterized. All 21 isolates were found to have the N526K mutations in their ftsI genes, and their ampicillin MIC(50) values were 4-8 times that of beta-lactamase-negative ampicillin-susceptible strains. The difficulty in detection of BLNAR strains was discussed.
authors.affiliation: Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory, Public Health Agency of Canada, Winnipeg, Manitoba, Canada. david.horn@jefferson.edu
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Shuel
authors.forename: Raymond S W
authors.initials: RS
authors.lastname: Tsang
mesh_terms: D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D019943:Amino Acid Substitution / Q000235:genetics; D019980:Amoxicillin-Potassium Clavulanate Combination / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D000668:Ampicillin Resistance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002170:Canada; D002675:Child, Preschool; D004269:DNA, Bacterial / Q000235:genetics; D005260:Female; D006192:Haemophilus Infections / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology / Q000302:isolation & purification; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D020125:Mutation, Missense; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D001618:beta-Lactamases / Q000096:biosynthesis
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D046915:Penicillin-Binding Proteins; D019980:Amoxicillin-Potassium Clavulanate Combination; D000667:Ampicillin; D001618:beta-Lactamases