Molecular characterization of a clinical Haemophilus parainfluenzae isolate with cefotaxime resistance and decreased susceptibility to fluoroquinolones

Abstract We report an H. parainfluenzae clinical isolate resistant to cefotaxime and with decreased susceptibility to ciprofloxacin recovered from a patient with cystic fibrosis. The isolate had elevated MICs of ampicillin (256 mg/L), amoxicillin-clavulanate (8 mg/L), cefuroxime (8 mg/L) and cefotaxime (4 mg/L), and showed a β-lactamase-producing amoxicillin-clavulanic acid-resistant (BLPACR) phenotype. A bla TEM-1 plus five amino acid substitutions in the PBP3 were found: Ser385Thr, Val511Ala, Ile519Val, Asn526Lys and Asp551Leu. MIC of ciprofloxacin was 0.5 mg/L, and substitutions in gyr A (Ser84Tyr) and par C (Ser84Phe) genes were detected.