HOMEPRODUCTSCOMPANYCONTACTFAQResearchDictionaryPharmaSign Up FREE or Login

Molecular characterization of fluoroquinolone resistance in nontypeable Haemophilus influenzae clinical isolates.

Abstract
Nontypeable Haemophilus influenzae (NTHi) is a common cause of respiratory infections in adults, who are frequently treated with fluoroquinolones. The aims of this study were to characterize the genotypes of fluoroquinolone-resistant NTHi isolates and their mechanisms of resistance. Among 7,267 H. influenzae isolates collected from adult patients from 2000 to 2013, 28 (0.39%) were ciprofloxacin resistant according to Clinical and Laboratory Standards Institute (CLSI) criteria. In addition, a nalidixic acid screening during 2010 to 2013 detected five (0.23%) isolates that were ciprofloxacin susceptible but nalidixic acid resistant. Sequencing of their quinolone resistance-determining regions and genotyping by pulse-field gel electrophoresis and multilocus sequence typing of the 25 ciprofloxacin-resistant isolates available and all 5 nalidixic acid-resistant isolates were performed. In the NTHi isolates studied, two mutations producing changes in two GyrA residues (Ser84, Asp88) and/or two ParC residues (Ser84, Glu88) were associated with increased fluoroquinolone MICs. Strains with one or two mutations (n = 15) had ciprofloxacin and levofloxacin MICs of 0.12 to 2 μg/ml, while those with three or more mutations (n = 15) had MICs of 4 to 16 μg/ml. Long persistence of fluoroquinolone-resistant strains was observed in three chronic obstructive pulmonary disease patients. High genetic diversity was observed among fluoroquinolone-resistant NTHi isolates. Although fluoroquinolones are commonly used to treat respiratory infections, the proportion of resistant NTHi isolates remains low. The nalidixic acid disk test is useful for detecting the first changes in GyrA or in GyrA plus ParC among fluoroquinolone-susceptible strains that are at a potential risk for the development of resistance under selective pressure by fluoroquinolone treatment.
AuthorsCarmen Puig, José Manuel Tirado-Vélez, Laura Calatayud, Fe Tubau, Junkal Garmendia, Carmen Ardanuy, Sara Marti, Adela G de la Campa, Josefina Liñares
JournalAntimicrobial agents and chemotherapy (Antimicrob Agents Chemother) Vol. 59 Issue 1 Pg. 461-6 (Jan 2015) ISSN: 1098-6596 [Electronic] United States
PMID25385097 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
CopyrightCopyright © 2015, American Society for Microbiology. All Rights Reserved.
Chemical References
  • Anti-Bacterial Agents
  • DNA, Bacterial
  • Fluoroquinolones
  • Nalidixic Acid
  • Ciprofloxacin
  • Levofloxacin
  • DNA Topoisomerase IV
  • DNA Gyrase
Topics
  • Aged
  • Aged, 80 and over
  • Anti-Bacterial Agents (therapeutic use)
  • Bacterial Typing Techniques
  • Base Sequence
  • Ciprofloxacin (therapeutic use)
  • DNA Gyrase (genetics)
  • DNA Topoisomerase IV (genetics)
  • DNA, Bacterial (genetics)
  • Drug Resistance, Bacterial (genetics)
  • Female
  • Fluoroquinolones (therapeutic use)
  • Genetic Variation
  • Haemophilus Infections (drug therapy, microbiology)
  • Haemophilus influenzae (drug effects, genetics, isolation & purification)
  • Humans
  • Levofloxacin (therapeutic use)
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Multilocus Sequence Typing
  • Nalidixic Acid (therapeutic use)
  • Pulmonary Disease, Chronic Obstructive (microbiology)
  • Respiratory Tract Infections (drug therapy, microbiology)
  • Sequence Analysis, DNA

Join CureHunter, for free Research Interface BASIC access!

Take advantage of free CureHunter research engine access to explore the best drug and treatment options for any disease. Find out why thousands of doctors, pharma researchers and patient activists around the world use CureHunter every day.
Realize the full power of the drug-disease research graph!


Choose Username:
Email:
Password:
Verify Password:
Enter Code Shown: