Quinolone-Resistant Haemophilus influenzae in a Long-Term Care Facility: Clinical and Molecular Epidemiology

Abstract

We describe a clonal outbreak of quinolone-resistant Haemophilus influenzae (QRHI) from an affiliated long-term care facility (LTCF-A); the outbreak was associated with the clinical use of levofloxacin, which was determined to be a risk factor for acquisition of QRHI. The minimum inhibitory concentration to which 90% of isolates were susceptible (MIC90), as determined by broth microdilution, was >4 microg/mL for levofloxacin, >2 microg/mL for moxifloxacin, >2 microg/mL for gatifloxacin, and 8 microg/mL for gemifloxacin. The MIC90, as determined by Etest (AB Biodisk), was >32 microg/mL for levofloxacin, ciprofloxacin, moxifloxacin, and gatifloxacin. Having been a resident at LTCF-A and having chronic obstructive pulmonary disease were significant risk factors for acquisition of QRHI at our 500-bed hospital (New York Hospital Queens). All QRHI isolates were found to be genetically related by pulsed-field gel electrophoresis, were nontypeable, were susceptible to ceftriaxone and azithromycin, and were negative for beta -lactamase production. Emphasis on patient contact and respiratory isolation and placing colonized or infected patients in cohorts yielded a marked reduction in the prevalence of QRHI at LTCF-A.

Melting Curve Analysis for Rapid Detection of Topoisomerase Gene Mutations inHaemophilus influenzae

“…Recent reports have noted the prevalence of fluoroquinolone (FQ)-resistant H. influenzae (1,3,4,9,11,14,20,22,26). FQ-resistant H. influenzae often carries mutations in the quinolone resistance-determining regions (QRDRs) of the gyrA and the parC genes, which encode subunits of DNA gyrase and topoisomerase IV, respectively (9,11,16,18,23).…”

Emergence of Fluoroquinolone-Resistant Haemophilus influenzae Strains among Elderly Patients but Not among Children

“…The recent increase in BLNAR strains has become a severe problem, leading to community-acquired infections (8,19). Fluoroquinolone-resistant H. influenzae isolates have occasionally been reported worldwide (1,4,13,15), but they have rarely been reported in Japan (9,10). Fluoroquinolones are effective against the causative agents of atypical pneumonia, such as Chlamydophila pneumoniae and Mycoplasma pneumoniae, as well as those of typical bacterial pneumonia, S. pneumoniae and H. influenzae.…”

Quinolone-Resistant Haemophilus influenzae in a Long-Term-Care Facility: Nucleotide Sequence Characterization of Alterations in the Genes Encoding DNA Gyrase and DNA Topoisomerase IV

“…Concomitantly, the prevalence of resistant Streptococcus pneumoniae has increased (5,9), and occasionally resistant isolates of Haemophilus influenzae, which is generally highly susceptible to fluoroquinolones, have been recovered (1-4, 6, 10-12, 14, 15). Recently, an outbreak of levofloxacin-resistant H. influenzae was observed in a long-term care facility (13). Epidemiological data and electrophoretic analysis of DNA fragments from resistant isolates of the outbreak suggested that the resistant isolates were clonally related (13).…”

“…Recently, an outbreak of levofloxacin-resistant H. influenzae was observed in a long-term care facility (13). Epidemiological data and electrophoretic analysis of DNA fragments from resistant isolates of the outbreak suggested that the resistant isolates were clonally related (13). To characterize the DNA regions likely to be responsible for the resistance, we have examined isolates for nucleotide sequence changes within mutational hot spots, called quinolone resistance-determining regions (QRDRs), of genes encoding DNA gyrase and DNA topoisomerase IV.…”

“…Colonies on each plate were counted after overnight incubation. The MIC at which 99% of isolates were inhibited (8) Clinical isolates of H. influenzae were recovered during a 1-year study (May 2001 to May 2002) in which 28 cases of levofloxacin-resistant H. influenzae were identified in a longterm health care facility in Queens, N.Y. (13). At the same time, levofloxacin-susceptible H. influenzae was recovered from seven patients in the facility.…”