Epidemiology of elevated fluoroquinolone MICs of S. pneumoniae, H. influenzae, and M. catarrhalis from the GLOBAL Study (1999–2005)

Abstract number: P1234

Brown N., Draghi D., Sahm D., Pillar C.

Objective: Isolates (ISO) were collected during 1999, 2002, 2003, and 2005 as part of the GLOBAL study, during which 360 S. pneumoniae (SP) showed levofloxacin (LFX) MICs geqslant R: gt-or-equal, slanted2 mg/L by broth microdilution. Serotyping profiles of these SP were determined in this study. Previous experience has shown that in studies where LFX resistance rates were in excess of 1% that it was often the result of an outbreak of clonal ISO. To address the relatedness of SP ISO from 2005 with elevated LFX MICs, pulsed-field gel electrophoresis (PFGE) was performed and related to QRDR profile and serotype (ST). In addition, 8 ISO of H. influenza (HI) and M. catarrhalis (MC) with elevated LFX MICs (geqslant R: gt-or-equal, slanted0.05 mg/L) were subjected to PFGE analysis to determine relatedness, if any.

Methods: ISO were centrally tested by broth microdilution (CLSI; M7-A7) and interpreted according to CLSI M100-S16 and M45-P (MC). 84 SP with MICs geqslant R: gt-or-equal, slanted2 mg/L were STed using standard methodology. ISO of SP, HI, and MC from 2005 with elevated LFX MICs underwent PFGE. ISO with geqslant R: gt-or-equal, slanted90% similarity in PFGE pattern were considered related. SP were further characterised by sequencing the quinolone resistance determining regions (QRDRs) of gyrA, gyrB, parC, and parE.

Results: Among the 360 SP with elevated LFX MICs from 1999–2005, 44 STs were identified and STs 23F, 14, and 19F were the most common (>10% each). Among the 2005 SP ISO (N=86), STs 8, 19F, and 23F were detected at >10%. Of these, there were 5 genetically related groups detected by PFGE (1 centre in Spain (ES) [n = 3], 2 separate centres in ES [n = 34], 1 centre in Hong Kong (HK) [n = 3], a separate centre in HK [n = 3], and 1 centre in Germany (DE) [n = 3]). Similar STs and QRDR profiles were observed within each group. The remaining SP ISO showed little genetic similarity with a wide distribution of STs. Little genetic relatedness was observed among ISO of HI and MC with elevated LFX MICs.

Conclusion: Among the SP from 2005 with elevated MICs to LFX, 5 clusters of genetically related ISO were detected suggesting outbreaks of certain lineages of this phenotype within centres in ES, DE, and HK. The remaining SP ISO were of variable ST, PFGE patterns and QRDR profiles. Few HI and MC ISO with elevated LFX MICs were detected in 2005, and no genetic relatedness was apparent among these ISO. These results illustrate the importance of utilising both surveillance and molecular epidemiological studies for monitoring the emergence and spread of resistance.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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