Sensitivity surveillance of Haemophilus influenzae isolates for several antibiotics in Gifu prefecture (2006)

KAERIYAMA MAKOTO, MIZUNAGA SHINGO, MITSUYAMA JUNICHI, YAMAOKA KAZUKIYO, ASANO YUKO, SAWAMURA HARUKI, SUEMATSU HIROYUKI, TERAJI MAYUMI, TSUCHIYA MASAKO, HASHIDO HIKONORI, MATSUKAWA YOKO, MATSUBARA SHIGENORI, MIYABE TAKANORI, WATANABE KUNITOMO, MIKAMO HIROSHIGE

doi:10.11553/antibiotics1968b.61.195

We investigated the susceptibility to antibacterials of 194 strains of Haemophilus influenzae isolated from medical facilities in Gifu prefecture between 2005 and 2006, and compared these results with those of 280 strains of H.influenzae isolated between 1999 and 2000. Additionally, the strains that had been separated between 2005 and 2006 were examined for β-lactamase (BL) production, the muta tion of ftsI gene coding for PBP3, the bla gene coding for TEM type of BL and the serotype. Referring to the CLSI breakpoint, H.influenzae strains were classified into the following categories: (1) β-lactamase-negative ampicillin-susceptible (BLNAS) strains, which showed BL negative, ampicillin (ABPC) and ampicillin/sulbactam (ABPC/SBT)-MIC<1μg/ml,(2) β-lactamase producing ampicillinresistant (BLPAR) strains, which showed BL producing and ABPC/SBT-MIC<2μg/ml,(3) β-lactamasenegative ampicillin-resistant (BLNAR) strains, which showed BL negative, ABPC and ABPC/SBT-MIC>μ g/ml,(4) β-lactamase-producing amoxicillin/clavulanic acid-resistant (BLPACR) strains, which showed BL producing and ABPC/SBT-MIC>2μg/ml. The prevalence of each resistance class were 71.8% for BLNAS, 7.9% for BLPAR, 19.6% for BLNAR and 0.7% for BLPACR in strains isolated between 1999 and 2000. But they were 38.1% for BLNAS, 4.6% for BLPAR, 54.6% for BLNAR and 2.6% for BLPACR in strains isolated between 2005 and 2006, indicating that the percentage of BLNAS and BLPAR decreased and that of BLNAR and BLPACR increased from 1999-2000 to 2005-2006. On the basis of ftsI substitutions and having bla gene, the strains isolated between 2005 and 2006 were classified into the following distribution: 24.2% for gBLNAS, 4.1% for gBLPAR, 10.8% for gLow-BLNAR, 57.7% for gBLNAR, and 3.1% for gBLPACR-II. Ratio of BLNAR belonging to gBLNAR and gLow-BLNAR based on the ftsI substitutions and having bla gene was higher than that based on the susceptibility pattern. The MIC₅₀ and MIC₉₀ for those strains isolated between 2005 and 2006 were as follows; 0.0039, 0.0156μg/ml for garenoxacin, 0.0078, 0.0156μg/ml for tosufloxacin and ciprofloxacin, 0.0156, 0.0313μg/ml for levofloxacin, 0.0313, 0.0625μg/ml for norfloxacin, 0.0625, 0.25μg/ml for piperacillin/ tazobactam, 0.0625, 0.5μg/ml for piperacillin, 0.125, 0.25μg/ml for ceftriaxone and cefditoren, 0.5, 1μg/ml for cefteram, chloramphenicol and tetracycline, 0.5, 2μg/ml for cefotaxime, 2, 8μg/ml for ampicillin, ampicillin/sulbactam and cefdinir. In comparison with the values for the strains isolated between 1999 and 2000, the MIC₅₀s of β-lactam for the strains isolated between 2005 and 2006 increased over 4 times.

Sensitivity surveillance of <I>Haemophilus influenzae</I> isolates for several antibiotics in Gifu prefecture (2006)

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