[Surveillance based on molecular epidemiology for Haemophilus influenzae Isolates in Gifu Prefecture].

ABSTRACT

We analyzed Haemophilus influenzae isolates in Gifu prefecture between May 2003 and August 2003. We conducted molecular-level epidemiological studies for 313 strains using PCR to identify resistant genes in H. influenzae. Our four sets of primers are as follows (i) p6 gene of P6 membrane protein, (ii) TEM-1 type beta-lactamase gene (bla), (iii) normal PBP 3 gene (ftsl), and (iv) mutational ftsl gene detected in beta-lactamase-nonproducing ampicillin (ABPC) resistant H. influenzae (BLNAR). H. influenzae strains were classified into 6 types based on PCR (i) beta-lactamase-nonproducing ABPC-susceptible strains (BLNAS; n = 85) with no any resistant genes, (ii) TEM-1 type beta-lactamase-producing ABPC resistant strains (BLPAR; n = 6), (iii) beta-lactamase-nonproducing and low-level ABPC-resistant strains (Low-BLNAR; n = 77) possessing Asn-526 --> Lys-526 amino acid substitution, (iv) BLNAR strains (n = 138) possessing Asn-526 --> Lys-526 and 3 amino acids substitutions detected around the Ser-Ser-Asn conserved motif, (v) beta-lactamase-producing amoxicillin-clavulanate resistant strains (BLPACR-I; n = 3) possessing TEM-1 and Low-BLNAR resistant genes, and (vi) beta-lactamase-producing amoxicillin-clavulanate resistant strains (BLPACR-II; n = 4) possessing TEM-1 and BLNAR resistant genes. Amoxicillin (AMPC) MIC90s in Low-BLNAR was 4 microg/mL and in BLNAR was 16 microg/mL. In oral cephalosporins, cefditoren MIC90 was the most excellent with 0.5 microg/mL against BLNAR. The prevalence of H. influenzae type b isolates in Matsubara Otorhinolaryngology Clinic was 66.7%. Selection of appropriate antimicrobial agents should be performed to prevent resistant microorganisms. Also, the vaccination for H. influenzae type b would be strongly recommended in near future.