[Surveillance on Pseudomonas aeruginosa isolated in Gifu prefecture (2004)].

We analyzed Pseudomonas aeruginosa isolates in Gifu prefecture between September and October 2004. We conducted antimicrobial susceptibility test for 266 strains isolated from 8 medical institutes and 1 clinical laboratory, based on broth microdilution method. The MIC50 and MIC90 of piperacillin, amikacin, imipenem, and ciprofloxacin were 4 and 64, 4 and 8, 1 and 16, 0.25 and 8 microg/mL, respectively. The strains isolated from urine had higher MIC level in comparison with from sputum, which was remarkable in penicillins, cephalosporins and fluoroquinolones. We isolated 7 strains of multi-drug resistant Pseudomonas aeruginosa (MDRP), in which 3 strains showed under 16 microg/mL in MIC against anti-MRSA (methicillin-resistant Staphylococcus aureus) drug arbekacin. Continuous surveillance would be needed for antimicrobial resistance on P. aeruginosa in Gifu prefecture.

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

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.

[Epidemiology of Streptococcus pneumoniae isolates in Gifu Prefecture].

We analyzed Streptococcus pneumoniae isolates confirmed by direct PCR in Gifu prefecture between May 2002 and August 2002. We analyzed isolates of 254 strains from 6 hospitals to determine antibiotic susceptibility, genotype of penicillin-binding protein (PBP) genes and macrolide resistant genes, and the serotypes distribution of isolates from Matsubara Otorhinolaryngology Clinic. Isolates in which abnormal PBP genes of pbp1a, pbp2x, and pbp2b were identified by PCR were classified based on PCR results as follows; (i) penicillin-susceptible (PSSP) with 3 normal PBP genes, (ii) penicillin-intermediate (PISP) with an abnormal pbp2x, (iii) PISP with an abnormal php2b, (iv) PISP with abnormal pbp2x and pbp2b, (v) PISP with abnormal pbpla and pbp2x, (vi) penicillin-resistant (PRSP) with 3 abnormal PBP genes. The overall incidence of PRSP, PISP and PSSP was 121 (49%), 109 (42%) and 24 (9%), respectively, and there was a significant difference among some hospitals (p<0.05). However, there was no significant difference among the hospitals for the incidence of abnormal macrolide-resistant genes (mefA, ermB). Panipenem showed an excellent antimicrobial activity for injectable carbapenems against PRSP, following biapenem, imipenem, and meropenem. Cefditoren (CDTR) showed an excellent antimicrobial activity for oral cephalosporins against PRSP, following cefteram and cefcapene. Interestingly, there were 2 and 3 strains on MIC of CDTR for 8 and 4 microg/mL, respectively. The prevalent pneumococcal serotypes of isolates in Matsubara Clinic were 6 (17/55), following by 40 (8/55), 9 (6/5) and 15 (5/55). The endemic strains were observed in this study using pulsed field gel electrophoresis. These findings suggest the needs to continue the surveillance of bacterial resistance not only in the nationwide but also in the distict.