Sporadic isolations of a multi-drug resistant Pseudomonas aeruginosa clone during a 14-month epidemic in a general hospital in Hiroshima.

BACKGROUND: During 2005-2007, we experienced sporadic isolations of multidrug-resistant (MDRP) Pseudomonas aeruginosa from wards in a general hospital in Hiroshima. The objective of this study was to analyze epidemiology relationships and the mode of spread of the strains. METHODS: Clonality was assessed using pulsed-field gel electrophoresis (PFGE) and serotyping. MICs were determined using the microdilution broth method. Investigations of the affected patients' movements and environmental sampling from the affected wards were conducted. RESULTS: An abrupt increase in MDRP isolations began at the end of 2005 and ended in February 2007. A total of 25 MDRP strains were sporadically isolated from nine wards. Fourteen strains were genotypically and serologically identical. Analysis of the patients' movements identified that six of the 14 MDRP-positive patients became positive for MDRP when they were in the intensive care unit (ICU), and two became positive after the patients moved from the ICU to another nursing unit. Four MDRP strains were isolated from patients who did not stay in the ICU and were in ward E6, which had the second highest number of isolations. In July 2006, environmental sampling of the hospital identified a toilet brush in ward E6 that was contaminated with MDRP that was genotypically and serologically identical to the clinical isolates. CONCLUSIONS: Our study suggests that the sporadic increase in MDRP isolates during 2005-2007 in the general hospital in Hiroshima was due to an epidemic of an MDRP clone. Continuity and spread of infection was probably due to cross infection and contamination in the hospital with the MDRP strain.

[Results of antimicrobial susceptibilities of strains clinically isolated at 8 institutions in Hiroshima City to major oral antimicrobial drugs, mainly new quinolone drugs. Hiroshima Levofloxacin Susceptibility Surveillance Group].

To evaluate the resistance for major oral antimicrobial agents, mainly new quinolones, we carried out a drug susceptibility surveillance of 3,050 strains of 11 microbial species clinically isolated at 8 institutions such as general hospitals and examination centers in Hiroshima city. 10 antimicrobial agents were used: 3 new quinolone drugs, 5 beta-lactam drugs, minocycline and clarithromycin. Among Gram-positive bacteria, methicillin resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis showed low susceptibility to the new quinolone drugs, while methicillin susceptible Staphylococcus aureus (MSSA) and Streptococcus pneumoniae were highly sensitive to these drugs. Among Gram-negative bacteria, Pseudomonas aeruginosa showed high resistance for the new quinolone drugs, but enteric bacteria and Haemophilus influenzae did not show marked resistance, maintaining almost good sensitivity to these drugs. To reduce the appearance of resistant bacteria, appropriate antimicrobial agents should be selected. Drug susceptibility surveillance in the community will be also important in the future.

[The antimicrobial susceptibilities and serotypes of Pseudomonas aeruginosa isolated from sputum].

During the period of January 1992 and August 1995, 75 strains of Pseudomonas aeruginosa were isolated from sputum at the Hiroshima Prefectural Hiroshima Hospital. The antimicrobial susceptibilities and serotypes of those strains were investigated. The results are summarized as follows: 1. The analyses of antimicrobial susceptibilities revealed that meropenem (MEPM) was the most active among the carbapenems tested against those P. aeruginosa strains with MIC of < or = 6.25 micrograms/ml. All of the strains were thus found to be susceptible to MEPM, while 9 strains out of 75 (12%) were resistant to imipenem showing cross-resistance to biapenem. 2. The activities of the beta-lactams other than carbapenems were found to be the order of cefozopran > or = ceftazidime > aztreonam > piperacillin with MIC50 and MIC90 ranging of 3.13-6.25 micrograms/ml and 25- > or = 100 micrograms/ml, respectively. 3. Among aminoglycosides tested, 3 strains (4.0%) of the strains showed resistance to amikacin, however none of them were resistant to tobramycin. 4. Distribution of serotypes among the strains was; type G 22.7%, type M 21.3%, type A 16.0%, type B 13.3% and type E 8.0%. Strains of types M and E showed multiple resistance to beta-lactams except carbapenems. As documented in this study, the frequency of isolation of beta-lactam-resistant P. aeruginosa (including carbapenem-resistant) is steadily increasing. Continuous surveillance of antimicrobial susceptibility among clinically isolated P. aeruginosa seems to be necessary.

[Laboratory and clinical studies of norfloxacin in respiratory tract infections].

Norfloxacin (NFLX), a new quinolone antibacterial agent, was investigated for its antibacterial activity and clinical efficacy on respiratory tract infections. The results obtained are summarized as follows: 1. Antibacterial activities were evaluated against 127 strains of various bacteria isolated from clinical sources. MIC80's of this drug were: against Staphylococcus aureus and Streptococcus pyogenes 1.56 micrograms/ml; Haemophilus influenzae 0.05 microgram/ml or less; and Klebsiella sp. and Enterobacter sp. 0.10 microgram/ml. These antibacterial activities were superior to these of ampicillin and cephalexin, except against S. pyogenes. 2. Clinical responses to NFLX in a total of 32 cases with respiratory tract infections were excellent in 9 cases, good in 12, fair in 9, poor in 2, with an efficacy rate of 65.6%. Neither adverse reactions nor abnormalities of laboratory test results were observed.

[Experimental and clinical studies on cefmetazole in the field of internal medicine].

Susceptibilities in various types of clinical isolates to cefmetazole (CMZ) were determined by the disk method and the serial agar dilution method for MIC measurement. CMZ showed high antibacterial activity for all Gram-positive cocci except E. faecalis, and for H. influenzae, E. coli, Klebsiella sp. and Proteus sp.. CMZ was administered on 33 patients with infections, mainly biliary tract infections, in the field of internal medicine. The clinical efficacy of the drug was 86.7% for infections of the biliary tract, 80.0% for respiratory tract infections, 100% for urinary tract infections and 76.7% for all cases. There were no adverse reaction or changes in laboratory findings caused by CMZ in any of the patients.