[One-year surveillance study of antimicrobial resistance in major bacteria except for MRSA isolated in eight medical facilities in Kumamoto prefecture].

To investigate the current status of drug-resistant bacteria (except MRSA) in Kumamoto prefecture, a study was conducted to determine the isolation numbers and ratios of extended-spectrum beta-lactamase (ESBL)-Escherichia coli, ESBL-Klebsiella species, ESBL-Proteus mirabilis, two-drug resistant Pseudomonas aeruginosa, (resistant to two drugs either carbapenems, quinolones and aminoglycosides) multi-drug-resistant Pseudomonas aeruginosa, multi-drug-resistant Acinetobacter baumannii, and vancomyacin-resistant Enterococcii in eight general hospitals from May in 2009 to April in 2010. ESBL-E. coli was mostly isolated, and two-drug resistant P. aeruginosa came second. The isolation ratio of overall drug-resistant bacteria did not increase, while the isolation ratio of two-drugs resistant P. aeruginosa declined, suggesting that infection control was successfully conducted in these hospitals. However, the isolation numbers of ESBL-Klebsiella spp. and two-drug resistant P. aeruginosa were variable in each hospital. Furthermore, drug-resistant bacteria were occasionally spread into another medical facilities by patients transferred from these hospitals, indicating that sharing information on drug-resistant bacteria between medical facilities is required.

[Usefulness and limit of Gram staining smear examination].

Gram staining is one of the most simple and inexpensive methods for the rapid diagnosis of bacterial and fungal infections. It yields results much faster than culture, and provides important data for the patient's treatment and prognosis. However, a difference exists in the quality and quantity of information yielded by Gram staining smears based on the experience and knowledge of those conducting the tests. Therefore, a risk of misdiagnosis based on the information obtained from Gram staining smears is also present. The Gram staining conditions and morphology of bacteria sometimes change due to antimicrobial therapy. Species of Gram-negative rods sometimes become filamentous and pleomorphic. Gram-positive bacteria may become gram variable (change in staining condition) after antimicrobial therapy. Even bacteria that are easy to mis-identify exist, because the morphology of bacteria may be similar. Enterococcus faecalis is a Gram-positive diplococcus, forming Gram-positive clustered cocci in specimens from blood culture bottles, resembling Streptococcus pneumoniae. Acinetobacter baumannii is a Gram-negative diplococcus in sputum, resembling Moraxella (Branhamella) catarrhalis. Pasteurella multocida is a small-sized, Gram-negative short rod in the sputum, resembling Haemophilus influenzae. Prevotella intermedia is a small-sized, Gram-negative short rod in sputum, resembling Haemophilus influenzae. Capnocytophaga sp. is a Gram-negative fusiform (thin needle shape) rod present in clinical specimens, resembling Fusobacterium nucleatum.

[Hospital-acquired Streptococcus pneumoniae infection].

Three elderly patients were consecutively found to harbor or to become infected with intermediate-level penicillin-resistant Streptococcus pneumoniae in a hospital respiratory ward. All the isolates from the respective patients produced mucoid-type colonies on sheep blood agar plates and were found to have an identical antibiogram, indicating that those were resistant against erythromycin, clarithromycin, clindamycin and minocycline. Pulse-field gel electrophoresis of genomic DNA digested Sma I and Apa I demonstrated homology among the isolates, which may suggest person-to-person spread in a hospital setting. With this, it is an urgent to establish the institution-based infection control precautions against S. pneumoniae.