[Current topics on infectious diseases].

In April 2012, the Japanese Health authority recommended the establishment of an inter-hospital connection and cooperation system for infection control in each local area. This system is aimed at improving the risk of hospital-related infection in each local area units. An important role of the system is monitoring the trend of drug-resistant bacteria and detecting outbreaks; therefore, development of a bacterial laboratory system is a major subject for participating hospitals. Increasingly drug-resistant bacteria, such as extended-spectrum beta-lactamase-producing bacteria, MRSA, especially relatively high MIC strains against vancomycin (2 microg/ml), multi-drug resistant Gram-negative bacteria including Pseudomonas aeruginosa are serious issues for public health. The isolating ratio of these drug-resistant bacteria is different among hospitals even in the same local area. This is the point of organizing an inter-hospital infection control system. Last year, The Japanese Society for Respiratology developed management guidelines for Nursing Home and Health Care facility-associated pneumonia(NHCAP). This Japanese guideline and USA guidelines for similar situations state almost the same position. Namely, such pneumonia patients should be treated empirically with combination antibiotics covering drug-resistant bacteria, especially for MRSA and P. aeruginosa; however, in spite of this strengthened antibiotic coverage policy, one multicenter cohort study showed that guideline-based strengthened therapy increased the mortality of patients. The author drew the conclusion that too strong combination antibiotic therapy may be harmful to elderly patients. From these results, it should be considered that the causative agents of pneumonia cannot be determined from respiratory specimens so exactly, because the specimens include merely colonized bacteria and also anaerobic causative agents.

[Clinical microbiological investigation of vancomycin intermediate Staphylococcus aureus during glycopeptide therapy].

We isolated three strains of vancomycin intermediate Staphylococcus aureus (VISA) from a blood sample of a patient with infective endocarditis (VISA-1), postoperative pneumonia sputum (VISA-2), and pyogenic spondylitis blood sample (VISA-3). These VISA strains did not carry vanA, vanB, vanC1, or vanC2/C3 genes. Cell wall thickening was observed. VISA-1 and VISA-3 PFGE patterns showed the completely same pattern compared to the PFGE pattern of methicillin-resistant Staphylococcus aureus first isolated from patients 1 and 3. After 10 days on brain heart infusion agar, wall thickening in all three type of VISA was unchanged, but VISA-2 and VISA-3 reversed vancomycin susceptibility. The most suitable use of vancomycin in patients with MRSA infection thus appears to be in reducing the opportunity for cell wall thickening.