Masanori Iwamoto

Yearly changes of isolated organisms from the respiratory tract in Hokusho Central Hospital

Isolated organisms from the respiratory tract have been studied in our hospital from 1986 to 1993. The total number of samples were 18,345 and samples which showed 10(5) cfu/ml organisms were 8648 in our hospital for 8 years. Enterobacteriacae, Pseudomonas aeruginosa, Haemophilus influenzae, Streptococcus pneumoniae, and glucose nonfermenting gram-negative rods were major isolates in 8 years. Haemophilus influenzae, which used to be the commonest isolate, decreased from 10.9% in 1993 while Enterobacteriacae increased from 8.9% in 1986 to 17.6% in 1993. S. pneumoniae and H. influenzae were major isolates from out-patients consisting of 50%, followed by Enterobacteriacae, P. aeruginosa and MSSA. Enterobacteriacae and P. aeruginosa were major isolates from in-patients, followed by MRSA and beta-Streptococcus. Streptococcus agalactiae, Serratia marcescens and Corynebacterium spp. prevailed especially in the geriatric ward. S. pneumoniae, H. influenzae and M. catarrhalis were major isolates from patients with pneumoconiosis, especially in winter.

A study of respiratory infection and sepsis caused by MRSA at Hokusho Central Hospital

At Hokusho Central Hospital, we studied the isolation rate of methicillin-resistant Staphylococcus aureus (MRSA) from 1985 to 1989; respiratory infection with MRSA, in 1989; and sepsis of MRSA, from 1988 to 1989. The isolation rate of MRSA from sputum increased from 0% in 1985 to 65.4% in 1989. MRSA was isolated mainly from elderly patients in a geriatric ward, with 55 of 67 strains (82%) being isolated from these patients in 1989. MIC80 of isolated MRSA strains was 0.01 microgram/ml to rifampicin, 0.02 microgram/ml to mynomycine, 3.13 micrograms/ml to vancomycin, 12.5 micrograms/ml to ofloxacin and 100 micrograms/ml to imipenem in 1989. One-third of the 60 isolated cases showed respiratory infections including 10 cases of pneumonia and 10 sepsis patients and 11 blood samples in 1988 and 1989, especially 92.9% of S. aureus isolated in 1989 was MRSA. Four of the 6 patients with respiratory infections of MRSA and 1 of the 3 patients with MRSA sepsis were treated successfully by a combination therapy of imipenem/cilastatin and cefazolin.