[Susceptibilities of bacteria isolated from patients with respiratory infectious diseases to antibiotics (1994)]

Bacteria isolated from lower respiratory tract infections were collected in cooperation with institutions located throughout Japan, since 1981. IKEMOTO et al. have been investigating susceptibilities of these isolates to various antibacterial agents and antibiotics, and characteristics of the patients and isolates from them each year. Results obtained from these investigations are discussed. In 23 institutions around the entire Japan, 492 strains of presumably etiological bacteria were isolated mainly from the sputum of 421 patients with lower respiratory tract infections from October 1994 to September 1995. MICs of various antibacterial agents and antibiotics were determined against 70 strains of Staphylococcus aureus, 101 strains of Streptococcus pneumoniae, 92 strains of Haemophilus influenzae, 61 strains of Pseudomonas aeruginosa (non-mucoid strains), 25 strains of Pseudomonas aeruginosa (mucoid strains), 48 strains of Moraxella subgenus Branhamella catarrhalis, 14 strains of Klebsiella pneumoniae etc., and the drug susceptibilities of these strains were assessed except for those strains that died during transportation. 1. S. aureus. S. aureus strains for which MICs of oxacillin were higher than 4 micrograms/ml (methicillin-resistant S. aureus) accounted for 51.4%, but the frequency of the drug resistant bacteria decreased comparing to the previous year's 56.0%. Vancomycin showed the highest activity against S. aureus with MIC80 of 0.5 microgram/ml. 2. S. pneumoniae. Most of the drugs tested showed potent activities against S. pneumoniae. Imipenem of carbapenems showed the most potent activity with MIC80 was 0.063 microgram/ml. Erythromycin and clindamycin showed low activities with MIC80s > or = 256 micrograms/ml. Among these strains, however, 46.5% and 68.3% of strains, were quite sensitive toward these agents, respectively, with MICs of 0.063 microgram/ml. 3. H. influenzae. The activities of all drugs were potent against H. influenzae tested. Cefmenoxime a cephem, showed the most potent activity, the MICs of this drug against all of the 92 strains were 0.063 microgram/ml. Ofloxacin also showed a potent activity, and inhibited about 96% of strains with MIC of 0.063 microgram/ml. 4. P. aeruginosa (mucoid strains). Tobramycin showed the most potent activity against P. aeruginosa (mucoid strains) with MIC80 of 0.5 microgram/ml. Gentamicin, arbekacin and ciprofloxacin showed next potent activities, and their MIC80s were 2 micrograms/ml. 5. P. aeruginosa (non-mucoid strains). Tobramycin showed the most potent activity against P. aeruginosa (non-mucoid strains) with MIC80 of 2 micrograms/ml. Comparing to the activities against P. aeruginosa (mucoid strains), the activities of all the drugs tested were lower against P. aeruginosa (non-mucoid strains). 6. K. pneumoniae. Carumonam showed the most potent activity against K. pneumoniae with MIC80 of 0.063 microgram/ml. Cefozopran showed the next most potent activity with MIC80 of 0.125 microgram/ml. Ampicillin and cephems except cefpodoxime, cefozopran and cefditoren showed low activities and their MIC80s were > or = 16 micrograms/ml, and their MICs were all higher than > or = 4 micrograms/ml. 7. M. (B.) catarrhalis. Imipenem and ofloxacin showed the most potent activities against M. (B.) catarrhalis, their MIC80s were 0.063 microgram/ml. Erythromycin and minocycline showed the next highest activities with their MIC80s at 0.25 microgram/ml. Also, we investigated year to year changes in the background of patients, the respiratory infectious diseases, and the etiology of bacteria. Patients characteristics, in this period of investigation showed varieties of infectious diseases found in patients in a high age bracket, and the patients over age 60 accounted for 62.0% of all the cases. Different lower respiratory tract infectious were distributed as follows: chronic bronchitis and bacterial pneumonia accounted for the greatest number of cases with 35.6%, 27.1%, respectively, followed by