[Chronological variations in blood isolates and their susceptibility to various antibiotics]

Chronological variation in blood isolates obtained from 1968 to 1982 was studied. Escherichia coli was the most frequent isolates followed by Klebsiella species, glucose-non-fermentative Gram-negative rods (excluding Pseudomonas aeruginosa), Enterobacter-Serratia group, and Staphylococcus aureus. The isolation of glucose-non-fermentative Gram-negative rods, about half of which being Achromobacter xylosoxidans, increased greatly in number from 1980. A total of 113 strains of blood isolates was examined for susceptibility to various antibiotics. Although there was a significant increase in S. aureus resistant to GM, these strains were susceptible to cephalosporins. In the 9 strains of GM-resistant aerobic Gram-negative rods (2 strains of Klebsiella, 2 strains of Enterobacter, 4 strains of Serratia and 1 strain of P. aeruginosa), 3 strains of Serratia species were also resistant to AMK. Two strains of LCM-resistant Bacteroides fragilis were susceptible to LMOX, but 1 strain was not inhibited by 100 micrograms/ml of CFX. Among the clinical specimens, differences were found in the rate of isolation of resistant strains, particularly in the case of Serratia and P. aeruginosa. Antibiotic resistant strains were isolated more frequently from urine and the least frequently from sputum. Since the frequency of isolation of resistant strains varied according to organism, clinical material and year of isolation, microbiological laboratories should develop their own data base from which clinicians can make rational therapeutic decisions.