Susceptibility of blood isolates to various antibiotics, in particular to cephalosporins.

Of 760 bacterial pathogens isolated from blood cultures of acutely ill patients in a general hospital in Hong Kong for 1 year, 69.9% of the isolates were Gram-negative aerobes mainly Escherichia coli and Klebsiella pneumoniae, 22.0% were Gram-positive aerobes mainly Staphylococcus aureus and enterococci and 8.1% were anaerobes mainly Bacteroides spp. The susceptibility of the aerobic isolates to various antibiotics was tested. Ampicillin was found to be active mainly against the enterococci and some other Gram-positive organisms while most isolates of Staph. aureus and the Gram-negative bacteria were resistant. In contrast, cephalothin was found only slightly less active than the second generation cephalosporins against Gram-negative blood isolates but considerably more active against Staph. aureus and other Gram-positive isolates. The three aminoglycosides tested, i.e., gentamicin, tobramycin and amikacin, showed similar good activity against E. coli, K. pneumoniae and Proteus mirabilis, but amikacin had the broadest spectrum of activity in inhibiting most of the other Gram-negative isolates as well as isolates of Staph. aureus. The third generation cephalosporins, cefotaxime, cefoperazone, latamoxef (moxalactam), ceftriaxone and ceftazidime, all had a high activity against the Gram-negative but a reduced activity against the Gram-positive bacteria. Ceftazidime had the broadest spectrum of activity in inhibiting all the Gram-negative isolates including Pseudomonas aeruginosa, while cefotaxime showed the best overall activity against both Gram-positive and Gram-negative blood isolates.