Ronald F. Schell

Activity of nine antimicrobial agents against Lancefield group C and group G streptococci.

The activity of nine antimicrobial agents against 44 strains of group C and group G streptococci was studied using a microtiter broth dilution technique. Several antimicrobial agents, including third-generation cephalosporins, the newer semisynthetic penicillins, and erythromycin, exhibited good activity against the organisms. Occasional tolerance to various agents was observed. No cross-tolerance was observed in this study.

The Activity of Ceftazidime Compared with Those of Aztreonam, Newer Cephalosporins and Sch 29482 against Nonfermentative Gram-Negative Bacilli

The activity of ceftazidime was compared with those of aztreonam, newer cephalosporins and Sch 29482 against nonfermentative gram-negative bacilli. Ceftazidime was consistently more active (MIC less than or equal to 8 micrograms) against the nonfermenters. Only Flavobacterium odoratum, F. spp., Pseudomonas alcaligenes, P. maltophilia and P. stutzeri demonstrated substantial resistance (MIC90 greater than or equal to 64 micrograms) to ceftazidime. Sch 29482 and ceftriaxone also exhibited good activity (MIC90 less than or equal to 8 micrograms) against many of the nonfermenters. The broad activity of ceftazidime, however, makes it a potentially more useful therapeutic agent against these microorganisms.

Activity of Eleven Antimicrobial Agents against Methicillin-, Methicillin- and Rifampin-Resistant Staphylococcus aureus

Activity of eleven antimicrobial agents against methicillin-, methicillin- and rifampin-resistant Staphylococcus aureus was studied using a microtiter broth dilution technique. Coumermycin was the most active agent. Vancomycin, rifampin, fusidic acid and N-formimidoyl-thienamycin showed excellent activity against methicillin-resistant St. aureus (MRSA). Antimicrobial susceptibility pattern was similar for MRSA and methicillin- and rifampin-resistant St. aureus. 8% of MRSA were resistant to trimethoprim and sulfamethoxazole.

In Vitro and Clinical Evaluation of Ceforanide

Ceforanide, a new cephalosporin antibiotic with a long half-life (three hours), was evaluated for its antimicrobial activity, pharmacology, and clinical efficacy. Fifty-two patients with 56 infections due to susceptible organisms received ceforanide, 0.5 g, 1 g, or 2 g, intramuscularly or intravenously every 12 hours for four to 60 days (average: 14.1 days). The in vitro studies of our clinical isolates showed that 12.0 μg/ml or less of ceforanide inhibited all Streptococcus pneumoniae, beta hemolytic streptococci group A, B, F, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Hemophilus influenzae. After a 1 gram intramuscular dose, the mean peak serum concentration at one hour was 44.0 μg/ml, and at 12 hours was 3.8 μg/ml. After a 1 gram intravenous dose, the mean peak serum concentration was 65.0 μg/ml, and the mean trough serum concentration at 12 hours was 9.6 μg/ml. The infections treated included ten pneumonias, ten urinary tract infections, seven bacteremias, two osteomyelitis, and 35 skin-soft tissue infections. Of the 56 evaluable infections treated, 52 had a clinical cure with only four failures. Ceforanide was well tolerated, with no patients developing thrombophlebitis, or liver or renal abnormalities. Three patients developed abnormal Coombs reactions and one had diarrhea.

The Activity of Ceftazidime, Other β-Lactams, and Aminoglycosides against Pseudomonas aeruginosa

The inhibitory and bactericidal activities of ceftazidime, cefoperazone, ceftriaxone, piperacillin, and five aminoglycosides were determined against 50 tobramycin-susceptible and 25 multidrug-resistant isolates of Pseudomonas aeruginosa. Ceftazidime was the most active beta-lactam and tobramycin the most active aminoglycoside. The combination of piperacillin and tobramycin was synergistic in most cases. The combination of cephalosporin and tobramycin showed mostly addition or indifference, as did combination of two beta-lactams. No antagonism was observed.

LSH Hamster Model of Syphilitic Infection and Transfer of Resistance with Immune T Cells

The immunologic basis of host defense in syphilis has not been elucidated. The humoral immune response appears to afford only negligible protection. The disease progresses from a local lesion to secondary syphilis with 24% of patients developing relapsing secondary lesions despite the development of a vigorous antibody response. Passive immunization of rabbits or hamsters with immune serum (1–5) or immunoglobulin (6) has failed to prevent infection of animals with Treponema pallidum.

Activity of Cefsulodin, other β-Lactams, and Aminoglycosides against Pseudomonas aeruginosa

Cefsulodin was the most active of the cephalosporins and exhibited 4-16 times more activity than carbenicillin or ticarcillin against 50 clinical isolates of Pseudomonas aeruginosa. Azlocillin and piperacillin showed good activity, while tobramycin was the most effective aminoglycoside. The activity of cefsulodin was unaltered by increases in inocula, but resistance was induced easily. When combined with gentamicin, no synergistic or antagonistic activity was observed against multiply resistant isolates.

In vitro Antimicrobial Activity of Ceftizoxime

The antimicrobial activity of ceftizoxime was compared to cefamandole, cefoperazone, cefotaxime, cephalothin, and lamoxactam (moxalactam) against 549 bacteria. It had activity similar to cefotaxime and lamoxactam against most members of the Enterobacteriaceae. Ceftizoxime should prove useful against gram-negative bacteria except Pseudomonas aeruginosa and Acinetobacter spp.