Saroj Shah

Silver Sulphadiazine: A Comprehensive in vitro Reassessment

The antimicrobial activity of silver sulphadiazine has been determined agonist 409 strains from 12 different genera. MICs were usually in the range 16-64 micrograms/ml. Multi-resistant species, such as methicillin-resistant Staphylococcus aureus and Acinetobacter spp., were uniformly sensitive. MICs always exceeded the reported aqueous solubility of silver sulphadiazine. No resistant strains were found, and there was no correlation between MIC of silver sulphadiazine and resistance to sulphonamides. Time-kill experiments showed that sulphonamide-resistant S. aureus (but not Staphylococcus epidermidis) were killed significantly more slowly than were sulphonamide-sensitive strains.

A microbiological assessment of silver fusidate, a novel topical antimicrobial agent.

The silver salt of fusidic acid is a novel antimicrobial agent. Against staphylococci, in vitro tests showed silver fusidate was more active than silver sulphadiazine, and the activities of the sodium and the silver salts of fusidic acid were correlated. Against streptococci, enterococci, clostridia, Candida albicans and a range of Gram-negative bacilli, silver fusidate was of similar activity to silver sulphadiazine. Silver fusidate at 1 g/l was bactericidal against eight strains of staphylococci, irrespective of their susceptibility to sodium fusidate. Emergence of resistance to silver fusidate was rare.

Potentiation of Catechin Gallate-Mediated Sensitization of Staphylococcus aureus to Oxacillin by Nongalloylated Catechins

ABSTRACT (−)−Epicatechin gallate (ECg) and (−)−epigallocatechin gallate (EGCg) reduce oxacillin resistance in mecA-containing strains of Staphylococcus aureus. Their binding to staphylococcal cells is enhanced by the nongalloyl analogues (−)−epicatechin (EC) and (−)−epigallocatechin (EGC). EC and EGC significantly increased the capacity of ECg and EGCg to reduce levels of staphylococcal oxacillin resistance.

Comparative anti-anaerobic activity of Men 10700, a penem antibiotic

The in vitro activity of Men 10700, a new penem, has been compared with that of metronidazole, clindamycin, ciprofloxacin, co-amoxiclav, imipenem and three third generation cephalosporins against 120 strains of anaerobes. The organisms tested comprised Clostridium perfringens, Clostridium difficile, Bacteroides fragilis and speciated members of the genera Fusobacterium, Veillonella and Peptostreptococcus. Men 10700 showed activity similar to that of imipenem, and was more potent than metronidazole against all species except C. difficile and P. anaerobius. The spectrum of activity of Men 10700 suggests this agent may be useful for treating infections caused by anaerobes.

Activities of ciprofloxacin, levofloxacin, ofloxacin and sparfloxacin against speciated coagulase-negative staphylococci sensitive and resistant to fluoroquinolones

A total of 119 strains of coagulase-negative staphylococci isolated from clinical specimens were speciated and tested for sensitivity to methicillin and four fluoroquinolones (ciprofloxacin, sparfloxacin, levofloxacin and ofloxacin). Resistance to fluoroquinolones was significantly more common in Staphylococcus haemolyticus (43%) than in Staphylococcus epidermidis (11%). Methicillin-resistant strains of S. haemolyticus were more often resistant to ciprofloxacin than were methicillin-resistant strains of S. epidermidis (P < 0.05). Sparfloxacin was the most active against fluoroquinolone-sensitive strains, and levofloxacin was twice as active as ofloxacin. There was cross-resistance between the four fluoroquinolones. Levofloxacin was the most active against resistant strains, but MICs obtained for all the compounds seemed to be outside the clinically useful range for the treatment of systemic infections.

Post-antibiotic effects of miocamycin, roxithromycin and erythromycin on Gram-positive cocci

The 16-membered macrolide miocamycin (MOM) has been compared with the 14-membered compounds erythromycin and roxithromycin in terms of causing post-antibiotic effects (PAE). Five strains of methicillin-resistant Staphylococcus aureus, 3 Streptococcus pyogenes, 3 S. agalactiae and 3 enterococci, of differing phenotypes of resistance to erythromycin, were tested. PAE were measured follwonig exposure of cocci to 1 x, 3 x and 10 x MICs of each antibiotic. Against the staphylococci and group A streptococci the three macrolides gave similar results, PAE of 1- h at 1 x MIC, 2-4 h at 3 x MIC and > 4 h at 10 x MIC being observed. For group B streptococci and the only erythromycin-sensitive enterococcus tested, PAE due to MOM were at least double those due to erythromycin or roxithromycin, at each concentration tested. MOM produced significant PAE for the strains that were inducibly resistant to erythromycin and roxithromycin.

Comparative anti-gonococcal activity of S-565, a new rifamycin.

The in vitro activity of S-565, a semi-synthetic rifamycin chemically related to rifampicin but with a longer half-life, has been compared with that of rifampicin, ciprofloxacin, spectinomycin, azithromycin and amoxycillin against Neisseria gonorrhoeae. Modal MICs against 20 strains were 0.13 mg/l for rifampicin and 0.5 mg/l for S-565. There was cross-resistance between the two rifamycins, and each selected for resistance at similar rates. In a time-kill study, S-565 was more rapidly bactericidal than rifampicin at x 1 and x 2 MIC.