Chuck Lewin

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In a study of 110 Pseudomonas cepacia isolates from patients without cystic fibrosis, the in vitro potencies of three new compounds, meropenem, PD 127391, and PD 131628, were comparable to those of ceftazidime and ciprofloxacin and exceeded those of chloramphenicol and co-trimoxazole. The MICs of ceftazidime, ciprofloxacin, meropenem, and the PD compounds(More)
The SOS DNA repair system is induced in bacteria treated with 4-quinolones. However, whether the response exacerbates or repairs the damage caused by these drugs is still unclear. The recA13 and the recB21 mutations impair recombination repair and render bacteria unable to induce the SOS response when treated with nalidixic acid or other agents that affect(More)
All 4-quinolones that have been examined display rapid bactericidal activity which is biphasic. At concentrations above the MIC, the lethality of the drugs increases until a concentration known as the optimum bactericidal concentration (OBC) beyond which the bactericidal activity then declines. The biphasic response appears to be due to the inhibition of(More)
Ciprofloxacin and ofloxacin are known to exert a second bactericidal mechanism (termed B) against Escherichia coli which functions even when protein synthesis is inhibited by chloramphenicol or when RNA synthesis is inhibited by rifampicin. However, the bactericidal activity of ciprofloxacin against a coagulase-negative staphylococcus (Staphylococcus(More)
Sparfloxacin was found to display a biphasic response against Escherichia coli, Staphylococcus aureus and Staphylococcus epidermidis in nutrient broth. Its optimum bactericidal concentration was found to be identical for all three species which contrasts with other clinically available fluoroquinolones that are more active against E. coli than against(More)
Enoxacin and lomefloxacin were found to display a biphasic response when their bactericidal activities were investigated against Escherichia coli KL16 in nutrient broth. Although enoxacin required bacterial protein and RNA synthesis to exert bactericidal activity, it was able to kill non-dividing bacteria. On the other hand, the protein synthesis inhibitor(More)
The bactericidal activities of ciprofloxacin, ofloxacin and DR-3355 have been investigated against Enterococcus faecalis, Staphylococcus aureus and Staphylococcus epidermidis over 24 h. The three fluoroquinolones were found to be rapidly bactericidal against the staphylococci, killing over 99% of the bacteria during the first 3 h of exposure with a further(More)
The 4-quinolone PD127,391 displays a biphasic effect on Escherichia coli, Staphylococcus aureus and S. epidermidis in nutrient broth. It is as active as ciprofloxacin in terms of its optimum bactericidal concentration against E. coli. However, against staphylococci it is six times as active as ciprofloxacin or any other 4-quinolone previously investigated.(More)
Trimethoprim was more potent than zidovudine as an inducer of the SOS response in Escherichia coli. The level of induction by each compound initially increased with rising drug concentration and then fell; this effect was less marked with zidovudine than with trimethoprim. The SOS response did not appear to be involved in the inhibition of bacterial(More)
Ciprofloxacin, unlike nalidixic acid, can kill Escherichia coli cells in the absence of synthesis of protein or RNA. Hence, chloramphenicol or rifampicin do not abolish the bactericidal activity of ciprofloxacin against wild-type E. coli. Protein and RNA synthesis were not required for the bactericidal activity of ciprofloxacin against nalB, nalC and nalD(More)