The in-vitro activity of faropenem, a novel oral penem

Abstract

The in-vitro activity of faropenem, a novel oral penem, was studied in comparison with other beta-lactam antimicrobials against 711 recent clinical isolates including Gram-negative, Gram-positive and anaerobic bacteria. MIC data showed that faropenem was active against most members of the Enterobacteriaceae (MICs < or = 4 mg/L), with reduced activity against Serratia spp. (MIC90 = 32 mg/L). In common with its comparators, faropenem had weak activity against Pseudomonas aeruginosa and Stenotrophomonas maltophilia (MIC > 128 mg/L). Faropenem was active against staphylococci, although for MRSA MICs were raised (MIC90 = 2 mg/L) compared with those for MSSA (MIC90 = 0.12 mg/L). Faropenem was also found to be active against streptococci, Neisseria spp., Enterococcus faecalis and beta-lactamase-producing and non-producing strains of Haemophilus influenzae and Moraxella catarrhalis. Of the anaerobic bacteria studied, faropenem was most active against peptostreptococci and Clostridium perfringens (MIC90 < or = 1 mg/L) and Bacteroides fragilis (MIC90 = 4 mg/L). An increase in inoculum from 10(4) to 10(6) cfu raised faropenem MICs for Morganella morganii from 0.06-1 mg/L to 2-4 mg/L and for MRSA from 0.25-2 mg/L to 8 mg/L (a similar increase was not observed for MSSA). The MICs of faropenem were not affected by the presence of either 20% or 70% (v/v) serum. MICs for faropenem to 11 well characterized beta-lactamase producers were similar to those of non-producers. In hydrolysis studies, faropenem was shown to be highly stable to a number of beta-lactamases, including TEM-1, SHV-1, the extended spectrum beta-lactamases, TEM-3 and TEM-9, and the beta-lactamase produced by Staphylococcus aureus (NCTC 11561).

In Vitro Activities of Faropenem against 579 Strains of Anaerobic Bacteria

“…Faropenem, a new oral penem antibiotic, is highly stable to a number of ␤-lactamases produced by clinical isolates. Faropenem had significant activity against the common respiratory pathogens Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis and poor activity against Pseudomonas aeruginosa, Stenotrophomonas maltophilia, and Enterococcus faecium (18). This study was designed to evaluate the activity of faropenem, an oral penem antibiotic, against a wide range of clinically significant anaerobic bacteria.…”

Genetic Analysis of Faropenem-resistant Enterococcus faecalis in Urinary Isolates

“…E. faecalis is susceptible to ampicillin and is also susceptible to imipenem and faropenem, a difference from E. faecium. In fact, most of the E. faecalis isolates are treatable with these antibiotics [1,2,14]. We have found few reports of faropenemresistant E. faecalis, but we isolated faropenem-resistant E. faecalis strains in the urine of patients with UTIs.…”

“…Among UTIcausing enterococci, multi-drug resistant E. faecalis such as vancomycin-resistant strains (VRE) have been reported increasingly in many countries, and in Japan the isolation frequency is similar and has increased alarmingly [12,13]. Most isolates of E. faecium are already resistant to penicillins, cephems and penems [1,2], but E. faecalis is susceptible to and can be treated with penicillins including imipenem and faropenem [1,2,14].…”

Protein Binding of Antimicrobials: Methods for Quantification and for Investigation of its Impact on Bacterial Killing

“…A wide variety of serum concentrations in test medium, ranging from 20% to 100% serum, have been used by different investigators in studies examining changes in antimicrobial activity in relation to PB (50,52,55,56,58,60,(62)(63)(64). In order to minimize the growth-inhibiting effects of serum on bacterial growth, most studies have limited the human serum concentration in test media to 70%.…”