In Vitro Susceptibility of Relatively Resistant Bacteria to Imipenem

Abstract

In vitro activity of imipenem was tested against 965 clinical isolates from a major referral center in Saudi Arabia. Many of these strains were highly resistant to commonly used antibiotics, such as ampicillin, cephalosporins, gentamicin, piperacillin, and ticarcillin. All the 727 isolates of Enterobacteriaceae, Acinetobacter, Staphylococcus aureus, enterococci, and other streptococci were susceptible to imipenem. The majority of the strains of Pseudomonas aeruginosa (95%) and S. epidermidis (90%) were also inhibited. Nine of the 11 isolates of pseudomonads other than P. aeruginosa were resistant to this antibiotic. Imipenem. 1989; 9(3): 272-275 Imipenem (N-formimidoylthienamycin monohydrate) is a new thienamycin antibiotic produced by Streptomyces cattleya. Although it contains a beta-lactam ring, structurally, it is quite distinct from the penicillins, cephalosporins, and cephamycins. This unique structural difference of imipenem is apparently responsible for its having the broadest antimicrobial activity of currently available beta-lactam antibiotics and for its resistance to hydrolysis by chromosomal or plasmid-mediated beta-lactamases. SM Hussain Qadri, A Al-Hosain, In Vitro Susceptibility of Relatively Resistant Bacteria to

Antibacterial Activity of FCE 22101 against Relatively Resistant Blood Culture Isolates

“…MIC values for the majority of the isolates were found to be similar to those reported in the literature. Barry et al [1989] reported an MIC range of 2.0-32 ag/ml for Serratia marcescens; we found it to be 0.5-8.0 pg/ml, even though previous reports have indicated this or ganism to be significantly more resistant to penicillins, cephalosporins, and amino glycosides at this institution [Qadri et al, 1987;Qadri and Al-Hosain, 1989;Neu et al, 1985]. Of the ten beta lactams we tested, the only drug which had a slightly better in vitro activity than FCE 22101 was imipenem.…”

“…Thus, Murray et al [1985] found that 92-78% of Escherichia coli were susceptible to trimethoprim-sulfamethox azole in the USA compared to only 56-60% sensitivity of isolates in Chile, Brazil, Honduras, Costa Rica and Thai land. Previous reports from Saudi Arabia have shown that clinical isolates, espe cially gram-negative bacteria, were more resistant to beta lactam antibiotics and aminoglycosides compared to those in the United States [Qadri et al, 1987, However, many of these bacteria have been found to be highly susceptible to imi penem [Qadri and Al-Hosain, 1989]. FCE 22101 is a relatively new synthetic drug be longing to the same class as imipenem.…”