PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9410064

[Meropenem: microbiologic perspective].

J A García-Rodríguez·E García Sánchez·M J Fresnadillo Martínez
View original source ↗Export metadata ↓

Abstract

Meropenem is a beta-lactamic carbapenem derived from thienamycin and is structurally characterized by the presence of a beta-methyl group in position C1 which confers stability to the molecule versus renal dehydropeptidase 1 (DHP-1), thereby making the coadministration of an enzyme inhibitor unnecessary. Its esterochemical configuration of the lateral chain in C2 (dimethyl carbomoilpyrrolidenethium) increases the activity versus gram negative bacteria (enterobacteria and pseudomonas) and moreover, may explain the reduction in the proconvulsive effect observed in imipenem/cilastatin. Meropenem has great bactericide power and has a very wide spectrum of activity depending on it low molecular weight and zwiterionic structure, stability versus almost all the clinically important beta-lactamases and high affinity for the PBPs. It covers gram positive aerobes (Staphylococcus aureus, coagulase negative staphylococci, streptococci including Streptococcus pneumoniae resistant to penicillin, Enterococcus faecalis, Rhodococcus equi, Listeria monocytogenes) and gram negative bacteria (enterobacteria, P. aeruginosa, Acinetobacter, Aeromonas, Plesiomonas, Vibrio, Haemophilus influenzae, Neisseria, Moraxella) and anaerobes (Bacteroides, Prevotella, Porphyromonas, Fusobacterium, Clostridium, Peptostreptococcus, and Propionibacterium acnes), being more active than imipenem versus gram negatives: P. aeruginosa (2-4-fold), enterobacteria (2-32-fold) and H. influenzae (4-8-fold) and less active versus the gram positives (enterococci, streptococci and staphylococci). Meropenem has no activity on Enterococcus faecium, S. aureus resistant to methycillin, Stenotrophomonas maltophilia and other genera producers of chromosomic methalo-beta-lactamases (carbapenemases). Resistance may be due to impermeability given the loss of the OprD porin (OprD2 in enterobacteria and P. aeruginosa) loss of different membrane proteins (Proteus mirabilis, Proteus rettgeri, Enterobacter cloacae, Enterobacter aerogenes), modifications of the PBPs (gram positive) and the production of carbapenemases (chromosomic methalo-beta-lactamases).

Explore related subjects

Bacteria, AerobicDrug Resistance, MicrobialGram-Positive BacteriaHydrogen-Ion ConcentrationMeropenemMicrobial Sensitivity TestsStructure-Activity RelationshipThienamycinsJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

J A García-Rodríguez, E García Sánchez, M J Fresnadillo Martínez. 1997. [Meropenem: microbiologic perspective].. https://pubmed.ncbi.nlm.nih.gov/9410064/

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2001

Aerobic biodegradation studies of nonylphenol ethoxylates in river water using liquid chromatography-electrospray tandem mass spectrometry.

The aerobic biodegradation of nonylphenol ethoxylates (A9PEO) was kinetically investigated in a laboratory-scale bioreactor filled with riverwater, spiked at a concentration of 10 mg L(-1) nonionic surfactants. Analyses of the samples applying liquid chromatography-electrospray mass spectrometry (LC-ES-MS) after solid-phase enrichment revealed a relatively fast primary degradation of A9PEO with >99% degradation observed after 4 days. Contrary to the generally proposed degradation pathway of EO chain shortening, it could be shown that the initiating step of the degradation is omega-carboxylation of the individual ethoxylate chains: metabolites with long carboxylated EO chains are identified (A9PEC). Further degradation proceeds gradually into short-chain carboxylated EO with the most abundant species being AgPE2C. The oxidation of the nonyl chain proceeds concomitantly with this degradation, leading to metabolites having both a carboxylated ethoxylate and an alkyl chain of varying lengths (CAPEC). The identity of the CAPEC metabolites was confirmed by the fragmentation pattern obtained with LC-ES-MS/MS. Both A9PEC and CAPEC metabolites are still present in the bioreactor after 31 days. In the aerobic degradation pathway, A9PEO2 is formed only to a minor extent and is even further degraded in several days. The endocrine disruptor nonylphenol was not found as a metabolite in this study.

Bacteria, Aerobic↗
PubMed2001

Substrate interactions in BTEX and MTBE mixtures by an MTBE-degrading isolate.

Groundwater contaminant plumes from recent accidental gasoline releases often contain the fuel oxygenate MTBE (methyl tert-butyl ether) together with BTEX (benzene, toluene, ethylbenzene, o-xylene, m-xylene and p-xylene) compounds. This study evaluates substrate interactions during the aerobic biotransformation of MTBE and BTEX mixtures by a pure culture, PM1, capable of utilizing MTBE for growth. PM1 was unable to degrade ethylbenzene and two of the xylene isomers at concentrations of 20 mg/L following culture growth on MTBE. In addition, the presence of 20 mg/L of ethylbenzene or the xylenes in mixtures with MTBE completely inhibited MTBE degradation. When MTBE-grown cells of PM1 were exposed to MTBE/benzene and MTBE/toluene mixtures, MTBE degradation proceeded, while the degradation of benzene and toluene was delayed for several hours. Following this initial lag, benzene and toluene were degraded rapidly, while the rate of MTBE degradation slowed significantly. MTBE degradation did not increase to previous rates until benzene and toluene were almost entirely degraded. The lag in benzene and toluene degradation was presumably due to the induction of the enzymes necessary for BTEX degradation. Once these enzymes were induced, sequential additions of benzene or toluene were degraded rapidly, and growth on benzene and toluene was observed. The results of this study suggest that BTEX and MTBE degradation occurs primarily via two independent and inducible pathways. If subsurface microbial communities behave similarly to the culture used in this study, the observed severe inhibition of MTBE degradation by ethylbenzene and the xylenes and the partial inhibition by benzene and toluene suggest thatthe biodegradation of MTBE in subsurface environments would most likely be delayed until MTBE has migrated beyond the BTEX plume.

Bacteria, Aerobic↗
PubMed2001

Respiratory electron transport and light-induced energy transduction in membranes from the aerobic photosynthetic bacterium Roseobacter denitrificans.

Membrane fragments isolated from the aerobic phototrophic bacterium Roseobacter denitrificans were examined. Ninety-five percent of the total NADH-dependent oxidative activity was inhibited either by antimycin A or myxothiazol, two specific inhibitors of the cytochrome bc1 complex, which indicates that the respiratory electron transport chain is linear. In agreement with this finding, light-induced oxygen uptake, an electron transport activity catalyzed by the "alternative quinol oxidase pathway" in membranes of several facultative phototrophic species, was barely detectable in membranes of Rsb. denitrificans. Redox titrations at 561-575 nm, 552-540 nm, and 602-630 nm indicated the presence of three b-type cytochromes (Em,7 of +244 +/- 8, +24 +/- 3, -163 +/- 11 mV), four c-type cytochromes (Em,7 of +280 +/- 10, +210 +/- 5, +125 +/- 8, and 20 +/- 3 mV) and two a-type cytochromes (Em,7 of +335 +/- 15, +218 +/- 18 mV). The latter two a-type hemes were shown to be involved in cytochrome c oxidase activity, which was inhibited by both cyanide (I50 = 2 microM) and azide (I50 = 1 mM), while a soluble cytochrome c (c551, Em,7 = +217 +/- 2 mV) was shown to be the physiological electron carrier connecting the bc1 complex to the cytochrome c oxidase. A comparison of the ATP synthesis generated by continuous light in membranes of Rsb. denitrificans and Rhodobacter capsulatus showed that in both bacterial species photophosphorylation requires a membrane redox poise at the equilibrium (Eh > or = +80 < or = +140 mV), close to the oxidation-reduction potential of the ubiquinone pool. These data, taken together, suggest that, although the photosynthetic apparatus of Rsb. denitrificans is functionally similar to that of typical anoxygenic phototrophs, e.g. Rba. capsulatus, the in vivo requirement of a suitable redox state at the ubiquinone pool level restricts the growth capacity of Rsb. denitrificans to oxic conditions.

Bacteria, Aerobic↗