Epidemiological and Clinical Complexity of Amoxicillin-Clavulanate-Resistant Escherichia coli

Abstract

Two hundred twelve patients with colonization/infection due to amoxicillin-clavulanate (AMC)-resistant Escherichia coli were studied. OXA-1-and inhibitor-resistant TEM (IRT)-producing strains were associated with urinary tract infections, while OXA-1 producers and chromosomal AmpC hyperproducers were associated with bacteremic infections. AMC resistance in E. coli is a complex phenomenon with heterogeneous clinical implications.A moxicillin-clavulanate (AMC) is one of the most frequently used antimicrobials in many countries (1, 2). Over the last years, an increase in the rate of resistance to AMC has been noted among Escherichia coli isolates in several areas (3-5), which has been related to an increase in the consumption of this antibiotic (3). However, to our knowledge, there are no recent clinical studies investigating infections caused by AMC-resistant E. coli. The objective of this study is to analyze the clinical epidemiology and features of infections caused by AMC-resistant E. coli.A cross-sectional multicenter study was performed in 7 Spanish tertiary centers. Each center was committed to include up to 44 patients from whom AMC-resistant E. coli (MIC of Ն32 [amoxicillin]-16 [clavulanate] mg/liter and/or disk inhibition zone of Յ13 mm) were isolated from clinical samples (22 communityonset and 22 nosocomial isolates) from 15 January to 15 May 2010. Overall, 257 AMC-resistant E. coli isolates were collected. A previous publication reported the mechanism of resistance to AMC and clonality for all these isolates (6). For the present analysis, 13 patients harboring isolates with more than one mechanism of resistance to AMC, 3 patients harboring isolates for which the mechanism of resistance was not elucidated, and 37 patients with isolates producing extended-spectrum ␤-lactamases (ESBLs) were excluded; thus, 212 patients are studied here. Epidemiological and clinical data were collected by reviewing the clinical charts and interviewing the patients or their relatives. The study was approved by the ethics committees of the participating centers. Isolates were considered nosocomial if obtained from patients who were hospitalized for Ͼ48 h. Community isolates were classified as health care associated according to previously described criteria (7). CDC criteria (8) were used for establishing whether the patients had an infection and the types of infection.The microbiological methods used were previously reported in detail (6). Briefly, antibiotic susceptibility was confirmed by microdilution according to CLSI recommendations (9). The mechanisms of resistance to AMC of the 212 isolates included here, as determined from the previously reported data (6), were as follows: hyperproduction of TEM-1 or SHV-1 (HPen) (54 isolates . Isolates showing resistance to at least one of the following families/drugs (in addition to AMC and ampicillin) were considered multidrug resistant: aminoglycosides, cephalosporins, carbapenems, piperacillin-tazobactam, ciprofloxacin, and trimethoprim-sulfamethoxazole (10). The number of abov...

Molecular identification of aminoglycoside-modifying enzymes in clinical isolates of Escherichia coli resistant to amoxicillin/clavulanic acid isolated in Spain

“…Among the 257 isolates, 110 (42.8%) caused nosocomial infections and 147 (57.2%) putatively caused community-acquired infections [4,15].…”

“…aspx), in the last decade aminoglycoside-resistant E. coli isolates from blood have increased from 6.8% (2001) to 15.6% (2012) in Spain.…”

Inhibitor-Resistant TEM- and OXA-1-Producing Escherichia coli Isolates Resistant to Amoxicillin-Clavulanate Are More Clonal and Possess Lower Virulence Gene Content than Susceptible Clinical Isolates

“…The production of OXA-1 and inhibitor-resistant TEM (IRT) ␤-lactamases is the most common plasmid-borne mechanism of AMC resistance in E. coli and does not affect other broad-spectrum ␤-lactam antibiotics (5). Clinical data for patients infected by AMC-resistant E. coli have also been provided by our group (6). However, there is very little information available about the population structure and virulence-associated determinants of OXA-1-and IRT-producing E. coli isolates compared with the amount of information available for AMCsusceptible clinical isolates.…”

Characteristics of gram-negative urinary tract infections caused by extended spectrum beta lactamases: pivmecillinam as a treatment option within South Dublin, Ireland

“…The principle risk factor in that study was previous use of coamoxiclav, confirming that increased consumption leads to increased resistance. Resistance mechanisms of E. coli to coamoxiclav include B-lactamase overproduction, AmpC cephalosporinase hyperproduction and inhibitor-resistant penicillinases [37]. Resistance is acquired by clonal and non-clonal spread, dissemination of mobile elements with different bla genes and eventual mutations in individuals organisms [38].…”