Healthcare Associated Infections Caused by Gram-negative Bacilli in Adult Intensive Care Units: Identification of AmpC Beta-Lactamases Mediated Antimicrobial Resistance

Abstract

Healthcare associated infections (HAIs) caused by AmpC β-lactamases producers are clinically significant as they can mediate resistance to cephalosporins, penicillins, monobactams and cephamycins. Objectives: To find out the prevalence of AmpC producers among Gram-negative bacilli recovered from HAIs in adult intensive care units (ICUs) and to identify the risk factors associated with AmpC β-lactamases production. In addition, we compared the antimicrobial resistance patterns in AmpC positive and negative isolates. Methodology: A prospective study was conducted over one year duration on samples collected from patients suffering from HAIs in the adult ICUs of Mansoura Emergency Hospital, Mansoura-Egypt. Isolated Gram-negative bacilli were subjected to cefoxitin disk diffusion test to screen for AmpC production. Presumptive AmpC producers were then confirmed by AmpC disk test, disk approximation test and AmpC E test. Results: Out of the recovered 240 Gram-negative bacilli, 73 isolates (30.4%) were AmpC producers. Acinetobacter baumannii represented the highest AmpC production (44.4%). Significant risk factors for AmpC β-lactamases production included previous exposure to antibiotic therapy, prolonged duration of antibiotic therapy before development of HAIs and presence of a central line or endotracheal tube. Resistance to all tested antimicrobials, with the exclusion of imipenem and meropenem, was significantly associated with AmpC producers. Conclusion: Increased prevalence of AmpC producers among Gram-negative isolates was observed in our study. Thus, early detection of AmpC producing bacteria is necessary to avoid treatment failure. Establishment of antibiotic stewardship policy and enhanced infection prevention and control measures are necessary to avoid spread of resistant infections in ICUs.

Antimicrobial activity of cefepime-tazobactam combination against extended spectrum beta-lactamase and/or AmpC beta-lactamase- producing gram-negative bacilli

“…In this study, a higher percentage of AmpC production was observed among A. baumannii (30%), followed by K. pneumoniae (12.5%) than among E. coli isolates (2%). A similar finding was observed by Sultan et al who reported that 44.4% of A. baumannii isolates were AmpC-producers, which was greater than the AmpC production rates of E. coli (35.5%) and K. pneumoniae (30.4%) [ 30 ]. Yilmaz et al found that 10% of K. pneumoniae isolates were AmpC-producers and 0.9% in E. coli [ 31 ].…”

“…A lower rate was recorded by another study which showed AmpC production in 2.6% of studied Enterobacterales isolates [ 27 ], whereas higher percentage rates of 28.3% and 19.5% were reported [ 28 , 29 ]. Sultan et al reported that 49% of GNB isolates were AmpC-producers [ 30 ]. The observed differences in prevalence rates could be attributed to various factors such as variations in the geographic regions, sample sizes, types of specimens analyzed, the specific species of bacteria isolated, study population, and the extent of antibiotic usage in different settings [ 4 ].…”

“…Another study recorded a 20.9% resistance rate to imipenem [ 40 ]. Sultan et al observed lower resistance rates to imipenem and meropenem (13.7, and 8.2%, respectively) among AmpC-producers isolates [ 30 ]. The least effective carbapenem evaluated in our investigation was ertapenem (68% sensitivity).…”

Antimicrobial Activity of Cefepime-Tazobactam Combination against Extended Spectrum Beta-Lactamase and/or AmpC Beta-Lactamase- Producing Gram-negative Bacilli

“…Another study recorded a 20.9% resistance rate to imipenem [44]. Sultan et al observed lower resistance rates to imipenem and meropenem (13.7, and 8.2%, respectively) among AmpCproducers isolates [35]. The least effective carbapenem evaluated in our investigation was ertapenem (68% sensitivity).…”

“…Most of our isolates were resistant to both combinations (72.35% and 78.73%, respectively). Sultan et al reported a 97.3% resistance rate to piperacillin-tazobactam among AmpCproducer isolates [35].…”