From the Guidelines
AmpC-producing E. coli infections should be treated with carbapenems, such as ertapenem, as they are the most reliable options, according to the guidelines by the Surgical Infection Society and the Infectious Diseases Society of America 1. When considering treatment options for AmpC-producing E. coli, it's crucial to note that these bacteria have developed resistance to many commonly used antibiotics.
- The production of AmpC beta-lactamases allows these bacteria to break down various beta-lactam antibiotics, including penicillins, cephalosporins, and beta-lactamase inhibitor combinations.
- The guidelines recommend avoiding the use of ampicillin-sulbactam due to high rates of resistance among community-acquired E. coli 1.
- Ertapenem is listed as a single-agent therapy for mild-to-moderate community-acquired intra-abdominal infection, making it a suitable option for treating AmpC-producing E. coli infections 1.
- However, the Expert Panel expresses concern that broad use of ertapenem may hasten the appearance of carbapenem-resistant Enterobacteriaceae, Pseudomonas, and Acinetobacter species 1.
- Treatment duration typically ranges from 7-14 days, depending on the infection site and severity, and appropriate antibiotic susceptibility testing is essential before finalizing treatment 1.
From the Research
Ampicillin Resistance in E. coli
- Ampicillin resistance in E. coli is a growing concern, with studies showing that exposure to penicillin antibiotics, including ampicillin, is a significant risk factor for the development of resistance 2.
- The mechanism of ampicillin resistance in E. coli involves the production of beta-lactamases, which break down the antibiotic, as well as changes in the bacterial cell wall and membrane 3.
- Research has shown that ampicillin-resistant E. coli strains can be induced in the laboratory by exposing sensitive strains to sub-inhibitory concentrations of ampicillin 3.
- The use of quantitative mass spectrometry has been explored as a method for rapid detection of ampicillin resistance in E. coli, with a turnaround time of 90 minutes 4.
Clinical Implications
- Ampicillin-resistant E. coli infections are associated with longer hospital stays and higher mortality rates compared to susceptible infections 5.
- The emergence of ampicillin-resistant E. coli is a significant clinical problem, particularly in hospitalized patients who have received antibiotics in the past 2, 6.
- Effective treatment of ampicillin-resistant E. coli infections requires the use of alternative antibiotics, such as piperacillin-tazobactam or carbapenems 5, 2.
Resistance Patterns
- Ampicillin-resistant E. coli strains often exhibit resistance to other antibiotics, including ciprofloxacin and gentamicin 5, 6.
- The resistance pattern of ampicillin-resistant E. coli strains can vary depending on the specific strain and the location of the infection 5, 6.
- Whole-genome sequencing has been used to analyze the genetic changes associated with ampicillin resistance in E. coli, including mutations in genes involved in cell wall synthesis and antibiotic efflux 3.