Gram-negative bacteremia: Which empirical antibiotic therapy?

Antibiotic Stewardship: Strategies to Minimize Antibiotic Resistance While Maximizing Antibiotic Effectiveness

Empiric therapy of the septic patient in the hospital is challenging. Antibiotic stewardship is concerned with optimizing antibiotic use and minimizing resistance. Clinicians should avoid overcovering and overtreating colonizing organisms in respiratory secretions and urinary catheters. Empiric therapy should take into account the prevalence of multidrug-resistant organisms in the hospital setting. The most effective resistance prevention strategies is to preferentially select a low resistance potential antibiotic, which should be administered in the highest possible dose without toxicity for the shortest duration to eliminate the infection.

Trends in Antimicrobial Resistance against Enterobacteriaceae Strains Isolated from Blood: A 10-year Epidemiological Study in Mainland China (2004-2014)

Background:

Antimicrobial resistance is a serious problem that compromises the empirical treatment of infections, resulting in a lack of effective antibiotics and high medical expenses. Here, we aimed to monitor the trends in antimicrobial resistance among Enterobacteriaceae isolated from blood samples in mainland China.

Methods:

A total of 2240 Enterobacteriaceae isolates from blood were collected from hospitalized patients at 19 tertiary hospitals between October 2004 and June 2014. The minimum inhibitory concentrations of all isolates were determined using the agar dilution method according to the Clinical and Laboratory Standards Institute 2016 guidelines.

Results:

The most commonly isolated bacteria were Escherichia coli, compromising 47.0% (1053/2240) of the total isolates, followed by Klebsiella spp. (26.3%), Salmonella spp. (10.4%), and Enterobacter spp. (9.2%). The detection rates of extended-spectrum β-lactamases (ESBLs) among E. coli were 68.9% (2004–2005), 73.2% (2007–2008), 67.9% (2009–2010), 72.6% (2011–2012), and 58.4% (2013–2014), whereas those in ESBL-producing Klebsiella pneumoniae were slightly decreased (75.9%, 50.0%, 41.4%, 40.2%, and 43.0%, respectively). Carbapenems were the most potent agents against the Enterobacteriaceae isolates, followed by moxalactam, tigecycline, and amikacin. However, there was a decrease in the susceptibility rates for carbapenems in all species, particularly K. pneumoniae (decreased by 10.6% for imipenem) and Enterobacter aerogenes (decreased by 21.1% for imipenem). Reviving antibiotics (tigecycline and polymyxins) showed good in vitro activity against Enterobacteriaceae.

Conclusions:

The activity of antibiotics against Enterobacteriaceae isolated from blood was decreased overall. Large proportions of ESBL-producing isolates were identified among E. coli and Klebsiella spp. Carbapenem-resistant isolates have become a major challenge in the treatment of infections.

Predominance of healthcare-associated cases among episodes of community-onset bacteraemia due to extended-spectrum β-lactamase-producing Enterobacteriaceae

Extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE) are endemic pathogens worldwide. Infection with ESBL-PE may be associated with inadequate antibiotic therapy and a poor outcome. However, risk factors for ESBL-PE community-acquired infections are ill-defined. An observational multicentre study was performed in 50 hospitals to identify the prevalence of and risk factors for community-acquired ESBL-PE bacteraemia. All patients presenting with community-onset Enterobacteriaceae bacteraemia were recorded over a 2-month period (between June and November 2013). Risk factors and 14-day outcomes of patients were investigated. Among 682 Enterobacteriaceae bacteraemia episodes recorded, 58 (8.5%) were caused by ESBL-PE. The most frequent species isolated were Escherichia coli (537; 76.7%) and Klebsiella spp. (68; 9.7%), of which 49 (9.1%) and 8 (11.8%), respectively, were ESBL-producers. Most ESBL-PE episodes were healthcare-associated, and only 22 (38%) were apparently community-acquired. The main risk factor for community-acquired ESBL-PE bacteraemia was a prior hospital stay of ≥5 days within the past year. The overall 14-day survival was 90%; only 4 (6.9%) of 58 patients with ESBL-PE bacteraemia died. Inadequate initial antibiotic therapy was administered to 55% of patients with ESBL-PE bacteraemia but was not associated with increased 14-day mortality. Although many patients had community-onset ESBL-PE bacteraemia, almost two-thirds of the episodes were actually healthcare-associated, and true community-acquired ESBL-PE bacteraemia remains rare. In our essentially non-severely ill population, inappropriate initial therapy was not associated with a higher risk of mortality.