Temporal trends in in vitro antimicrobial susceptibility patterns of bacteria isolated from foals with sepsis: 1979–2010

Abstract

SummaryReasons for performing the study: Monitoring the development of antimicrobial resistance is important for the rational selection of appropriate antimicrobial drugs to initiate treatment of foals with sepsis. Objectives: To identify temporal trends in antimicrobial susceptibility patterns of bacteria isolated from foals with sepsis. Study design: Retrospective review of medical records. Methods: Foals aged <30 days with a diagnosis of sepsis, confirmed by culture of bacteria, were included. Susceptibility data, expressed as minimum inhibitory concentrations (MICs) (MIC50, MIC90, MIC range) and percent of isolates that were susceptible to a particular antimicrobial drug, were compared for bacteria isolated from foals during 3 different time periods: 1979-1990, 1991-1997 and 1998-2010. The Cochran-Armitage trend test and the Jonckheere-Terpstra test were used for statistical analysis. Results: A total of 1091 bacterial isolates were cultured from 588 foals. Enterobacteriaceae, Actinobacillus spp. and β-haemolytic Streptococcus spp. showed a decrease in percent of isolates susceptible to gentamicin over time. Enterobacteriaceae, Actinobacillus spp. and β-haemolytic Streptococcus spp. showed an increase in MIC values for amikacin. Enterobacteriaceae showed a decrease in percent of isolates susceptible to ceftiofur. Enterococcus spp. and Pseudomonas spp. showed increased MIC values to ceftiofur. Enterobacteriaceae showed increased MIC values to ceftizoxime. Enterococcus spp. became more resistant to imipenem and showed increased MIC values to ticarcillin/clavulanic acid. In contrast, several trends in increased susceptibility were also seen. Conclusions: Based on these in vitro results, the combination of amikacin and ampicillin remains an appropriate choice for initiating treatment of sepsis in foals while awaiting culture and susceptibility test results, although increasing development of resistance to amikacin was demonstrated. The decrease in in vitro activity of ceftiofur against Enterobacteriaceae is of concern. Similarly, the development of resistance of Enterococcus spp. to imipenem is an important finding that warrants monitoring in the future. Judicious use of antimicrobials is therefore crucial.

A retrospective analysis of antimicrobial resistance in bacterial pathogens in an equine hospital (2012–2015)

“…Few studies have reported isolation of ESBL-producing Enterobacteriaceae from equine infections such as infected wounds, septic arthritis and sepsis (Dolejska et al, 2011;Dierikx et al, 2012;Smet et al, 2012;Walther et al, 2014). Resistance rates against 3rd or 4th generation cephalosporins in Enterobacteriaceae from clinical samples are 5-14% and an increase over time was noted (Clark et al, 2008;Dierikx et al, 2012;Theelen et al, 2014). In our collection, the prevalence of pESBL-producing E. coli and K. pneumoniae ssp.…”

“…showed high resistance rates against b-lactam antimicrobials. Resistance towards penicillin is frequent in equine isolates (Clark et al, 2008;Theelen et al, 2014), while resistance towards other b-lactams, especially cephalosporins, is rarely reported (Clark et al, 2008;Theelen et al, 2014). Here, 68% of staphylococci showed cephalosporin resistance due to methicillin resistance.…”

“…causing musculoskeletal infections have been reported (Herdan et al, 2012;Theelen et al, 2014). Ampicillin alone or in combination with sulbactam and chloramphenicol remain reasonable treatment options (Weese, 2009;Theelen et al, 2014).…”

“…causing musculoskeletal infections have been reported (Herdan et al, 2012;Theelen et al, 2014). Ampicillin alone or in combination with sulbactam and chloramphenicol remain reasonable treatment options (Weese, 2009;Theelen et al, 2014). Low-level resistance towards penicillin and gentamicin is intrinsic to enterococci, but combinations of both drugs can remain effective (Weese, 2009;Hollenbeck and Rice, 2012).…”

“…There are numerous studies from different countries describing antimicrobial resistance in equine pathogens (Clark et al, 2008;Theelen et al, 2014;Toombs-Ruane et al, 2015). Results from these studies aid practitioners in making an evidence based antimicrobial drug choice in cases where prompt therapy is needed and culture and susceptibility testing results cannot be awaited.…”