Differences in isolation rate and antimicrobial susceptibility of bacteria isolated from foals with sepsis at admission and after ≥48 hours of hospitalization

Abstract

Background Antimicrobial treatment protocols for foals with sepsis that do not improve clinically often are adjusted based on bacteriological and antimicrobial susceptibility testing results from samples collected at hospital admission. Objectives To evaluate whether hospitalization for ≥48 hours affects bacteriological and antimicrobial susceptibility testing results. Animals Two‐hundred sixty‐seven foals <30 days of age admitted to a neonatal intensive care unit and diagnosed with sepsis. Methods Medical records were reviewed retrospectively to identify foals with sepsis and positive bacteriological cultures. Results from samples collected at hospital admission were compared to those collected ≥48 hours after admission. Logistic regression for clustered data and exact logistic regression were used for statistical analysis. Results Three‐hundred fifty‐three unique bacterial isolates were obtained from 231 foals at hospital admission and 92 unique bacterial isolates were obtained from 57 foals after ≥48 hours of hospitalization. Relative isolation frequency after ≥48 hours of hospitalization increased for Acinetobacter spp., 0.6% versus 3.3% (odds ratio [OR], 7.63; 95% confidence interval [CI], 1.28‐45.45); Enterococcus spp., 4.8% versus 19.6% (OR, 5.37; 95% CI, 2.64‐10.90); Klebsiella spp., 5.1% versus 10.9% (OR, 2.27; 95% CI, 1.05‐4.89); Pseudomonas spp., 3.0% versus 7.6% (OR, 3.49; 95% CI, 3.49‐240.50); and Serratia spp., 3.0% versus 5.4% (OR, 20.23; 95% CI, 2.20‐186.14). Bacteria isolated after ≥48 hours of hospitalization were less susceptible to all tested antimicrobial drugs, except for imipenem. Conclusions and Clinical Importance Decreased antimicrobial susceptibility of bacteria isolated after ≥48 hours of hospitalization provides a rationale for repeated bacteriological culture and susceptibility testing in hospitalized foals with sepsis.

Surgical repair of congenital lateral luxation of the patella in an Arabian foal using a polypropylene mesh

“…The combination of amikacin and ampicillin has been established to be an appropriate choice of initial treatment of neonatal sepsis in foals in several studies (Theelen et al . 2013, 2019, 2020).…”

Systemic antimicrobial therapy in foals

“…These results provide a rationale for repeating bacteriological culture and susceptibility testing of hospitalised foals and emphasise the importance of hospital hygiene in equine neonatal intensive care units (Theelen et al . 2020). It is clear from the studies already published that bacterial susceptibility is also region‐ and hospital‐dependent, therefore local monitoring of this information to guide antimicrobial selection is recommended (Marsh and Palmer 2001a,b; Theelen et al .…”

“…Isolation rates and antimicrobial susceptibility profiles from bacteria isolated from foals with sepsis after > 48h of hospitalisation differ significantly from those collected at hospital admission (Theelen et al . 2020). This demonstrates that previous test results should not be used for selection of alternative drugs for treatment if initial treatment is unsuccessful.…”

Responsible antimicrobial use in critically ill adult horses

“…However, due to increasing microbial resistance, pressure on veterinarians is mounting to adhere to responsible use of antimicrobial drugs. A recent study in a UK referral hospital over a ten-year period demonstrated an increase in prevalence of extended spectrum beta lactamase (ESBL)-producing E. coli as well as increased antimicrobial resistance to frequently used antimicrobials including doxycycline, gentamicin and 3rd generation cephalosporins (Isgren, Edwards et al 2019); other studies have confirmed increasing resistance in bacteria isolated from horses, particularly after antimicrobial therapy (Maddox, Williams et al 2011, Theelen, Wilson et al 2020.…”

“…However, due to increasing microbial resistance, pressure on veterinarians is mounting to adhere to responsible use of antimicrobial drugs. A recent study in a UK referral hospital over a 10-year period demonstrated an increase in prevalence of extended-spectrum beta-lactamase (ESBL)producing E. coli as well as increased antimicrobial resistance to frequently used antimicrobials including doxycycline, gentamicin and third-generation cephalosporins (Isgren et al 2019); other studies have confirmed increasing resistance in bacteria isolated from horses, particularly after antimicrobial therapy (Maddox et al 2011;Theelen et al 2020). Unnecessary or unnecessarily long use of antimicrobial drugs enhances development of resistance in pathogens, increases the cost of treatment and exposes the patient to possible side effects, most noticeably disruption of the intestinal microbiome and antimicrobial-induced diarrhoea (Gronvold et al 2010;Johns et al 2012;Barr et al 2013;Costa et al 2015).…”