Abstract
The aim of this study was to identify shifts in antimicrobial resistance in the Hampshire region including correlations between patient demographic and antibiotic prescribing to inform safe and effective antimicrobial stewardship. 475 ESBL and AmpC producing bacteria, from various infection sites, were obtained from four hospital laboratories in Hampshire, UK, during 2010 and 2012. All isolates were identified to species level. ESBL production and antimicrobial susceptibility testing was performed using disc diffusion methodology. Multiplex PCR and gel electrophoresis was used to detect the BlaCTX, BlaTEM and BlaSHV resistance determinants. Corresponding patient data included patient age, gender, location, clinical details and previous antibiotic therapy. Patient information revealed mean ages of 60 and 62 for the 2010 and 2012 cohorts respectively, with ages ranging from 3 months to 96. ESBL production was the most prevalent resistance mechanism (65% in 2010, 79% in 2012), produced mostly by E.coli (85% in 2010, 84% in 2012). While 9 of the 13 antibiotics demonstrated increased resistance, 4 demonstrated a decrease. CTX was the most prevalent resistance determinant (38% in 2010 and 27% in 2012), followed by dual expression of CTX & TEM, TEM, TEM & SHV, SHV, SHV & CTX and all three resistance determinants. A significant correlation between patient age and joint expression of TEM & SHV was observed in 2010, in 2012, patient age significantly correlated with joint CTX and SHV expression. Significant differences could also be determined between resistance determinant type and antimicrobial resistance. This study shows that the incidence of ESBL and AmpC infections and resistance to commonly used antibiotics within Hampshire is increasing both within the hospital and community setting. This emphasises the need for judicious antibiotic prescribing to safeguard this valuable medical commodity.
Highlights
Since the emergence of extended spectrum betalactamase (ESBL) producing organisms in 1983 [1] their prevalence has continued to rise worldwide contributing significantly to antimicrobial resistance
This study shows that the incidence of ESBL and AmpC infections and resistance to commonly used antibiotics within Hampshire is increasing both within the hospital and community setting
Samples were obtained from patients ranging in age from 3 months to >90 years, our demographic analysis indicates that patients over the age of 50 had a higher incidence of ESBL infections (Table 2)
Summary
Since the emergence of extended spectrum betalactamase (ESBL) producing organisms in 1983 [1] their prevalence has continued to rise worldwide contributing significantly to antimicrobial resistance. These plasmid mediated bacterial enzymes provide resistance to early and third generation cephalosporins and monobactams. ESBL groups have been classified according to their amino-acid sequences. Those first described were derivatives of the beta-lactamase enzymes TEM-1, TEM-2 and SHV-1; further mutations within these classes have since been identified with more than 160 and 100 variants respectively. Since its discovery there has been over 65 variants of the CTX-M enzyme identified [3]
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