Prevalence of Antibiotic Resistance Over Time in a Third-Level University Hospital

Abstract

This study evaluated the spread and possible changes in resistance patterns of ESKAPE bacteria to first-choice antibiotics from 2015 to 2019 at a third-level university hospital after persuasive stewardship measures were implemented. Isolates were divided into three groups (group 1, low drug-resistant; group 2, multidrug/extremely drug-resistant; and group 3, pan-resistant bacteria) and a chi-squared test (χ²) was applied to determine differences in their distributions. Among the 2,521 isolates, Klebsiella pneumoniae was the most frequently detected (31.1%). From 2015 to 2019, the frequency of isolates in groups 2 and 3 decreased from 70.1% to 48.6% (χ² = 63.439; p < 0.0001). Stratifying isolates by bacterial species, for K. pneumoniae, the frequency of PDR isolates decreased from 20% to 1.3% (χ² = 15.885; p = 0.003). For Acinetobacter baumannii, a statistically significant decrease was found in groups 2 and 3: from 100% to 83.3% (χ² = 27.721; p < 0.001). Also, for Pseudomonas aeruginosa and Enterobacter spp., the frequency of groups 2 and 3 decreased from 100% to 28.3% (χ² = 225.287; p < 0.001) and from 75% to 48.7% (χ² = 15.408; p = 0.003), respectively. These results indicate that a program consisting of persuasive stewardship measures, which were rolled out during the time frame of our study, may be useful to control drug-resistant bacteria in a hospital setting.

Keywords: ESKAPE; Southern Italy; antimicrobial resistance; hospital units.

FIG. 1.

Activities of the Infectious Diseases unit during the study period. Total activities should be interpreted as the total number of days of in-hospital admissions, days of hospital admissions, outpatient consultations, and human immunodeficiency virus testing (including pretest and post-test counseling).

FIG. 2.

Overall number and frequency of bacterial isolates. Bacterial isolates are divided into three groups by antibiotic resistance patterns: group 1 (low resistant bacteria), group 2 (highly resistant bacteria), and group 3 (pan-resistant bacteria, PDR).

FIG. 3.

Overall frequency of antimicrobial drug resistance among MDR, XDR, and PDR isolates (Gram-negative bacteria). (A–D) show susceptibility rates to first-choice antibiotics among Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. isolates, respectively. MDR, multidrug resistance; XDR, extensively drug resistant; PDR, pandrug resistant.

FIG. 4.

Number and frequency of bacterial isolates per calendar years (A), hospital units (B), and different sites (C). Bacterial isolates are divided into three groups by antibiotic resistance patterns: group 1 (low resistant bacteria), group 2 (highly resistant bacteria), and group 3 (pan-resistant bacteria, PDR). MU, medical units; SU, surgical units; CICU, cardiac intensive care unit; ICU, intensive care unit; U, urine; B, blood; W, wound swabs; R, respiratory samples; O, other samples (miscellaneous).

FIG. 5.

Number and frequency of Gram-negative bacterial isolates resistant to selected first-choice antibiotics by calendar years.