Colonizations and infections due to 3GCR Enterobacteriaceae in a University hospital in Italy

BACKGROUND: The spread of third-generation cephalosporin-resistant Enterobacteriaceae (3GCREB) is an increasing issue in terms of antimicrobial resistance and infection prevention and control (IPC), especially in the hospital setting. We aimed to investigate the burden of colonizations and infections caused by 3GCREB in an Italian teaching hospital. METHODS: We performed a retrospective study on cases of 3GCREB isolation from microbiological specimens (from gastrointestinal, urinary, blood, respiratory and cutaneous systems) which were detected over a year period (January-December 2022) at the University Hospital of Verona, Italy. We reviewed the corresponding patients’ charts to retrieve clinical information and classify cases as colonizations vs. infections. Infections counted as hospital-acquired (HAI) when the 3GCREB was detected after the third day following admission, otherwise as community-acquired infection (CAI). RESULTS: Of 2,451 3GCREB isolates retrieved, 1,815 (74.1%) were from rectal swabs. The monthly detection trend was consistent throughout the year with a minimum in February (n = 159) and a maximum in August (n = 238); monthly average was 204 isolates. The majority of 3GCREB isolates (n = 1,887; 77%) were classified as colonizations. Of the 564 3GCREB isolates which were classified as infections (23% of total isolates), 305 (54.1%) were HAIs and 259 (45.9%) were CAIs. The highest proportion of HAIs (n = 121; 39.7%) was detected in medical units, followed by intensive care areas (n = 100; 32.8%) and surgical units (n = 84; 27.5%). CONCLUSIONS: Comparing the percentages of patients with 3GCREB colonization and infection, we conclude the presence of 3GCREB in our hospital to be about 3 times higher than when only patients with 3GCREB infections are considered. This highlights the importance of surveillance to protect fragile patients. IPC training of staff is essential to counter the intra-hospital spread of these pathogens. KEY MESSAGES: • Prevalence of 3GCREB is an increasing healthcare issue in the hospital setting and medical directions should focus on staff IPC training to counter the spread of these pathogens. • Detection of 3GCREB colonizations is crucial to track the spread of multidrug-resistant organisms, identify cases and protect fragile patients.