A three-year study entailing molecular characterization and epidemiology of Clostridium difficile in an Italian tertiary care hospital.

In Italy, there are limited studies on the molecular epidemiology of Clostridium difficile, possibly due to insufficient laboratory diagnostic capacity, low awareness and lack of high-quality surveillance systems. The aim of this study was to evaluate the diffusion of C. difficile in a tertiary care hospital and to genotype all the collected strains in order for hospital staff to take corrective action. All specimens were subjected to a CDI diagnostic algorithm. This included highly specific toxin PCRs and multilocus sequence typing (MLST) to obtain clear, unequivocal genotypization. During a three-year study period, as part of routine C. difficile testing, 711 stool samples were collected from 522 patients to detect the presence of toxigenic genes. After testing, 106 different samples were identified as toxigenic. The proportions of non-toxigenic and toxigenic isolates were respectively 8.7% (62/711) and 14.9% (106/711). The most infection findings in wards for toxigenic strains were in Internal Medicine (56), followed by Neurology (11) and Gastroenterology (11). Three novel sequence types (STs) were found. The two most prevalent STs in wards were clade 1 ST-378 (40) and clade 1 ST-379 (33). Other healthcare-acquired strains were clade 4 ST-37 (11) and clade 5 ST-11 (7). Two STs, namely clade 3 ST-5 (10) and clade 1 ST-380 (5), were isolated among external patients. To prevent an increase in outbreak probability, an active surveillance programme combined with proper hand hygiene, environmental cleaning and contact precautions should be implemented.