Hemolysin-Producing Strains among Diarrheagenic Isolated from Children under 2 Years Old with Diarrheal Disease.

Even if serotyping based on O antigens is still routinely used by most laboratories for the detection of diarrheagenic , this method can provide false-positive reactions, due to the high diversity of O antigens. Molecular methods represent a valuable tool that clarifies these situations. In the Bacteriology Laboratory of Mureș County Hospital, between May 2016 and July 2019, 160 diarrheagenic strains were isolated from children under 2 years old with diarrheic disease. The strains were identified as Shiga toxin-producing (STEC)/enteropathogenic (EPEC) via agglutination with polyvalent sera. STEC strains were serotyped using monovalent sera for serogroup O157. Simplex PCR was performed on the strains to determine the presence of the gene, and, for the positive ones, the hemolytic activity was tested. Antibiotic susceptibility of the identified diarrheagenic strains was also investigated. STEC strains were the most frequently identified (49.1%), followed by EPEC (40.2%). The A gene was identified in 12 cases, representing 18.2% of the STEC strains. Even if the extended-spectrum β-lactamase (ESBL)-producing strains represented only 10%, a relevant percentage of multidrug-resistant (MDR) strains (24%) was identified.