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

Abstract

Even if serotyping based on O antigens is still routinely used by most laboratories for the detection of diarrheagenic Escherichia coli, 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 E. coli strains were isolated from children under 2 years old with diarrheic disease. The strains were identified as Shiga toxin-producing E. coli (STEC)/enteropathogenic Escherichia coli (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 hlyA gene, and, for the positive ones, the hemolytic activity was tested. Antibiotic susceptibility of the identified diarrheagenic E. coli strains was also investigated. STEC strains were the most frequently identified (49.1%), followed by EPEC (40.2%). The hlyA 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.

Profiling the Virulence and Antibiotic Resistance Genes of Cronobacter sakazakii Strains Isolated From Powdered and Dairy Formulas by Whole-Genome Sequencing

“…However, highly virulent clinical ST8 strains of C. sakazakii that bear plasmid pESA3 have been found to lack the cpa gene, suggesting the likely presence of other virulence genes as responsible for the disease ( Jang et al, 2020 ). Hemolysins (Hly) are outer membrane proteins or exoproteins found in various pathogens belonging to the Enterobacteriaceae family, such as Escherichia coli , Klebsiella , Enterobacter , and Gram-positive pathogens such as Bacillus cereus , with hemolytic capacity ( Mare et al, 2020 ; Mazzantini et al, 2020 ). This hly gene was found when analyzing the C. sakazakii BAA-894 strain that was isolated from the neonatal intensive care unit outbreak in 2001 ( Himelright et al, 2002 ).…”

Genomic Characterization of Cronobacter spp. and Salmonella spp. Strains Isolated From Powdered Infant Formula in Chile

“… Jang et al (2020) noted that highly virulent C. sakazakii ST8 clinical strains that carry the pESA3 plasmid do not possess the cpa gene; this indicates that the disease can be associated with other virulence factors. Hemolysins (Hly) are outer membrane proteins occurring in various pathogens belonging to the Enterobacteriaceae family that have hemolytic ability, such as E. coli , Klebsiella , and some gram-positive pathogens ( Mare et al, 2020 ; Mazzantini et al, 2020 ). Other important genes of the C. sakazakii strains isolated from PIF are nanAKT that encode for exogenous sialic acid utilization.…”

Acute Infectious Gastroenteritis: The Causative Agents, Omics-Based Detection of Antigens and Novel Biomarkers

“…The WHO Global Burden of Foodborne Diseases report estimates that more than 300 million illnesses and nearly 200,000 deaths are caused by diarrheagenic Escherichia coli (DEC) globally each year. DEC is one of the major causal agents of diarrhoea in children under 5 years of age in developing countries [ 68 , 69 , 70 ], whereas children under 2 years of age are at the highest risk of infection with Enteropathogenic Escherichia coli [ 71 , 72 ] and Escherichia coli O157:H7 [ 71 , 73 ]. However, the major cause of paediatric infections in certain areas such as Ahvaz, Iran, were non-O157:H7 E. coli [ 74 ].…”