Khalid Ibrahim Sallam

Prevalence, genetic characterization and virulence genes of sorbitol-fermenting Escherichia coli O157:H- and E. coli O157:H7 isolated from retail beef

Sorbitol-fermenting (SF) Escherichia coli O157:H- strains have emerged as important pathogens and have been associated with a higher incidence of progression to hemolytic-uremic syndrome (HUS) than non-sorbitol fermenting (NSF) E. coli O157:H7. The present study was carried out to determine the prevalence of SF E. coli O157:H- and NSF E. coli O157:H7 strains in retail beef products in Mansoura, Egypt. The contamination rates with rfbEO157-positive E. coli O157 strains were 26.7% (8/30), 10% (3/30) and 3.7% (1/27) in ground beef, beef burger, and fresh beef samples, respectively with an overall mean of 13.8% (12/87) among all meat products tested. SF E. coli O157:H- were the most dominant among the isolated O157 strains. Of the fifteen O157 strains isolated, 11 (73.3%) were SF E. coli O157:H-, while the remaining 4 (26.7%) were NSF E. coli O157:H7. The 11 SF O157H- strains were genetically positive for sfpA gene. Restriction fragment length polymorphism (RFLP) analysis for fliC gene demonstrated a similar pattern for both SF and NSF O157 isolates. PCR assays verified the existence of stx1 gene in 7 (46.7%) and stx2 gene in 13 (86.7%) of the 15 O157 strains isolated. Unexpectedly, two of the 15 O157 strains isolated were negative for Shiga toxin genes. The eae gene was identified in all of the 15 O157 strains except in one NSF O157:H7 strain. EHEC-hlyA gene was detected in 14 (93.3%) of the 15 O157 isolates, nonetheless only 11 strains showed enterohemolytic phenotype on blood agar. A combination of the four virulence genes, stx1, stx2, eae and EHEC-hlyA were detected in 7 (46.7%) strains, while six (40%) strains were positive for stx2, eae and hlyA genes. This is the first record for isolation of E. coli O157: H- in Egypt as well as in the African continent.

Rapid determination of total aflatoxins and ochratoxins A in meat products by immuno-affinity fluorimetry

Total aflatoxins (AFT) and ochratoxin A (OTA) levels were estimated using the VICAM AflaTest and OchraTest immunoaffinity fluorometric method in a total of 50 meat products (25 each of beef luncheon and beef burger) purchased from different supermarkets in Mansoura city, Egypt. All the meat samples analyzed were contaminated with both AFT and OTA with mean values of 1.1 μg/kg and 5.23 μg/kg, respectively, for beef luncheon and mean values of 3.22 μg/kg and 4.55 μg/kg, respectively, for beef burger. None of the beef luncheon and burger samples analyzed exceeded the permissible limits set by FDA for AFT, but 40% of beef burgers exceeded the FAO AFT permissible limit. Similarly, 52% and 36% of beef luncheon and beef burger samples exceeded the FAO OTA permissible limit. Application of the immunoaffinity fluorometric method is an accurate, safe and rapid method for mycotoxins determination in meat products to ensure their safety for human consumption.

Occurrence, genetic characterization and antimicrobial resistance of Salmonella isolated from chicken meat and giblets

SUMMARY This study was undertaken to survey the presence of Salmonella in 200 chicken samples collected from Mansoura, Egypt. Salmonella was detected in 16% (8/50), 28% (14/50), 32% (16/50) and 60% (30/50) of whole chicken carcasses, drumsticks, livers and gizzards, respectively, with an overall prevalence of 34% (68/200) among all samples. One hundred and sixty-six isolates were identified biochemically as Salmonella, and confirmed genetically by PCR, based on the presence of invA and stn genes. The spvC gene, however, was detected in only 25.3% (42/166) of the isolates. Isolates were serotyped as Salmonella Enteritidis (37.3%), S. Typhimurium (30.1%), S. Kentucky (10.8%), S. Muenster (8.4%), S. Virchow (4.8%), S. Anatum (4.8%), S. Haifa (1.2%), and four were non-typable. Antimicrobial susceptibility tests of the Salmonella isolates revealed that 100% were resistant to each of erythromycin, penicillin, and amoxicillin, while 98.8%, 96.4%, 95.2%, and 91.6% were resistant to nalidixic acid, sulphamethoxazole, oxytetracycline, and ampicillin, respectively. Multidrug resistance was evident for 92.8% of the isolates. The high contamination level of chicken meat with multidrug-resistant Salmonella can constitute a problem for public health.

Draft genome sequences of two ciprofloxacin-resistant Salmonella enterica subsp. enterica serotype Kentucky ST198 isolated from retail chicken carcasses in Egypt

OBJECTIVES Salmonella enterica serotypes, particularly antimicrobial-resistant strains, pose a major threat to public health worldwide. This study describes the draft genome sequences of two ciprofloxacin-resistant Salmonella enterica subsp. enterica serotype Kentucky isolates (H5 and H18) recovered from chicken carcass rinsates in Mansoura, Egypt. METHODS Antimicrobial susceptibility phenotypes were determined for the two Salmonella Kentucky isolates by broth microdilution using a Sensititre™ system. Genomic DNA from both isolates was sequenced using an Illumina MiSeq system. Antimicrobial resistance genes were identified using ARG-ANNOT, and multilocus sequence typing (MLST) was performed using MLST 1.8. RESULTS The draft genome for Salmonella Kentucky H5 contained 4.84Mbp in 54 contigs, and that for Salmonella Kentucky isolate H18 contained 4.94Mbp in 64 contigs. Sequence analysis using ARG-ANNOT identified the presence of the resistance genes blaTEM-57, aadA1, aadA2, cmlA1, sul3 and tetA in both isolates, whereas dfrA, sul2, floR, and aph(3)-Ia were found in isolate H18 only. The amino acid substitutions Ser83Phe and Asp87Gly in GyrA and Thr57Ser and Ser80Ile in ParC were detected in both isolates. Both isolates belonged to ST198. CONCLUSION The draft genome sequences allowed identification of a ciprofloxacin-resistant Salmonella Kentucky ST198 epidemic clone with multidrug resistance in poultry products produced for human consumption in Egypt. These data indicate that poultry continues to be a reservoir for this persistent clone.