Multiresistance to antibiotics of Salmonella enterica serovar Typhimurium strains producing extended spectrum beta-lactamases (ESBLs).

The purpose of the study is to give the rising incidence of Salmonellosis and the continuous decrease of sensitivity of Salmonella to a range of antibiotics, the prime importance of the choice of optimal anti-infective chemotherapy in order to prevent the selection of multidrug-resistant strains (MDR). We have studied 54 strains of Salmonella sent for further investigation to "Cantacuzino" NIRDMI Bucharest. The statistical analysis was based on the interpretation pathogen susceptibility and analyzed according to CLSI recommendations 2009, which revealed that 8 (14,81%) identified as S. enterica serovar Typhimurium group, presented a phenomenon of MDR. S. Typhimurium strains producing ESBL showed resistance mechanisms associated with beta-lactam resistance to aminoglycosides, quinolones, sulfonamides and tetracyclines.

Incidence of virulence-encoding genes among enteric Escherichia coli strains isolated from healthy subjects.

Escherichia coli, heterogeneous species consisting of commensal and pathogenic strains, is causing a broad spectrum of intestinal and extra intestinal diseases, ranging from asymptomatic infections to septicaemia, according to its capacity to produce different virulence factors. The incidence of different virulence-associated genes among the strains isolated from healthy subjects, taking into account that the human gastrointestinal tract is considered an important source for spreading E. coli strains, was evaluated. A total of 241 E. coli strains isolated from 41 healthy subjects, working in the food chain and coming to the laboratory for periodical medical control, were investigated for harbouring patogenicity factors--encoding genes. Extra intestinal virulence-associated genes, pap, sfa/foc, afa, hly, cnf and intestinal ones eaea, bfp, agg, It, st, vtx1 (stx1), vtx2 (stx2) and ipaH, were targeted by PCR using cellular lysate for total DNA. Genes encoding for adherence were the most prevalent. A number of 67 strains (27.80%) were positive for pap genes and 34 strains (14.11%) presented PCR positive results when afa genes were targeted, but sfa/foc genes were identified in only 10 strains (4.15%). Genes encoding for toxigenesis were less prevalent. A total of 9 strains amplified hly genes, 2.49% were positive for cnf genes and only 2 strains presented vtx1(stx1) gene. The results are in concordance with those which demonstrate that healthy subjects carrying strains possessing virulence-encoding genes could represent a reservoir for environmental circulation of such strains, considered life-threatening when a receptive host is encountered.

Application of pulsed-field gel electrophoresis to laboratory surveillance of small community outbreaks of Salmonella enterica serovar Typhimurium.

Infectious diarrhea syndrome is an important cause of human morbidity around the world, and Salmonella genus remains one of the most prevalent etiology. Salmonella enterica serovar Typhimurium outbreak-associated isolates received by the Laboratory for Enteric Pathogens from N.I.R.D.M.I. "Cantacuzino" for confirmation and typing were analyzed by genomic pulsed-field gel electrophoresis (PFGE) and phage susceptibility testing to establish their relatedness. Both typing methods proved to have similar discriminatory power. The isolates originating from the same outbreak belonged to the same phage type and showed indistinguishable PFGE profiles. The molecular characterization of autochthonal Salmonella enterica Typhimurium outbreak human isolates provided laboratory evidence that epidemiologically related isolates collected from community outbreaks of disease were also genetically related. In order to improve the national and international surveillance of major foodborne pathogens the reference laboratory centers are required to establish and maintain the capacity to perform a wide range of both phenotypic and genotypic methods to support outbreak investigations.