Shiga toxin-producing Escherichia coli O157:H7 from extensive cattle of the fighting bulls breed

Phage Cocktail Targeting STEC O157:H7 Has Comparable Efficacy and Superior Recovery Compared with Enrofloxacin in an Enteric Murine Model

O157:H7 is the most important Shiga toxin-producing Escherichia coli (STEC) serotype in relation to public health. Given that antibiotics may contribute to the exacerbation of STEC-related disease and an increased frequency of antibiotic-resistant strains, bacteriophage (phage) therapy is considered a promising alternative. However, phage therapy targeting enteric pathogens is still underdeveloped with many confounding effects from the microbiota. Here we comprehensively compared the therapeutic efficacy of a phage cocktail with the antibiotic enrofloxacin in a mouse model of STEC O157:H7 EDL933 infection. Enrofloxacin treatment provided 100% survival and the phage cocktail treatment provided 90% survival. However, in terms of mouse recovery, the phage cocktail outperformed enrofloxacin in all measured outcomes. Compared with enrofloxacin treatment, phage treatment led to a faster elimination of enteric pathogens, decreased expression levels of inflammatory markers, increased weight gain, maintenance of a stable relative organ weight, and improved homeostasis of the gut microbiota. These results provide support for the potential of phage therapy to combat enteric pathogens and suggest that phage treatment leads to enhanced recovery of infected mice compared with antibiotics. IMPORTANCE With the increasing severity of antibiotic resistance and other adverse consequences, animal experiments and clinical trials investigating the use of phages for the control and prevention of enteric bacterial infections are growing. However, the effects of phages and antibiotics on organisms when treating intestinal infections have not been precisely studied. Here, we comprehensively compared the therapeutic efficacy of a phage cocktail to the antibiotic enrofloxacin in a mouse model of STEC O157:H7 EDL933 infection. We found that, despite a slightly lower protection rate, phage treatment contributed to a faster recovery of infected mice compared with enrofloxacin. These results highlight the potential benefits of phage therapy to combat enteric infections.

Microencapsulated phages show prolonged stability in gastrointestinal environments and high therapeutic efficiency to treat Escherichia coli O157:H7 infection

Escherichia coli (E. coli) O157:H7 bacterial infection causes severe disease in mammals and results in substantial economic losses worldwide. Due to the development of antibiotic resistance, bacteriophage (phage) therapy has become an alternative to control O157:H7 infection. However, the therapeutic effects of phages are frequently disappointing because of their low resistance to the gastrointestinal environment. In this study, to improve the stability of phages in the gastrointestinal tract, E. coli O157:H7 phages were microencapsulated and their in vitro stability and in vivo therapeutic efficiency were investigated. The results showed that compared to free phages, the resistance of microencapsulated phages to simulated gastric fluid and bile salts significantly increased. The microencapsulated phages were efficiently released into simulated intestinal fluid, leading to a better therapeutic effect in rats infected with E. coli O157:H7 compared to the effects of the free phages. In addition, the microencapsulated phages were more stable during storage than the free phages, showing how phage microencapsulation can play an essential role in phage therapy.

Molecular profiling and antimicrobial susceptibility of Escherichia coli O157:H7 isolated in Bulgaria

The purpose of this study was to detect the presence of shiga-toxin producing Escherichia coli (STEC) in faeces of healthy dairy cattle and to determine the sensitivity of isolates to several anti­microbial drugs. A total of 1,104 anal swab samples originating from 28 cattle farms were examined. After the primary identification, 30 strains were found to belong to serogroup О157. By means of conventional multiplex PCR, isolates were screened for presence of resistance genes stx1, stx2 and eaeА. Twenty-nine strains possesses amplicons with a size corresponding to genes stx2 and eaeA, one had amplicons also for the stx1 gene and one lacked amplicons of all three genes. Twenty-eight strains demonstrated amplicons equivalent to gene H7. The results from phenotype analysis of resistance showed preserved sensitivity to ceftriaxone, ceftazidime, cefotaxime, cephalothin, streptomycin, gentamicin, tetracycline, enrofloxacin and combinations sulfamethoxazole/trimethoprim and amoxicillin/clavulanic acid. Sensitivity to ampicillin was relatively preserved, although at a lower extent.

Molecular characterization of enterohemorrhagic E. coli O157 isolated from animal fecal and food samples in Eastern China

Objective. To elucidate the extent of food contamination by enterohemorrhagic Escherichia coli (EHEC) O157 in Eastern China. Methods. A total of 1100 food and animal fecal samples were screened for EHEC O157. Then, molecular characterization of each isolate was determined. Results. EHEC O157 was isolated as follows: pig feces, 4% (20/500); cattle feces, 3.3% (2/60); chicken feces, 1.43% (2/140); pork, 2.14% (3/140), milk, 1.67% (1/60); and chicken meat, 1.67% (1/60). The stx1, stx2, eae, and hlyA genes were present in 26.7% (8/30), 40% (12/30), 63.3% (19/30), and 50% (15/30) of the O157 isolates, respectively. Molecular typing showed that strains from fecal and food samples were clustered into the same molecular typing group. Furthermore, the isolates from pork and pig feces possessed the same characterization as the clinical strains ATCC35150 and ATCC43889. Biofilm formation assays showed that 53.3% of the EHEC O157 isolates could produce biofilm. However, composite analyses showed that biofilm formation of EHEC O157 was independent of genetic background. Conclusions. Animal feces, especially from pigs, serve as reservoirs for food contamination by EHEC O157. Thus, it is important to control contamination by EHEC O157 on farms and in abattoirs to reduce the incidence of foodborne infections in humans.

Regional variation in the prevalence of E. coli O157 in cattle: a meta-analysis and meta-regression

BACKGROUND

Escherichia coli O157 (EcO157) infection has been recognized as an important global public health concern. But information on the prevalence of EcO157 in cattle at the global and at the wider geographical levels is limited, if not absent. This is the first meta-analysis to investigate the point prevalence of EcO157 in cattle at the global level and to explore the factors contributing to variation in prevalence estimates.

METHODS

Seven electronic databases- CAB Abstracts, PubMed, Biosis Citation Index, Medline, Web of Knowledge, Scirus and Scopus were searched for relevant publications from 1980 to 2012. A random effect meta-analysis model was used to produce the pooled estimates. The potential sources of between study heterogeneity were identified using meta-regression.

PRINCIPAL FINDINGS

A total of 140 studies consisting 220,427 cattle were included in the meta-analysis. The prevalence estimate of EcO157 in cattle at the global level was 5.68% (95% CI, 5.16-6.20). The random effects pooled prevalence estimates in Africa, Northern America, Oceania, Europe, Asia and Latin America-Caribbean were 31.20% (95% CI, 12.35-50.04), 7.35% (95% CI, 6.44-8.26), 6.85% (95% CI, 2.41-11.29), 5.15% (95% CI, 4.21-6.09), 4.69% (95% CI, 3.05-6.33) and 1.65% (95% CI, 0.77-2.53), respectively. Between studies heterogeneity was evidenced in most regions. World region (p<0.001), type of cattle (p<0.001) and to some extent, specimens (p = 0.074) as well as method of pre-enrichment (p = 0.110), were identified as factors for variation in the prevalence estimates of EcO157 in cattle.

CONCLUSION

The prevalence of the organism seems to be higher in the African and Northern American regions. The important factors that might have influence in the estimates of EcO157 are type of cattle and kind of screening specimen. Their roles need to be determined and they should be properly handled in any survey to estimate the true prevalence of EcO157.

Salmonella spp. and Shiga toxin-producing Escherichia coli prevalence in an ocellated lizard (Timon lepidus) research center in Spain

The aim of this work was to study the epidemiological status of Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) in an ocellated lizard research center focusing on the risk and hygiene aspects. Fecal and environmental samples were collected and examined for Salmonella spp. and STEC. Isolates were detected using real-time polymerase chain reaction (RT-PCR) and characterized using serotyping and pulsed-field gel electrophoresis (PFGE). Overall, 52% of samples were positive for Salmonella spp. using RT-PCR and seven isolates were obtained from samples from ocellated lizards and their environment, whereas no samples were positive for STEC. Salmonella isolates belonged to S. enterica subsp. enterica serovar Kibusi and S. enterica subsp. salamae serovars 41:z10:z6 and 18:z10:z6, some of which have previously been isolated from human sources. Indistinguishable and closely related PFGE types were found, which supported the existence of horizontal transmission between animals due to crowding of animals and the persistence of Salmonella in the environment. The results of the current study emphasize the need for improved prevention efforts and good hygiene practices in research centers, recuperation centers, and zoos with reptiles to minimize the exposure of personnel and visitors to this pathogen.