Inhibitory effect of black and red pepper and thyme extracts and essential oils on enterohemorrhagic Escherichia coli and DNase activity of Staphylococcus aureus

In this study, extracts and essential oils of Black and Red pepper and Thyme were tested for antibacterial activity against Escherichia coli O157:H7 and Staphylococcus aureus. Black and Red pepper and Thyme were provided from Iranian agricultural researches center. 2 g of each plant powder was added to 10 cc ethanol 96 degrees. After 24 h, the crude extract was separated as an alcoholic extract and concentrated by distillation method. Plants were examined for determining their major component and essential oils were separated. Phytochemical analyses were done for detection of some effective substances in extracts. The antibacterial activity against. Escherichia coli O157:H7 and Staphylococcus aureus was tested and the results showed that all extracts and essential oils were effective and essential oils were more active. The extracts and oils that showed antimicrobial activity were later tested to determine the Minimum Inhibitory Dilution [MID] for those bacteria. They were also effective on the inhibition of DNase activity. This study was indicated that extracts and essential oils of Black and Red pepper and Thyme can play a significant role in inhibition of Escherichia coli O157:H7 and Staphylococcus aureus

Genetic transformation in antibiotic resistant escherichia coli O157:H7

Five hundred stool samples were collected from patients with diarrhea [infants and children under ten years of age] admitted to the Pediatric and Maternity Hospital in Erbil City from March 2007 to September 2007. The samples were cultured on different culture media and according to the colony morphology, biochemical reactions and by the use of API 20E system, 35 [7%] were diagnosed as E.coli I, 8 [1.6%] E.coli II, 17 [3.4%] E.coli III, 22 [4.4%] E.coli IV, 8 [1.6%] Shigella dysenteriae, 16 [3.2%] Salmonella arizonae, 12 [2.4%] Salmonella typhi and 6 [1.2%] Vibrio cholerae. In addition, cases of Entamoeba histolytica 175 [35%], Giardia lamblia 102 [20.4%] and Hymenolepis nana 2 [2.4%] were identified. No infectious agents were found in 75 [15%] of the samples. 22 [4.4%] of the samples had mixed infections. The sensitivity of E.coli O157:H7 isolate to different antibiotics was performed. There was a variation in the resistance ranging from 8.5-90%. The determination of the site of genes responsible for the antibiotic resistance in E.coli O157:H7 was performed using the genetic transformation method for E.coli DH5 alpha laboratory strain with the DNA that is absent from the highly resistant strains, E.coli O157:H7 4 and E. coli O157:H7 6. The transformation process succeeded when using the plasmid DNA for strain 4 and failed when using strain 6. It was evident that the genes responsible for resistance to the following antibiotics were located on the plasmid DNA: amoxicillin, amoxiclav, ampicillin, cephalexine, cefixime, cefotaxime, doxycyclin, gentamycin, nalidixic acid, nitrofurantoin, rifampicin, streptomycin and tetracycline. Whereas the genes responsible for the following antibiotic resistance were located on the chromosome: amikacin, erythromycin, chloramphenicol, ciprofloxacin, tobramycin and trimethoprim

Examination of diarrheal stools in Hat Yai City, South Thailand, for Escherichia coli O157 and other diarrheagenic Escherichia coli using immunomagnetic separation and PCR method.

A total of 493 stool samples from diarrheal patients in Songklanagarind Hospital, in southern Thailand, were examined for Escherichia coli O157 by the culture method combined with an immunomagnetic separation (IMS) technique. E. coli O157 was not found, although the IMS-based method could detect 10(2)-10(3) CFU of artificially inoculated O157/g of stool samples. Polymerase chain reaction was also used for the detection and identification of diarrheagenic E coli from 530 stool samples. The target genes were eae for enteropathogenic E. coli (EPEC), stx for enterohemorrhagic E. coli (EHEC), elt and est for enterotoxigenic E. coli (ETEC), ipaH for enteroinvasive E. coli (EIEC), and aggR for enteroaggregative E. coli (EAggEC). Fifty-eight diarrheagenic E. coli strains were detected in 55 stool samples (10%) from 32 children and 23 adults. These included 31 EAggEC strains (5.8%), 13 ETEC strains (2.5%), 13 EPEC strains (2.5%), and one EIEC strain (0.2%). EHEC was not detected. The diarrheagenic E. coli strains were found mainly in children under 2 years of age (24 of 32 children). EAggEC strains and ETEC strains were susceptible to several antibiotics whereas the EPEC strains exhibited resistance to these antibiotics.