Analysis for prevalence and physical linkages amongst integrons, ISEcp1, ISCR1, Tn21 and Tn7 encountered in Escherichia coli strains from hospitalized and non-hospitalized patients in Kenya during a 19-year period (1992-2011)

Background: We determined the prevalence and evidence for physical linkage amongst integrons, insertion sequences, Tn21 and Tn7 transposons in a collection of 1327 E. coli obtained over a 19-year period from patients in Kenya. Results: The prevalence of class 1 integrons was 35%, class 2 integrons were detected in 3 isolates but no isolate contained a class 3 integron. Integron lacking the 3'-CS or those linked to sul3 gene or IS26 or those containing the ISCR1 were only detected in multidrug resistant (MDR) strains. The dfrAs were the most common cassettes and their prevalence was: -dfrA1( 28%), dfrA12( 20%), dfA17( 9%), dfrA7( 9%), and dfrA16( 5%). The aadA were the second most abundant cassettes and their prevalence was: -aadA1( 25%), aadA2( 21%), and aadA5( 14%). Other cassettes occurred in lower prevalence of below 5%. Prevalence of Tn21, ISEcp1, ISCR1 and IS26 was 22%, 10%, 15%, and 7% respectively. Majority of Tn21 containing integrons carried a complete set of transposition genes while class 2 integrons were borne on Tn7 transposon. The qnrA genes were detected in 34( 3%) isolates while 19( 1%) carried qnrB. All qnr genes were in MDR strains carrying integrons containing the ISCR1. Close to 88% of blaTEM-52 were linked to IS26 while = 80% of blaCTX-Ms and blaCMYs were linked to ISEcp1. Only a few studies have identified a blaCTX-M-9 containing an ISEcp1 element as reported in this study. Multiple genetic elements, especially those borne on incIl, incFII, and incL/M plasmids, and their associated resistance genes were transferrable en bloc to E. coli strain J53 in mating experiments. Conclusions: This is the first detailed study on the prevalence of selected elements implicated in evolution of resistance determinants in a large collection of clinical E. coli in Africa. Proliferation of such strains carrying multiple resistance elements is likely to compromise the use of affordable and available treatment options for majority of poor patients in Africa. There is therefore a need to monitor the spread of these highly resistant strains in developing countries through proper infection control and appropriate use of antimicrobials

Clinical resistance and decreased susceptibility in Streptococcus suis isolates from clinically healthy fattening pigs

Streptococcus suis (S. suis) has often been reported as an important swine pathogen and is considered as a new emerging zoonotic agent. Consequently, it is important to be informed on its susceptibility to antimicrobial agents. In the current study, the Minimum Inhibitory Concentration (MIC) population distribution of nine antimicrobial agents has been determined for nasal S. suis strains, isolated from healthy pigs at the end of the fattening period from 50 closed or semiclosed pig herds. The aim of the study was to report resistance based on both clinical breakpoints (clinical resistance percentage) and epidemiological cutoff values (non-wild-type percentage). Non-wild-type percentages were high for tetracycline (98%), lincomycin (92%), tilmicosin (72%), erythromycin (70%), tylosin (66%), and low for florfenicol (0%) and enrofloxacin (0.3%). Clinical resistance percentages were high for tetracycline (95%), erythromycin (66%), tylosin (66%), and low for florfenicol (0.3%) and enrofloxacin (0.3%). For tiamulin, for which no clinical breakpoint is available, 57% of the isolates did not belong to the wild-type population. Clinical resistance and non-wild-type percentages differed substantially for penicillin. Only 1% of the tested S. suis strains was considered as clinically resistant, whereas 47% of the strains showed acquired resistance when epidemiological cutoff values were used. In conclusion, MIC values for penicillin are gradually increasing, compared to previous reports, although pigs infected with strains showing higher MICs may still respond to treatment with penicillin. The high rate of acquired resistance against tiamulin has not been reported before. Results from this study clearly demonstrate that the use of different interpretive criteria contributes to the extent of differences in reported antimicrobial resistance results. The early detection of small changes in the MIC population distribution of isolates, while clinical failure may not yet be observed, provides the opportunity to implement appropriate risk management steps

Disinfection by hydrogen peroxide nebulization increases susceptibility to avian pathogenic Escherichia coli

Background: Avian pathogenic Escherichia coli (APEC) are the major cause of economic losses in the poultry industry worldwide. Traditionally, antibiotics are used to treat and prevent colibacillosis in broilers. Due to resistance development other ways of preventing/treating the disease have to be found. Therefore during this study the nebulization of low concentrations of hydrogen peroxide (H2O2) was tested in the presence of chickens to lower pathogenicity of APEC. Results: Significantly higher total lesion scores and higher E. coli concentrations were found in the spleen of chickens exposed to 2 % H2O2 compared to those exposed to 1 % H2O2 and control chickens which had been exposed to nebulization with distilled water. Higher total lesions scores and E. coli concentrations in the spleen were found in chickens exposed to 1 % H2O2 in comparison to control chickens (not significant). Conclusion: H2O2 is rendering animals more prone to APEC infection contraindicating H2O2 nebulization in the presence of chickens

Prevalence of Rabbit Hemorrhagic Disease (RHD) in wild rabbits (Oryctolagus cuniculus) in Flanders, Belgium, 1999-2002

During the period of July 1999 through June 2002, carcasses of wild rabbits that had been shot or found dead and livers originating from wild rabbits that had been shot for consumption were collected in Flanders. One hundred and twelve carcasses were suitable for necropsy and histological and bacteriological analysis; histological analysis was possible in 41 livers. Considering the 112 rabbit carcasses only, Rabbit Hemorrhagic Disease (RHD) was found to be present in 33.9% of the cases. RHD was the most prevalent wild rabbit pathology detected in this study, before staphylococcosis (12.5%), and myxomatosis (10.7%). None of the liver samples from rabbits shot for consumption were positive for RHD. Of the 38 histologically RHD positive samples, 24 were analyzed with the hemagglutination (HA) technique, yielding 58.3% positive results. Seven samples that were histologically positive for RHD but HA negative were examined by transmission electron microscopy and were found positive for calicivirus. This proves that HA-negative RHD strains are circulating in the Flemish wild rabbit population