Horizontal Gene Transfer: A Vehicle for the Dissemination of Resistance and Virulence Determinants during Colonization and Disease

The successful in vivo horizontal transfer of mobile genetic elements carrying resistance and virulence determinants have contributed immensely to a global dissemination of virulent and multi-drug resistant pathogens. In addition, the pathogenesis of MRSA infection is enhanced via initial colonization of the skin through the component of the microbial surface antigen recognizing adhesive matrix molecules and by their ability to evade host immune response. Furthermore, it was also observed that the genetic diversity of pathogenic MRSA is due to its’ ability to rapidly acquire resistance and virulence determinants. A characteristic feature that made it one of the most important nosocomial pathogen worldwide. Similarly, the expression of virulence gene in MRSA has been observed to be regulated by the accessory gene regulator system (agr). These system is made up of a series of genes whose product build up quorum-sensing regulatory mechanisms that is growth dependent. In addition, at a certain growth stage, the agr systems triggers a pronounced changes in the expression of genes called the quorum sensing. The findings of this review affirms the importance of horizontal gene transfer in the dissemination of resistance and virulence determinants and as well as the genetic diversity of MRSA

Dissemination of resistance and virulence determinants in methicillin-resistant Staphylococcus aureus during colonization and disease: a review

The successful in vivo horizontal transfer of mobile genetic elements carrying resistance and virulence determinants have contributed immensely to a global dissemination of virulent and multi-drug resistant pathogens. The pathogenesis of MRSA infection is enhanced via initial colonization of the skin through the component of the microbial surface antigen recognizing adhesive matrix molecules and by their ability to evade host immune response. Furthermore, it was also observed that the genetic diversity of pathogenic MRSA is due to its’ ability to rapidly acquire resistance and virulence determinants. A characteristic feature that made it one of the most important nosocomial pathogen worldwide. Similarly, the expression of virulence gene in MRSA has been observed to be regulated by the accessory gene regulator system (agr). These system is made up of a series of genes whose product build up quorum-sensing regulatory mechanisms that is growth dependent. At a certain growth stage, the agr systems triggers a pronounced changes in the expression of genes called the quorum sensing. The findings of this review affirmed the importance of horizontal gene transfer in the dissemination of resistance and virulence determinants and as well as the genetic diversity of MRSA

Persistence of antibacterial resistance and virulence gene profile of methicillin resistant Staphylococcus aureus (MRSA) isolated from humans and animals

The persistence of antibacterial resistance and virulence gene profile of well characterized MRSA isolated from animals and human was determined using antibiotic susceptibility testing and PCR amplification of virulence and methicillin resistance gene. Antibiotic susceptibility testing revealed a general reduction in the rate of resistance to antibiotics previously tested. Isolates were currently susceptible to minocycline a tetracycline derivative, amikacin and gentamicin respectively. Resistance to cefoxitin and oxacillin were currently observed in 64 and 79% of all the isolates which in the case of cefoxitin it was less than the 86% while a bit higher in oxacillin as reported in the previous study. In addition, currently 57%, 43% and 36% of the isolates were resistant to amoxicillin, tetracycline and erythromycin which is less than the isolates previous resistance profile to amoxicillin and erythromycin whereas unchanged in the case of tetracycline. Four (29%) of the isolates were also currently resistant to vancomycin, doxycycline and amoxicillinclauvulanic acid; while only two isolates were resistant to vancomycin and three isolates were resistant to doxycycline in the previous study. No changes were observed in the number of isolates resistant to amoxicillin-clauvulanic acid. Resistance to more than one class of antibiotics was observed in 64% of the isolates. Currently we observe loss of methicillin resistance determinants mecA and susceptibility to all antibiotics tested in three isolates and reduced susceptibility in two isolates

Molecular Epidemiology: A Valuable Tool for Determination of Emerging and clonality of Methicillin Resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading nosocomial pathogen that is also emerging as a zoonotic pathogen. In this review, it was observed that rapid emergence of new MRSA clones at a higher frequency has ushered in a new knowledge on the clonality and epidemic potentials of MRSA. Secondly, the success of treatment and management of MRSA infection is threatened by the diversity in the clonal types. This is because different clones harbours different antibiotics resistance characteristics and as such respond differently to treatment. Furthermore, clonal replacement of hospital-acquired MRSA with community -acquired MRSA has also been observed. Thirdly, the transmission of MRSA even though previously thought to be exclusively within the hospital setting through hand contact and nasal colonization has now spread to the community and in addition human to animal and animal to human transmission has also been observed. Similarly, pet owners, veterinarians and farmers have been described as high-risked group with potentials of becoming reservoirs of MRSA. Furthermore, the adoption of hand hygiene in healthcare setting have to a great extent reduced the incidence of MRSA in the hospital. And lastly, the advent of molecular typing such as Pulsed Field Gel Electrophoresis (PFGE), Multi Locus Sequence Typing (MLST), Staphylococcal protein A typing (Spa typing) and Double Locus Sequence Typing (DLST) have proven to be a useful tool in providing valuable information on the evolution and clonal diversity of MRSA. These in turn help researchers to answer some pertinent questions on the epidemiology of MRSA

Occurrence of Campylobacter species from broiler chickens and chicken meat in Malaysia

Campylobacter is reported as a major cause of foodborne illness worldwide. Consumption of contaminated chicken meat is considered a significant risk factor of Campylobacter infection in humans. This study investigated the occurrence of non-Campylobacter jejuni-Campylobacter coli, in broiler chickens (n = 210) and chicken meat (n = 109). The samples were collected from seven broiler chicken farms (n = 210 cloacal swabs), 11 markets (n = 84 chicken meat), and 5 supermarkets (n = 25 chicken meat) located in different districts of Selangor State. Campylobacter were isolated from cloacal swabs using the Cape Town Protocol and from meat samples using the method of Duffy et al. (2007) with some modifications for Campylobacter isolations which were reported effective in the isolation of non-C. jejuni-C. coli Campylobacter species. The isolates were identified by Gram staining for cellular morphology, wet mount for motility and biochemical tests. Confirmation of presumed Campylobacter isolates was carried out using multiplex PCR (mPCR). One hundred seven (107/210) or 50.9% and twenty-nine (29/109) or 26.6% of chickens and chicken meat samples respectively were positive for Campylobacter species. Among the Campylobacter isolates from chickens, C. jejuni was the most predominantly isolated species (69.5%), followed by C. coli (16.2%). Campylobacter fetus and C. upsaliensis were the non-C. jejuni-C. coli Campylobacter species isolated in this study, at 9.3% and 2.5% respectively. Overall, the findings indicated broiler chickens were colonized not only by the common Campylobacter species but also by other Campylobacter species. We found the Cape Town Protocol useful to detect the occurrence of non-C. jejuni-C. coli isolates in chickens

Molecular epidemiology: a valuable tool for determination of emerging and clonality of methicillin resistant Staphylococcus aureus (MRSA)

Methicillin-resistant Staphylococcus aureus (MRSA) is one of the leading nosocomial pathogen that is also emerging as a zoonotic pathogen. In this review, it was observed that rapid emergence of new MRSA clones at a higher frequency has ushered in a new knowledge on the clonality and epidemic potentials of MRSA. Secondly, the success of treatment and management of MRSA infection is threatened by the diversity in the clonal types. This is because different clones harbours different antibiotics resistance characteristics and as such respond differently to treatment. Furthermore, clonal replacement of hospital-acquired MRSA with community -acquired MRSA has also been observed. Thirdly, the transmission of MRSA even though previously thought to be exclusively within the hospital setting through hand contact and nasal colonization has now spread to the community and in addition human to animal and animal to human transmission has also been observed. Similarly, pet owners, veterinarians and farmers have been described as high-risked group with potentials of becoming reservoirs of MRSA. Furthermore, the adoption of hand hygiene in healthcare setting have to a great extent reduced the incidence of MRSA in the hospital. And lastly, the advent of molecular typing such as Pulsed Field Gel Electrophoresis (PFGE), Multi Locus Sequence Typing (MLST), Staphylococcal protein A typing (Spa typing) and Double Locus Sequence Typing (DLST) have proven to be a useful tool in providing valuable information on the evolution and clonal diversity of MRSA. These in turn help researchers to answer some pertinent questions on the epidemiology of MRSA

Horizontal gene transfer: a vehicle for the dissemination of resistance and virulence determinants during colonization and disease

The successful in vivo horizontal transfer of mobile genetic elements carrying resistance and virulence determinants have contributed immensely to a global dissemination of virulent and multi-drug resistant pathogens. In addition, the pathogenesis of MRSA infection is enhanced via initial colonization of the skin through the component of the microbial surface antigen recognizing adhesive matrix molecules and by their ability to evade host immune response. Furthermore, it was also observed that the genetic diversity of pathogenic MRSA is due to its’ ability to rapidly acquire resistance and virulence determinants. A characteristic feature that made it one of the most important nosocomial pathogen worldwide. Similarly, the expression of virulence gene in MRSA has been observed to be regulated by the accessory gene regulator system (agr). These system is made up of a series of genes whose product build up quorum-sensing regulatory mechanisms that is growth dependent. In addition, at a certain growth stage, the agr systems triggers a pronounced changes in the expression of genes called the quorum sensing. The findings of this review affirms the importance of horizontal gene transfer in the dissemination of resistance and virulence determinants and as well as the genetic diversity of MRSA

Helicobacter pullorum in broiler chickens and the farm environment: A one health approach

Aim: This study aimed to investigate the occurrence of Helicobacter pullorum in broiler chickens and their farm environment. Materials and Methods: The ceca from 100 broiler chickens from ten farms were sampled from processing sites or markets. The cecal contents were aseptically collected from each cecum and cultured. The farms were visited, and environmental samples were collected which included water, house flies, floor swabs and soils in chicken houses. Results: H. pullorum was present in 51% of the broilers; 17.5% of the flies were found to carry H. pullorum and Campylobacter spp., 30% of house floors were positive, while all water samples were negative. Conclusion: Flies could have picked up the organisms from the chickens' feces and/or the environment of the chicken houses or they could be one of the sources in the spread of the organisms. This study also showed that broiler chickens are potential reservoirs for H. pullorum and may serve as a source of infection for humans through the food chain

Development of an in-house Rose Bengal plate test for diagnosis of brucellosis in goat

Brucellosis, caused by Brucella melitensis, is a significant problem for both public and animal health worldwide. The Rose Bengal plate test (RBPT) antigen from Brucella melitensis local isolates were developed in this study. The performance of the assay was investigated using serum samples collected from goats. A total of 1063 serum samples obtained from goats were examined for the presence of antibodies against Brucella by in-house RBPT (LRBPT), commercial RBPT (Veterinary Laboratory Agency – VLA, UK) and Compliment Fixation test (CFT). The sensitivity and specificity was calculated using CFT as the gold standard. Out of 1063 goats sera analyzed 364 (34.24%), 335 (31.51%), and 373 (35.08%) were found to be positive by LRBPT, commercial RBPT and CFT, respectively. The sensitivity calculated for the LRBPT, was 90.1% compared to commercial RBPT 85.0%. However, the specificity of the LRBPT was lower (95.9%), than the commercial RBPT (97.4%). Furthermore the LRBPT has better value of NPV (94.7%) than commercial RBPT NPV (92.3%). While the PPV, of the commercial RBPT is higher (94.6%) than LRBPT (92.3%) respectively. High sensitive and low cost LRBPT compared to cRBPT B. melitensis RBPT test was successfully developed in this present study. Therefore it was concluded that this diagnostic test kit can complement and replace the available commercial RBPT which is relatively more expensive and less sensitive in detection of brucellosis in goats. It could also be used for epidemiological surveillance of caprine brucellosis in Malaysia

Detection of virulence genes and antibiotic resistance profiles of Staphylococcus aureus isolated from animals

Aims: This study was designed to determine the virulence genes and antibiotic resistance profiles of Staphylococcus aureus isolated from dogs, cats, chickens and horses. Methodology and results: A total of 15 S. aureus isolates were used in this study. Antibiogram and screening of virulence genes was carried out using disc diffusion method and polymerase chain reaction. The results obtained showed that a total of 9 S. aureus isolates were resistant towards oxacillin (60%), 9 isolates were resistant towards neomycin (60%) and 8 isolates were resistant towards tilmicosin (53%). Resistance to amoxicillin, tetracycline and vancomycin was also observed in 6 (40%) of the isolates. Additionally, 5 (33%) of the isolates showed resistance towards streptomycin and linzolide while 4 (27%) of the isolates were resistant towards rifampin, erythromycin and mupirocin. Lastly, 3 (20%) of the isolates were resistant towards doxycycline. Intermediate resistance to amoxicillin and doxycycline was also observed. Virulence gene profiling showed that 4 (26.7%) of the isolates were positive for hlβ and SspA, 9 of the isolates (60%) showed positive for geh and 12 of the isolates (80%) showed positive for Set-1. Similarly, 2 (13.3%) of the isolates showed positive for etA and Seu while only 1 isolate (6.7%) showed positive for PVL and hla. None of the isolates were positive for tst-1 and etB. Conclusion, significance and impact of study: This study revealed reduced susceptibility and multiple drug resistance (MDR) in four isolates, and susceptibility to all antibiotics in two isolates in addition to low carriage rate of virulence gene in all isolates. Thus, indicating resistance development in majority of the isolates and the need to regulate indiscriminate use of antibiotics in animals