Research on the Phenotypic Characterization of Mrsa Strains Isolated from Animals

Keywords: chromogen, methicillin, MRSA, resistanceIntroduction: Currently, both in staphylococci isolated from animals with different diseases, as well as in humans, the MRSA strains (Methicillin Resistant S. aureus) are monitored, as the methicillin resistance is associated with the resistance to other antibiotic groups.Methicillin resistance is encoded by mec staphylococcal chromosomal cassettes (SCCmec), which are islands of resistance. These strains can be identified by molecular biology tests and tests that reveal several phenotypic characteristics.The research was made in order to characterize and identify phenotypically the MRSA staphylococci strains isolated from animals.Materials and Methods: Researches were made on 240 coagulase positive and coagulase negative strains of staphylococci. Mannitol fermentation was tested on Champan medium, free coagulase was revealed on Baird-Parker medium and to identify S. aureus subsp. aureus was used the chromogenic medium Chromatic Staph.Methicillin-resistant strains were detected by disc diffusion method, using biodiscs with methicillin, oxacillin and cefoxitin. Also, to identify the MRSA strains, was used the chromogenic medium Chromatic MRSA.Results: The isolates were positive to mannitol and produced complete haemolysis or were unhaemolytic. A total of 44 strains produced free coagulase on Baird-Parker medium, considered coagulase positive strains, while 196 were coagulase negative strains.The isolates conducted differently to methicillin: 22,08% of strains were resistant, 51,25% of strains were susceptible and 26,66% had intermediate resistance, while the resistant strains to oxacillin were 42,91%.The increased frequency of methicillin-resistant strains of staphylococci and, particularly, MRSA strains, determined using the cefoxitin disk diffusion test, which is more reliable than methicillin and oxacillin.On the MRSA chromogenic medium, the methicillin-resistant strains of staphylococci formed colonies with pigment from mauve to orange mauve.Conclusion: The obtained results by disk diffusion test on resistance patterns to 3 beta-lactams, resistant to penicillinase, indicated a different frequency of the resistant strains to these antibiotics.Cefoxitin disk diffusion test revealed a frequency of 2,51% of resistant strains, that can be considered MRSA strains

Serological investigations regarding the effect of infection with swine influenza virus H1N1 on the evolution of enzootic pneumonia in wild boars from western Romania

Abstract The transmission of infectious diseases between wild animals and domestic animals is becoming a global issue of growing interest for the pig producing industry and human public health. In medical literature, that are several reports that wild boars may act as a reservoir for economically important infectious diseases that endemically affect domestic pigs, such as enzootic pneumonia and swine influenza. Although the risk of transmission of these diseases between wild boars and domestic pigs is likely to increase in Western Romania, there is very few data on the seroprevalence of Mycoplasma hyopneumoniae and swine influenza virus in wild boar populations. Therefore, the aim of the present study was to determine the seroprevalence of infection caused by Mycoplasma hyopneumoniae in wild boar populations from Western Romania in order to contribute to the information necessary for the control of the disease. Also, in order to determine the effect of infection with swine influenza virus H1N1 on the evolution of enzootic pneumonia, the value of seroprevalence for both types of infections was compared. The seroprevalence of infection with Mycoplasma hyopneumoniae, reported to the total number of samples tested on nine hunting grounds (which belong to Caraș-Severin County, Timiș County, and Bihor County) was 66.67%. The seroprevalence of swine influenza virus infection, reported to the total number of samples tested on 25 hunting grounds (which belong to Caraș-Severin County, Timiș County, and Bihor County) was 11.80%. Mixed infections with Mycoplasma hyopneumoniae and swine influenza virus subtype H1N1 were detected in two out of the three counties included in the study (Timiș County and Bihor County), with a substantial increase in Mycoplasma hyopneumoniae seropositivity. The results obtained in this study provide information on the disease exposure and health status of wild boars suggesting that Mycoplasma hyopneumoniae and swine influenza virus are widespread in wild boar populations from Western Romania and that these pathogens represent a source of infection for domestic pigs, as well as humans

A variant of the direct immunofluorescence technique used in the routine diagnosis of PRRS syndrome

Laboratory diagnosis of PRRS syndrome is based on virus detection, isolated strain characterization and antibody detection. Given the severity of the disease, rapid diagnostic methods are used to detect the nucleocapsid viral antigen present in the target organs (lymph nodes, lungs). From swine youth corpses from disease outbreaks, inguinal lymph nodes were taken, and from swine youth with characteristic respiratory symptoms, samples of oronasal fluid were taken. The nucleocapsid viral antigen was detected using the anti PRRSV monoclonal antibody kit labeled with fluorescein isothiocyanate (BIO 268). The smears made of lymph nodes and oronasal fluid to which they were identified, in the microscopic field, the described aspects were considered positive. Thus, 26 samples of lymph nodes (65%) and 9 oronasal fluid samples (45%) were positive, which were controlled to confirm PRRS virus presence by RT-PCR technique. All positive samples of lymph nodes and oronasal fluid positive to the IFD technique in the adapted working variant were confirmed as positive samples by the RT-PCR technique