Prevalence and antimicrobial resistance of MRSA across different pig age groups in an intensive pig production system in Australia

This observational study aimed to determine MRSA prevalence using strain‐specific real‐time PCR at the pig level, stratified by age groupings, within a pig enterprise. A total of 658 samples were collected from individual pigs (n = 618) and the piggery environment (n = 40), distributed amongst five different pig age groups. Presumptive MRSA isolates were confirmed by the presence of mecA, and MALDI‐TOF was performed for species verification. All isolates were tested against 18 different antimicrobials. MRSA was isolated from 75.2% (95% CI 71.8–78.6) of samples collected from pigs, and 71% of the MRSA isolates from this source were identified as community‐associated (CA)‐MRSA ST93, while the remainder were livestock‐associated (LA)‐MRSA ST398. Amongst environmental isolates, 80% (CI 64.3–95.7) were ST93 and the remainder ST398. All MRSA isolates from pigs and the environment were susceptible to ciprofloxacin, gentamicin, linezolid, mupirocin, rifampicin, sulfamethoxazole–trimethoprim, teicoplanin and vancomycin. Phenotypic rates of resistance were penicillin (100%), clindamycin (97.6%), erythromycin (96.3%), ceftiofur (93.7%), chloramphenicol (81.2%), tetracycline (63.1%) and amoxicillin–clavulanate (63.9%). A low prevalence of resistance (9.2%) was observed against neomycin and quinupristin–dalfopristin. The probability of MRSA carriage in dry sows (42.2%) was found to be significantly lower (p < .001) when compared to other age groups: farrowing sows (76.8%, RR1.82), weaners (97.8%, RR 2.32), growers (94.2%, RR 2.23) and finishers (98.3%, RR 2.33). Amongst different production age groups, a significant difference was also found in antimicrobial resistance for amoxicillin–clavulanate, neomycin, chloramphenicol and tetracycline. Using the RT‐PCR assay adopted in this study, filtering of highly prevalent ST93 and non‐ST93 isolates was performed at high throughput and low cost. In conclusion, this study found that weaner pigs presented a higher risk for CA‐MRSA and antimicrobial resistance compared to other age groups. These findings have major implications for how investigations of MRSA outbreaks should be approached under the One‐Health context.     

An Improved Synthesis of 7, 8-Epoxy-1,3,11-cembratriene- 15R(α), 16-diol,a Cembranoid of Marine Origin with a Potent Cancer Chemopreventive Activity

An effective method for the synthesis of 7,8-epoxy-1,3,11-cembratriene- 15R(α),16-diol and its in vitro Epstein-Barr Virus Early Antigen (EBV-EA) Activation Chemopreventive Assay are reported. This semisynthetic product is a new cembranoid with a potent tumor inhibitory activity that is expected to be a lead compound for a new class of chemopreventive agents of marine origin.     

Detection of antibodies to equine arteritis virus by a monoclonal antibody-based blocking ELISA.

A potent ELISA antigen was prepared from equine arteritis virus (EAV) by differential centrifugation of EAV-infected cell culture fluid, followed by solubilization of the preparation by Triton X-100 treatment. Using this antigen and a mouse monoclonal antibody against the G(L) protein of EAV, a reliable blocking ELISA (bELISA) was developed for the detection of EAV antibodies in equine sera. The bELISA was evaluated using a total of 837 test serum samples. The relative sensitivity (n = 320) of the bELISA compared to the serum neutralization (SN) test was 99.4%. The bELISA appears to be a highly specific test, the specificity of which did not appear to be adversely affected by previous exposure of horses to non-EAV-containing biologicals. Of 119 serum samples, 21 from horses without any history of exposure to EAV and 98 from racetrack Thoroughbreds, 118 were negative in the SN test and bELISA. One sample was SN-negative but suspicious with the bELISA. Based on testing 465 SN-negative field samples and 52 SN-negative samples from experimental horses, and excluding any sera giving a suspicious reaction, the relative specificity of the bELISA was 97.7%. Samples should be examined undiluted and diluted 1/10 in the bELISA because the testing of sera of high neutralizing antibody titer may be affected by a prozone-like phenomenon. The bELISA is a more rapid and cost-efficient test than the SN test for the detection of EAV antibodies in equine sera.     

Empirical Models for Predicting the Dry Matter Yield of Grass Silage Swards Using Plant Tissue Analyses

Quantifying spatial variability in forage grass yield within individual fields is hampered by the lack of accurate yield monitoring equipment. Here, it is shown how dry matter (DM) yield of silage swards can be predicted on the basis of their mineral composition. This empirical method of predicting yield enables diagnoses of sward nutrient status to be made simultaneously from the tissue test information, and provides a unique opportunity for identifying the nutritional and non-nutritional factors responsible for variability in sward productivity at sub-field scales. Maps of sward DM yield at first, second and third cut silage stages in 1999, and at first cut silage stage in 2000, on a large (7.9 ha) grassland field were produced using two different yield models: one model for first cut and a separate model for second and third cuts. The maps indicated that DM production varied considerably across the field, particularly at first cut, but that the pattern of yield variability at this cut was consistent from 1999 to 2000. The results of the plant tissue tests suggested that N deficiency had been responsible for limiting DM production on the lower yielding parts of the field.     

Gordon memorial lecture: people, poultry and pathogenic mycoplasmas

Man in managing poultry for human benefit has found that his methods may precipitate or exacerbate certain diseases: among which are the mycoplasmosis of fowls and turkeys. Control measures for these conditions have therefore been sought and to make them effective it has been necessary to study the epidemiology, diagnosis and pathogenesis of these conditions. Much is now known about their epidemiology although certain aspects still require investigation. More sensitive and specific methods of diagnosis are also required and although it is possible to control these conditions by eradication the mycoplasmosis are still an economic problem. Under existing management systems, therefore, development and use of effective vaccines and additional drugs are essential. It is noteworthy that the pathogenesis of at least one of the avian mycoplasmosis is similar to human immune-complex disease. In further elucidation of this complex the fowl may be a useful experimental animal. Thus the association of people, poultry and pathogenic mycoplasmas not only involves attempts to control the pathogens in order to attain maximum production by poultry but also could include the utilisation of poultry and the pathogen in an attempt to elucidate some of the diseases of people.     

Myelitis in a cat infected with Toxoplasma gondii and feline immunodeficiency virus

Severe necrotizing myelitis secondary to localization and reactivation of Toxoplasma gondii within the spinal cord of a domestic shorthair cat was diagnosed by use of light and electron microscopy and immunohistochemistry. The cat also was infected with feline immunodeficiency virus. This case may have useful comparative features to T gondii infections in human patients with acquired immunodeficiency syndrome.