Non-aureus staphylococci and mammaliicocci (NASM) are one of the most common causes of subclinical mastitis in dairy animals and the extent of damage by intramammary infections (IMI) caused by NASM is still under debate. The different effects of NASM on the mammary gland may be associated with differences between bacterial species. NASM are normal and abundant colonizers of humans and animals and become pathogenic only in certain situations. The veterinary interest in NASM has been intense for the last 25 years, due to the strongly increasing rate of opportunistic infections. Therefore, the objective of this review is to provide a general background of the NASM as a cause of mastitis and the most recent advances that exist to prevent and fight the biofilm formation of this group of bacteria, introduce new biomedical applications that could be used in dairy herds to reduce the risk of chronic and recurrent infections, potentially responsible for economic losses due to reduced milk production and quality. Effective treatment of biofilm infection requires a dual approach through a combination of antibiofilm and antimicrobial agents. Even though research on the development of biofilms is mainly focused on human medicine, this technology must be developed at the same time in veterinary medicine, especially in the dairy industry where IMI are extremely common.
Mastitis in goats is mainly caused by coagulase-negative Staphylococcus (CNS). The identification methods for this group are based on evaluating the expression of phenotypic characteristics such as the ability to metabolize various substrates; however, this is disadvantageous as these methods are dependent on gene expression. In recent years, genotyping methods such as the Multiple Locus Variable-Number Tandem Repeat Analysis (MLVA) and gene identification have been useful for epidemiological study of several bacterial species. To develop a genotyping method, the genome sequence of Staphylococcus chromogenes MU970 was analysed. The analysis showed nine virulence genes described in Staphylococcus aureus. The MLVA was developed using four loci identified in the genome of S. chromogenes MU970. This genotyping method was examined in 23 strains of CNS isolated from goat mastitis. The rate of discrimination for MLVA was 0.8893, and the highest rates of discrimination per the index of Simpson and Hunter-Gaston were 0.926 and 0.968 for the locus 346_06, respectively. The virulence genes were present in all strains of S. chromogenes but not in other CNS. The genotyping method presented in this paper is a viable and easy method for typifying CNS isolates from mastitis cases in different regions and is an ideal mean of tracking this disease.
El objetivo de este estudio fue analizar el proceso de producción de leche de vaca de un sistema familiar con manejo orgánico que sirve de materia prima para lácteos, con la finalidad de mejorar la eficiencia de su producción a través de un análisis de inocuidad y calidad con un estudio de trazabilidad microbiológico. Se evaluó la calidad e inocuidad de la leche cruda, pasteurizada y sus derivados, identificando los riesgos microbiológicos de la misma desde su obtención hasta su transformación, implementando un sistema de trazabilidad. La metodología consistió en recolectar muestras de leche de vacas Jersey (Bos taurus) en dos etapas: en la primera, en el máximo nivel de producción; en la segunda, los animales se encontraban próximos al secado. Se realizó un conteo de bacterias mesofílicas y coliformes en leche y lácteos, donde se obtuvieron cantidades por encima del límite permitido por la NOM-243-SSA1-2010. En el análisis bacteriológico general de leche se identificó a Staphylococcus aureus y Escherichia coli. Es necesario encaminar al personal que labora en unidad de lácteos en las buenas prácticas de higiene y de manufactura para disminuir las cargas microbiológicas, cumplir con las normas establecidas y asegurar la salud del consumidor.
Mastitis can be caused by infectious agents, bacterial mastitis is the most common, in Mexico, and data regarding mastitis in goats are scarce. The aim of this work was to identify the bacteria most frequently present in goats with mastitis and assess isolate susceptibility to chemotherapeutic agents. A total of 460 samples of goat milk were obtained from the states of Guanajuato, Querétaro, and Morelos and Mexico City. A total of 56 bacteriapositive samples were obtained. Of these bacteria-positive samples, 33 were identified as belonging to the Staphylococcus genus, representing 58.92% of the positive samples. Of the 33 Staphylococcus-positive samples, 16 were identified as S. epidermidis, representing 48.48% of the Staphylococcus-positive samples; 5 each were identified as S. simulans and S. xylosus, each representing 15.15% of the Staphylococcus-positive samples; 3 were identified as S. lentus, representing 9.09% of the Staphylococcus-positive samples; 2 were identified as S. aureus, representing 6.06% of the Staphylococcus-positive samples; and 1 each was identified as S. caprae and S. cohnii, each representing 3.03% of the Staphylococcus-positive samples. Resistance to streptomycin, ampicillin, polymyxin B, tetracycline and tobramycin was assessed using an antibiogram on all specimens that were Staphylococcus-positive. The differences observed in the efficacies of the evaluated drugs illustrate the importance of carrying out tests for the identification of and evaluation of antimicrobial susceptibility in bacterial agents related to mastitis
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