RESUMO
Staphylococcus chromogenes TA showed significantly lower growth under iron-deprived conditions, and adding an iron supplement (lactoferrin or ferritin) resulted in no improvement in growth; in contrast, growth of S. chromogenes IM was significantly recovered with ferritin iron supplementation. OnlyStaphylococcus hominis strains originating from quarter milk were able to significantly utilize ferritin as an iron source to reverse the growth inhibition caused by chelating agent 2,2'-bipyridyl in varying degrees. Both S. chromogenes strains (IM and TA) and all S. hominis strains were unable to significantly use lactoferrin as an iron source for growth recovery.
RESUMO
ABSTRACT Mycoplasma spp. is reported as a highly contagious mastitis-causing bacteria in dairy cattle, without successful or low response to most common antibiotic treatments due to the lack of cell wall. In Colombia it has been reported in the Central Andean region during 2014. The aim was to estimate the prevalence of Mycoplasma spp. in bulk tank milk using microbiological and molecular diagnosis. A random longitudinal study enrolling 220 commercial dairy farms located in four provinces of the mid-western region of Colombia from four pasteurizer companies was performed. Bulk tank milk samples were collected once monthly for three months period for determining somatic cell count (SCC) and microbiological and molecular diagnosis of Mycoplasma spp. cultures were done without pre-enrichment procedures directly in mycoplasma agar with cefoperazone to inhibit growth of opportunistic microorganisms, plates were incubated under 37° C and atmosphere of 10% CO2 and inspected during a 10d period. Molecular analysis was done by a multiplex PCR using specific primers targeting the 16S-23S rARN gene of Mycoplasma spp. and from non-pathogenic bacteria occasionally found in milk. LnSCC average of included dairy farms was 6.19 x103 cells/mL, Mycoplasma spp. was not isolated during microbiological cultures, and no DNA belonging to the species was detected by PCR in the 220 bulk tanks milk, with an estimated prevalence lower than 2.3%. This finding shows that there is not microbiological or molecular evidence that demonstrates the presence of the pathogen in the milk from the mid-western region of Colombia at herd level.
RESUMEN Mycoplasma spp. está descrito como una bacteria causante de mastitis altamente contagiosa en ganado lechero, sin o con baja respuesta a tratamientos antibióticos convencionales debido a que carece de pared celular. En Colombia ha sido reportado en la región Andina Central durante 2014. El objetivo fue estimar la prevalencia de Mycoplasma spp. en leche de tanques de enfriamiento empleando diagnósticos microbiológicos y moleculares. Se realizó un estudio aleatorio longitudinal que incluyó 220 lecherías comerciales en cuatro departamentos del centro-occidente colombiano acopiadas por cuatro compañías pasteurizadoras. Se recolectaron muestras de leche del tanque de enfriamiento mensualmente durante tres meses para determinar el recuento de células somáticas (SCC) y el diagnóstico microbiològico y molecular de Mycoplasma spp. Los cultivos se realizaron sin procedimientos de preenriquecimiento directamente en agar micoplasma con cefoperazona para inhibir crecimiento de microorganismos oportunistas, los agares se incubaron a 37° C con una atmosfera del 10% CO2 e inspeccionados durante 10d. Los análisis moleculares se realizaron por PCR multiplex usando cebadores específicos para los genes 16S-23S rRNA del Mycoplasma spp. y de algunas bacterias oportunistas ocasionales en la leche. El promedio del LnSCC fue de 6.19 x103 células/ mL, Mycoplasma spp. no fue aislado de los cultivos microbiológicos y no se encontró ADN de a esta especie mediante PCR en los 220 tanques de leche. Lo anterior indica una prevalencia estimada menor a 2,3%. Se concluye que no existe evidencia micro-biológica ni molecular para demostrar la presencia del patógeno en la leche de la región centro-occidente colombiana a nivel de hato.
RESUMO
O objetivo do presente estudo foi avaliar a capacidade de estafilococos não aureus (NAS) isolados de diferentes nichos ecológicos (leite, ambiente e ápice do teto), associados a vacas leiteiras, de inibir os principais agentes etiológicos da mastite bovina (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis e Escherichia coli). Neste estudo, 38 isolados NAS de diferentes nichos ecológicos foram avaliados quanto à capacidade de inibir o crescimento in vitro de importantes patógenos causadores de mastite pelo método cross-streaking. No total, 19 (50%) isolados de NAS (oito isolados de S. chromogenes, 10 de S. fleurettii e um de S. haemolyticus) apresentaram inibição contra os principais patógenos causadores de mastite. No entanto, a inibição dos patógenos causadores da mastite bovina por isolados de NAS foi maior contra bactérias Gram-positivas. Além disso, o presente estudo não sugeriu que os nichos ecológicos influenciam a capacidade do NAS de inibir os principais patógenos causadores da mastite bovina. Com base nesses resultados, concluiu-se que certos isolados de NAS apresentam potencial efeito protetor contra os principais patógenos da mastite, pelo menos in vitro.(AU)