The Emergence of Antimicrobial Resistance and Virulence Characteristics in Enterococcus Species Isolated from Bovine Milk.

Enterococcus spp., including E. faecalis and E. faecium, pose risks to dairy farms as opportunistic pathogens. The study evaluates antimicrobial resistance (AMR) and virulence characteristics of Enterococcus spp. isolated from bovine milk. Bile esculin agar was used to assess 1471 milk samples, followed by colony identification, gram staining, catalase tests, and 45 °C incubation. PCR analysis targeted E. faecalis and E. faecium in characteristic Enterococcus spp. colonies, with MALDI-TOF used for negative samples. Multiple tests, including disk diffusion, chromogenic VRE agar for vancomycin resistance, Vancomycin Etest® for MIC determination, and PCR for virulence factors (cylA, esp, efaA, ace, asa1, gelE, and hyl genes), were performed. Out of 100 identified strains, E. durans (30.66%), E. faecium (26.28%), and E. faecalis (18.25%) were predominant. AMR in Enterococcus spp. varied, with the highest rates against rifampicin (27%), tetracycline (20%), and erythromycin (18%). Linezolid (5%), vancomycin, ciprofloxacin, and teicoplanin (3% each) had lower prevalence. E. faecium and E. faecalis showed high AMR to rifampicin, erythromycin, and tetracycline. Thirty-two strains (18.98%) grew on VRE Chromoselect agar, while 4 (2 E. faecalis and 2 E. faecium) showed vancomycin resistance by MIC values. E. faecalis carried gelE (45.5%) and asa1 (36%), and E. gallinarum had 9.1% with the asa1 gene. Detecting resistant Enterococcus in bovine milk supports control strategies for enterococci on dairy farms, highlighting AMR concerns in the food chain.

Paternal low-dose benzo(a)pyrene exposure in rats impairs sexual development and fertility of the paternal lineage in F2 generation: A transgenerational study.

The field of Paternal Origins of Health and Disease (POHaD) is highly relevant but remains under-explored. The F2 generation from males indirectly exposed (F1 - via germ cells) to benzo(a)pyrene (BaP), named PF2, was investigated in this study under parameters of sexual development and reproductive performance of male and female rats. Male Wistar rats (F0) were exposed to BaP (0.1 µg/kg/day) for 31 consecutive days (gavage) during prepuberty. The F0 rats were mated with untreated females to produce male offspring (F1), which were exposed to BaP via germ cells. The F1 males were later mated with untreated females to obtain the PF2 generation, which was the focus of our investigation. Our findings showed that PF2 males exhibited a decrease in anogenital distance, fertility potential, testosterone levels, and type A sperm. Meanwhile, PF2 females had an earlier vaginal opening, lower lordosis scores, and decreased fertility. Furthermore, changes in the histomorphology of the testis/epididymis and ovary/uterus were observed. The repercussions of the PF2 generation indicate that these animals showed losses in both sexual development and fertility potential, and we can conclude that this damage remained due to paternal transgenerational inheritance caused by a low dose of BaP.

Long-term reproductive effects of benzo(a)pyrene at environmentally relevant dose on juvenile female rats.

Since studies on the reproductive consequences after the exposure to environmentally relevant doses of Benzo(a)pyrene (BaP) during critical stages of development are scarce, this study evaluated female reproductive parameters of adult rats exposed to a low dose of BaP during the juvenile phase. Female rats (Post-natal 21) were treated with BaP (0 or 0.1 µg/kg/day; gavage) for 21 consecutive days. During the treatment, no clinical signs of toxicity were observed. Nevertheless, the ages of vaginal opening and first estrus were anticipated by the BaP-exposure. At the sexual maturity, the juvenile exposure compromised the sexual behavior, as well as the placental efficiency, follicle stimulating hormone levels, placenta histological analysis, and ovarian follicle count. A decrease in erythrocyte, platelet, and lymphocyte counts also was observed in the exposed-females. Moreover, the dose of BaP used in this study was not able to produce estrogenic activity in vivo. These data showed that juvenile BaP-exposure, at environmentally relevant dose, compromised the female reproductive system, possibly by an endocrine deregulation; however, this requires further investigation.