Streptococcus agalactiae is an important zoonotic pathogen that affects milk production and quality and poses a threat to public health. Treatment of infections with this bacterium exploits antimicrobials, to which the resistance of S. agalactiae is a growing problem. Addressing the possibility of a correlation between this pathogen’s genetic factors for antimicrobial resistance and virulence, this study attempted to identify the relevant genes.

This study was carried out on a total of 550 lactating animals; 310 and 240 cows and buffaloes, respectively which were examined for signs of clinical mastitis (swelling, hotness, redness, and apparent milk change) from different dairy farms and veterinary units located at El-Fayoum Governorate during the period from May 2017 to November 2017. Clinical examination proved that out of these animals, a total of 126 animals (87 cattle and 39 buffaloes) were found with clinical mastitis. Streptococcus species were recovered from 73 animals including; 29(39.7%) and 44(60.0%) cows and buffaloes, respectively. Furthermore, out of the 73 Streptococci isolates recovered from cows and buffaloes; there were 10(13.7%) and 15(20.5%) S. agalactiae, 5(6.8%) and 10(23.7%) S. dysgalactiae, 8 (10.6%) and 7 (13.7%) S. uberis, 3(4.1%) and 10(13.7 %) E. fecalis and 3(4.1%) and 2(2.7%) S. lactarius, respectively. Anti-microbial susceptibility testing showed that the highest resistance was recorded against penicillin, gentamicin, streptomycin, and doxycycline (100%). Conversely, the highest sensitivity was recorded against ceftriaxone, ciprofloxacin, and sulfamethoxazole-trimethoprim (100%). Biofilm formation capacity was phenotypically assessed on YESCA CR agar medium and showed that all examined S. agalactiae and S. dysgalactiae were strong biofilm producers, meanwhile, 78%, 50%, and 75% of S. uberis, S. lactarius, and E. fecalis were biofilm positive isolates respectively. Application of PCR technique revealed that enterotoxins producing genes; sed, seb were found in 20% and 80% of isolates, in order. Biofilm-associated genes; fnbA and icaA genes were detected in 90% and 70%, respectively. Resistance genes; mecA and blaZ, genes were possessed in 90% and 70% of isolates, respectively.

Previous studies have reported on the phytotherapeutic potential of propolis from southern Brazil (Urupema, Santa Catarina State), in particular, its efficacy in the treatment of bovine mastitis. The present study evaluates the effect of seasonal variation on the chemical composition of propolis from southern Brazil and its resultant antimicrobial and cytotoxic activities in the context of treating bovine mastitis. Antimicrobial activity against Staphylococcus aureus was assessed, along with the cytotoxicity and induction of apoptosis in MAC-T bovine mammary epithelial cells. With the exception of spring propolis, the flavonoid quercetin was the main compound present in all samples. The minimum inhibitory concentration (MIC) of propolis against S. aureus from mastitic milk was 140 μg/mL for samples collected during the spring, autumn, and winter seasons, but 280 μg/mL for samples collected in summer. For MAC-T cells, the spring propolis extract was more toxic with an IC50 of 120 μg/mL. However, for 120 μg/mL of spring propolis extract, only 0.77% of necrotic and 37% of apoptotic MAC-T cells were found, respectively. Nonetheless, the induction of cell deaththrough apoptosis by propolis extract suggests less severe damage to bovine mammary glands. Moreover, only negligible seasonal variation was found in the chemical composition of propolis from southern Brazil, and no biological activities were determined to be harmful. Therefore, this propolis shows promise as an alternative to commercial antimicrobials in the control of bovine mastitis, offering support for organic milk production.

MicroRNAs (miRNAs), a class of noncoding small RNAs, have been recognised as potential biomarkers of mammary gland conditions, including bovine mastitis diagnosis. The aim of this study was to quantify selected miRNAs in the milk of mastitic cows.

Objective: The influence of intramammary infection (IMI) and types of bacteria was assessed on somatic cell count (SCC) in dairy cows milk with respect to breed, age, parity, stage of lactation, milk production, and mammary quarter location. Materials and methods: After recording data in a structured questionnaire, 360 samples of quar¬ter milk were collected. The samples were subjected to SCC and isolation and identification of bacteria. The data were analyzed to find out the significant influence of independent factors on SCC and IMI. Results: The infected quarters had a significantly higher mean SCC (210.52 × 103 cells/ml) compared to uninfected ones (32.72 × 103 cells/ml). The mean SCC was the highest for IMI with Enterobacter spp. (338.00 × 103 cells/ml) followed by Bacillus spp. (319.20 × 103 cells/ml), coagulase-negative Staphylococci (CNS) (268.17 × 103 cells/ml), Staphylococcus aureus (218.31 × 103 cells/ ml), and Escherichia coli (200.75 × 103 cells/ml) and the lowest for Pseudomonas aeruginosa (66.33 × 103 cells/ml). Milk of rear quarters had a significantly higher SCC than the front quarters. SCC increased with increasing age, parity, and lactation stage regardless of whether cows are infected or not. The IMI was more prevalent in rear quarters (42.2%) and cows at early (≤7 days) lactation (100.0%). Cows having a parity of ≥5 and crossbred and high yielding (>5 l) cows had also a higher rate of IMI of 38.2%, 36.7%, and 38.2%, respectively. Conclusion: The IMI and type of bacteria were the principal factors for SCC variation. Besides, mammary quarter location, age, and parity should be taken into consideration during the inter¬pretation of SCC. [J Adv Vet Anim Res 2020; 7(2.000): 314-319]

A 5-year old Holstein Friesian cross breed cow was presented to Madras Veterinary College Teaching Hospital with the history of reduced milk yield. Clinical examination of udder revealed normal milk color and soft udder. The milk pH was 7.0, with California Mastitis Test score 3+, Electrical Conductivity 270U, and Somatic Cell Count as 328,000. Isolation and identification of causative agent revealed Methicillin Resistant Staphylococcus aureus (MRSA) from the sub-acute mastitis sample. Agar disc diffusion method for antimicrobial susceptibility revealed that the MRSA was sensitive to Enrofloxacin, Gentamicin, Oxytetracycline and Amoxicillin+Sulbactam. On the other hand, the isolate was resistance to Amoxicillin, Penicillin G, Ceftriaxone and Methicillin. The isolate was positive for β-lactamase resistance by Nitrocefin test. The MRSA was confirmed for the presence of mecA and blaZ target genes by polymerase chain reaction (PCR). The cow was treated with Enrofloxacin, Vitamin E and inorganic Selenium, and was recovered after 5 days of post-treatment.

Staphylococci are the most typical bacteria found in cattle with mastitis, either Staphylococcus aureus or coagulase-negative Staphylococci (CNS). The study’s goal was to determine the prevalence of Staphylococci in bovine mastitis, the antimicrobial profile, and evaluate the concentration of pro-inflammatory interleukins (IL-4, IL-6, IL-10) related to the inflammatory response in clinical mastitis by ELISA. S. aureus (54%) and CNS (19%) were detected in 400 samples of milk from both clinical and subclinical bovine mastitis. The S. aureus isolates revealed higher resistance to ampicillin (100%), followed by amoxicillin-clavulanic acid (98.1%), cefotaxime (88.9%), erythromycin (63.2%), cefuroxime (63%), and tetracycline (61.1%). Furthermore, the CNS isolates showed high resistance against amoxicillin-clavulanic acid (100%), followed by ampicillin (94.7%), cefotaxime (89.5%), erythromycin (79.6%), cefuroxime (89.5%), and tetracycline (73.7%). However, the high susceptibility of S. aureus and CNS was observed to imipenem and ciprofloxacin. Furthermore, Cows with clinical mastitis reported high levels of IL-6 in both their serum and their milk. While they have much lower levels of IL-4 and IL-10 than normal ones (P < 0.001). In conclusion, it is recommended that laboratory results be carefully interpreted to avoid antimicrobial therapy for Staphylococci that is not clinically relevant and to ensure the advisable use of antimicrobials. Also, further study on the application of interleukins as therapeutic agents against bovine mastitis should be considered.

Public health is at risk because Streptococcus agalactiae is increasingly linked to incidences of bovine mastitis in Egypt. In this study, enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) were used to explore the genotyping of several antibiotic resistant Streptococcus agalactiae isolated from bovine mastitis and retail milk. Also, antimicrobial resistance genes were detected. Two hundred and sixty-six (46.7%) strains were isolated from samples of milk obtained from cases of bovine mastitis in dairy farms and retail markets representing 34 (5.96%) Streptococcus agalactiae and 232 (40.7%) other Streptococcus species strains based bacterial identification. By using of disc diffusion assays, it was examined the susceptibility of all Streptococcus isolates to twelve antimicrobial agents. The   highest prevalence of resistance of Streptococcus species was observed against ampicillin (65.5%), amoxicillin (56%), tetracycline (52.5%), ofloxacin (47.8%), and nitrofurantoin (46.9%). High proportion of the S. agalactiae isolates were resistance to amoxicillin (83%), followed by tetracycline (82.4%), nitrofurantoin (64.7%), azithromycin (61.8%), and ampicillin (50%). Most (88.2%) of S. agalactiae showed multiple antibiotic resistances (MAR) phenotypes with MAR index of 0.1-0.7 and 28 different MAR patterns. The results of genetic antimicrobial resistance of S. agalactiae strains revealed amplification of blaTEM (23%) and blaCTX (26%) genes in β-lactam-resistant strains, erm(B) gene (20%), mef(A) (35%) in macrolides resistant isolates, and tet(M) in  (44%) tetracycline resistant strains. Using ERIC-PCR, the present study showed the genetic diversity and heterogeneity among S. agalactiae strains (n=34) that were classified into 19 distinct ERIC-PCR groups (A–S).  Between them, ERIC O (20.6%, 7) was the most widespread group. These results indicated that milk samples served as source of MAR S. agalactiae, consequently posing threats to public health, so the improvement of the hygiene regimen on the farms and promotion of the wise use of antimicrobials are necessary. The obtained findings showed that milk samples were a source of MAR S. agalactiae, endangering public health. As a result, it is essential to enhance farm hygiene practices and promote the responsible use of antimicrobials. Additional research on the epidemiology of S. agalactiae is required to add bacterial genetic information in order to help in rational vaccine strategy in the future.