mastitis

Investigating the concentrations of Serum Amyloid A (SAA), IL-6, and IL-8 in the serum during episodes of clinical and subclinical mastitis holds significant value. This study aimed to evaluate the diagnostic value of SAA, IL-6, and IL-8 in the early detection of subclinical mastitis in cows infected by Escherichia coli (E.coli) and staphylococcus infections. This cross-sectional analytical study, conducted in 2023 in Department of Veterinary, Behbahan Branch, Islamic Azad University, Behbahan, Iran, evaluated inflammatory markers in 79 dairy cows with clinical and subclinical mastitis. The cows divided into three groups: healthy cows, cows with subclinical mastitis, and cows with clinical mastitis. These groups were then evaluated for Serum Amyloid A (SAA), IL-6, and IL-8. The diagnostic value of the inflammatory markers was determined by calculating the areas under the curves (AUCs) of the ROC curves. Generally, among the patients with a positive culture test (57%), 19% were found to be infected with E. coli, 22.8% with Streptococcus uberis, and 15.2% (12 cases) with Staphylococcus aureus. A strong correlation was observed between the mean SCC and the values of IL-6 (P<0.005), IL-8 (P<0.005), and SAA (P<0.005). Additionally, SAA showed a strong correlation with IL-8 (P<0.005). The value of IL-6 was moderately correlated with both IL-8 (P<0.005) and SAA (P<0.005). The sensitivity and specificity of SCC (0.98), SAA (0.90), IL-6 (0.95), and IL-8 (0.87) were high for diagnosing mastitis in cows. The present study revealed that mastitis in dairy cows is associated with an increase in inflammatory cytokines such as amyloid A, IL-6, and IL-8. The study suggests that variations in these biomarkers could be utilized for disease diagnosis.

Mastitis is an inflammatory disease of the mammary gland, caused by many infectious agents such as bacteria, fungi, and viruses. Streptococci are reported to be among the major pathogens causing bovine mastitis around the world, which may cause clinical and subclinical forms of mastitis. Mastitis is one of the primary diseases of dairy cows and is responsible for remarkable economic losses due to reduction in quantity and quality of milk, cost of treatment, and the early culling of the cows. Considering the existence of substantial industrial and traditional dairy cattle farms in Chaharmahal and Bakhtiari province and the fact that mastitis is the most common disease in dairy industries, this study aimed to identify the role of streptococci in subclinical mastitis in dairy cows in Chaharmahal and Bakhtiari province. For this purpose,134 subclinical mastitis milk samples were collected from 8 dairy farms in Chaharmahal and Bakhtiari province, based on the california mastitis test (CMT) results and screened for the streptococcal cause of mastitis. DNAs were extracted from collected specimens and PCR was performed with specific primers for Streptococcus agalactiae, Streptococcus uberis, and Streptococcus dysgalactiae. Out of 134 mastitis milk samples 10 (7.5%), 14 (10.4%), and 5 (3.7%) samples were positive for S. agalactiae, S. uberis, and S. dysgalactiae respectively. The result of this research shows that 21.6 (29:134) percent of mastitis in dairy cattle farms in the studied region may be due to streptococci. The obtained data can be used in management and prevention strategies for cattle mastitis control in Chaharmahal and Bakhtiari province.

It has been determined that there is a direct relationship between the severity of mastitis and the virulence factors produced by bacterial agents. Identifying bacterial virulence factors is neccecary for designing suitable vaccines against mastitis. The aim of the present study was molecular diagnosis of selected virulence factors of endemic isolates of S. aureus involved in bovine mastitis. A total of 180 milk samples were collected from cows with clinical (37 samples, 20.6%) and subclinical (143 samples, 79.4%) mastitis from 8 semi-industrial dairy farms of Chaharmahal and Bakhtiari province, Iran. After culture and purification, coagulase, catalase and oxidase tests were performed. DNA was extracted from S. aureus suspected colonies. Final confirmation was performed using PCR test on the specific 23S rRNA gene of the bacteria. Thirty one (17.22%) out of the 180 collected samples were found to be positive for S. aureus by PCR, of which 2 cases were related to clinical mastitis and 29 cases were related to subclinical mastitis. The highest frequency of virulence genes was related to the Coa gene (90.32%), followed by ClfB (87.09%), LukD, and fnbB (80.64%), LukE (77.41%), fnbA (74.19%), Hla (48.38%). The lowest frequency was related to the Hlb gene (45.16%). Based on the obtained results, the diagnosis of the virulence factors of S. aureus has the potential of being used in the development of vaccines for the prevention of mastitis.

Staphylococcus aureus is one of the most common causes of mastitis worldwide. This study aimed to determine the prevalence and antimicrobial resistance (AMR) patterns of S. aureus in mastitic milk samples collected from camel farms in Matrouh Governorate, Egypt. A total of 200 mastitic camel milk samples were evaluated for S. aureus using both conventional culture-based and molecular-based methods. Antibiotic susceptibility testing of S. aureus isolates was conducted using disc diffusion and agar dilution methods, with antibiotic resistance genes identified through polymerase chain reaction with specific primers. Out of samples tested, 60 (30.00%) were positive for S. aureus. The isolates displayed the highest of resistance against piperacillin-tazobactam (55.00%) followed by trimethoprim- sulfamethoxazole (45.00%) and amoxicillin (40.00%). Half of the isolates were multidrug-resistant (MDR). The AMR genes included methicillin-resistant gene (mecA), β-lactamase gene (blaZ), tetracycline resistance gene (tetK), erythromycin resistance gene (ermB) and vancomycin resistant gene (vanA) were detected in 100%, 100%, 95.00%, 90.00% and 20.00% of the isolates, respectively. In conclusion, the presence of MDRS aureus as a cause of clinical camel mastitis is a significant veterinary and public health concern. These findings highlight the importance of proper antibiotic use in Egyptian camel farms and the need for molecular techniques to fully understand the genetic profile of antimicrobial-resistant S. aureus isolates.

Bovine mastitis causes a lot of economic losses, and the appearance of resistant strains of bacteria has led to the use of alternative natural bioagents for treatment. It is generally believed that high levels of fat and/or protein in foods may protect bacteria against the effects of essential oils (EOs). The purpose of this paper was to investigate the effect of EOs of Mentha piperita (peppermint) and Mentha pulegium (pennyroyal) on three bovine mastitis bacteria (Escherichia coli, Streptococcus agalactiae, and Staphylococcus aureus) in milk. Gas chromatography/mass spectrometry was used for the analysis of EOs. Antibacterial effects of the EOs on bacteria were evaluated with minimum bactericide concentration (MBC), minimum inhibitory concentration (MIC), and time-kill assay. Major components of peppermint EO were carvone (63.02%) and limonene (24.48%), and those of pennyroyal EO were pulegone (48.16%), eucalyptol (14.57%), and piperitenone (10.09%). The MIC and MBC were 0.62% and 1.25% for pennyroyal, 0.31-1.25% and 0.62-2.5% for peppermint, 0.31-0.62% and 0.62-2.5% for peppermint and pennyroyal, respectively. At 6-h, the bacterial reduction of treatments compared to the control group was significant for E. coli and S. agalactiae bacteria. The S. agalactiae and S. aureus counts significantly decreased in the peppermint and pennyroyal group at 24-h. In conclusion, peppermint and pennyroyal EO showed an antibacterial effect on these three bacteria and can be evaluated as an adjunct or alternative to antibiotics in the treatment of bovine mastitis.

Bacillus licheniformis is a gram-positive, endospore-forming, saprophytic and facultative anaerobe that is resistant to heat and environmental conditions. This study was the first to isolate and confirm B. licheniformis as a cause of bovine mastitis in Iran. In the summer of 2020, 105 samples of mastitic milk were collected from dairy farms around Tehran and sent to the microbiology laboratory of the Faculty of Veterinary Medicine at the University of Tehran. The bacterial pathogens were identified using selective and differential culture media and confirmed by PCR to contain the toxin synthetase genes licA, licB and licC in mastitic isolates of B. licheniformis. Resistance patterns to 19 antibiotics were determined for two isolates of B. licheniformis. Staphylococcus aureus and Escherichia coli were identified as the most important organisms in the samples. B. licheniformis was isolated from the two samples containing all three genes. Both isolates were resistant to streptomycin, trimethoprim-sulfamethoxazole, cefixime, ampicillin, bacitracin, clindamycin, and gentamicin. B. licheniformis was reported for the first time in Iran as a cause of bovine mastitis with clinical symptoms. The first isolation of toxin-producing strains of B. licheniformis from mastitic cows in Iran raises concerns about the safety of dairy products. In principle, selected strains with toxigenic potential should not be used as feed additives and animal feed. However, whole genome sequencing is proposed to search for genes coding for toxins.

Mastitis is a well-recognized and costly disease of dairy cattle. Mycoplasma bovis is one of the most important causal agents of mastitis in dairy cows. In respect to the importance of mastitis caused by Mycoplasma, the objective of the present study was to evaluate of presence of M. bovis in bulk milk of dairy cattle farms of Hamedan province, Iran. For this purpose, a total of 125 bovine bulk tank milk samples were collected from 31 dairy farms of Hamedan, Iran. After that, California Mastitis Test (CMT) and Somatic Cell Count (SCC) were done on the milk samples. Then using DNA extraction kit, the total DNA was extracted from each sample. The PCR followed by nested PCR (nPCR) was performed for specific detection of M. bovis. Based on PCR for genus detection, totally, 19 out of 125 (15.2%) bulk tank milk samples were contaminated with Mycoplasma spp. In addition, 11 samples (8.8 %) were contaminated by M. bovis based on nested PCR results. Moreover, the results showed that 26 of 125 bulk milk samples (20.8 %) and 102 of 125 bulk milk samples (81.6 %) have high rate score by CMT and SCC, respectively. Statistical analysis showed a positive correlation between CMT and SCC results. In the present study, the presence of M. bovis in the bulk tank milk samples suggests that more hygiene practices are required to avoid transmitting this pathogen among dairy cow herds of Hamadan region. According to the presence of Mycoplasma in bulk tanks of this region, the present study suggested that the frequency of Mycoplasma contamination in individual cows be determined.

The increasing importance of antibiotic resistance shows the need for determining indices of the epidemiology of infection.

This study aimed to determine the virulence genes and antibiotic resistance profiles of Staphylococcus aureus isolated from bovine mastitis cases.

A total of 200 cattle were selected based on California Mastitis Test (CMT) results, and the samples were cultured in the laboratory. Grown colonies were examined by conventional phenotypic methods and confirmed using PCR amplification of 16S rRNA gene. The prevalence of the virulence genes was also defined. The results of phenotypic and molecular tests were compared using SPSS software by McNemar test. Then, the confirmed isolates were tested for antibiotic susceptibility using the disc diffusion method.

Of the 200 positive CMT cattle, 24 animals were positive for S. aureus and confirmed using 16S rRNA gene amplification. Statistical analysis showed that the phenotypic and genotypic tests of hemolysin genes were not significantly different (P>0.01). PCR analysis revealed the presence of coa and clfa genes in more than half of the cases. Overall, nine genetic profiles of virulence factors were found among S. aureus isolates. The highest and lowest resistance rates were against penicillin and gentamicin, respectively.

Our findings showed a high rate of antibiotic resistance. So, accurate and fast diagnosis and antimicrobial susceptibility tests should be considered before prescribing the drugs.

Methicillin-resistant Staphylococcus aureus (MRSA), affecting livestock and human beings, has become a global public health hazard with economic consequences.

The current study was designed to investigate the prevailing MRSA-associated subclinical mastitis and associated risk factors in dairy buffaloes. The study also highlighted the genetic variations and in silico-based proteomic differences among MRSA isolates.

Out of 516 milk samples, 45.93% (237/516) were found positive for subclinical mastitis, while the prevalence of S. aureus was recorded 56.12%. The methicillin resistance in S. aureus isolates was evaluated by oxacillin disc diffusion test and molecular identification of the mecA gene.

The results revealed a phenotypic and molecular prevalence of MRSA at 45.11% and 18.79%, respectively. The risk factor analysis revealed that among various assumed risk factors, parity, milking hygiene, milker care during milking, milk yield, housing system, and floor type were significantly associated with subclinical mastitis in buffaloes. The sequencing and phylogenetic analysis showed no significant genetic variations among study isolates and depicted a high similarity with isolates from Africa, USA, India, Italy, Turkey, and Iran. The in-silico protein analysis showed that all sequences had the same protein motifs resembling penicillin protein 2a except Buff-13, whose protein structure resembles alpha-catenin-like protein hmp-1.

The current study was the first report of the genotypic characterization and in silico protein analysis of MRSA from dairy buffaloes in Pakistan. The result highlighted the importance of antimicrobial resistance (AMR) and development of control strategies against MRSA infections.

Biofilm production by Staphylococcus aureus is a prevailing cause of multidrug resistance. The evolutionary mechanisms of adaption with host and pathogenicity are poorly understood.

The present study aimed to investigate the biofilm-forming potential, associated multidrug resistance, and the evolutionary analysis of S. aureus isolated from bovine subclinical mastitis.

122 S. aureus isolates were subjected to Congo red agar method (CRA), microtitre plate method (MTP), and PCR to check the biofilm-forming potential. The Kirby-Bauer disk diffusion method was used to evaluate the antibiotic resistance pattern. The icaA gene of isolates was subjected to molecular and evolutionary analysis using different bioinformatics tools.

The results showed that 63.93% of S. aureus isolates carried the icaA gene and the detection rate of CRA was higher (36.07%) compared to the MTP test (24.59%). A total of 78.21% and 56.41% of biofilm-positive isolates were methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA), respectively. All S. aureus isolates (100%) showed multidrug resistance. The molecular analysis showed an evolutionary link between isolates and revealed a strong codon bias, three different recombination events, and positive selection in some residues of the semi-conserved segments of the icaA gene.

The study concluded that biofilm-positive isolates have a high tendency to exhibit methicillin, vancomycin, and multidrug resistance. The findings suggest that mutation and selection are the most likely causes of codon bias in the icaA gene sequences. The variations led by recombination events and positive selection are suggestive of bacterial strategy to combat antimicrobial effects and to escape the host’s immune surveillance.

Staphylococcus aureus is responsible for many infections in humans and animals from skin and soft tissue infections to life-threatening diseases. In this study to explore the origin of S. aureus infections in humans, the antibiotic resistance profile and the variety of virulence factors in S. aureus isolates were examined in three groups: a healthy human population, cheese, and the milk of sheep with mastitis.

The examination of some virulence factors in S. aureus isolates obtained from the healthy human population, sheep mastitis, and cheese.

A total of 400 nasal swab samples from healthy students, 30 cheese samples, and 122 sheep milk samples were collected for the detection of S. aureus isolates from January 1, 2018, to March 1, 2018. The frequency of hla, hlb, Acme/arcA, pvl, and tsst-1 virulence genes and mecA gene was determined in each group by PCR assay.

There was a direct relationship between the antibiotic susceptibility profile of the isolates from a healthy population and those from mastitis milk samples. Of 400 nasal samples, 15% (60/400) were positive for S. aureus, of which 60% (36/60) were positive for mecA. While 50% (15/30) of cheese samples were positive for S. aureus. of which 7 cases (46.66%, 7/15) were positive for mecA. The prevalence of S. aureus among students was dependent on gender (P=0.025). Also, 47.5% (58/122) of milk samples from sheep mastitis were positive for S. aureus, and 41.37% (24/58) were positive for the mecA gene. Based on PCR results, the highest rate of hla (68.33%, 41/60), hlb (53.33%, 32/60), and Acme/arcA (46.66%, 28/60) genes were related to a healthy population, and the highest frequency of pvl (41.38%, 24/58), and tsst-1 (27.59%, 16/58) was related to milk samples (P<0.05). A significant correlation was observed between the presence of the arginine catabolic mobile element (ACME)-arcA gene and resistance to methicillin (P<0.05).

The high rate of virulence factors in the S. aureus isolates obtained from mastitis and dairy products is an alert point, because they could be source of the spreading of S. aureus to humans. There is an essential need for continuous monitoring to control staphylococcal food poisoning.

Mastitis is one of the most critical problems for dairy cattle worldwide. The purpose of this study was to determine whether mastitis is caused by bacteria in the dairy cows of traditional farms. In this randomized clinical trial, 54 Holstein cows with clinical mastitis (from October 2020 to September 2021) were selected from the traditional farms located in the suburbs of Tabriz city. All cows were subjected to sampling during four seasons according to the National Mastitis Council (NMC) guidelines and the collected samples were rapidly sent to the Veterinary faculty’s microbiological laboratory for bacterial cultures. The distribution of mastitis was evaluated according to the stage of lactation, parity, season, and types of bedding system. The results were as follows: E. coli 39%, Streptococcus uberis 21%, Streptococcus agalactia 7%, and Staphylococcus aureus 33%. The results of this study showed that parturition, increased number of parity, wet and rainy seasons, as well as sawdust and cow manure bedding are among the risk factors for mastitis. In conclusion, in traditional farms, unlike industrial farms, environmental mastitis has more importance than contagious mastitis. Regarding the presence and shedding of E. coli microorganisms in the milk, this should be highlighted as a concern for public health.

Antimicrobial resistance (AMR) is a burning issue in the present era. Mastitis in dairy animals is one of the most important causes of huge production loss to dairy farmers.

The study aims to find the prevalence, antimicrobial resistance profile, and resistance genes in the extended-spectrum beta-lactamase-producing Escherichia coli in mastitic milk.

A total of 125 milk samples were collected from Beetal goats suffering from clinical mastitis from different districts of Punjab and processed for bacterial isolation and further identification. The drug resistance profile of ESBL-producing E. coli and its associations with molecular markers was analyzed using statistical analysis.

The prevalence of ESBL-producing E. coli in dairy goats of Punjab was recorded as 6.4%. The isolates showed the highest resistance to the beta-lactam group of antibiotics. The resistance percentages of streptomycin, gentamicin, tetracycline, chloramphenicol, clotrimazole, and colistin were 50%, 37.5%, 50%, 25%, 25%, and 50%, respectively. The isolates showed intermediate resistance to imipenem (12.5%) and tetracycline (25%). The ESBL-producing E. coli isolates harbored the resistance genes blaCTXM (100%), blaTEM (62.5%), blaSHV (25%), blaOXA (37.5%), tetA (37.5%), tetB (25%), aadA (37.5%), sul1 (25%), MOXM (12.5%), DHAM (25%), and blaCMY-2 (50%). Tetracycline and sulphonamide resistances were statistically associated with their respective resistance genes (P<0.05). Streptomycin resistance was not statistically associated with the presence of the aadA gene (P>0.05). The genes blaIMP and blaNDM were not recorded in any of the isolates. In this study, 12.5% of the isolates showed co-resistance to colistin and carbapenem.

Antimicrobial resistance is a hot topic and requires immediate attention.