Subclinical Mastitis Milk Research Articles

Milk miRNA expression in buffaloes as a potential biomarker for mastitis.

Buffaloes have the highest potential for production due to a promising gene pool that is being enhanced and upgraded. Mastitis is a significant health impediment that greatly diminishes milk yield and quality, affecting rural farmers' livelihoods. The traditional gold standard used for diagnosing mastitis or subclinical mastitis is CMT, but it has the drawback of false positive or negative results. Subclinical mastitis, if not treated promptly, can lead to mammary tumors. To address the gap in early diagnosis of subclinical mastitis in CMT-negative milk of buffaloes, we performed a retrospective analysis and evaluated the milk miRNA expression profiles as potential biomarkers. Thirty buffalo milk samples based on clinical signs and CMT were divided into normal, subclinical, and clinical mastitis. SCC evaluation showed significant differences between the groups. The data analysis demonstrated that the elevation of miR-146a and miR-383 differed substantially between normal, subclinical, and clinical mastitis milk of buffaloes with 100% sensitivity and specificity. The relationship of SCC with miR-146a and miR-383 in normal/healthy and subclinical mastitis was positively correlated. The overexpression of miR-146a and miR-383 is associated with inflammation. It can be a valuable prognostic and most sensitive biomarker for early mastitis detection in buffaloes with SCC below 2 lakhs and CMT-ve, enhancing the accuracy of subclinical mastitis diagnosis.

Identification of Extended Spectrum Beta Lactamases Producing Pseudomonas aeruginosa from Subclinical Mastitis Milk Samples in an Organized Dairy Farm of SVVU, Andhra Pradesh

The present study was conducted during August 2021 at Buffalo Research Station, Venkatarammanagudem of West Godavari District, Andhra Pradesh, India and was aimed to detect the presence of extended-spectrum beta-lactamases (ESBL) producing P. aeruginosa from sub-clinical mastitis that are apparently healthy Murrah buffaloes. Inflammation of the udder by microbial infection is one of the leading economic disease in the dairy sector. Most of the pathogens especially Pseudomonas aeruginosa are refractory to the antibiotic theraphy. Nowadays, the antimicrobial resistance owed by the bacteria is at an alarming rate. Pseudomonas aeruginosa, a multi drug resistant pathogen carry the extended spectrum beta lactamase genes in its plasmids and thus become resistant to antibiotic therapy. A total of 276 milk samples were collected from 69 milch animals in the month of August, 2021 comprising from all the four quarters of each buffalo. Nine (n=9) (3.26%) P. aeruginosa isolates were identified from the sub-clinical mastitis milk samples from the total 276 samples collected in the study. The isolates on morphological analysis were typical to P. aeruginosa. Seven isolates were positive for phenotypical beta-lactamases production. A total of 1 and 2 isolates were found reactive of the blaSHV and blaOXA genes, and two isolates harboured both blaSHV and blaOXA genes, respectively on PCR assay. No blaTEM gene was found in the isolates. Antibiogram of the ESBL producing P. aeruginosa isolates (n=7) possessed 100% resistance against most of the commonly used antimicrobials like ampicillin, amoxycillin, clindamycin, co-trimoxazole oxytetracycline, streptomycin and ceftriaxone (85%). The P. aeruginosa isolates were sensitive to amikacin (100%), ciprofloxacin (87.4%), gentamicin (84%), norfloxacin (84.8%) and enrofloxacin (82%).

Identification ofantibiotic resistance genes inEscherichia coli from subclinical mastitis milk indairy cows and goats, East Java Province.

Antibiotics are still used totreat mastitis indairy cows inIndonesia. This study aimed toanalyse antibiotic resistance genes inEscherichia coli (E.coli) from subclinical mastitis milk inEast Java Province, Indonesia. Thesamples consisted ofsubclinical mastitis milk from cows and goats. Atotal of592-quarter cow's milk and 71goat's milk samples from both halves ofthe udder were collected from 67farms inLumajang, Banyuwangi, Malang, Sidoarjo, Jember, Pasuruan, Probolinggo, and Mojokerto. Subclinical mastitis samples were screened using the California mastitis test (CMT). E.coli was identified byphenotypic and genotypic methods. E.coli wasconfirmed with aprimer specific tothe polymerase chain reaction (PCR) technique. Gene resistance ofE.coli was tested using the multiplex-PCR (mPCR) technique with primers encoding the genes temoneira enzyme (TEM), oxacillinase (OXA), sulfhydryl variable (SHV), and cefotaximase-munich IV (CTX-M IV). These genes were chosen because mastitis treatment generally uses oxacilline and β-lactam antibiotics. All data obtained were analysed descriptively. Theresults show that six isolates ofE.coli (46.15%) carried asingle resistance gene (TEM orSHV) and two isolates (33.33%) were confirmed asmultiple drug-resistant organisms (MDROs) (TEM and SHV). Theresistance genes were found insamples originating from Blitar, Banyuwangi, Lumajang, and Pasuruan Regencies. This research implies that antibiotic-resistance genes found inE.coli oncertain farms are dangerous and may allow gene transmission toother bacteria that make treatment for mastitis orother bacterial infections ineffective.

PCR-based detection of Streptococcus agalactiae from milk of bovine subclinical mastitis

PCR-based detection of Streptococcus agalactiae from milk of bovine subclinical mastitis

Molecular characteristics and antimicrobial susceptibility profiles of bovine mastitis agents in western Türkiye.

Identifying bovine mastitis agents using molecular methods to reveal their phylogenetic relationships and antimicrobial resistance profiles is essential for developing up-to-date databases in mastitis cases that cause severe economic losses. This study examined bacterial mastitis agents in cows with clinical and subclinical mastitis observed in various dairy cattle farms to reveal their phylogenetic relationships and antibiotic resistance properties. Sixty-two clinical and subclinical bovine mastitis milk samples were collected from 15 dairy farms. The polymerase chain reaction (PCR) was used to amplify the 16S rRNA gene regions of the bacteria. The 16S rRNA gene sequences obtained from sequencing include the V4-V6 regions. The strains were compared using a similarity analysis method that produced phylogenetic trees using the Molecular Evolutionary Genetics Analysis 11 program. Antibiotic susceptibilities were determined using the Kirby-Bauer disk diffusion method. Sixty-three bacteria were isolated and identified in this study. The most isolated bacteria from all mastitis cases were Staphylococcus spp. (30.2%), Escherichia coli (25.4%), Streptococcus spp. (14.3%), and Aerococcus spp. (7.9%), respectively. The phylogenetic trees were drawn from the 16S rRNA sequences. Some of these bacteria showed resistance to different types of antibiotics at varying rates. The bacteria isolated in this study originated from environmental sources. Regular cleaning of barns and proper hygiene practices are essential. Regular screenings for mastitis should be conducted in herds instead of the random or empirical use of antibiotics.

Influence of Bacterial Species on Physical Characteristics and Somatic Cell Counts in Clinical and Subclinical Mastitis Milk of Kundhi Buffaloes

Influence of Bacterial Species on Physical Characteristics and Somatic Cell Counts in Clinical and Subclinical Mastitis Milk of Kundhi Buffaloes

Prevalence and antibiotic susceptibility profile of Staphylococcus aureus in clinical and subclinical mastitis milk samples

Background: Staphylococcus aureus is the most commonly isolated bacterial pathogen in clinical and subclinical mastitis among cows. This study aimed to investigate the prevalence of Staphylococcus aureus, including MRSA (Methicillin-resistant Staphylococcus aureus), in cows with clinical and subclinical mastitis in Cumilla and Chattogram regions. Additionally, antimicrobial resistance patterns were identified. Methods: A total of 429 milk samples were collected from different teats of 125 cows with clinical and subclinical mastitis across 15 farms. Standard bacteriological methods were applied to isolate and identify Staphylococcus aureus. Confirmation of Staphylococcus aureus was achieved through PCR for the presence of the nuc gene. Antimicrobial susceptibility testing was conducted for 11 antimicrobials. Isolates showing resistance to cefoxitin and oxacillin underwent mecA gene screening to identify MRSA. Multivariable logistic regression models were used to identify risk factors associated with the presence of Staphylococcus aureus Results: The study revealed that 13.54% (95% CI, 5.00–38.78%) of mastitis-infected cows tested positive for Staphylococcus aureus. Staphylococcus aureus isolates showed the highest resistance to penicillin, cloxacillin, and streptomycin (61.54%, 53.85%, and 53.85%, respectively), while manifesting the least resistance to ciprofloxacin, ceftriaxone, and sulfamethoxazole + trimethoprim (92%, 77%, and 77%, respectively), and gentamycin (69.23%). The prevalence of MRSA was 2.08% (95% CI, 1.55–38.34%). Conclusion: This study represents the first report of MRSA in clinical and subclinical mastitis milk samples in Bangladesh. The findings emphasize the importance of ongoing monitoring of Staphylococcus aureus and MRSA in mastitis cases, considering their prevalence and patterns of antimicrobial resistance.

Draft genome sequence of multidrug-resistant Escherichia coli MAHK_SCM_BAU_30A strain isolated from a subclinical mastitis cow in Bangladesh.

This study announces the sequence of a multidrug-resistant Escherichia coli MAHK_SCM_BAU_30A strain isolated from bovine subclinical mastitis milk in 2022 in Bangladesh. Our assembled genome had a length of 4,884,948 bp, three plasmids, two CRISPR arrays, five prophages, 51 predicted antibiotic resistance, and 72 predicted virulence factor genes.

Exploring the Milk Microbiota of Healthy and Mastitic Nili Ravi Buffalo Using 16S rRNA Gene Base Metagenomic Analysis.

The Nili Ravi, a buffalo breed from Pakistan, significantly contributes to the dairy industry. Mastitis is one of the major challenges affecting milk production in this breed. The objective of the current study was to identify the bacterial communities and diversity in healthy and mastitic milk of this breed. Milk samples (n = 14) were collected from Nili Ravi buffaloes with different udder health statuses, i.e., healthy (5), subclinical mastitis (4), and clinical mastitis (5). The DNAs were extracted, subjected to partial amplification of 16S rDNA (V3 and V4 regions), and sequenced using the Illumina platform. The results revealed variations in the bacterial communities in the milk of animals with different udder health statuses. Proteobacteria was the predominant phylum in the healthy group, while clinical and subclinical mastitis milk had a higher abundance of Firmicutes. Dominant bacterial genera in the healthy group were Streptococcus (11.60%), Herbaspirillum (7.65%), and Staphylococcus (4.70%), whereas the clinical mastitis group was dominated by Streptococcus (33.96%), Staphylococcus (7.87%), and Corynebacterium (2.68%), and the subclinical mastitis group was dominated by Bacillus (15.70%), Corynebacterium (6.70%), and Staphylococcus (6.58%). Assignment of operational taxonomic units at the species level resulted in most species being assigned to uncultured or unknown bacteria or remaining unassigned. Alpha diversity indices indicated lower microbial diversity in the clinical mastitis group, while beta diversity indices showed a scattered pattern of sample clustering in PCA plots among different groups. It is concluded that bacterial diversity in the milk of Nili Ravi buffaloes suffering from clinical mastitis is lower compared to healthy and subclinical mastitis cases. It is concluded that the variations in the microbiota of healthy and mastitic milk may be further investigated and exploited as signature microbes associated with the udder health status of Nili Ravi buffalo.

Impact of subclinical mastitis on uterine health, reproductive performances and hormonal profile of Zebu × Friesian crossbred dairy cows in and around Jimma town dairy farms, Ethiopia

A longitudinal observational study was carried out from January 2020 to July 2021 to assess the impact of subclinical mastitis (SCM) on reproductive performance and its association with uterine health of crossbred dairy cows. The California Mastitis Test (CMT) and cytobrush technique were used to screen subclinical mastitis and subclinical endometritis, respectively. Milk samples positive for subclinical mastitis were subjected to bacteriological analysis. Data from 84 clinically healthy cows collected and analyzed. The present study revealed a prevalence of subclinical mastitis of 51.2% (43 of 84). The mean days from calving to first service interval were significantly longer in subclinical mastitis positive cows than negative (control) cows (120.51 ± 24.5 and 85.15 ± 28.3, respectively) (P < 0.05). The mean number of services per conception was significantly higher in positive cows (2.51 ± 0.83) than in negative cows (1.59 ± 0.81) (P < 0.05). Lower conception and pregnancy rates at first services were observed in subclinical mastitis cows. Risk factors analysis revealed that prevalence of subclinical mastitis significantly differed with the parity and body condition score (P < 0.05). The current study revealed that subclinical mastitis was significantly and directly associated with subclinical endometritis (P < 0.05). Subclinical mastitis significantly decreased (P = 0.000) progesterone concentrations and increased (P = 0.001) the cortisol concentrations. Staphylococcus aureus were the most predominant bacterial isolates from subclinical mastitic milk, followed by coagulase negative staphylococci (CNS) and streptococci. This study concludes a high prevalence of subclinical mastitis caused by Staphylococcus aureus could inflict harmful effects on reproductive performance of dairy cows, emphasizing the relevance of mastitis control programs in dairy farms.

Comparative study on genotypic properties of Pseudomonas aeruginosa isolated from subclinical mastitis in Türkiye

The results of antibacterial therapy in mastitis may be related to not only the antibiotic sensitivity of the etiological factors, but also to their abilities carrying integron and virulence genes. Integrons are mobile DNA element that can capture and carry genes, particularly those responsible for antibiotic resistance. Pseudomonas aeroginosa has numberless virulence factors which are contributed to bacterial invasion and toxicity. The aim of this study is to investigate antibiotic resistance, integron and virulence gene profiles of P. aeruginosa isolates obtained from cow milk with subclinical mastitis; further, was to evaluate the relationship between the antimicrobial resistance of bacteria with the of integron and virulence gene carrying. Material of the study is consisted with 32 (9.8%) of P. aeruginosa isolates obtained from 326 subclinical mastitic milk samples. After the bacterial identification was done by classical conventional methods, polymerase chain reaction (PCR) was used to verify the genus and species identifications of the isolates and to determine the integron and virulence gene profiles. Using disk diffusion method, antimicrobial resistance was determined to fifteen antibiotics against belonging to eleven antimicrobial families. The relationship the presence of integron and virulence genes associated with antibiotic resistance, further the relationship the presence of virulence genes and antimicrobial resistance was calculated with the Chi-Square (χ2) test. Ten of virulence genes (lasl, lasR, lasB, rhll, rhlR, rhlAB, plcH, plcN, ppyR, exoT) were found in all isolates whilst a virulence gene (aprA) was not present in any isolate. It was found that 34.4% of the isolates carried any integron gene. The results showed that the relationship is important between the presence of int genes and gentamicin, amikacin, tetracycline, cefoperazone, imipenem, aztreonam, ciprofloxacin, enrofloxacin resistance and exoU virulence gene presence. Also; there were also important associations between resistance to certain antibiotics and the presence of P. aeroginosa virulence genes: ciprofloxacin with lasA; netilmicin, cefoperazone and ciprofloxacin with pilB; netilmicin and ciprofloxacin with pelA; amikacin with algD, algU, algL; aztreonam with toxA; enrofloxacin with pvdA. All isolates obtained in this study showed multiple antibiotic resistance (MDR). In these cases, the presence of integron and some virulence genes could play a prominent role in the resistance of P. aeroginosa isolates to antimicrobial drugs. This study could be important in that it is the first study to show the presence of integrons and virulence genes in P. aeroginosa isolates originating from mastitic cow milk in Turkey. The presence of antibiotic-resistant P. aeroginosa strains in cattle farms may also pose a public health risk, as these bacteria can transmit their resistance genes to humans through food consumption.

Genomic mapping milk microbiota from healthy, sub-clinical and clinical mastitis of Jersey Friesian cattle in a Malaysian farm

Bovine mastitis is the persistent, inflammatory reaction of the udder due to physical trauma or microorganism infection. The milk from healthy and mastitis cows presents an ecosystem of microbial communities, which can influence the mechanisms and pathophysiology of mastitis. Hence, there is a possible shift in microbiome composition in healthy, subclinical and clinical mastitis. This study reported the composition of microbiota in the udder of Jersey Friesian cows in one of the local farms located in Pahang, Malaysia. From the 16s amplicon sequencing analysis, the core microbiota was dominated by phyla of Firmicutes, Proteobacteria, Actinobacteriota, and Bacteroidota. Most of the predominant genera from healthy groups were mainly Ralstonia, Staphylococcus, Corynebacterium, Turicibacter, Acinetobacter, Escherichia, Aerococcus, and Streptococcus. Furthermore, the majority of subclinical mastitis milk was populated by genera of Ralstonia, Escherichia, Aerococcus, and Corynebacterium, whereas, Streptococcus, Ralstonia and Escherichia were predominant in clinical mastitis samples. The alpha and beta diversity analysis indicated that microbiota from healthy and subclinical were more diverse compared to clinical mastitis microbiota. Therefore, predominant genera from clinical mastitis samples might be the potential of causative mastitis pathogens in the respective farm. The use of culture-independent analysis presented here revealed a wide bacterial diversity and variation between different clinical statuses.

Phenotypic and Genotypic Identification of Typical and Atypical Staphylococcus aureus Isolated From Bovine Milk Samples

This study aimed to determine the phenotypic and genotypic identification and differentiation of typical coagulase positive Staphylococcus aureus (CPSA) and atypical coagulase negative Staphylococcus aureus (CNSA) from other Staphylococci isolated form bovine milk. Out of 111 milk samples, 67 Staphylococcus strains were isolated, phenotypically, based on resistance to Acriflavine; Staphylococcus aureus (S. aureus) was detected in 44 isolates of them (30 CPSA strains and 14 CNSA strains). Twenty five from CPSA and 5 from CNSA isolates were positive for slime production on Congo red agar plates. Genotypically, the all five tested typical Staphylococcus aureus (CPSA) as well as three atypical Staphylococcus aureus (CNSA) strains encoded all investigated genes (nuc, spa-x and clfA), while the other two atypical CNSA strains, one encoded only nuc gene and the other encoded both nuc and clfA genes. Acriflavine sensitivity test must be included in the routine of phenotypic identification S. aureus as the gold method together with tube coagulase test. PCR analysis is most important confirmation method by detection of nuc gene. Genotypically both typical and atypical S. aureus isolates are virulent. Typical and atypical S. aureus isolated from isolated from bovine milk samples sold in dairy shops were with higher percentage than subclinical mastitic milk samples threating public health hazard. Attention must be paid toward detection and identification of atypical tube coagulase negative S. aureus strains.

Isolation and identification of fungi from subclinical mastitic milk.

Isolation and identification of fungi from subclinical mastitic milk.

Antibiogram and virulence profiling reveals multidrug resistant Staphylococcus aureus as the predominant aetiology of subclinical mastitis in riverine buffaloes.

Staphylococcus spp. are the major causal agents of mastitis in dairy animals worldwide leading to profound economic losses and public health threats. Recently, Staphylococcus aureus has emerged as a multidrug resistant and zoonotic pathogen. This study aimed to characterize S. aureus in subclinical mastitis (SCM) milk samples of riverine buffaloes in Bangladesh through antibiogram and virulence gene(s) profiling, and 16S rRNA gene sequencing. We characterized S. aureus in SCM milk samples (N = 500) of riverine buffaloes through antibiogram and virulence gene(s) profiling, and 16S rRNA gene sequencing. Out of 500 milk samples tested, 188 (37.6%) were found positive for SCM. From 188 SCM samples, 291 isolates were obtained with a prevalence of S. aureus in 37.4% (109/291) isolates. Phylogenetic analysis revealed the evolutionary divergence of S. aureus isolates in bubaline SCM milk samples. The antibiogram profiling showed that about 96.0% S. aureus isolates were multidrug resistant (MDR). Notably, 29 and 16 isolates harboured methicillin-resistant (mecA) and panton-valentine leucocidin (pvl) genes, respectively, and 46 plasmid-bearing isolates were MDR. Nine Staphylococcal enterotoxins (SEs/SEls) including sea (11.9%), sec (7.4%), sed (4.6%), seg (3.7%), and seh (3.7%) were detected with 72.48% toxinotypes comprising a single gene. This study therefore suggests S. aureus as the single-most aetiology (∼37.0%) of SCM in riverine buffaloes, and emergence of MDR, enterotoxin producing, and virulent S. aureus strains could impose potential threats to animal welfare and public health.

Molecular identification of Enterococcus spp associated with subclinical mastitis in dairy animals in Algeria and their antimicrobial resistance profile

Enterococcus genus is one of the opportunistic pathogens and responsible for mastitis in dairy animals. This study aimed to investigate the occurrence of enterococci associated with subclinical mastitis in goat, cow and camels in Algeria and to assess their antimicrobial resistance profiles. A total of 374 milk samples from udder quarters were tested for a subclinical mastitis (SCM) using the CMT. The positive samples were subjected to microbiological analysis for identification of Enterococcus spp by biochemical and molecular techniques using 16S rDNA sequencing and phylogenetic analyses. Eight strains of enterococci were tested to their antibiotic sensitivity profiles. The data revealed that 34, 31% of samples showed presence of SCM, meanwhile Enterococcus spp were occurred in 38.9% of positive milk. According to phenotypic criteria, 50 isolates were identified as Enterococcus faecium 70% (35/50) followed by Enterococcus faecalis 18% (9/50) and 12 % (6/50) were nonenterococci. Only eight isolates were confirmed to be Enterococcus spp using 16S rDNA sequencing technique. The antibiotic susceptibility showed that 85.5 % and 62.5% of Enterococcus feacium were resistant to Oxacillin and Penicillin respectively, while most of isolates were susceptible to Ciprofloxacin. In this study, Vancomycin-resistant enterococci (VRE) were found in 37.5% of isolates. Nevertheless, 62.5% of the tested strains displayed multi-drug resistances (MDR) across different patterns. This study highlights virulence and harmfulness of Enterococcus strains isolated from subclinical mastitic milk, which suggest continuous inspection and monitoring of dairy animals in Algeria.

Use of Multivariate Adaptive Regression Splines, Classification Tree and Roc Curve in Diagnosis of Subclinical Mastitis in Dairy Cattle

Subclinical mastitis is one of the most significant diseases that cause economic losses in dairy cattle farming. This investigation was conducted on 112 head Holstein Friesian cows in order to reveal relationship between subclinical mastitis and electrical conductivity milk composition and milk quality. In the study, CMT (California Mastitis Test) and CSCC (Classified Somatic Cell Count) used in diagnosis of subclinical mastitis were used as a binary response variable i.e. healthy and unhealthy. Potential predictors included here were lactation number, days in milk (DIM), L, a, b, H, C, milk fat, milk protein, lactose, milk freezing point, SNF, density, solids, pH and electrical conductivity. CART, CHAID, Exhaustive CHAID, QUEST and multivariate adaptive regression splines (MARS) were used as data mining algorithms that help to make an accurate decision about detecting influential factors increasing risk of subclinical mastitis.In conclusion, better classification performances of CART and MARS data mining algorithms were determined compared with those of remaining algorithms in order to correctly discriminate healthy and unhealthy cows.

Phenotyping and genotyping studies on extended-spectrum β-lactamase-producing Escherichia coli isolates from mastitic cows on dairy farms in Egypt

Background and Aim:Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae have become a serious public health hazard worldwide. This importance is derived from the increase of new variants, particularly blaTEM, blaSHV, and blaCTX-M genes. This study aimed to examine ESBL-producing Escherichia coli isolated from different governorates in Egypt from dairy cows infected with subclinical and clinical mastitis.Materials and Methods:This study examined 207 milk samples for the resistance of isolates against 14 different antibiotics and ran serological identification of ESBL-producing E. coli isolates with complete antibiotic resistance. Genotypic and sequencing analyses of several resistance genes were conducted using a polymerase chain reaction.Results:E. coli was identified in cases with subclinical mastitis (80.5%) and clinical mastitis (85.7%). ESBL-producing E. coli was isolated from 38.2% of subclinical mastitic milk compared to 39.3% in clinical cases, where O26:k60, O125:k70, and O25:k11 were the serotypes with complete resistance to antibiotics. ESBL-producing E. coli isolates were resistant to cefotaxime, amoxicillin, cloxacillin, oxacillin, rifampicin, and penicillin in 100% but susceptible to amoxicillin and clavulanic acid in 82.5% of the cases. Results also revealed that 51.25%, 52.5%, 66.25%, 77.5% and 60% of ESBL-producing E. coli isolates were responsive to ciprofloxacin, ofloxacin, norfloxacin, levofloxacin, and gentamycin, respectively. The detected genes were registered in GenBank as MW345819.1 and MW345820.1 for the E. coli blaTEM gene and MW295407 for the E. coli blaSHV gene.Conclusion:This study found ESBL-producing E. coli in mastitic milk samples from Egyptian dairy farms and confirmed the occurrence and circulation of the main antibiotic genes (blaTEM and blaSHV) in the samples. Regular and thorough surveillance of ESBL-producing E. coli and subsequent preventive actions are essential for preventing the spread of these resistance genes in the future, which could pose serious and catastrophic health risks. Authorities should cling to the concept of One Health to minimize the risk of new varieties.

Novel Streptococcus uberis sequence types causing bovine subclinical mastitis in Hainan, China.

To determine the molecular epidemiology, genotypes and phenotypes of the major species of Streptococcus associated with bovine subclinical mastitis in Hainan, China. In total, 150 subclinical mastitis milk samples were collected from two large dairy farms in Hainan. On the basis of biochemical tests and 16S rDNA sequencing, 39samples were Streptococcus positive and the most frequently isolated species was Streptococcus uberis (n=29, 74.4%). According to multilocus sequence typing (MLST), and assays of biofilm formation, antimicrobial susceptibility, resistance and virulence genes, the S. uberis isolates were clustered into nine new sequence types (STs; ST986-ST994) but were not merged into a clonal group (except for ST991 [CC143]). All isolates produced biofilm, but most weakly. The dominant virulence pattern was hasABC+sua+gapC+oppF+pauA+mtuA+cfu (27/29, 91.1%), based on the 11 virulence genes tested. The majority of isolates (88.46%) carried at least one resistance gene, and more than half (58.62%) were multidrug-resistant. The main resistance genes were linB (65.5%), ermB (37.9%) and tetS (34.5%), among the six antibiotic resistance genes and 11 antimicrobials tested. Environmental S. uberis is important in bovine subclinical mastitis in Hainan. Streptococcus uberis isolates in Hainan, China, show distinct MLST, virulence and antibiotic resistance characteristics.

The prevalence, genetic diversity and antibiotic resistance of Staphylococcus aureus associated with subclinical bovine mastitis in Balikesir, Turkey

Subclinical mastitis caused by Staphylococcus aureus is very common in dairy cows and creates serious problems on dairy farms. In this study, we investigated the prevalence, genetic diversity and antimicrobial resistance of S. aureus from subclinical bovine mastitis on 12 dairy herds in Balikesir province of Turkey, by SCCmec and spa typing. Ninety-five isolates of S. aureus were isolated from 725 subclinical mastitic milk samples that exceeded the somatic cell count (SCC) limit of 4 x 105 cell/mL. The frequency of MRSA (methicillin-resistant Staphylococcus aureus) and MSSA (methicillin-sensitive S. aureus) was 6.3% (6 isolates) and 93.68% (89 isolates) respectively. SCCmec types of MRSA isolates were community-associated CA-MRSA type IVb (4 isolates) and type IVd (two isolates), while the spa types were T 005 and T 5163 (three isolates from each). The resistance rate of MRSA isolates was 100% for oxacillin and cefoxitin, 83% for penicillin, ampicillin, clindamycin, erythromycin and 66% for gentamicin and trimethoprim/sulfamethoxazole. However, compared to MRSA, the resistance of MSSA isolates was relatively lower. This study supported the scientific data on the occurrence of MRSA and MSSA in subclinical mastitis, and highlighted the need for preventive measures to eliminate or decrease S. aureus contamination of milk in dairy herds.