Isolation, Biochemical and Molecular Identification, and In-Vitro Antimicrobial Resistance Patterns of Bacteria Isolated from Bubaline Subclinical Mastitis in South India

Pathogen group-specific risk factors for intramammary infection in water buffalo

A cross-sectional study was conducted to estimate the prevalence of intramammary infection (IMI) associated bacteria and to identify risk factors for pathogen group-specific IMI in water buffalo in Bangladesh. A California Mastitis Test (CMT) and bacteriological cultures were performed on 1,374 quarter milk samples collected from 763 water buffalo from 244 buffalo farms in nine districts in Bangladesh. Quarter, buffalo, and farm-related data were obtained through questionnaires and visual observations. A total of 618 quarter samples were found to be culture positive. Non-aureus staphylococci were the predominant IMI-associated bacterial species, and Staphylococcus (S.) chromogenes, S. hyicus, and S. epidermidis were the most common bacteria found. The proportion of non-aureus staphylococci or Mammaliicoccus sciuri (NASM), S. aureus, and other bacterial species identified in the buffalo quarter samples varied between buffalo farms. Therefore, different management practices, buffalo breeding factors, and nutrition were considered and further analyzed when estimating the IMI odds ratio (OR). The odds of IMI by any pathogen (OR: 1.8) or by NASM (OR: 2.2) was high in buffalo herds with poor milking hygiene. Poor cleanliness of the hind quarters had a high odds of IMI caused by any pathogen (OR: 2.0) or NASM (OR: 1.9). Twice daily milking (OR: 3.1) and farms with buffalo purchased from another herd (OR: 2.0) were associated with IMI by any pathogen. Asymmetrical udders were associated with IMI-caused by any bacteria (OR: 1.7). A poor body condition score showed higher odds of IMI by any pathogen (OR: 1.4) or by NASM (OR: 1.7). This study shows that the prevalence of IMI in water buffalo was high and varied between farms. In accordance with the literature, our data highlight that IMI can be partly controlled through better farm management, primarily by improving hygiene, milking management, breeding, and nutrition.

Unveiling distinct genetic features in multidrug-resistant Escherichia coli isolated from mammary tissue and gut of mastitis induced mice

Escherichia coli is one of the major pathogens causing mastitis in lactating mammals. We hypothesized that E. coli from the gut and mammary glands may have similar genomic characteristics in the causation of mastitis. To test this hypothesis, we used whole genome sequencing to analyze two multidrug resistant E. coli strains isolated from mammary tissue (G2M6U) and fecal sample (G6M1F) of experimentally induced mastitis mice. Both strains showed resistance to multiple (>7) antibiotics such as oxacillin, aztreonam, nalidixic acid, streptomycin, gentamicin, cefoxitin, ampicillin, tetracycline, azithromycin and nitrofurantoin. The genome of E. coli G2M6U had 59 antimicrobial resistance genes (ARGs) and 159 virulence factor genes (VFGs), while the E. coli G6M1F genome possessed 77 ARGs and 178 VFGs. Both strains were found to be genetically related to many E. coli strains causing mastitis and enteric diseases originating from different hosts and regions. The G6M1F had several unique ARGs (e.g., QnrS1, sul2, tetA, tetR, emrK, blaTEM-1/105, and aph(6)-Id, aph(3″)-Ib) conferring resistance to certain antibiotics, whereas G2M6U had a unique heat-stable enterotoxin gene (astA) and 7192 single nucleotide polymorphisms. Furthermore, there were 43 and 111 unique genes identified in G2M6U and G6M1F genomes, respectively. These results indicate distinct differences in the genomic characteristics of E. coli strain G2M6U and G6M1F that might have important implications in the pathophysiology of mammalian mastitis, and treatment strategies for mastitis in dairy animals.

Nutritional analysis and characterization of carbapenemase producing-Klebsiella pneumoniae resistant genes associated with bovine mastitis infected cow's milk

The current study was designed to analyze nutritional parameters and to characterize carbapenemase producing-Klebsiella pneumoniae isolates from bovine mastitic cow's milk. Out of 700 milk samples K. pneumoniae was identified by phenotypic and molecular techniques along with their antibiogram analysis and nutritional analysis was performed using the procedure of Association of Official Analytical Chemists. Carbapenemase-producing K. pneumoniae was detected by phenotypic CarbaNP test followed by molecular characterization of their associated resistant genes blaVIM, blaKPC, blaOXA-48, blaNDM, and blaIMP along with insertion sequence common region 1 (ISCR1) and integrons (Int1, Int2, and Int3) genes. Among nutritional parameters, fat content was observed (2.99%) followed by protein (2.78%), lactose (4.32%), and total solid (11.34%), respectively. The prevalence of K. pneumoniae among bovine mastitis was found 25.71%. Antibiogram analysis revealed that more effective antibiotics was ceftazidime (80%) followed by amikacin (72%), while highly resistant antibiotics was Fusidic acid (100%). Distribution of carbapenemase producer K. pneumoniae was found 44.4%. Among carbapenem resistant genes blaKPC was found 11.25%, blaVIM 2.75%, blaNDM 17.5%, and blaOXA-48 7.5%, while blaIMP gene was not detected. Furthermore, distribution of ISCR1 was found 40%, while integron 1 was found 61.2% followed by integron 2 (20%), and integron 3 (5%). In conclusion, the recent scenario of carbapenemase resistant K. pneumoniae isolates responsible for mastitis may affect not only the current treatment regime but also possess a serious threat to public health due to its food borne transmission and zoonotic potential.

Characterisation of Milk Microbiota from Subclinical Mastitis and Apparently Healthy Dairy Cattle in Free State Province, South Africa

Bovine mastitis is an inflammation of the udder tissue of the mammary gland brought on by microbial infections or physical damage. It is characterised by physical, chemical, and biological changes in the udder and milk. While several different bacterial species have been identified as causative agents of mastitis, many subclinical mastitis (SCM) cases remain culture-negative. The aim of this study was to characterise milk microbiota from SCM and apparently healthy dairy cows (non-SCM) by 16S rRNA sequencing. Alpha-diversity metrics showed significant differences between SCM cows and non-SCM counterparts. The beta-diversity metrics in the principal coordinate analysis significantly clustered samples by type (PERMANOVA test, p < 0.05), while non-metric dimensional scaling did not (PERMANOVA test, p = 0.07). The overall analysis indicated a total of 95 phyla, 33 classes, 82 orders, 124 families, 202 genera, and 119 bacterial species. Four phyla, namely Actinobacteriota, Bacteroidota, Firmicutes, and Proteobacteria collectively accounted for more than 97% of all sequencing reads from SCM and non-SCM cow samples. The most abundant bacterial classes were Actinobacteria, Bacilli, Bacteroidia, Clostridia, and Gammaproteobacteria in non-SCM cow samples, whilst SCM cow samples were mainly composed of Actinobacteria, Alphaproteobacteria, Bacilli, Clostridia, and Gammaproteobacteria. Dominant bacterial species in non-SCM cow samples were Anthropi spp., Pseudomonas azotoformans, P. fragi, Acinetobacter guillouiae, Enterococcus italicus, Lactococcus lactis, whilst P. azotoformans, Mycobacterium bovis, P. fragi, Acinetobacter guillouiae, and P. koreensis were dominant in the SCM cow samples. The current study found differences in bacterial species between SCM and non-SCM cow milk; hence, the need for detailed epidemiological studies.

An overview on the prevalence and potential impact of antimicrobials and antimicrobial resistance in the aquatic environment of India

India at present is one of the leading countries in antimicrobial drug production and use, leading to increasing antimicrobial resistance (AMR) and public health problems. Attention has mainly been focused on the human and food animals' contribution to AMR neglecting the potential contribution of the perceptibly degraded aquatic environment in India. The paper reviews the available published literature in India on the prevalence of antimicrobial residues and their dissemination pathways in wastewater of pharmaceutical industries, sewage treatment plants, hospitals, riverine, community pond water, and groundwater. The prevalence of antimicrobial residue concentration, pathogenic and non-pathogenic bacteria antimicrobial resistant bacteria (ARB), their drug resistance levels, and their specific antimicrobial resistant genes (ARGs) occurring in various water matrices of India have been comprehensively depicted from existing literature. The concentration of some widely used antimicrobials recorded from the sewage treatment plants and hospital wastewater and rivers in India has been compared with other countries. The ecotoxicological risk posed by these antimicrobials in the various water matrices in India indicated high hazard quotient (HQ) values for pharmaceutical effluents, hospital effluents, and river water. The degraded aquatic environment exhibited the selection of a wide array of co-existent resistant genes for antibiotics and metals. The review revealed improper use of antibiotics and inadequate wastewater treatment as major drivers of AMR contaminating water bodies in India and suggestion for containing the challenges posed by AMR in India has been proposed.

Antimicrobial susceptibility and biofilm forming ability of staphylococci from subclinical buffalo mastitis

The starting objective of this research communication was to determine the prevalence of subclinical mastitis in buffalo in Turkey. We also seeked to isolate and identify staphylococci, determine their antimicrobial susceptibilities and biofilm-forming abilities as well as investigating the presence of biofilm-related genes and microbial surface components recognizing adhesive matrix molecules. A total of 107 (66.9%) staphylococci (28 S. aureus and 79 coagulase-negative staphylococci, CoNS) were isolated from 160 mastitic milk samples collected from 200 lactating water buffalos. The staphylococci were especially resistant to beta-lactams except for cefoxitin but were less resistant to the other antimicrobials that were tested. Based on the Congo red agar method, 92.9% of the S. aureus and 70.9% of the CoNS isolates were positive for biofilm-forming ability, while all S. aureus and 97.5% of CoNS isolates were positive by a microtiter plate analysis. The presence of icaA and icaD genes was not always correlated with biofilm synthesis, and even in the absence of these genes, the isolates were able to synthesize biofilm.

The prevalence and risk factors of subclinical mastitis in water buffalo (Bubalis bubalis) in Bangladesh

Subclinical mastitis (SCM) in water buffalo is responsible for reduced milk yield and quality. This cross-sectional study was carried out to a) estimate the prevalence of SCM, b) identify risk factors associated with SCM, and c) identify farm-level risk factors associated with bulk milk somatic cell count (BMSCC). The buffalo farms included in this study represented five rearing systems: free-range, semi-free-range, household, semi-intensive, and intensive, providing a total of 3491 functional quarters of 880 lactating buffalo on 248 farms. The California mastitis test score was used to identify SCM. Bulk milk samples (n = 242) were used for farm-level BMSCC. Quarter and buffalo-level risk factors for SCM were measured using questionnaires and observations. The overall SCM prevalence was high at 27.9% at the quarter-level (25th and 75th percentiles: 8.3% and 41.7%) and 51.5% at buffalo-level (25th and 75th percentiles: 33.3% and 66.7%). The geometric mean BMSCC was 217,000 cells/mL of milk (ranging from 36,000-1,213,000 cells/mL), which is low on average, but some farms could improve substantially. The buffalo rearing system, udder location (left versus right), teat shape, udder asymmetry, number of milkers, and having a quarantine facility were associated with buffalo udder health. Our findings suggest that mainly using free-range rearing systems may help decrease the prevalence of SCM primarily by employing buffalo breeding and better farm biosecurity, and udder health control strategies can be designed based on our findings.

Antibiotic-resistant bacteria in bovine milk in India

Antibiotic resistance (ABR) is a global issue that draws the attention of all healthcare experts in the veterinary and medical fields. Of various factors, indiscriminate and unregulated antibiotic usage in the animals reared for food production, especially in cows and buffaloes suffering from mastitis, contribute significantly to the rising incidence of resistant bacteria. A literature survey reveals the spread of resistant strains of mastitis-causing bacteria, like Staphylococcus aureus and Escherichia coli, to humans. In addition, antibiotic residues detected in milk samples against all major groups of antibiotics are likely to enter the human body through the food chain and aggravate the condition. The cumulative effects of ABR have emerged as a silent killer. The benefits of systematic surveillance on ABR in India are yet to be available. Here is an attempt to understand the ABR burden in India associated with bovine milk and its mitigation strategies.

Molecular Characterization of Methicillin-Resistant Staphylococci from the Dairy Value Chain in Two Indian States

Bovine milk and milk products may contain pathogens, antimicrobial resistant bacteria, and antibiotic residues that could harm consumers. We analyzed 282 gram-positive isolates from milk samples from dairy farmers and vendors in Haryana and Assam, India, to assess the prevalence of methicillin-resistant staphylococci using microbiological tests, antibiotic susceptibility testing, and genotyping by PCR. The prevalence of genotypic methicillin resistance in isolates from raw milk samples was 5% [95% confidence interval, CI (3-8)], with 7% [CI (3-10)] in Haryana, in contrast to 2% [CI (0.2-6)] in Assam. The prevalence was the same in isolates from milk samples collected from farmers [5% (n = 6), CI (2-11)] and vendors [5% (n = 7), CI (2-10)]. Methicillin resistance was also observed in 15% of the isolates from pasteurized milk [(n = 3), CI (3-38)]. Two staphylococci harboring a novel mecC gene were identified for the first time in Indian dairy products. The only SCCmec type identified was Type V. The staphylococci with the mecA (n = 11) gene in raw milk were commonly resistant to oxacillin [92%, CI (59-100)] and cefoxitin [74%, CI (39-94)], while the isolates with mecC (n = 2) were resistant to oxacillin (100%) only. All the staphylococci with the mecA (n = 3) gene in pasteurized milk were resistant to both oxacillin and cefoxitin. Our results provided evidence that methicillin-resistant staphylococci occur in dairy products in India with potential public health implications. The state with more intensive dairy systems (Haryana) had higher levels of methicillin-resistant bacteria in milk.

Isolation and identification of specific lytic bacteriophages as a biocontrol agent against Serratia odorifera PBA-IAUF-1 and Kluyvera intermedia PBA-IAUF-6 causing bacterial canker in the grape and Siberian pear

Bacterial canker, a prevalent disease among fruit trees, is a significant concern. The use of phage therapy is presently seen as a dependable biological strategy to control bacterial diseases in fruits. The objective of this research was to use various biochemical and molecular techniques to determine the types of bacteria responsible for causing cankers in various fruits. Additionally, their ability to cause disease in the fruit tissues was assessed, the specific bacteriophages targeting these bacteria were isolated and identified. The bacteria were separated from different parts of the infected fruits like grapes and Siberian pears. The selection of fruit tissues showing signs of canker disease was performed, and the validation of the isolates' pathogenicity was confirmed following Koch's principles. Subsequently, in order to establish a conclusive identification of the bacterial species, molecular identification was conducted through the sequencing of a specific fragment within the 16S rRNA following amplification by PCR by using universal primers, RW01 and DG74. Isolation and titration of phages specific to fruit spoilage bacteria was done by spot and double-layer agar method, and the growth curve of the isolated bacteriophage was drawn. The phages were detected by transmission electron microscopy (TEM). The results of the study proved the presence of canker causing agents, Kluyvera intermedia PBA-IAUF-6 with the code Sh6 in the Siberian pears, and Serratia odorifera PBA-IAUF-1 with the code Rz3 in the grape fruits, which were deposited in GenBank with the accession numbers of KU878579 and KU168605, respectively. Isolation of the specific bacteriophages to the S. odorifera PBA-IAUF-1 and K. intermedia PBA-IAUF-6 bacterial strains were done from the effluent of South Isfahan wastewater treatment plant and Caspian Sea water, respectively. The titer of the specific phage to S. odorifera PBA-IAUF-1 and K. intermedia PBA-IAUF-6 was detected in the samples as 2.2 × 10-5 and 5 × 10-11 PFU/ml, respectively. An electron micrograph of a bacteriophage that targets two different bacterial strains revealed phages with a geometrically shaped head and a flexible tail, which resembled viruses from the Siphoviridae family.

First report on delineation of differentially expressed genes and pathways in milk somatic cells of mastitic and healthy Murrah buffaloes

Despite immense contribution of buffaloes as dairy species, limited studies have addressed the bubaline mastitis as compared to cattle. This was the first differential transcriptomic study investigating the alterations induced by clinical mastitis in buffalo milk relative to healthy controls. Comparative gene expression profiling of three biological replicates of each group identified 1014 up-regulated and 999 down-regulated genes in the diseased buffaloes (Fold change > 2, FDR < 0.05). Activation of immune and inflammatory responses were the most enriched GO terms in the mastitic animals, with higher transcript abundance of many genes coding for anti-microbial proteins such as β-defensins, perforin, granzymes, granulysin, cathelicidins etc. Analysis of the gene regulatory interactions of the up-regulated DEGs identified many hub genes that govern the cellular and macromolecular metabolic processes (E2F4, E2F1, RBL2, FOXM1, IRF1 and MYB). This study contributes to an insightful understanding of molecular mechanisms governing immune response of buffaloes to mastitis.

The Influence of Bacteria Causing Subclinical Mastitis on the Structure of the Cow’s Milk Microbiome

Mastitis is the most expensive disease of dairy cattle across the world and is the main reason for the use of antibiotics in animal husbandry. The aim of this study was to analyze the microbiome of raw milk obtained from a semi-subsistence farm located in the Kuyavian–Pomeranian Voivodeship in Poland. Milk from healthy cows and from cows with subclinical mastitis was analyzed. The following pathogenic bacteria were found in milk from individuals with subclinical mastitis: Escherichia coli or Streptococcus agalactiae. The composition of drinking milk was assessed on the basis of 16S rRNA gene sequencing using the Ion Torrent platform. Based on the conducted research, significant changes in the composition of the milk microbiome were found depending on the physiological state of the cows. The microbiome of milk from healthy cows differed significantly from the milk from cows with subclinical mastitis. Two phyla dominated in the milk from healthy cows: Firmicutes and Proteobacteria, in equal amounts. On the contrary, in the milk from cows with diagnosed subclinical mastitis, one of the types dominated: either Firmicutes or Proteobacteria, and was largely predominant. Moreover, the milk microflora from the ill animals were characterized by lower values of the determined biodiversity indicators than the milk from healthy cows. The presence of pathogenic bacteria in the milk resulted in a significant reduction in the share of lactic acid bacteria in the structure of the population of microorganisms, which are of great importance in the production technology of regional products.

Virulence and enterotoxin gene profile of methicillin-resistant Staphylococcus aureus isolates from bovine mastitis

Bovine mastitis is a major infectious disease affecting dairy animals resulting in enormous economic losses, prolonged antibiotic treatment, reduced milk yield and death of livestock. Emergence of Methicillin-resistant Staphylococcus aureus (MRSA) among bovine mastitis is matter of concern for animal health and dairy industry. The present study was conducted to detect the distribution of virulence and enterotoxin genes among MRSA isolates from bovine mastitis. Out of 500 milk samples, 126 isolates were identified as Staphylococcus and from these only 56 were S. aureus. S.aureus were resistant to cefoxitin (75%), ceftazidime (75%), amoxicillin (71.4%), cefodaxime (67.8%), cefepime (66.1%), oxacillin (64.3%), norfloxacin (60.7%) and gentamicin (58.9%). Only 42 isolates were identified as MRSA strains among staphylococci isolates. MRSA were harbouring virulence genes; mecA (100%), coa (100%) and nuc (100%). The other virulence factors such as hlg (80.9%, 34/42), pvl (47.6%, 20/42) and spa (92.8%, 39/42) were also reported. Molecular characterisation of enterotoxin genes revealed that out of 42 tested isolates 11 were found negative (26%) for any enterotoxin gene whereas 7 (16.6%), 6 (14.3%), 18 (42.8%), 1 (2.3%), 26 (61.9%),27(64.2%),3 (7.1%) were found positive for sea, seb, sec, sed, seg, sei, and seq enterotoxin respectively.

Antimicrobial resistance, virulence genes and biofilm formation in Enterococcus species isolated from milk of sheep and goat with subclinical mastitis

This study is designed to discuss the antimicrobial resistance, virulence determinants and biofilm formation capacity of Enterococcus spp. isolated from milk of sheep and goat with subclinical mastitis in Qena, Egypt. The obtained isolates were identified by the VITEK2 system and 16S rDNA sequencing as E. faecalis, E. faecium, E. casseliflavus and E. hirae. Overall, E. faecalis and E. faecium were the dominant species recovered from mastitic milk samples. The antimicrobial susceptibility test evidenced multidrug resistance of the isolates against the following antimicrobials: oxacillin (89.2.%), followed by vancomycin (75.7%) and linezolid (70.3%). Also, most of these isolates (73%) could form biofilms. For example, 18.9% of Enterococcus strains formed strong biofilm, whereas 32.4% of isolates formed moderate biofilm and 21.6% of isolates formed weak biofilm. The most prevalent resistance genes found in our isolates were blaZ (54%), vanA (40%), ermB (51.4%), tetM (13.5%) and optrA (10.8%). Moreover, asa1 (37.8%), cylA (42.3%), gelE (78.4%), esp (32.4%), EF3314(48.6%) and ace (75.5%) were the most common virulence genes. A significant correlation was found between biofilm formation, multidrug resistance and virulence genes of the isolates. This study highlights several aspects of virulence and harmfulness of Enterococcus strains isolated from subclinical mastitic milk, which necessitates continuous inspection and monitoring of dairy animals.

Easy Access to Antibiotics; Spread of Antimicrobial Resistance and Implementation of One Health Approach in India

Antimicrobial resistance (AMR) is a global public health concern because of its fast spread. India, one of the world's top consumer of antibiotics and second most populated country has its unique constraints of social, cultural and economic strata. The continual self-medication, use of antibiotics for the growth promotion in animals, and accumulation of residual antibiotics in the environment challenge the implementation of AMR containment policy. Hence, the present review attempts to delineate the influence of antibiotics abuse on the human, animal and environmental health under the realm of one health. It was based on the literature search using public databases to highlight the rapid surge in the burden of AMR in India affecting various sectors and/or ecosystems in India. It was found that the irrational and overuse of antibiotics in different sectors have led to the emergence of extended antimicrobial resistance wherein the environment acts as a reservoir of antibiotic resistance genes (ARGs); completing the cycle of contamination and recontamination. There are efforts by government policy makers to reduce the burden of AMR in the country to reduce the health risks, through the One Health approach. Parallel efforts in educating healthcare professionals, strict legislation for pharmacies and pharmaceutical companies should be prioritize. At the same time surveillance of newly emerged AMR pathogens, prioritising research focusing on AMR, and awareness camps or programs among the local population is critical while addressing the consequences of spared of AMR in India.

Occurrence and aetiology of subclinical mastitis in water buffalo in Bangladesh

Subclinical mastitis (SCM) in water buffalo is a production disease associated with decreased milk yield and impaired milk quality and safety. Water buffalo is an important livestock species in Bangladesh, but information about the occurrence and aetiology of SCM in this species is scarce. A cross-sectional study was conducted as part of the Udder Health Bangladesh Programme to (i) determine the occurrence of SCM and bulk milk somatic cell count (SCC) in water buffalo in Bangladesh, (ii) identify pathogens causing SCM and (iii) evaluate penicillin resistance in isolated staphylococci strains. Sixteen buffalo farms in the Bagerhat and Noakhali regions of Bangladesh were selected for study and a bulk milk sample was collected from each farm. In addition, 299 udder quarter milk samples were collected from 76 animals. The bulk milk samples were assessed by direct SCC and the quarter milk samples by California mastitis test (CMT). The occurrence of SCM calculated at quarter and animal level was 42.5 and 81.6%, respectively. Milk samples from 108 CMT-positive quarters in 48 animals and 38 randomly selected CMT-negative quarters in 24 animals were investigated using bacteriological culture. Estimated mean bulk milk SCC was 195 000 cells/ml milk (range 47 000- 587 000 cells/ml milk). On culture, estimated quarter-level intramammary infection (IMI) was 40.4%. The identity of isolated bacteria was confirmed by MALDI-TOF mass spectrometry. Non-aureus staphylococci (NAS) were the most common pathogens (24.7%) and, among 36 NAS tested, 36.1% were resistant to penicillin. Thus there was high occurrence of SCM on the study farms, with relatively high penicillin resistance in NAS. Further studies are needed to identify underlying risk factors and develop an udder health control strategy for water buffalo in Bangladesh.

Global and countrywide prevalence of subclinical and clinical mastitis in dairy cattle and buffaloes by systematic review and meta-analysis

In the present study, subclinical mastitis (SCM) and clinical mastitis (CM) prevalence for various countries in the World were calculated by using online and offline databases. The SCM and CM prevalence studies reported during 1967-2019 were collected, reviewed, and a meta-analysis was done in R-Software. A total of 222 and 150 studies from the World and 103 and 37 studies from India on SCM and CM, respectively were included. The pooled prevalence of SCM and CM were 42% [Confidence Interval (CI) 38-45%, Prediction Interval (PI) 10-83%] and 15% [CI 12-19%, PI 1-81%] in the World respectively, 45% [CI 40-49%, PI 11-84%] and 18% [CI 14-23%, PI 3-60%] in India respectively. Continent-wise analysis indicated a higher prevalence of SCM in North America and CM in Europe and among the countries, a higher SCM prevalence in Uganda and CM in the United Kingdom was observed. Further, species-wise indicated a higher SCM and CM prevalence in buffaloes of the World than the cattle. Based on method-wise, SCM and CM prevalence were high in somatic cell count and clinical examination, respectively in the World. The SCM prevalence was higher than CM and indicated the importance of SCM in dairy cattle. This might result in low milk productivity in dairying and may set off losses to dairy farmers. Hence, there is an urgent need to reduce the SCM and CM prevalence by implementing scientific dairy management, good feeding practices, and timely therapeutic interventions for increasing the benefits from dairying to the farmers in the World.

Molecular characterization of KPC-2-producing Klebsiella pneumoniae ST258 isolated from bovine mastitis

Bovine mastitis, an inflammation of the mammary gland of dairy cattle, is the most prevalent disease causing economically important losses, reduced milk production, early culling, veterinary expenses, and higher death rates. Bovine mastitis infections are the main cause for the use of antibiotics; however, the emergence of multidrug-resistant bacteria and the poor or nil response to antibiotics has become a critical global health problem. The goal of this study was the characterization of bacterial infections associated with clinical bovine mastitis. All the isolates were multidrug-resistant and were negative for the production of extended spectrum β-lactamases. However, all isolates were identified as carbapenemase-producing organisms by the Carba NP test. The carbapenemase identified was the product of the KPC-2 gene. The isolates were identified as Klebsiella pneumoniae and contained virulence genes for fimbriae, lipopolysaccharides, nitrogen starvation genes, and siderophores. Sixty-nine percent of the KPC-2-producing isolates had the same plasmid profile, although the genetic mobilization of resistance by bacterial conjugation was unsuccessful. The carbapenemase corresponded to the plasmid-borne KPC-2 gene identified by Southern blot hybridization. The assay showed a positive signal in the 90 kb (69% of the isolates), 165 kb (31% of the isolates), and 130 kb (6% of the isolates) plasmids. The IncFII_y and IncFII_k replicons were detected among these K. pneumoniae isolates. The PFGE and MLST analysis showed that all of the isolates are comprised by two clones (A and B) belonging to Sequence Type 258. This is the first report of K. pneumoniae producing carbapenemase KPC-2 isolated from bovine mastitis.

Polymorphisms in TLR4 Gene Associated With Somatic Cell Score in Water Buffaloes (Bubalus bubalis)

Considering the importance of the diseases affecting the productive performance of animals in the dairy industry worldwide, it is necessary to implement tools that help to control and limit the occurrence of such diseases. As the increased somatic cell counts (SCC) are a direct expression of the inflammatory process, they are candidates to become the usual parameter for assessing udder health regarding milk quality and for monitoring mastitis incidences. Toll-Like Receptors are membrane proteins that play a key role in immunity, recognizing pathogens and, subsequently, activating immune responses. The present study was conducted to identify single nucleotide polymorphisms in the TLR4 gene of buffaloes and to analyze its associations with somatic cell counts. DNA samples of 120 Murrah buffaloes were used. The whole coding region of the TLR4 gene was amplified by polymerase chain reaction reactions and sequenced for polymorphism scanning. A total of 13 polymorphisms were identified for the sequenced regions of the TLR4, most of which are in the coding region. The association with the somatic cell score was highly significant (p < 0.001) for all identified polymorphisms of TLR4 gene (g.54621T>A, g.54429G>T, g.54407T>A, g.46616C>A, g.46613T>G, g.46612A>G, g.46611C>A, g.46609T>G, g.46541C>G, g.46526C>A, g.46516T>C, g.46376C>T, g.46372T>C). Therefore, it is suggested that the markers of the TLR4 gene can be used as molecular markers for mastitis resistance in buffaloes, due to their association with somatic cell counts.

Variability in in vitro biofilm production and antimicrobial sensitivity pattern among Pasteurella multocida strains

Biofilm production, hitherto an uncharacterized feature among circulating Pasteurella multocida strains, was studied along with the antibiotic susceptibility pattern. On the basis of biofilm formation ability, all the strains were categorized into four groups under six different culture conditions: strong biofilm-forming (22%), moderate (19%), weak (51%), and non-adherent (7%). Strains from serogroups A and B formed significant biofilms in at least one culture condition whereas strains from serogroup D were unable to form biofilms. All strains were found to be susceptible to tetracycline. In addition, the correlation between diverse factors (host, capsule type, clinical condition and the tadD gene) as well as antimicrobial susceptibility in biofilm production were analyzed by Joint distribution models, and showed that enrofloxacin and azithromycin resistant strains were positively correlated with strong biofilm production.

Antimicrobial resistance: Call for rational antibiotics practice in India

It is a well-known fact that microorganisms are developing resistance to antimicrobial drugs present in the market that is known as antimicrobial resistance (AMR). This resistance in microbes is a great matter of concern among the scientific fraternity. This review article focuses on antibiotics and their respective resistant microbes, factors that cause resistance among microbes, and consequences of AMR at global as well as Indian scenario. This article would be a helpful resource in nutshell for making the ground for discovery of new antibiotics that will be more effective toward microbes.

Insights Into the Resistome of Bovine Clinical Mastitis Microbiome, a Key Factor in Disease Complication

Bovine clinical mastitis (CM) is one of the most prevalent diseases caused by a wide range of resident microbes. The emergence of antimicrobial resistance in CM bacteria is well-known, however, the genomic resistance composition (the resistome) at the microbiome-level is not well characterized. In this study, we applied whole metagenome sequencing (WMS) to characterize the resistome of the CM microbiome, focusing on antibiotics and metals resistance, biofilm formation (BF), and quorum sensing (QS) along with in vitro resistance assays of six selected pathogens isolated from the same CM samples. The WMS generated an average of 21.13 million reads (post-processing) from 25 CM samples that mapped to 519 bacterial strains, of which 30.06% were previously unreported. We found a significant (P = 0.001) association between the resistomes and microbiome composition with no association with cattle breed, despite significant differences in microbiome diversity among breeds. The in vitro investigation determined that 76.2% of six selected pathogens considered "biofilm formers" actually formed biofilms and were also highly resistant to tetracycline, doxycycline, nalidixic acid, ampicillin, and chloramphenicol and remained sensitive to metals (Cr, Co, Ni, Cu, Zn) at varying concentrations. We also found bacterial flagellar movement and chemotaxis, regulation and cell signaling, and oxidative stress to be significantly associated with the pathophysiology of CM. Thus, identifying CM microbiomes, and analyzing their resistomes and genomic potentials will help improve the optimization of therapeutic schemes involving antibiotics and/or metals usage in the prevention and control of bovine CM.

Quantitative alterations in bovine milk proteome from healthy, subclinical and clinical mastitis during S. aureus infection

Bovine mastitis, caused by Staphylococcus aureus, is a major impediment to milk production and lacks markers to indicate disease progression in cows and buffaloes. Thus, the focus of this study was to identify proteins marking the transition from subclinical to clinical mastitis. Whey proteins were isolated from 6 group's i.e. healthy, subclinical and clinical mastitis of Holstein Friesian cow and Murrah buffalo. Mass spectrometry and statistical analysis (ANOVA and t-tests) were performed on 12 biological samples each from cow and buffalo (4 per healthy, subclinical and clinical mastitis) resulting in a total of 24 proteome datasets. Collectively, 1479 proteins were identified of which significant proteins were shortlisted by a combination of fold change (≤ 0.5 or ≥ 2) and q < 0.05. Of these proteins, 128 and 163 indicated disease progression in cow and buffalo, respectively. Change in expression of haptoglobin and fibronectin from Holstein Friesian while spermadhesin and osteopontin from Murrah correlated with disease progression. Similarly, angiogenin and cofilin-1 were upregulated while ubiquitin family members were downregulated during disease transition. Subsequently, selected proteins (e.g. osteopontin and fibrinogen-α) were validated by Western blots. The results of this study provide deeper insights into whey proteome dynamics and signature patterns indicative of disease progression. BIOLOGICAL SIGNIFICANCE: Bovine mastitis is the most lethal infectious disease causing a huge economic loss in the dairy industry. In an attempt, to understand the dynamics of whey proteome in response to S. aureus infection, whey protein collected from healthy, subclinical and clinical mastitic HF and Mu were investigated. A total of 1479 proteins were identified, of which 128 and 163 had signature pattern in each stage indicative of the progression of the disease. The results of the present study provide a foundation to better understand the complexity of mastitis that will ultimately help facilitate early therapeutic and husbandry-based intervention to improve animal health and milk quality.

Occurrence and characteristics of methicillin-resistant Staphylococcus aureus (MRSA) in buffalo bulk tank milk and the farm workers in Italy

The aim of the present study was to assess the occurrence of MRSA in buffalo dairy farms and in buffalo tank milk from Italy, and to provide information about the antimicrobial resistance profile and molecular characteristics of the isolates. We collected 75 bulk tank milk (BTM) samples from 75 farms and 24 nasal swabs from 24 farm operators. Three (4%) of the 75 BTM samples and 1 (4%) of the 24 human nasal swabs tested positive for MRSA. The milk isolates belonged to the genotypes ST1/t127/Va and ST72/t3092/V, while the human isolate was characterized as ST1/t127/IVa. All isolates were multidrug resistant but vancomycin susceptible; they carried the icaA gene but tested negative for the pvl and ses genes. ST72 is a CA-MRSA commonly found in South Korea, and this is the first report of its detection in Europe. Although we found a low prevalence of MRSA in the farms we surveyed, this study clearly demonstrates, for the first time in Europe, that MRSA can be found in dairy buffalo farms and in raw buffalo milk. Therefore, the risk of human colonization/infection with MRSA linked to the handling of raw milk or consumption of contaminated dairy products should not be ruled out.

Technological interventions and advances in the diagnosis of intramammary infections in animals with emphasis on bovine population-a review

Mastitis, an inflammation of the udder, is a challenging problem in dairy animals accounting for high economic losses. Disease complexity, degree of economic losses and increasing importance of the dairy industries along with public health concerns envisages devising appropriate diagnostics of mastitis, which can offer rapid, accurate and confirmatory diagnosis. The various diagnostic tests of mastitis have been divided into general or phenotypic and specific or genotypic tests. General or phenotypic tests are those that identify general alterations, which are not specific to any pathogen. Genotypic tests are specific, hence confirmatory for diagnosis of mastitis and include specific culture, polymerase chain reaction (PCR) and its various versions (e.g. qRT-PCR), loop-mediated isothermal amplification, lateral flow assays, nucleotide sequencing, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and other molecular diagnostic methods. However, for highly specific and confirmatory diagnosis, pure cultures still provide raw materials for more sophisticated diagnostic technological interventions like PCR and nucleotide sequencing. Diagnostic ability of like infra-red thermography (IRT) has been shown to be similar to California mastitis test and also differentiates clinical mastitis from subclinical mastitis cases. As such, IRT can become a convenient and portable diagnostic tool. Of note, magnetic nanoparticles-based colorimetric biosensor assay was developed by using for instance proteolytic activity of plasmin or anti-S. aureus antibody. Last but not least, microRNAs have been suggested to be potential biomarkers for diagnosing bovine mastitis. This review summarizes the various diagnostic tests available for detection of mastitis including diagnosis through general and specific technological interventions and advances.

Antimicrobial resistance in the environment: The Indian scenario

Antimicrobial resistance (AMR) continues to pose a significant public health problem in terms of mortality and economic loss. Health authorities of several countries including India have formulated action plans for its containment. In this fight against AMR, it is important to realize the contribution by all the following four spheres: humans, animals, food and environment. This review incorporates all the spheres of One Health concept from the Indian perspective. India has one of the highest rates of resistance to antimicrobial agents used both in humans and food animals. The environment, especially the water bodies, have also reported the presence of resistant organisms or their genes. Specific socio-economic and cultural factors prevalent in India make the containment of resistance more challenging. Injudicious use of antimicrobials and inadequate treatment of waste waters are important drivers of AMR in India. Use of sludge in agriculture, improper discard of livestock animals and aquaculture industry are considered AMR contributors in other countries but Indian data regarding these are lacking. Efforts to combat AMR have been initiated by the Indian health authorities but are still at preliminary stages. Keeping in view the challenges unique to India, future directions are proposed.

Diversity of Virulence Genes in Multidrug Resistant Escherichia coli from a Hospital in Western China

Background

Escherichia coli strains are the most commonly isolated bacteria in hospitals. The normally harmless commensal E. coli can become a highly adapted pathogen, capable of causing various diseases both in healthy and immunocompromised individuals, by acquiring a combination of mobile genetic elements. Our aim was to characterize E. coli strains from a hospital in western China to determine their virulence and antimicrobial resistance potential.

Methods

A total of 97 E. coli clinical isolates were collected from the First Affiliated Hospital of Chengdu Medical College from 2015 to 2016. Microbiological methods, PCR, and antimicrobial susceptibility tests were used in this study.

Results

The frequency of occurrence of the virulence genes fimC, irp2, fimH, fyuA, lpfA, hlyA, sat, and cnf1 in the E. coli isolates was 93.81, 92.78, 91.75, 84.54, 41.24, 32.99, 28.86, and 7.22%, respectively. Ninety-five (97.9%) isolates carried two or more different virulence genes. Of these, 44 (45.4%) isolates simultaneously harbored five virulence genes, 24 (24.7%) isolates harbored four virulence genes, and 17 (17.5%) isolates harbored six virulence genes. In addition, all E. coli isolates were multidrug resistant and had a high degree of antimicrobial resistance.

Conclusion

These results indicate a high frequency of occurrence and heterogeneity of virulence gene profiles among clinical multidrug resistant E. coli isolates. Therefore, appropriate surveillance and control measures are essential to prevent the further spread of these isolates in hospitals.

Short communication: Detection of antibiotic resistance, mecA, and virulence genes in coagulase-negative Staphylococcus spp. from buffalo milk and the milking environment

The aim of this study was to determinate whether coagulase-negative staphylococci (CNS) from buffalo milk or the milking environment possess virulence factors that are associated with intramammary infections or antimicrobial resistance. Milk samples (n = 320) from 80 lactating buffalo were evaluated for clinical and subclinical mastitis by physical examination, the strip cup test, California Mastitis Test (CMT), and somatic cell count (SCC) over a 4-mo period. In addition, swabs were obtained from the hands of consenting milkers (16), liners (64), and from the mouths (15) and nostrils (15) of buffalo calves. No clinical cases of mastitis were observed; however, CMT together with SCC results indicated that 8 animals had subclinical mastitis. Eighty-four CNS isolates were identified by MALDI-TOF MS and cydB real-time PCR (qPCR) and then evaluated by qPCR for presence of the eta, etb, sea, sec, cna, seb, sei, seq, sem, seg, see, and tst toxin genes, adhesion- and biofilm-associated genes (eno, ebps, fib, fnbA, coa), and the methicillin resistance gene (mecA). Resistance to antibiotics commonly used for mastitis treatment in Brazil was determined using the Kirby-Bauer test. Two strains were positive for the see and eta toxin genes; and mecA (1), eno (27), ebps (10), fnbA (10), and coa (5) genes were also detected. A notable number of isolates were resistant to erythromycin (30), penicillin (26), and cotrimoxazole (18); importantly, 10 vancomycin-resistant isolates were also detected. A smaller number of isolates were resistant to rifampicin (8), oxacillin (7), clindamycin (5), cefepime (4), tetracycline (3), ciprofloxacin (2), and chloramphenicol (1), and none were resistant to gentamicin or ciprofloxacin. Isolates with resistance to 2 (13 isolates), 3 (3), 4 (3), 5 (1), and 6 (1) antibiotics were detected. Taken together, our findings suggest that CNS isolates may not be a significant cause of clinical or even subclinical mastitis in buffaloes, but they may be a reservoir of virulence and antibiotic resistance genes.

Phenotypic and genotypic methods for identification of slime layer production, efflux pump activity, and antimicrobial resistance genes as potential causes of the antimicrobial resistance of some mastitis pathogens from farms in Menoufia, Egypt

Mastitis caused by multi- or pan-drug resistant bacteria is a growing health concern. A total of 110 milk samples were collected: Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, Enterococcus faecalis, and Escherichia coli were present in 54/110 (49.09%), 37/110 (33.63%), 25/110 (22.72%), 7/110 (6.36%), and 50/110 (45.45%) samples, respectively. A total of 20 methicillin-resistant S. aureus (MRSA) isolates, 19 Streptococcus sp. isolates, and 15 E. coli isolates were selected, and 100% were positive for (coagulase and hemolysins), streptokinase, and hemolytic activity, respectively. A number of 11 E. coli isolates were serotyped, and the serotypes were: O26, O55, O111, O119, O124, O125, O127, and O158. The antimicrobial resistance index ranges for MRSA, Streptococcus sp., and E. coli were 0.49-0.83, 0.39-0.83, and 0.56-1, respectively. The most effective antimicrobials on Gram-positive isolates were cephradine, ciprofloxacin, doxycycline, norfloxacin, and vancomycin, while doxycycline and norfloxacin were effective on E. coli serotypes. All of the selected isolates exhibited slime layer production. The efflux pumps of the 12 MRSA, 12 Streptococcus sp., and 11 E. coli isolates exhibited activity with ethidium bromide concentrations of 1, 1.5, and 0.5 µg/ml, respectively. There was a simultaneous antimicrobial activity of the efflux pump inhibitor chlorpromazine with amoxicillin/clavulanic acid, erythromycin, and oxacillin, to which the isolates were resistant. The 12 MRSA isolates harboured the methicillin resistance genes mec(A,A1, and A2), mecA1, and mecC at frequencies of 9/12 (75%), 9/12 (75%), and 8/12 (66.7%), respectively, and the penicillin resistance gene BlaZ was present at a frequency of 5/12 (41.7%). The distributions of erm(A), erm(B), erm(C), erm(F), erm(G), and erm(Q) were 8/12 (66.7%), 5/12 (41.7%), 12/12 (100%), 2/12 (16.7%), 0/12 (0.0%), and 8/12 (66.7%), respectively. The 12 Streptococcus sp. isolates harboured mec(A, A1, and A2), mecA1, mecC, and blaZ at rates of 4/12 (33.33%), 4/12 (33.33%), 5/12 (41.7%), and 4/12 (33.33%), respectively. The frequencies of erm(A) and erm(F) were 4/12 (33.33%), and 9/12 (75%), respectively. The 11 E. coli isolates harboured the extended-spectrum β-lactamases integrase1, integrase2, blaCTX-M, blaCTX-M-1, and blaTEM at frequencies of 10/11 (90.90%), 11/11 (100%), 9/11 (81.81%), 6/11 (54.54%), and 10/11 (90.90%), respectively. Moreover, the frequencies of erm(A), erm(B), erm(C), erm(F), erm(G), and erm(Q) were 7/11 (63.63%), 4/11 (36.36%), 4/11 (36.36%), 5/11 (45.45%), 10/11 (90.90%), and 10/11 (90.90%), respectively. Our results demonstrated the high antimicrobial resistance of the investigated isolates and confirmed the existence of multiple mechanisms underlying multidrug resistance.

Histopathological and microbiological findings in buffalo chronic mastitis: evidence of tertiary lymphoid structures

Buffalo mastitis is an important economic problem in southern Italy, causing qualitative/quantitative alterations in milk and resulting in economic losses due to the sub-clinical course and chronic evolution. We investigated 50 udders of slaughtered buffaloes and subjected them to effectual microbiological screening to evaluate macro and microscopic mammary gland changes, immune-characterize the cell infiltrates, and compare the degree of tissue inflammation with somatic cell counts. Numerous Gram-positive and Gram-negative bacteria were isolated from all samples, majority of which were environmental mastitis pathogens. Histological features referable to chronic mastitis were observed in 92% udders. Lymphocytes, plasma cells and macrophages were found to evolve into aggregates in 48% udders, which often organized to form tertiary lymphoid structures (TLSs). A predominance of interstitial CD8+ over CD4+ lymphocytes and, in TLSs, scattered CD8+ lymphocytes in the mantle cells and CD79+ lymphocytes in germinal centers, were evidenced. Environmental pathogens are known to persist and cause chronic inflammatory changes in buffaloes, where CD8+ lymphocytes play an important role by controlling the local immune response. Moreover, the TLSs evidenced here for the first time in buffalo mastitis, could play a role in maintaining immune responses against persistent antigens, thereby contributing in determining the chronic course of mastitis.

Novel lytic bacteriophages of Klebsiella oxytoca ABG-IAUF-1 as the potential agents for mastitis phage therapy

Mastitis is an inflammation of the mammary gland that occurs when pathogenic microorganisms enter the udder. Even though tremendous advancements in veterinary diagnosis and therapeutics, mastitis is still the most frequent and costly disease of dairy herds overall the world. The purpose of this research was to isolate and identify the lytic phages as a potential method for biological control of bovine mastitis. In this study Klebsiella oxytoca was isolated from contaminated milk samples of Isfahan dairy herds, Isfahan, Iran and characterized as K. oxytoca ABG-IAUF-1 and its 16s-rRNA sequence was deposited in GenBank under the accession numbers of MF175803.1. Then, the four novel specific lytic bacteriophages of K. oxytoca ABG-IAUF-1 from Isfahan public wastewater were isolated and identified. The results of transmission electron microscopy indicated that theses isolated phages were related to Myoviridae and Podoviridae families of bacteriophages. Also the analysis of the growth curve of K. oxytoca ABG-IAUF-1 before and after treatment with lytic phage showed the 97% success rate of the phages in preventing of bacterial growth. This is the first report indicating the use of bacteriophages as the potential agents for eliminating the pathogenic bacteria responsible for bovine mastitis in Iran. The applications of these lytic phages could be an asset for biocontrolling of pathogenic agents in medical and veterinary biotechnology.

Characterization of difference in structure and function of fresh and mastitic bovine milk fat globules

Characterization of milk fat globule (MFG) was performed to investigate the difference in MFG membrane (MFGM) between fresh and mastitis Holstein Friesian cow milk. Lipid distribution investigated by exogenous phospholipids using microscopy showed higher phospholipid content in fresh compared to mastitic MFGM. Xanthine oxidase assay indicative of membrane impairment revealed lower activity in mastitic samples compared to fresh globules. Of note, significantly higher roughness of globule surface and zeta potential was observed in mastitis compared to fresh globules. Influence of globule membrane on the interaction with L. fermentum demonstrated preferential adhesion of bacteria to fresh compared to mastitic globules including enhanced extent of binding. Results of the present study provides an insight of the interfacial changes occurring at the globule surface as well as highlighting the importance of selective bacterial interaction with milk components for the potential development of functional food with relevance to human health.

Antibacterial effects and resistance induction of silver and gold nanoparticles against Staphylococcus aureus-induced mastitis and the potential toxicity in rats

Staphylococcus aureus (S. aureus) is one of the prevalent mastitis-inducing pathogens worldwide. The resistance of S. aureus to antibiotics is a common issue for dairy farms. Recently, nanoparticles (NPs) have been used for treating antibiotic-resistant bacteria. We therefore aimed to investigate the antimicrobial effect of silver and gold NPs (AgNPs and AuNPs, respectively) and the resistance developed by S. aureus as well as the toxic effects of both NPs in rats. We used 198 S. aureus strains to determine the antibacterial effects of AgNPs and AuNPs. The microdilution method was used to establish the minimum inhibitory concentrations (MICs) of both NPs. To induce resistance, 20 S. aureus strains were passaged 10 times in broth medium with sublethal doses of NPs and an additional 10 times without NPs to examine the stability of resistance. Histopathology was performed after oral administration to the rats with the study doses of 0.25, 0.5, 1, and 2 mg/kg of NPs for 30 days. The MICs of 10-nm AgNPs, 20-nm AgNPs, 10-nm AuNPs, and 20-nm AuNPs against S. aureus were 14.70 ± 1.19 μg/ml, 9.15 ± 0.13 μg/ml, 24.06 ± 2.36 μg/ml, and 18.52 ± 1.26 μg/ml, respectively. Most strains developed strong resistance when treated with 20-nm or 10-nm AgNPs, whereas only two strains were resistant to 10-nm AuNPs and three strains to 20-nm AuNPs. No cross-resistance between NPs and various antibiotics was identified in any of the adapted S. aureus strains. Organ histopathology revealed that 0.25, 0.5, and 1 mg/kg doses of AgNPs and AuNPs were not toxic to rat tissue. In contrast, a higher dose (2 mg/kg) of NPs impaired all organs tested. This study demonstrates the antibacterial effects of NPs. S. aureus strains develop resistance less frequently against AuNPs than AgNPs, and neither AuNPs nor AgNPs was toxic to rats at low doses.

Impact of intramammary inoculation of inactivated Lactobacillus rhamnosus and antibiotics on the milk microbiota of water buffalo with subclinical mastitis

Water buffalo mastitis represents a major issue in terms of animal health, cost of therapy, premature culling and decreased milk yeld. The emergence of antibiotic resistance has led to investigate strategies to avoid or reduce antibiotics' based therapies, in particular during subclinical mastitis. The use of Generally Regarded As Safe bacteria (GRAS) such as Lactobacillus rhamnosus to restore the unbalance in mammary gland microbiota could provide potential corrective measures. The aim of this study was to investigate the changes in milk microbiota after the intramammary treatment with inactivated cultures of Lactobacillus rhamnosus of mammary gland quarters naturally affected by subclinical mastitis as compared to antibiotic therapy.A number of 43 quarters affected by subclinical mastitis with no signs of clinical inflammation and aerobic culture positive for pathogens were included in the study. The experimental design was as follows: 11 quarters were treated with antibiotics, 15 with inactivated cultures of Lactobacillus rhmnosus and 17 with PBS as negative control, by means of intrammary injection. Samples were collected at eight time points, pre- (T-29, T-21, T-15, T-7, T0 days) and post- treatment (T1, T2, and T6 days). Microbiological culture and Somatic Cell Count (SCC) were perfomed on all the samples, and microbiota was determined on milk samples collected at T0 and T6 by amplifying the V4 region of 16S rRNA gene by PCR and sequencing using next generation sequencing technique. Treatment with Lactobacillus rhamnosus elicited a strong chemotactic response, as determined by a significant increase of leukocytes in milk, but did not change the microbiological culture results of the treated quarters. For what concerns the analysis of the microbiota, the treatment with Lactobacillus rhamnosus induced the modification in relative abundance of some genera such as Pseudomonas and 5-7N15. As expected, antibiotic treatment caused major changes in microbiota structure with an increase of Methylobacterium relative abundance. No changes were detected after PBS treatment. In conclusion, the present findings demonstrated that the in vivo intrammmary treatment with Lactobacillus rhamnosus has a transient pro-inflammatory activity by increasing SCC and is capable to modify the microbiota of milk after six days from inoculation, albeit slightly, even when the bacterial cultures were heat inactivated. Further studies are necessary to assess the potential use of this GRAS as supportive therapy against mastitis.

Virulence gene profiles and molecular genetic characteristics of diarrheagenic Escherichia coli from a hospital in western China

Background

Diarrheagenic Escherichia coli (DEC) is one of the most important etiological agents of diarrheal diseases. In this study we investigated the prevalence, virulence gene profiles, antimicrobial resistance, and molecular genetic characteristics of DEC at a hospital in western China.

Methods

A total of 110 Escherichia coli clinical isolates were collected from the First Affiliated Hospital of Chengdu Medical College from 2015 to 2016. Microbiological methods, PCR, antimicrobial susceptibility test, pulsed-field gel electrophoresis and multilocus sequence typing were used in this study.

Results

Molecular analysis of six DEC pathotype marker genes showed that 13 of the 110 E. coli isolates (11.82%) were DEC including nine (8.18%) diffusely adherent Escherichia coli (DAEC) and four (3.64%) enteroaggregative Escherichia coli (EAEC). The adherence genes fimC and fimH were present in all DAEC and EAEC isolates. All nine DAEC isolates harbored the virulence genes fyuA and irp2 and four (44.44%) also carried the hlyA and sat genes. The virulence genes fyuA, irp2, cnf1, hlyA, and sat were found in 100%, 100%, 75%, 50%, and 50% of EAEC isolates, respectively. In addition, all DEC isolates were multidrug resistant and had high frequencies of antimicrobial resistance. Molecular genetic characterization showed that the 13 DEC isolates were divided into 11 pulsed-field gel electrophoresis patterns and 10 sequence types.

Conclusions

To the best of our knowledge, this study provides the first report of DEC, including DAEC and EAEC, in western China. Our analyses identified the virulence genes present in E. coli from a hospital indicating their role in the isolated DEC strains’ pathogenesis. At the same time, the analyses revealed, the antimicrobial resistance pattern of the DEC isolates. Thus, DAEC and EAEC among the DEC strains should be considered a significant risk to humans in western China due to their evolved pathogenicity and antimicrobial resistance pattern.

Identification of Variable Traits among the Methicillin Resistant and Sensitive Coagulase Negative Staphylococci in Milk Samples from Mastitic Cows in India

Methicillin resistant Staphylococcus aureus causing bovine mastitis has been very well investigated worldwide. However, there are only limited reports on the characterization of methicillin resistant and sensitive coagulase negative staphylococci (CoNS) across the globe. Hence, in the present study, we aim to determine the phenotypic traits based on antimicrobial susceptibility profile and genotypic characterization by verifying the presence of resistance determinants, virulence and toxin genes present in the CoNS causing clinical mastitis. We obtained 62 CoNS isolates from 167 mastitic milk samples collected from three different states of India. The 62 isolates comprises of 10 different CoNS species S. sciuri, S. haemolyticus, S. chromogenes, S. saprophyticus, S. xylosus, S. simulans, S. agnetis, S. epidermidis, S. gallinarum, and S. cohinii. Susceptibility screening against 11 antibiotics determined 45.16% isolates as multidrug resistant (resistant to more than two class of antibiotic), 46.74% resistant (one or two antibiotic class) and 8.06% isolates were pan-sensitive (sensitive to all drugs). High resistance was observed against oxacillin and cefoxitin, whereas all isolates were susceptible toward vancomycin and linezolid. Fifty three isolates were methicillin resistant and 9 isolates were sensitive as determined by oxacillin susceptibility assay. The methicillin resistance gene, mecA was found in 95.16% isolates and staphylococcal cassette chromosome mec (SCCmec) typing predominantly revealed Type III (n = 34) and Type V (n = 18). Interestingly, 11.9% of mecA positive isolates were oxacillin susceptible and referred as oxacillin susceptible mecA positive staphylococci (OS-MRS). Additionally, genes encoding for enterotoxin, (sea, seb, seh, see) toxic shock syndrome (tsst), exfoliatin (eta, etb, etd) and virulence (pvl, Y-hlg) were also screened. Of all the genes examined, 67.74% of isolate were positive for the Y-hlg gene, followed by the sea gene in 25.8% whereas in none of the isolates the eta and the etb gene was amplified. The study also highlights the incidence of clinical isolates of CoNS, which are harboring the toxin and the virulence genes rendering them as a more potential threat. This is the first report of animal origin OS-MRS from India, which emphasizes on the inclusion of both the genetic and phenotypic test for proper characterization of CoNS and preventing resistant strain misidentification.

Performance of MALDI biotyper compared with Vitek™ 2 compact system for fast identification and discrimination of Staphylococcus species isolated from bovine mastitis

This study was designed to evaluate the ability of MALDI Biotyper (MBT) compared with Vitek^™ 2 compact system for accurate identification of Staphylococcus aureus (S. aureus) and coagulase‐negative staphylococci (CNS) strains and discriminate methicillin‐sensitive S. aureus (MSSA) from methicillin‐resistant S. aureus (MRSA). Throughout Al‐Qassim region, Saudi Arabia, a total of 198 isolates of S. aureus (132 MSSA and 66 MRSA) and 44 CNS were collected from five dairy farms where the prevalence of staphylococcal mastitis was reported. The results produced by Vitek^™ 2 compact system demonstrated that 123/132 MSSA isolates (93.18%), 61/66 MRSA (92.42%), and 37/44 CNS species (84.09%) were correctly identified. However; 130/132 MSSA (98.48%), 64/66 MRSA (96.96%), and 44/44 CNS (100%) were correctly identified by MBT with score ≥2. 00. The principal component analysis (PCA) dendrogram generated by MBT illustrated that the tested isolates were classified into two groups of Staphylococcus species at the distance level of 600. S. aureus isolates were found to be closely related with higher peak intensities in the mass of 3,993 Da, 4,121 Da and 5,845 Da were detected in MRSA, whereas, that were lost in MSSA. Conclusion: This study verified that MBT is an alternative powerful tool for precise identification and discrimination of Staphylococcus species.