Bovine mastitis: Risk factors and isolation of Gram-negative bacteria in Western Algeria

Bovine mastitis particularly the subclinical form, poses a significant global challenge to the dairy industry affecting milk yield and quality with high economic losses. A cross-sectional study was conducted between February and May 2023 to determine the prevalence and determinants of subclinical mastitis (SCM) in dairy cows under smallholder dairy farms in Dar es Salaam. A structured questionnaire was administered to 192 households, and 381 cows screened for subclinical mastitis by California Mastitis Test (CMT). Five percent of 1,524 examined teats were blind, the prevalence of SCM was 70.8% at farm, 75.6% at herd and 66.8% at quarter levels. The SCM occurrence based on number of affected quarters per animal was statistically significance (P=0.0001) with 54.17% and 29.86% of cows had four and three-quarters respectively. Friesian and crossbreeds’ cows were more likely to be SCM positive compared (p = 0.0031) to Ayrshire breed. The late-lactation stage and mid-lactation stage were found to be risk factors for SCM. Moreover, farmers' awareness about mastitis, culling mastitic cow, and use of teat lubricants during milking were found to be protective factors. This study found a high prevalence of SCM which might cause economic losses and health public health implication to milk consumers. Thus, suggests on that raising farmers’ awareness about mastitis, use of teat lubricants, and monitoring older and middle-aged cows are the major factors that should be put into consideration for targeted interventions on reducing SCM in dairy cows in small-scale dairy farms in Dar es Salaam.

Summary Mastitis continues to be one of the economically most important diseases in dairy farming. Forty-six licensed dairy farms in the central region of Fars province were randomly selected in order to participate in a seasonal prevalence study. A cross-sectional study was designed to determine prevalence at cow and quarter level based on clinical signs for clinical mastitis and indirect tests for subclinical mastitis. 6180 quarters from 1545 dairy cows were tested by clinical examination and California mastitis test (CMT). Milk samples from both clinical and subclinical quarters were collected for bacteriological culture. 4714 (76.28%) quarters were healthy, 1335 (21.6%) quarters were positive by results of CMT (as indicated to subclinical mastitis), 44 (0.71%) quarters showed clinical mastitis signs and 87 (1.41%) quarters were blind. The clinical and subclinical mastitis prevalence at cow level was 2.2 and 42.5%, respectively. There was no significant difference in the prevalence of mastitis between different quarters, seasons and cities. The most prevalent isolated bacteria were coagulase positive staphylococci followed by Streptococci, Escherichia coli and coagulase negative staphylococci. Insufficient control measures such as pre and post milking hygiene and dry cow therapy in dairy farms and limited knowledge of farmers on the importance, identification and control of mastitis, especially subclinical forms, can be the main causes for the high prevalence of mastitis in Fars province.

Risk Factors for Peripartum Mastitis in Pasture-Grazed Dairy Heifers

Mastitis is considered to be the most devastating condition for the dairy farms of low and medium income countries due to its alarming impact on production and worldwide has been recognized as one of the most economically significant infectious diseases affecting the welfare of dairy animal. Chittagong is one of the dairy intensive regions of Bangladesh but comprehensive epidemiological studies addressing prevalence of and risk factors for subclinical mastitis (SCM) are scant. Therefore we aimed to approximate the prevalence of SCM in dairy cows along with the associated risk factors in dairy cows of Chittagong Metropolitan Area (CMA), Bangladesh. We included 114 cross breed (Holstein × Local) lactating cows, raised at 6 dairy farms in CMA between February to November, 2015 for this study. California Mastitis Test (CMT) was used to assess SCM at animal level. The overall prevalence of mastitis was 34.2% among the tested cows. Floor type, source of replacement cows, history of previous reproductive disorder, stage of lactation and cleanliness of floor was found significantly associated with SCM in univariate analysis. In random effect multiple logistic regression model, cemented floor was found to increase the odds of SCM by 5.03 times than that of brick floor. Similarly, cows with history of reproductive disorders had more risk of having SCM than that of cows without a history of reproductive disorders. Since the SCM is prevalent in the study area, the intervention strategy should focus on causal agent, improved management, frequent monitoring of SCM in milking cows with CMT and use of teat disinfectants; with minimal or no treatment with antimicrobial agents.

Bovine mastitis continues to be a leading cause of heavy economic losses in the dairy industry and a public health hazard globally. This cross-sectional study investigated the prevalence, etiologies of clinical and subclinical mastitis, and associated predisposing factors in Embu and Kajiado counties in Kenya. A semistructured questionnaire was administered to 154 smallholder dairy farmers to collect data on management practices, animal factors, and disease history. A total of 395 dairy cows were initially screened for subclinical mastitis using the California mastitis test (CMT), and milk samples were aseptically collected. Both CMT positive and CMT negative samples were analyzed using conventional bacteriological isolation and identification procedures. In the present study, the overall prevalence of mastitis based on CMT and clinical examination was 80% (316/395), out of which 6.8% (27/395) was clinical mastitis, while 73.1% (289/395) was subclinical mastitis. Based on culture, the overall prevalence of clinical and subclinical mastitis was 51.6% (815/1580), 74.4% (294/395), and 76.6% (118/154) at the quarter, cow, and farm level, respectively. From the 1574 milk samples analyzed by cultured, 1016 bacteria were yielded. The predominant bacteria were coagulase-negative Staphylococcus (CNS), 42.8% (435/1016), and in decreasing order, Streptococcus species, 22.2% (226/1016), Staphylococcus aureus, 15.7% (160/1016), and Pseudomonas aeruginosa, 5.1% (52/1016), and the least was Enterobacter species, 0.7% (7/1016), while 23.7% of the sample yielded no bacterial growth. Risk factor analysis revealed that milking mastitic cows last (p=0.002), using a clean udder drying towel for each cow (p=0.033) and previous history of mastitis (p=0.046) were significantly associated with presence of mastitis. The current study has shown a relatively high prevalence of subclinical mastitis with CNS as predominant bacteria. Therefore, control measures are urgently warranted. Management factors such as milking mastitic cows last, using a clean towel for udder drying for each cow, and culling mastitic cows should be considered and included in the Kenyan mastitis control programs.

A study was conducted on 360 dairy cows (1440 quarters) to determine the prevalence of mastitis by California Mastitis Test (CMT) and Staphylococci in settled Fulani herds in Kaduna State, Nigeria. The prevalence of mastitis at cow level was 26.9% (97/360) and out of which 23.9% (86/360) and 3.1% (11/360) were subclinical mastitis and clinical mastitis respectively. The prevalence at quarter level was 21.7% (312/1440), and out of which 6.5% (28/1440) was clinical mastitis and 19.7% (284/1440) was subclinical mastitis respectively. Statistical analysis showed that there was significant difference in the occurrence of mastitis among the age group (P<0.05). The prevalence at quarter level was 25.2% (157/624) in adult cows, 20.2% (97/480) in young adults and 17.3% (58/336) in old cows. Similar pattern of occurrence was recorded for both clinical and subclinical mastitis as the adults had 21.8% and 3.4 %, young adults had 19.8% and 0.4% and old cows had 15.8% and 1.5% respectively. The CMT scores showed that 55 (64.0%) of the milk samples had a score of 1+, 26 (30.2%) had a score of 2+, 3 (3.5) had a score of 3+ while only 2 (2.3%) had a score of “Trace”. Sixty seven (69.1%) of the samples that were positive for CMT were found to be culture positive and out of which 56.7% (55/97) were S. aureus and 12.3% (12/97) were coagulase-negative staphylococci (CONS). The high prevalence of both clinical and subclinical mastitis coupled with the isolation of S. aureus and CONS are of great public health concern and requires strict control and preventive measures. The study recommends standards hygienic measures during milking and culling of infected cows to stop the spread of pathogens to uninfected cows.Keywords: mastitis, prevalence, Cow milk, Staphylococcus spp, settled Fulani herds, Kaduna State

A cross-sectional study was carried out on 200 randomly selected farms in each of the Iringa and Tanga regions of Tanzania to estimate the prevalence and risk factors for subclinical...

Background/Objectives: Subclinical mastitis is a common and economically significant infection in dairy cows. This study aimed to assess the prevalence and antimicrobial susceptibility of bacteria causing subclinical mastitis in dairy cows in the Upper Cheliff Region, Northern Algeria, and to investigate the effects of subclinical mastitis on milk production and reproductive performance. Methods: A total of 263 cows from 23 farms were screened for subclinical mastitis using the California Mastitis Test (CMT) and sampled for isolation and identification of bacteria by MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was performed using the Vitek 2 system and disk diffusion method. Methicillin resistance in staphylococci and mammaliicocci was confirmed by mecA/mecC detection. Results: The results revealed a prevalence of subclinical mastitis of 58.9% at the cow-level and 31.1% at the quarter-level. The most prevalent microorganisms identified were Enterococcus faecium (E. faecium) (24.4%) and Enterococcus faecalis (E. faecalis) (20.5%), followed by non-aureus staphylococci (NAS) (16.9%), Escherichia coli (E. coli) (7.9%) and Staphylococcus aureus (S. aureus) (7.08%). Risk factors significantly associated with the prevalence of subclinical mastitis included parity, lower milk production (<12 L/day), poor animal cleanliness and a history of previous mastitis. Reproductive performance was significantly impaired in cows with subclinical mastitis, cows with longer calving-to-first-service intervals (130 vs. 102.7 days; p < 0.0001), more services per conception (2.5 vs. 1.9; p < 0.0001) and a lower pregnancy rate at first service (24.5% vs. 48.1%; p < 0.0001). Furthermore, 43.2% of cows with subclinical mastitis required three or more inseminations to achieve pregnancy. AST showed a low resistance rate for the antimicrobial agents most commonly used in human and veterinary medicine. Coagulase-negative staphylococci (CoNS) showed remarkable rates of methicillin-resistance (22.2%), as well as resistance towards fosfomycin (37.8%) and tetracycline (31.1%). A substantial proportion of E. coli isolates exhibited resistance to piperacillin (40%) and ciprofloxacin (15%). All S. aureus isolates were classified as MSSA without detection of mecA and mecC genes. Conclusions: The results of this study demonstrated that subclinical mastitis is prevalent in the Upper Cheliff region and is associated with reduced milk production and reproductive performance. The detection of pathogenic and resistant microorganisms in milk is alarming and requires effective management strategies to control subclinical mastitis and improve dairy farm productivity.

Mastitis is one of the most economically important diseases in dairy farms worldwide. It is particularly important in Ethiopia where no routine prevention and control practices are in place. This cross-sectional study was carried out between October 2017 and June 2018 to estimate the prevalence of mastitis, identify the associated risk factors and isolate bacterial causes in dairy farms located in southern Ethiopia using standard microbiological methods and questionnaire survey. A total of 686 lactating cows which were found in 122 selected dairy farms were investigated by physical examination and California mastitis test. The overall cow-level prevalence of mastitis was 54.2% (95% CI: 50.5 – 57.9%). Based on the study site, the prevalence was 55.7% in Hawassa, 54.3% in Arsi Negele, 52.6% each in Wondo Genet and Wolayta Soddo towns with no significant (p &gt; 0.05) difference among the sites. The majority of mastitis cases were subclinical (48.1%) while the clinical mastitis was only 6.1%. Of the 122 herds tested, 109 (89.3%; 95% CI: 82.1 – 93.9%) had at least a cow positive for mastitis. The study showed that high parity number (OR = 1.6; p = 0.015), flat (OR = 4.5; p &lt;0.001) and round (OR = 2; p &lt;0.001) teat end shape, history of mastitis in preceding lactation (OR = 3.3; p &lt;0.001), and slightly (OR = 3.5; p &lt; 0.001), moderately (OR = 4.9; p &lt; 0.001), and very dirty (OR = 9.2; p &lt; 0.001) udder and legs were the major risk factors which are significantly associated with higher prevalence of mastitis. Based on the available media and reagents, the major bacteria isolated from subclinical mastitic milk samples were Staphylococcus spp. (57.3%), Streptococcus spp. (18.6%), E. coli (17.3%) and Bacillus spp. (7.5%) in order of their abundance. The present study revealed a high prevalence of mastitis, particularly the subclinical one, and the associated risk factors. Enhancing the awareness of dairy farmers, regular screening of cows for subclinical mastitis, proper treatment of the clinical cases, improving the hygienic condition of the cows, and culling of chronically infected cows are critically important to prevent and control bovine mastitis.&#x0D; Keywords: Mastitis, Prevalence, Risk factors, Southern Ethiopia

The study was conducted from November 2015 to April 2016 to estimate the prevalence of clinical and subclinical mastitis in lactating cows, to assess the associated risk factors, and to isolate the major bacterial pathogens in dairy farms in selected district of Eastern Harrarghe Zone, Eastern Ethiopia. The study was carried out in 384 dairy cows based on data collection, farm visit, animal examination, California mastitis test (CMT), and isolation bacterial pathogens using standard techniques. In the present study the overall mastitis at cow level was 247 (64.3%). The prevalence of clinical and subclinical mastitis and quarter level prevalence for clinical and subclinical mastitis were 12.5% and 51.8% at cow level and 10.7% and 46.4% at quarter level, respectively. Clinically, 101 (6.6%) quarters which belong to 75 (19.5%) animals were found to be with blind teat. In the present study prevalence of mastitis was significantly associated with parity and age (p < 0.05). Bacteriological examination of milk sample revealed 187 isolates where coagulase negative Staphylococcus species (CNS) (34.2%) was the predominant species while Streptococcus faecalis (2.1%) was identified as the least bacteria. The present study concluded that prevalence of mastitis particularly the subclinical mastitis was major problem of dairy cows in the area and hence warrants serious attention.

Subclinical mastitis (SCM) is a major health problem of dairy animals in India and across the globe. An identification of potential risk factors of SCM can help for efficient udder health management in dairy animals. In this study, apparently healthy cows (HF crossbred: n = 45; Deoni: n = 43) were screened for SCM during different seasons through milk somatic cell count (SCC: reference test using 200 × 103 cells/ml as cut off value), California mastitis test (CMT) and differential electrical conductivity (DEC) test at an organized research farm. SCM positive milk samples (n = 34) were inoculated in selective media for Coliform sp., Streptococcus sp. and Staphylococcus sp. and DNA was isolated (n = 10) for species confirmation by 16s rRNA method. Both bivariate and multivariate models were used for risk assessment. We found the cumulative prevalence of 31 and 65% SCM in Deoni and crossbred cows, respectively. Screening of 328 crossbred cows under field conditions revealed point prevalence of 55% SCM. Multivariate analysis revealed stage of lactation (SOL), milk yield in previous lactation and test day milk yield in Deoni cows, as well as parity and mastitis treatment history in current lactation in HF crossbred cows as risk factors. SOL was a significant factor under field conditions. Receiver operated characteristic curve analysis revealed better accuracy of CMT than DEC. We found more mixed infections due to Staphylococcus sp. and Streptococcus sp. in culture, while 16s rRNA based molecular method revealed lesser-known pathogens associated with SCM. It is concluded that SCM prevalence rate is higher in crossbred than indigenous cows and these breeds have different risk factors for SCM. HF crossbred cows had similar SCM prevalence rate under different farming conditions, where CMT can be used for SCM diagnosis with excellent accuracy. The 16s rRNA method is useful for specific identification of lesser known and emerging mastitis pathogens.

One hundred twelve high yielding (>20kg/animal/day) crossbred cows having a history of clinical and sub-clinical mastitis in previous lactation were selected from 24 farms in Mohali and Ropar districts of Punjab. Thirty-three cows from eight farms served as control, and remaining were fed daily 10 g supplement per animal, containing chelated copper, zinc, chromium, vitamins E and A along with iodine for four weeks before calving. After calving, milk samples were collected on 10th and 40th day for analysis of somatic cell counts (SCC), sodium content, pH and electrical conductivity. The farm owners were provided with Mastect strips for routine check up for sub-clinical mastitis. Out of 79 experimental cows, only 17 showed positive signs for sub-clinical and clinical mastitis with Mastect strip test, which was confirmed by SCC in milk (2.97 x105 cells/ml milk). However, out of thirty three, twenty nine animals in control group were affected by sub-clinical mastitis as indicated by SCC (3.19 x105 cells/ml milk), which was later aggravated to clinical mastitis. The pH, electrical conductivity, SCC and sodium content in milk were higher (P<0.01) in animals affected by sub-clinical mastitis than the normal animals. In experimental group, SCC in 62 animals was within the normal range (0.75-2.50 x105 cells/ml milk) and no signs of sub-clinical or clinical mastitis were observed. The inference could be drawn that feeding a vitamins and chelated minerals based strategic feed supplement for four weeks prior to calving can reduce the incidence of sub-clinical and clinical mastitis significantly in dairy cows under farm conditions.

This pioneering study explored the therapeutic potential of human Wharton's jelly derived mesenchymal stem cells (hWJ-MSCs) as a novel regenerative treatment for subclinical (SCM) and clinical mastitis (CM) in dairy cows, a condition that poses significant economic and health challenges. hWJ-MSCs were isolated and characterized, and then administered intramammarily in two doses, seven days apart, to twelve cows that were divided into control, SCM, and CM groups. Comprehensive evaluations, including somatic cell count (SCC), proinflammatory cytokine profiles, milk yield, and bacteriological analyses, were conducted before treatment and on days 14 and 21 after treatment. The results revealed a remarkable reduction in SCC by 29.62 % in the SCM group and 70.46 % in the CM group, accompanied by a pronounced suppression of proinflammatory cytokines such as TNF-α and IL-1β. hWJ-MSCs therapy also led to substantial improvements in milk yield, with increases of 39.38 % and 14.32 % in the SCM and CM groups, respectively. Moreover, bacteriological analyses revealed the complete eradication of pathogenic agents, including Staphylococcus aureus and Escherichia coli, in nearly all treated patients. These findings underscore the potential of hWJ-MSCs to redefine mastitis management by offering a safe, effective, and antibiotic-free alternative, addressing both agricultural and global health concerns related to antimicrobial resistance. The significant therapeutic effects observed in this study suggest that hWJ-MSCs could be used to treat mastitis, paving the way for advanced stem cell-based interventions in veterinary medicine. Further large-scale studies are warranted to validate these promising results and establish hWJ-MSCs as a cornerstone of sustainable livestock health management.

Mastitis is the most prevalent disease of dairy animals, imparting huge economic losses to the dairy industry. There is always a dire need to monitor the prevalence of mastitis, its bacteriology, and evaluation of antimicrobial susceptibilities for mastitis control and prevention. Therefore, the objectives of this study were to investigate: (i) the prevalence of mastitis in cattle and buffaloes; (ii) identification of bacteria associated with mastitis; (iii) antimicrobial susceptibility of bacterial isolates. Milk samples (n = 1,566) from cattle (n = 1,096) and buffaloes (n = 470) were processed for detection of mastitis using the California mastitis test in the year 2018–19. A total of 633 mastitic milk samples were further processed for bacteriology and antimicrobial susceptibility testing by the disc diffusion method. Overall, the prevalence of clinical and subclinical mastitis was 17 and 57% in both species. Clinical mastitis was higher in cattle (20%) compared to buffaloes (11%), whereas subclinical was higher in buffaloes (66%) than cattle (53%). Besides, month-wise prevalence was higher in hot and humid months in both species. Staphylococci spp. (34%) were the most predominant bacterial isolates from mastitic milk, followed by Escherichia coli (19.4%), Streptococci spp. (9%), and Klebsiella spp. (8%). Most of the bacteria were susceptible to gentamicin (92%) and enrofloxacin (88%), when a panel of 16 different antimicrobials was tested. Nevertheless, most of the isolates were resistant to sulphamethoxazole (99%), lincomycin (98%), oxytetracycline (89%), ampicillin (86%), and doxycycline (85%). This study concludes a high prevalence of mastitis caused by Staphylococcal spp. in cattle and buffaloes belonging to the northwest of Pakistan, and gentamicin and enrofloxacin might be appropriate antimicrobial agents in the treatment of bovine mastitis.

Purposive cross-sectional types of study was carried out to determine the prevalence of mastitis in lactating dairy cows, and assess the associated risk factors in Alage agricultural technical vocational and training (ATVET) college dairy farm. The study was carried out in 138 dairy cows based on data collection, regular farm visit, clinical examination, and California mastitis test (CMT). In the present study, in general the prevalence of mastitis was 94 (68.11%) and (46.37%) at cow and quarter level respectively. The prevalence of clinical and subclinical mastitis was (16.67% and 51.44%), subclinical (5.25% and 41.12%) at cow and quarter level respectively. In this study prevalence of mastitis was considerably correlated with breed, parity and production status (milk yield per lactation period) (A°ÂÂ‘<0.05). However, stage of lactation and age of the cow was not statistically significant in this study. Taking into consideration the different huge losses that could be incurred by both clinical and subclinical mastitis, regular checkup for the exposure of subclinical mastitis and appropriate treatment of the clinical cases should be practiced and also attention should be paid for further detailed investigation and control measure of cases.