Subclinical mastitis in pastoralist dairy camel herds in Isiolo, Kenya: Prevalence, risk factors, and antimicrobial susceptibility

Molecular epidemiology and antibiotic resistance profiling of Staphylococcus aureus isolates from camel mastitis

Mastitis is considered one of milk-producing animals' most widespread infectious diseases. The present study evaluated the prevalence of antibiotic-resistant isolates of Staphylococcus aureus (S. aureus) including methicillin-resistant S. aureus (MRSA), β-lactam-resistant S. aureus (BRSA), aminoglycoside-resistant S. aureus (ARSA), and tetracycline-resistant S. aureus (TRSA) from the udder of dromedary camels along with the associated risk factors and the antibiogram of resistant isolates. Phylogenetic analysis of antibiotic-resistant genes with NCBI sequences was performed to check their homology. A total of 384 milk samples were collected and subjected to standard microbiological procedures to isolate S. aureus. The results revealed that 177 milk samples were found positive for subclinical mastitis (SCM) out of which 101 milk samples were found positive for S. aureus. The molecular assay found the prevalence of MRSA, BRSA, ARSA, and TRSA as 48.51 %, 46.53 %, 42.57 %, and 39.60 % by targeting the mecA, blaZ, accA-aphD, and tetK genes respectively. The study isolates significant similarities to each other and to previously reported sequences from other countries that were found by in-silico analysis, indicating the possibility of pathogen transboundary transmission. This study also revealed potential risk factors that aid in the spread of mastitis in camels. Among various risk factors, the most significant were farm hygiene, physiological status of animals, type of mastitis, teat injury, use of teat dips, and milk leakage (p < 0.05). The antibiogram of antibiotic-resistant isolates of S. aureus revealed that the highest resistance was observed against penicillin followed by amoxicillin and oxytetracycline while levofloxacin was the most sensitive drug. This study highlights the high prevalence of antimicrobial-resistant S. aureus in camel mastitis. Identified risk factors provide valuable insights into management practices that contribute to disease occurrence, aiding in the development of targeted control strategies. Additionally, antimicrobial susceptibility findings offer guidance for optimizing treatment protocols to effectively manage S. aureus-induced mastitis in camels and mitigate the spread of antimicrobial resistance.

Camel pastoralists' perceptions of udder health: results from a qualitative interview study in Northern Kenya

BACKGROUND

In the Horn of Africa, pastoralists depend on livestock for food security. Camels play a pivotal role, providing both milk and meat to these communities. Camel milk production is hampered by multiple factors, one of the main issues being diseases, in particular udder health issues such as mastitis; inflammation of the udder. This study aimed to enhance understanding of camel keeping pastoralists' perceptions of mastitis and attitudes toward its control in in camels. The study was carried out in Isiolo County in Kenya. Data collection involved focus group discussion (FGDs) with camel owners, herders and actors involved in the camel milk trade. Participants predominantly belonged to the Borana, Somali and Sakuye communities. The data pertaining to perceptions of udder health problems and preventive measures was thematically analysed, using an inductive approach.

RESULTS

Four themes were identified regarding pastoralists perceptions of udder health; (i) Importance of udder health; (ii) Economy; (iii) Herders' responsibilities and (vi) Udder health strategies. The results showed that camel pastoralists were skilled at detecting clinical mastitis and had developed strategies to maintain good udder health, such as adhering to a milking order, culling camels with faulty udders and applying treatment. The use of traditional knowledge in parallel with modern medical knowledge resulted in a multitude of treatment strategies without any standardised treatment routines. Awareness of subclinical mastitis, that is mastitis without any clinical signs, was very low and its detrimental effects of mastitis on milk production were poorly understood. Participants were largely positive to interventions that were sustainable, feasible, effective and accessible, such as using California Mastitis Test (CMT) and hand disinfectant.

CONCLUSIONS

Strategic milk hygiene work including selected interventions accompanied by targeted educational efforts and driven by economic incentives, could form the basis for future preventative work. This will need to be evaluated in the local context.

Prevalence and risk factors related to the mastitis in camels (Oued Souf, Algeria)

A cross-sectional study in Oued Souf, Algeria, from November 2023 to April 2024, investigated the prevalence and risk factors of mastitis in 300 she-camels, including 180 lactating camels. The overall mastitis prevalence was 31.10%, with 3.88% clinical and 27.22% subclinical cases, diagnosed through visual exams and the California Mastitis Test (CMT). Among 670 teats, the right hind quarter had the highest infection rate (15.47%), followed by the left hind (11.97%), right front (9.58%), and left front (8.38%) quarters. The highest mastitis prevalence (5.41%) was observed during early lactation. Bacteria isolated included Staphylococcus spp., Streptococcus spp., and E. coli, with staphylococci common in both clinical and subclinical cases. Antibiotic susceptibility tests revealed significant multi-drug resistance, particularly against oxacillin (19.5%) and oxytetracycline. Penicillin was the most effective treatment, with high susceptibility, while streptomycin and oxacillin were secondary options.The study also highlighted poor hygiene practices among camel owners: 93.33% did not wash udders or teats before milking, 90% did not wash hands, and none used disinfectants. Risk factors for mastitis included parity, lactation stage, age, and tick infestation. Poor hygiene practices were significantly associated with an increase in mastitis prevalence (P < 0.05). The study concludes that improved hygiene and management practices are essential to reduce mastitis in camels.

Transcriptomics-Based Study of Immune Genes Associated with Subclinical Mastitis in Bactrian Camels

The significant increase in demand for camel milk has led to a rapid increase in the number of Bactrian camels. However, the widespread occurrence of mastitis significantly impacts the development of the Bactrian camel milk industry and poses a public health risk. Despite this, there is a lack of research on the transcriptional response, immune response pathways, and changes in core genes of Bactrian camels with subclinical mastitis. This study aimed to reveal the changes in immune-related response pathways and gene transcription levels in Bactrian camels with subclinical mastitis by analyzing the blood transcriptional response after the occurrence of subclinical mastitis in natural conditions. This study focused on 7-year-old Bactrian camels and collected 2 mL of blood from the camels that tested positive with a 4-peak California Mastitis Test (CMT) and those that tested negative with a 3-peak CMT. RNA sequencing (RNA-Seq) technology was used to analyze gene expression in the blood samples. Gene expression was verified using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Overall, 1722 differentially expressed genes were sequenced in the blood samples of CMT-positive and CMT-negative Bactrian camels, including 1061 upregulated and 661 downregulated genes. After conducting gene ontology functional enrichment, 453 differentially expressed genes were identified. We also discovered pathways such as immune response, the G-protein-coupled receptor signaling pathway, and internal signal transmission. Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment detected 668 differentially expressed genes annotated onto 309 metabolic pathways, with significantly enriched immune pathways including cytokine-cytokine receptor interaction, complex and coalescence cascades, natural killer cell-mediated cytotoxicity, and T helper type 17 cell differentiation, among others. Through a STRING protein interaction database and cytoscape analysis, it was found that core differentially expressed genes related to immunity included IL10, CCL5, IL1B, OSM, TNFRSF1B, IL7, and CCR3, among others. The RT-qPCR results for six randomly selected core differentially expressed genes showed that the RT-qPCR expression pattern was consistent with the RNA Seq results. The immune-related genes in Bactrian camels affected by subclinical mastitis are primarily concentrated in the immune response and the cytokine-cytokine receptor interaction pathway. Given the importance of these pathways and the connections among related genes, the immune genes within these pathways may play a crucial role in the pathogenesis of subclinical mastitis in Bactrian camels. This study provides a valuable reference for investigating the immune regulatory mechanisms of subclinical mastitis in Bactrian camels.

[Dyspnea in a llama resulting from hyperkeratotic crusts in the area of the nasal openings]

This case report describes the clinical findings, diagnostic procedures, therapeutic options, and the outcome in a llama suffering from idiopathic, necrolytic, neutrophilic hyperkeratosis (INNH) around the nares. The exact pathogenesis and etiology of this disease remains unknown up to now . To date, only a few reports on this condition are available in the scientific literature. Information regarding prevalence of this disease among South American camelids is lacking.The multimodal therapeutic measures (surgically, medically, physically) and the course of the disease are presented. A lasting clinical improvement was achieved, although complete healing did not occur.

Antimicrobial resistance, virulence profiling, and drug repurposing analysis of Staphylococcus aureus from camel mastitis

Camel mastitis especially caused by Staphylococcus aureus (S. aureus), is a major risk to animal health and milk production. The current investigation evaluated the antibiotic susceptibility and virulence factors of S. aureus isolates from subclinical mastitis in camels. A total of 384 milk samples were collected and submitted to isolate S. aureus. The S. aureus isolates exhibiting resistance to Penicillin and Cefoxitin disc on Kirby-Bauer disc diffusion method were considered as β-lactam resistant S. aureus (BRSA) and methicillin-resistant S. aureus (MRSA) which were further confirmed by PCR targeting blaZ and mecA genes, respectively. The results showed that S. aureus was found in 57.06% of subclinical (SCM) positive camel milk samples. A high molecular prevalence of BRSA and MRSA were found to be 48.51% and 46.53% respectively depicting that treating these infections is challenging due to their high resistance levels. The phylogenetic analysis revealed a significant resemblance of the study isolates with each other and with already reported sequences from different countries which shows the potential for the spread of pathogen. Virulence profiling of antibiotic resistance strains showed the presence of virulence markers (nuc and coag genes), intercellular adhesion genes (icaA, icaD), Panton-Valentine leukocidin (pvl) gene, and enterotoxin-producing genes including sea, seb, sec, and sed. In-vitro antibiotic susceptibility testing revealed that the most resistant antibiotic group was penicillin followed by aminoglycosides and cephalosporins. Drug repurposing analysis of different non-antibiotics for combination therapies with resistant antibiotics was done to combat the S. aureus isolates harboring the mecA and blaZ genes. The results revealed the synergistic effect of amoxicillin, sulfamethoxazole, gentamicin, and doxycycline with ketoprofen, amikacin with flunixin meglumine, and gentamicin with N-acetylcysteine (NAC) against study isolates. The current investigation provides the status of antibiotic-resistant strains and virulence factors of S. aureus in the udder of dromedary camels. The combinational therapy of resistant antibiotics with non-antibiotics provides a potential therapeutic option for the treatment of resistant strains.

Determination of prevalence of subclinical mastitis, characterization of intra-mammary infection-causing bacteria, and antibiotic susceptibility in dairy camels in Jigjiga City, Somali region, Ethiopia

Background

Subclinical mastitis in camels, an inflammation of the udder without visible signs, can reduce milk quality and raise bacteria levels. Regular monitoring of camel milk is crucial for consumer safety.

Methods

A cross sectional study was conducted in Jigjiga city, Ethiopia to investigate the prevalence and characteristics of subclinical mastitis in she-camels. The study included 244 lactating she-camels from three privately-owned camel dairy farms, and a questionnaire survey was conducted with 60 camel owners.

Results

The overall prevalence of subclinical mastitis in she-camels was 10.6% (26/244), with no significant difference among the studied dairy farms. Risk factors that influenced the result of California Mastitis Test (CMT) included age and udder and leg hygiene. The study revealed that S. aureus was the most prevalent bacterium among the isolated bacteria, with a prevalence rate of 34.5%. This was followed by S. agalactiae, S. dysgalactiae, and Pasteurella multocida, with prevalence rates of 29.8, 19.4, and 16.2%, respectively. Among the isolated bacteria, 84.5% were sensitive to Erythromycin, 60% to Streptomycin, 44.7% to Oxytetracycline, and 36.7% to Tetracycline. Interviews with camel owners revealed that 66.7% used mixed herd grazing methods and reported feed shortage. Treatment practices for sick camels included modern veterinary drugs, traditional medicines, or a combination of both. The owners of camel dairy farms did not maintain proper hygiene practices during milking, such as not using soap when washing hands.

Conclusion

Addressing camel mastitis necessitates access to alternative drugs, comprehensive herder training, and enhanced management practices.

Co-created community contracts support biosecurity changes in a region where African swine fever is endemic – Part II: Implementation of biosecurity measures

Smallholder subsistence pig production is common in Uganda and African swine fever (ASF) is endemic in the country, with its spread driven by human activities along the smallholder value chain. Previous research in the study area has revealed that many stakeholders are aware of how ASF is spread, its prevention and control, and have a generally positive attitude towards biosecurity. Despite this, even basic biosecurity is largely lacking. Costs, as well as a lack of adaptation to the local context, culture and traditions have been identified as factors hindering biosecurity implementation. Community engagement and local ownership of disease problems are increasingly recognised as important for improving disease prevention and control. The objective of this study was to investigate the capacity of participatory action at community level with broad inclusion of stakeholders to improve biosecurity in the smallholder pig value chain. Specific attention was paid to participants' perceptions and experiences of implementing the biosecurity measures included in their co-created community contracts. The study was conducted in Northern Uganda in villages purposively selected on the basis of previous occurrences of ASF. In each village, farmers and traders were also purposively selected. At a first meeting, basic information about ASF was shared and participants presented with a list of biosecurity measures adapted for farmers and traders respectively. Participants discussed each measure in farmer and trader subgroups, decided on the measures to implement for one year, and signed a community contract to this effect. The following year, interviews were again undertaken and implementation support given. Interview data were coded and thematically analysed. Each subgroup chose a minimum of three and a maximum of nine measures, with wide variations between villages in their selection of measures. At the follow-ups, none of the subgroups had fully implemented what had been agreed in their contract, but all had changed some of their biosecurity routines. Some frequently recommended biosecurity measures, such as not borrowing breeding boars, were not considered feasible. Relatively simple and cheap biosecurity measures were rejected for reasons of cost, highlighting the participants' general level of poverty and the relevance of poverty as a specific factor governing disease control results. The participatory methodology allowing for discussions, co-creation and the option to refuse measures seemed to facilitate the implementation of measures that had initially been thought to be controversial. The broad community approach was deemed to be positive for strengthening community identity, cooperation and implementation.

Immunomodulatory Effects of Bacterial Toll-like Receptor Ligands on the Phenotype and Function of Milk Immune Cells in Dromedary Camel

(1) Toll-like receptors (TLR) are a family of pattern recognition receptors that sense distinct molecular patterns of microbial origin. Although the immune cell composition of camel milk has been recently described, host-pathogen interaction studies in the camel mammary gland are still scarce. The present study aimed to use a whole milk stimulation assay for investigating the modulatory effect of selected Toll-like receptor (TLR) ligands on the phenotype and function of milk immune cells. (2) Methods-camel milk samples (n = 7) were stimulated in vitro with the TLR4 ligand LPS or the TLR2/1 ligand Pam3CSK4, and separated milk cells were evaluated for stimulation-induced shape change, the expression of cell surface markers, phagocytosis, apoptosis, ROS production, and NETosis. Stimulation with PMA was used as a control stimulation. (3) Results-all stimulants induced shape change in milk cells, change in the expression of several cell markers, and increased cell apoptosis and NETosis. In addition, stimulation with Pam3CSK4 and PMA was associated with enhanced ROS production, while only PMA stimulation resulted in enhanced bacterial phagocytosis by milk immune cells. (4) Conclusions-our data indicates selective modulating effects of the TLR ligands LPS and Pam3CSK4 on camel milk phagocytes. These results may have implications for the use of synthetic TLR agonists as immunomodulatory adjuvants of the immune response to intra-mammary vaccines against mastitis pathogens.

Draft Genome Sequences of Enterococcus faecium, Enterococcus gallinarum, and Lactococcus lactis Strains Isolated from a Mastitis-Infected Camel in Isiolo County, Kenya

We report the draft genome sequences and annotation of Enterococcus faecium, Enterococcus gallinarum, and Lactococcus lactis isolates that were recovered from a mastitis-infected camel in Isiolo County, Kenya. Collectively, these data provide an invaluable repository for data mining to support the development of a potential multicomponent mastitis subunit vaccine.

Epidemiology and antimicrobial resistance of staphylococci other than Staphylococcus aureus from domestic animals and livestock in Africa: a systematic review

Introduction

Staphylococci other than Staphylococcus aureus (SOSA) in animals are becoming more pathogenic and antibiotic resistant and can potentially disseminate to humans. However, there is little synthesized information regarding SOSA from animals in Africa. This systematic review provides a comprehensive overview of the epidemiology and antimicrobial resistance of SOSA in companion animals (pets) and livestock in Africa.

Method

This systematic review (PROSPERO-CRD42021252303) was conducted according to the PRISMA guidelines, and 75 eligible studies from 13 countries were identified until August 2022. Three electronic databases (Pubmed, Scopus and Web of Science) were employed.

Results

The frequently isolated SOSA were S. epidermidis, S. intermedius, S. pseudintermedius, S. xylosus, S. chromogenes, S. hyicus, M. sciuri, S. hominis, and S. haemolyticus. Thirty (40%) studies performed antibiotic susceptibility testing (AST). Penicillin (58%) and tetracycline (28%) resistance were most common across all SOSA with high rates of resistance to aminoglycosides, fluoroquinolones, and macrolides in some species. Resistance to last-resort antibiotics such as linezolid and fusidic acid were also reported. Limited data on strain typing and molecular resistance mechanisms precluded analysis of the clonal diversity of SOSA on the continent.

Conclusion

The findings of this review indicate that research on livestock-associated SOSA in Africa is lacking in some regions such as Central and Western Africa, furthermore, research on companion animals and more advanced methods for identification and strain typing of SOSA need to be encouraged.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021252303.

Assessment of mastitis in camel using high-throughput sequencing

Camel milk is recognized as a functional food with significant economic value. Mastitis is one of the most common and costly diseases in the dairy industry. Mastitis, which is caused by pathogens such as bacteria, viruses, fungi, and algae, has an impact on the quality and quantity of milk produced as well as animal health and welfare. There is a paucity of data on the etiological factors that cause camel mastitis. This study reports the bacterial and fungal community involved in clinical camel mastitis using Illumina amplicon sequencing. A total of 25 milk samples were analyzed, including 9 samples with mastitis and 16 healthy samples. The bacterial community in healthy samples was significantly more diverse and abundant than in mastitis samples. The fungal population in mastitis samples, on the other hand, was more diverse and abundant. As compared to healthy samples, the genera Staphylococcus, Streptococcus, Schlegelella, unclassified Enterobacteriaceae, Lactococcus, Jeotgalicoccus. and Klebsiella were found to be abundant in mastitic milk. However, the genera Corynebacterium, Enteractinococcus, unclassified Sphingomonadaceae, Atopostipes, Paenibacillus, Pseudomonas, Lactobacillus, Sphingomonas, Pediococcus and Moraxella were reduced. In the fungal community, mastitis caused a significant increase in the relative abundance of the majority of taxa, including Candida, Phanerochaete, Aspergillus, Cladosporium and unclassified Pyronemataceae, while Penicillium and Alternaria showed a decline in relative abundance. In the bacterial and fungal communities, the discriminant analysis showed 19 and 5 differently abundant genera in healthy milk and mastitic milk, respectively. In conclusion, this study showed a microbiome dysbiosis linked to clinical camel mastitis, with opportunistic pathogens outgrowing commensal bacteria that were reduced. These findings are essential in designing an appropriate control program in the camel dairy herd, as well as in preventing and treating camel mastitis.

The prevalence, antimicrobial sensitivity, and factors associated with camel mastitis in Isiolo County, Kenya

Background and Aim

The one-humped camels (Camelus dromedarius) adapt very well to arid and semi-arid (ASALs) environments and continue to thrive and produce milk even during severe droughts when cattle, sheep, and goats experience high mortalities. These attributes make the dromedaries very vital for the survival of pastoralists, especially in the ASALs of Africa. Mastitis is among the most important diseases of camels and can cause significant economic losses, thereby endangering the livelihoods of pastoralists. This study aimed to estimate the prevalence, risk factors, and antimicrobial sensitivity of mastitis-causing pathogens in lactating camels in Isiolo County, Kenya.

Materials and Methods

This was a cross-sectional study conducted in July and August 2021. A questionnaire was administered to the camel keepers to capture data on herd-level factors. Lactating camels were then examined for any visible signs of clinical mastitis and as well as to capture data on other animal-level factors such as age, weight, and body condition score. A composite milk sample was collected aseptically from randomly selected camels in a herd. The samples were initially tested for somatic cell counts (SCC) using Somatos mini^® automatic cell counter. Culture and sensitivity testing was then carried out on any milk sample that had SCC ≥ 200,000 cells/mL. The descriptive analysis was initially used to summarize the continuous and categorical farm and camel factors, while mixed regression models were used to explore the association between/across mastitis and the farm as well as camel-level factors.

Results

A total of 210 lactating camels from 23 herds were selected and sampled in this study. The average age of camel keepers was 48.3 ± 16.3 years and they were involved in rearing camels for a mean of about 14.3 ± 8.6 years. The total number of camels in a herd ranged from 10 to 287, with the mean total herd milk production being 34.5 ± 24.9 L/day. The mean daily milk production per camel was 2.8 ± 1.7 L while the range for days in milk was between 21 and 787 days. The average age of camel first calving and the inter-calving interval was 56.3 ± 9.9 and 27.7 ± 9.9 months, respectively. The median parity of the dam was three and the body condition score was two. About 39.7% (83/210) of the sampled camels had clinical mastitis during the current lactation. The overall prevalence of mastitis (SCC ≥ 200,000 cells/mL) in camels was 17.6%. The main pathogens isolated were Streptococcus and Staphylococcus bacteria. Streptococcus isolates were mainly sensitive to ampicillin and resistant to cefaclor. All 18 Staphylococcus isolates were sensitive to tetracycline, while 12/18 isolates were resistant to ampicillin. The factors that were significantly associated with mastitis were the age of the respondent (p = 0.038), the number of years involved in camel rearing (p = 0.024), presence of clinical mastitis since calving (p = 0.039), body condition score (p = 0.040), and age of the dam at the time of examination (p = 0.072).

Conclusion

Results from this study revealed that mastitis is an important condition among camels in the pastoral communities of Isiolo County, Kenya. Thus, pastoralists should continue to be aware of and trained on mastitis occurrence and its control in the pastoral ecosystem to reduce potential economic losses.

Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry in veterinary medicine: Recent advances (2019-present)

Matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry (MS) has become a valuable laboratory tool for rapid diagnostics, research, and exploration in veterinary medicine. While instrument acquisition costs are high for the technology, cost per sample is very low, the method requires minimal sample preparation, and analysis is easily conducted by end-users requiring minimal training. Matrix-assisted laser desorption ionization-time-of-flight MS has found widespread application for the rapid identification of microorganisms, diagnosis of dermatophytes and parasites, protein/lipid profiling, molecular diagnostics, and the technique demonstrates significant promise for 2D chemical mapping of tissue sections collected postmortem. In this review, an overview of the MALDI-TOF technique will be reported and manuscripts outlining current uses of the technology for veterinary science since 2019 will be summarized. The article concludes by discussing gaps in knowledge and areas of future growth.

Draft Genome Sequence of Streptococcus agalactiae KALRO-LC1 Strain Isolated from a Mastitis-Infected Camel in Laikipia County, Kenya

We report the draft genome sequence of Streptococcus agalactiae KALRO-LC1 strain obtained from a mastitis-infected camel in Laikipia County, Kenya. The 2,201,604-bp draft genome is assembled into 3 contigs with a GC content of 35.87% and is predicted to contain 1,192 protein-coding sequences.

How GBS Got Its Hump: Genomic Analysis of Group B Streptococcus from Camels Identifies Host Restriction as well as Mobile Genetic Elements Shared across Hosts and Pathogens

Group B Streptococcus (GBS) literature largely focuses on humans and neonatal disease, but GBS also affects numerous animals, with significant impacts on health and productivity. Spill-over events occur between humans and animals and may be followed by amplification and evolutionary adaptation in the new niche, including changes in the core or accessory genome content. Here, we describe GBS from one-humped camels (Camelus dromedarius), a relatively poorly studied GBS host of increasing importance for food security in arid regions. Genomic analysis shows that virtually all GBS from camels in East Africa belong to a monophyletic clade, sublineage (SL)609. Capsular types IV and VI, including a new variant of type IV, were over-represented compared to other host species. Two genomic islands with signatures of mobile elements contained most camel-associated genes, including genes for metal and carbohydrate utilisation. Lactose fermentation genes were associated with milk isolates, albeit at lower prevalence in camel than bovine GBS. The presence of a phage with high identity to Streptococcus pneumoniae and Streptococcus suis suggests lateral gene transfer between GBS and bacterial species that have not been described in camels. The evolution of camel GBS appears to combine host restriction with the sharing of accessory genome content across pathogen and host species.

Comparative genomics of dairy-associated Staphylococcus aureus from selected sub-Saharan African regions reveals milk as reservoir for human-and animal-derived strains and identifies a putative animal-related clade with presumptive novel siderophore

Staphylococcus aureus infection is considered to be a neglected tropical disease with huge impact on human and animal health alike. Dairy production in sub-Saharan Africa (SSA) relies heavily on various animals such as cows, goats, and camels, depending on the region. S. aureus causes mastitis and exhibits high prevalence in raw milk. The population structure including genotypic and phenotypic traits of dairy S. aureus in relation to animal and human isolates is, however, unknown for SSA. In this work, 20 S. aureus dairy isolates from East and West Africa were selected for comparative genomics and phenotypic analysis. Comparing their population structure revealed a large diversity of different origins suggesting milk to be a reservoir for human and animal strains alike. Furthermore, a novel putative siderophore was detected in multiple strains in a distinct animal-clade with strains of global origin. This putative siderophore shares a high genetic identity with that from Streptococcus equi suggesting possible horizontal gene transfer. These findings combined with the virulence genes harbored by these dairy-derived strains such as pvl, human evasion factor scn, various enterotoxin, leucocidin and antibiotic resistance genes, stresses the need for an integrative One Health approach to tackle the problem of S. aureus infections in animals and humans in sub-Saharan Africa.

Postbiotic Gamma-Aminobutyric Acid and Camel Milk Intervention as Innovative Trends Against Hyperglycemia and Hyperlipidemia in Streptozotocin-Induced C57BL/6J Diabetic Mice

Diabetes is a serious disease that threatens human health worldwide. The study hypothesis is to investigate the novel trends that may aid in the prevention of diabetic complications. Camel milk was presented as traditional functional food, and Lactobacillus brevis KLDS_1.0727 and KLDS_1.0373 strains were shown to synthesize postbiotic Gamma-aminobutyric acid as a potential food additive, which can therapeutically intervene against hyperglycemia and hyperlipidemia in streptozotocin-induced C₅₇BL/6J mice. During a four-week timeframe, body weight and postprandial blood glucose levels were monitored. Post-euthanasia, blood plasma was obtained to investigate hyperlipidemia, insulin concentrations, liver, and renal functions. The liver, pancreas, kidney, and spleen underwent histopathological examinations. The results demonstrated that KLDS_1.0727 and KLDS_1.0373 (LAC_S1, LAC_S2) and camel milk treatments all had a significant influence on hypoglycemic activity, as evidenced by reduced postprandial blood glucose levels. LAC_S1, LAC_S2, and camel milk therapy significantly reduced blood hypolipidemic, and some liver enzymes such as (alanine aminotransferase and aspartate transaminase) levels. Therefore, we recommend consuming camel milk regularly and expanding its use with fermented foods containing L. brevis, one of the probiotics capable of producing gamma-aminobutyric acid (GABA) as future food additives that can improve human health and reduce the prevalence of several diseases disorders.

Risk factors associated with subclinical mastitis and its effect on physico-mineral features of camel milk

This study was carried out to determine the risk factors implicated in camel subclinical mastitis as well as the physico-mineral features of camel milk, there by examining the effect of this disease on those parameters. Milk samples were obtained from 125 lactating multiparous she-camels (aged 10-12 years) during early lactation from December 2020 to April 2021. The samples were screened for the presence of subclinical mastitis using the somatic cell count (SCC) test. In total, 73 (58.4%) samples showed the presence of subclinical mastitis, whereas the remaining 52 (41.6%) samples showed negative results for subclinical mastitis. Standard methods were used to appreciate the pH and mineral composition of the milk samples, such as Ca, Na, Cl, and K contents. In camels, unhygienic udder condition was identified as the major risk factor for the incidence of subclinical mastitis. Calf mortality and increased herd size were associated with a higher prevalence of subclinical mastitis. Tick infestations were also significantly associated with increased disease risk. Use of antisuckling devices, increase in milk yield, and weakness of body condition were identified as main risk factors and were primarily associated with the disease. However, udder lesions and deformities, milking frequency, and owner visits had no significant influence on the occurrence of subclinical mastitis. The overall mean pH value was 6.54 ± 0.01 and the mean values of Ca, Na, Cl, and K contents were 148.24 ± 2.55, 53.83 ± 1.52, 124.99 ± 1.80, and 240.22 ± 3.80 mg/100 g, respectively. When the level of milk from healthy animals and that from camels with subclinical mastitis (SCC > 2.4 × 10⁵) were compared, it showed that Na and Cl contents were significantly increased (p < 0.05) with the increase in SCC (56.52 vs.50.07 and 128.26 vs.120.40 mg/100 g, respectively). In contrast, there were no notable changes (p > 0.05) in the Ca, K, and pH values. In conclusion, udder hygiene, calf mortality, herd size, tick infestations, use of antisuckling devices, higher milk yield, and body condition were identified as the major risk factors that predispose the camels to subclinical mastitis. Furthermore, an increase in the Na and Cl levels in camel milk was observed along with udder inflammation. Consequently, the elevated Na and Cl levels in milk can be a sign of subclinical mastitis in camels.

Milk Immune Cell Composition in Dromedary Camels With Subclinical Mastitis

Mastitis represents one of the most important infectious diseases in camels with heavy economic losses due to reduced milk quantity and quality. Balanced immune cell composition and function in the mammary gland are essential for effective immune response to mastitis pathogens. The objective of the present study was to characterize the cellular immune response to subclinical mastitis in the mammary gland of dromedary camels. Therefore, immunostaining and flow cytometry were used to compare the cellular composition, leukocyte phenotype, and cell viability in camel milk from healthy she-camels (n = 8) and she-camels with subclinical mastitis (SCM; n = 6). In addition, the ex vivo phagocytic activity of milk phagocytes was compared between healthy and affected animals. The health status of the mammary gland was evaluated based on the California Mastitis Test (CMT) score. SCM (CMT score of ≥3 in the absence of clinical signs of mastitis) was found in six of the 56 sampled quarters (10.7 %) with only one affected quarter per animal. In comparison to milk from healthy camels, milk from SCM animals showed higher somatic cell count (SCC), higher numbers of CD45+ leukocytes with an expanded fraction of CD172a+ myeloid cells. Within the myeloid cell population, there was an increase in the percentage of granulocytes (CD172a⁺CD14^low) with a decreased percentage of macrophages (CD172a⁺CD14^high) in milk from affected animals compared to healthy animals. The decrease in lymphoid cells in SCM milk was mainly due to the decreased fraction of CD4+ helper T cells. Camel SCM was also associated with a stimulated phenotype, increased cell viability, and enhanced phagocytic activity of the milk phagocytes, macrophages and granulocytes. Collectively, the present study identified significant changes in SCC, leukocyte count, phenotype, viability, and function in association with subclinical mastitis in camels. The results of the present study support a better understanding of host-pathogen interaction mechanisms in the camel mammary gland.

Incidence, risk factors and economic impact of clinical mastitis in dromedary camel (Camelus dromedarius)

The study aimed to investigate the incidence, risk factors and economic impact of clinical mastitis in an organized camel herd located at Bikaner, Rajasthan, India. Furthermore, bacterial pathogens were isolated and identified using MALDI-TOF mass spectrometry analysis. The overall annual incidence of clinical mastitis was 25%, with highest incidence in Bikaneri and Mewari breed followed by Kachchhi and Jaisalmeri breeds. Animals with high peak yield appeared at higher risk, though statistical significance could not be established for any risk factor included in the study. Highest incidence was recorded in camels falling in 4th or higher parity group. In 80% cases, only one udder quarter was involved, while in rest 20% cases, two udder quarters were involved. Quarter-wise incidence was maximum in right fore-quarter followed by left fore-quarter, right hind-quarter and left hind-quarter. Important pathogens identified included Staphylococcus aureus, E. coli, Klebsiella pneumoniae, Staphylococcus epidermidis, Streptococcus uberis, Bacillus clausii and Corynebacterium amylocolatum. Other isolates included Staphylococcus hominis, Streptococcus pluranimalium, Aerococcus viridians and Moraxella osloensis. The mean cost of clinical mastitis per animal per month was calculated as Indian Rs. 181.63 (~ US$ 2.45), while the mean cost per animal per annum was Indian Rs. 2179.29 (~ US$ 29.37). The maximum cost incurred in purchase of drugs (43.63%), followed by cost of discarded milk plus milk production loss (18.17%) and cost of veterinary services (17.03%). To our knowledge, this is the first report documenting economic impact of clinical mastitis in camel.

Investigation of extramammary sources of Group B Streptococcus reveals its unusual ecology and epidemiology in camels

Camels are vital to food production in the drylands of the Horn of Africa, with milk as their main contribution to food security. A major constraint to camel milk production is mastitis, inflammation of the mammary gland. The condition negatively impacts milk yield and quality as well as household income. A leading cause of mastitis in dairy camels is Streptococcus agalactiae, or group B Streptococcus (GBS), which is also a commensal and pathogen of humans and cattle. It has been suggested that extramammary reservoirs for this pathogen may contribute to the occurrence of mastitis in camels. We explored the molecular epidemiology of GBS in camels using a cross-sectional study design for sample collection and phenotypic, genomic and phylogenetic analysis of isolates. Among 88 adult camels and 93 calves from six herds in Laikipia County, Kenya, GBS was detected in 20% of 50 milk samples, 25% of 152 nasal swabs, 8% of 90 oral swabs and 3% of 90 rectal swabs, but not in vaginal swabs. Per camel herd, two to four sequence types (ST) were identified using Multi Locus Sequence Typing (MLST). More than half of the isolates belonged to ST617 or its single-locus variant, ST1652, with these STs found across all sample types. Capsular serotype VI was detected in 30 of 58 isolates. In three herds, identical STs were detected in milk and swab samples, suggesting that extramammary sources of GBS may contribute to the maintenance and spread of GBS within camel herds. This needs to be considered when developing prevention and control strategies for GBS mastitis. The high nasal carriage rate, low recto-vaginal carriage rate, and high prevalence of serotype VI for GBS in camels are in stark contrast to the distribution of GBS in humans and in cattle and reveal hitherto unknown ecological and molecular features of this bacterial species.

Camel Mastitis: Prevalence, Risk Factors, and Isolation of Major Bacterial Pathogens in Gomole District of Borena Zone, Southern Ethiopia

As of other dairy animals, dromedary camel could be affected by mastitis, a complex disease occurring worldwide among dairy animals, with heavy economic losses largely due to clinical and subclinical mastitis. Yet, little is known about the occurrence and potential risk factors exposing to lactating camel mastitis in Ethiopia. Consequently, a cross-sectional study was carried out from November 2018 to April 2019 so as to determine the prevalence, associated risk factors, and major bacterial pathogens causing mastitis in traditionally managed lactating camels in Gomole district of Borena Zone. Consequently, 348 lactating camels were examined for clinical and subclinical mastitis, using California Mastitis Test (CMT). The overall prevalence of mastitis was 22.4% (78/348), including clinical 4.3% (15/348) and subclinical 18.1% (63/348) cases, respectively, whereas the quarter level prevalence of mastitis was 16.6% (232/1,392). Of the total 1,392 examined teats, the right hind (RHQ) (4.3%, 60/1392) and left hind quarters (LHQ) (4.3%, 60/1392) were the most frequently infected quarter, whereas the left front quarter (LFQ) (3.9%, 55/1392) was the least infected quarter. Age, body condition score, and lactation stages were significantly associated (p < 0.05) with lactating camel mastitis prevalence among the putative risk factors. Among 312 quarters milk samples subjected to bacteriological examination, 69.9% (218/312) yielded mastitis causing pathogens, both Gram-positive and -negative bacterial isolates, while no growth was observed in 30.1% (94/312) of quarters sampled. Of the bacterial isolates obtained by culturing, Streptococcus spp. excluding Streptococcus agalactiae (S. agalactiae) (26.1%; 57/218) and Coagulase negative Staphylococci (22.9%, 50/218) were the dominant isolates identified, whereas S. agalactiae (3.2%, 7/218) was the least isolates obtained. The prevalence of camel mastitis in the study area was found to be considerably high. Hence, implementation of integrated approaches has great importance in the study setting for the prevention and control of mastitis so as to improve quality of camel milk, minimize economic loss, and prevent significant public health risks.

Molecular Detection, Serotyping, and Antibiotic Resistance of Shiga Toxigenic Escherichia coli Isolated from She-Camels and In-Contact Humans in Egypt

This study aims to determine the prevalence of STEC in she-camels suffering from mastitis in semi-arid regions by using traditional culture methods and then confirming it with Serological and molecular techniques in milk samples, camel feces, as well as human stool samples for human contacts. In addition, an antibiotic susceptibility profile for these isolates was investigation. Mastitic milk samples were taken after California Mastitis Test (CMT) procedure, and fecal samples were taken from she-camels and human stool samples, then cultured using traditional methods to isolate Escherichiacoli. These isolates were initially classified serologically, then an mPCR (Multiplex PCR) was used to determine virulence genes. Finally, both camel and human isolates were tested for antibiotic susceptibility. Out of a total of 180 she-camels, 34 (18.9%) were mastitic (8.3% clinical and 10.6% sub-clinical mastitis), where it was higher in camels bred with other animals. The total presence of E. coli was 21.9, 13.9, and 33.7% in milk, camel feces, and human stool, respectively, whereas the occurrence of STEC from the total E. coli isolates were 36, 16, and 31.4% for milk, camel feces, and stool, respectively. Among the camel isolates, stx₁ was the most frequently detected virulence gene, while hlyA was not detected. The most detected virulence gene in human isolates was stx₂ (45.5%), followed by stx₁. Camel STEC showed resistance to Oxytetracycline only, while human STEC showed multiple drug resistance to Amoxicillin, Gentamycin, and Clindamycin with 81.8, 72.7, and 63.6%, respectively. Breeding camels in semi-arid areas separately from other animals may reduce the risk of infection with some bacteria, including E. coli; in contrast, mixed breeding with other animals contributes a significant risk factor for STEC emergence in camels.

Genomic analysis of group B Streptococcus from milk demonstrates the need for improved biosecurity: a cross-sectional study of pastoralist camels in Kenya

BACKGROUND

Streptococcus agalactiae (Group B Streptococcus, (GBS)) is the leading cause of mastitis (inflammation of the mammary gland) among dairy camels in Sub-Saharan Africa, with negative implications for milk production and quality and animal welfare. Camel milk is often consumed raw and presence of GBS in milk may pose a public health threat. Little is known about the population structure or virulence factors of camel GBS. We investigated the molecular epidemiology of camel GBS and its implications for mastitis control and public health.

RESULTS

Using whole genome sequencing, we analysed 65 camel milk GBS isolates from 19 herds in Isiolo, Kenya. Six sequence types (STs) were identified, mostly belonging to previously described camel-specific STs. One isolate belonged to ST1, a predominantly human-associated lineage, possibly as a result of interspecies transmission. Most (54/65) isolates belonged to ST616, indicative of contagious transmission. Phylogenetic analysis of GBS core genomes showed similar levels of heterogeneity within- and between herds, suggesting ongoing between-herd transmission. The lactose operon, a marker of GBS adaptation to the mammary niche, was found in 75 % of the isolates, and tetracycline resistance gene tet(M) in all but two isolates. Only the ST1 isolate harboured virulence genes scpB and lmb, which are associated with human host adaptation.

CONCLUSIONS

GBS in milk from Kenyan camel herds largely belongs to ST616 and shows signatures of adaptation to the udder. The finding of similar levels of within- and between herd heterogeneity of GBS in camel herds, as well as potential human-camel transmission highlights the need for improved internal as well as external biosecurity to curb disease transmission and increase milk production.