Subclinical Mastitis in a European Multicenter Cohort: Prevalence, Impact on Human Milk (HM) Composition, and Association with Infant HM Intake and Growth

Reduction of tumor necrosis factor (TNF) in milk of women receiving anti-TNF antibody

BACKGROUND

Tumor Necrosis Factor (TNF) are expressed in milk. Experimental data indicate enhanced brain growth and cognitive development in the mouse offspring given milk deficient in TNF and TNF-dependent chemokines. Although monoclonal antibodies against TNF (TNFmAb) are used during breastfeeding due to minimal milk excretion, whether it affects endogenous TNF levels in human milk is unclear.

METHODS

A prospective cohort study was conducted in 26 breastfeeding women with inflammatory bowel disease (IBD) and 31 non-IBD women. Milk TNF and related chemokines were measured at 5-6 weeks postpartum (early-lactation point) as a primary endpoint and further determined at 13-14 weeks postpartum. In a subset of their infants, neurocognitive development was assessed at 12 and 18 months of age using Bayley-III tool.

RESULTS

While milk TNF levels were not significantly different between the control and those with IBD, women with IBD receiving TNFmAb showed 70% lower median milk TNF than those without TNFmAb (P = 0.019) at early lactation period. TNF-dependent chemokines (MIP-1β and IP-10) also showed similar patterns. Neurocognitive development of the infants was not significantly different among the groups.

CONCLUSIONS

Women with IBD receiving TNFmAb show significantly lower milk TNF/chemokines at 5-6 weeks postpartum than those without TNFmAb.

CLINICALTRIALS

gov NCT03397108.

IMPACT

We found that milk concentrations of Tumor Necrosis Factor (TNF) and TNF-dependent chemokines (MIP-1β and IP-10) are low in women with inflammatory bowel disease who are receiving anti-TNF monoclonal antibody (TNFmAb), compared to those without concurrent anti TNF therapy. While maternal use of TNFmAb during breastfeeding is considered inconsequential to infant health due to their low levels of milk excretion, it affects profiles of endogenous cytokines in milk. Our findings provide a rationale to investigate human implications of the animal data in the literature that suggest enhancement of neurocognitive development of the offspring fed with milk deficient in TNF-dependent chemokines.

Human milk variation is shaped by maternal genetics and impacts the infant gut microbiome

Human milk is a complex mix of nutritional and bioactive components that provide complete nourishment for the infant. However, we lack a systematic knowledge of the factors shaping milk composition and how milk variation influences infant health. Here, we characterize relationships between maternal genetics, milk gene expression, milk composition, and the infant fecal microbiome in up to 310 exclusively breastfeeding mother-infant pairs. We identified 482 genetic loci associated with milk gene expression unique to the lactating mammary gland and link these loci to breast cancer risk and human milk oligosaccharide concentration. Integrative analyses uncovered connections between milk gene expression and infant gut microbiome, including an association between the expression of inflammation-related genes with milk interleukin-6 (IL-6) concentration and the abundance of Bifidobacterium and Escherichia in the infant gut. Our results show how an improved understanding of the genetics and genomics of human milk connects lactation biology with maternal and infant health.

Somatic cell count as an indicator of subclinical mastitis and increased inflammatory response in asymptomatic lactating women

Subclinical mastitis is an asymptomatic inflammatory condition that can be difficult to define and diagnose. In the dairy industry, subclinical mastitis is diagnosed by milk somatic cell counts (SCCs) of ≥250,000 cells mL-1. In this pilot study, we assessed the efficacy of this index to identify human subclinical mastitis by comparing SCC levels with the inflammatory response [interleukin-8 (IL-8) levels] in 37 samples from asymptomatic and 10 clinical mastitis (CM) lactating women. The milk microbiota was determined by 16S rRNA gene sequencing. The SCC of CM samples ranged from 310,000 to 6,600,000 cells mL-1. However, 14 of 37 (37.8%) asymptomatic samples had high SCC (250,000-460,000 cells mL-1), indicating subclinical mastitis. SCC levels significantly (P < 0.001) and positively correlated with milk IL-8 levels reflecting the escalating inflammatory response across subclinical and clinical mastitis samples. Samples with an SCC of ≥250,000 cells mL-1 showed significant increases in IL-8 responses when compared with milk samples from healthy women. The milk microbiome of CM samples was dominated by streptococcal and staphylococcal species (89.9% combined median relative abundance). In contrast, the combined median streptococcal/staphylococcal relative levels were 75.4% and 66.3% in milks from asymptomatic (subclinical mastitis) and healthy groups, respectively. The Streptococcus genus was increased in samples with an SCC of ≥250,000, although this should be interpreted with caution. Thus, the index of ≥250,000 somatic cells mL-1 could be a reliable indicator of subclinical mastitis in humans and should aid future studies investigating the impact of subclinical mastitis on maternal health, breastfeeding behaviors, infant health, and development.

IMPORTANCE

This pilot study suggests that SCC at a level of (greater than or equal to) 250,000 cells mL-1, as used in the dairy industry, is a suitable index to identify asymptomatic subclinical mastitis in lactating women since it reflects a significant increase in the inflammatory response compared to milk samples from healthy women. Using this index should aid studies into the short- and long-term consequences of subclinical mastitis for mother and infant.

Hesperetin regulates the intestinal flora and inhibits the TLR4/NF-κB signaling axis to protect the blood-milk barrier and prevent mastitis

The World Health Organization recommends breastfeeding for 6 months, but mastitis, a common disease during lactation, presents a major obstacle to fulfilling this recommendation. Maternal nutrient intake during lactation has been shown to be related to mastitis. Therefore, this study aimed to explore the effect of hesperetin, a phytonutrient, on mastitis. The oral administration of hesperetin to lipopolysaccharide (LPS)-induced mastitis mice alleviated their pathological damage, reduced the secretion of pro-inflammatory cytokines, and maintained the integrity of their blood-milk barrier. Moreover, our results showed that oral administration of hesperetin regulates the composition of the intestinal flora of mice. Fecal microbial transplantation (FMT) from the mice of hesperetin group alleviated LPS-induced mastitis in recipient mice. In additional, hesperetin attenuated the inflammatory response and increased the expression of tight junction proteins (TJs) in LPS-stimulated mouse mammary epithelial cells (mMECs). Through network pharmacological analysis and further research, we demonstrated hesperetin inhibits the expression of TLR4 and the activation of NF-κB signaling. In conclusion, hesperetin protects the blood-milk barrier and improve mastitis by regulating intestinal flora and inhibiting the activation of TLR4/NF-κB signaling axis. This study provides a theoretical basis for lactating females to consume hesperetin as a supplement to prevent mastitis and maintain mammary health.

Mammary epithelium permeability during established lactation: associations with cytokine levels in human milk

Objective

The cytokine profile of human milk may be a key indicator of mammary gland health and has been linked to infant nutrition, growth, and immune system development. The current study examines the extent to which mammary epithelium permeability (MEP) is associated with cytokine profiles during established lactation within a sample of US mothers.

Methods

Participants were drawn from a previous study of human milk cytokines. The present analysis includes 162 participants (98 Black, 64 White) with infants ranging from 1 to 18 months of age. Levels of cytokines were determined previously. Here we measure milk sodium (Na) and potassium (K) levels with ion-selective probes. Two approaches were used to define elevated MEP: Na levels ≥10 mmol/L and Na/K ratios greater than 0.6. Associations between maternal-infant characteristics, elevated MEP, and twelve analytes (IL-6, IL-8, TNFα, IL-1β, FASL, VEGFD, FLT1, bFGF, PLGF, EGF, leptin, adiponectin) were examined using bivariate associations, principal components analysis, and multivariable logistic regression models.

Results

Elevated MEP was observed in 12 and 15% of milk samples as defined by Na and Na/K cutoffs, respectively. The odds of experiencing elevated MEP (defined by Na ≥ 10 mmol/L) were higher among Black participants and declined with older infant age. All cytokines, except leptin, were positively correlated with either Na or the Na/K ratio. A pro-inflammatory factor (IL-6, IL-8, TNFα, IL-1β, EGF) and a tissue remodeling factor (FASL, VEGFD, FLT1, bFGF, PLGF, adiponectin) each contributed uniquely to raising the odds of elevated MEP as defined by either Na or the Na/K ratio.

Conclusion

This exploratory analysis of MEP and cytokine levels during established lactation indicates that elevated MEP may be more common in US populations than previously appreciated and that individuals identifying as Black may have increased odds of experiencing elevated MEP based on current definitions. Research aimed at understanding the role of MEP in mammary gland health or infant growth and development should be prioritized.

Phenotypic and genotypic characterization of erythromycin-resistant Staphylococcus aureus isolated from bovine subclinical mastitis in Egypt

Background and Aim

Subclinical mastitis (SCM) caused by erythromycin-resistant Staphylococcus aureus is a significant disease in lactating animals. Therefore, it is crucial to understand the genetic factors contributing to erythromycin resistance in S. aureus. This study aimed to estimate the prevalence of S. aureus in milk from subclinical mastitic cattle and buffaloes and tank milk samples as identified by probe-based real-time polymerase chain reaction (PCR) and the genotypic assessment of macrolide and erythromycin resistance profiles, as well as to analyze the phylogenetic relatedness of our local isolates of S. aureus.

Materials and Methods

In total, 285 milk samples were analyzed using the California mastitis test to detect SCM. Milk samples were cultured on different specific Staphylococcus media. The presence of S. aureus was confirmed by Gram staining, the catalase and coagulase tests, the detection of hemolytic activity, DNase agar testing, and biofilm activity in Congo red medium. The genotypic identification of S. aureus (nuc) was performed. The determinants of erythromycin (ermA, ermB, ermC, and ermT) and macrolide resistance (msrA) were screened in all isolates. DNA sequencing of our local isolates of S. aureus was used to analyze their phylogenetic relatedness. Moreover, histopathological examination of tissue specimens of mammary gland was performed.

Results

The S. aureus positivity rates were 36.4%, 48.8%, and 63.6% in cattle, buffalo, and bulk tank milk, respectively. Probe-based real-time PCR molecularly confirmed all 62 S. aureus isolates. Thirty-one isolates were subjected to PCR to create profiles of their genotypic erythromycin resistance. ermA, ermB, ermC, and ermT were present in 5 (8%), 26 (41.9%), 18 (29%), and 15 (24.1%) S. aureus isolates, respectively. Moreover, msrA was found in three (4.8%) strains. Eight PCR products were produced using standard PCR for DNA sequencing. Multiple sequence alignment, phylogenetic tree construction, and analysis of nuc in S. aureus revealed a high degree of homology (100%) with S. aureus strains isolated from milk in cases of bovine mastitis in India and Kenya. Histological analysis of udder tissues revealed extensive aggregation of mononuclear inflammatory cells in the interstitial connective tissue, primarily lymphocytes, and macrophages.

Conclusion

This study showed a high prevalence of erythromycin resistance in S. aureus isolates. This information is vital for controlling mastitis and the spread of resistance genes between bacterial strains and hosts. Moreover, the probe-based real-time PCR approach is helpful for the rapid screening of S. aureus isolates and the consequent efficient treatment and control of S. aureus mastitis.

Human Milk Sodium and Potassium as Markers of Mastitis in Mothers of Preterm Infants

Introduction: This prospective longitudinal study examined changes in milk sodium concentration (Na) and sodium:potassium ratio (Na:K), microbiological culture, milk production, and breast health in relation to mastitis after preterm birth. Methods: We studied women who gave birth at 29-34 weeks of gestation in a tertiary obstetric hospital in Perth, Western Australia. Milk samples, 24-hour milk production, and breast health data were collected every second day to day 10 postpartum, then every third day until infant discharge from the neonatal unit. Milk Na and K were measured at point of care (POC) using handheld ion selective meters, and Na:K calculated. Cultures were performed on postnatal days 8, 13, and every 6 days thereafter. For episodes of mastitis, milk was cultured at onset, and Na and Na:K measured daily until resolution. Women were followed up at 4 and 8 weeks postpartum. Results: In a sample of 44 women, 4 mastitis cases were detected in 3 women during their infants' neonatal stay; all had elevated milk Na and Na:K that resolved within 48 hours; 2/4 experienced reduced milk production and 1/4 had heavy growth of Staphylococcus epidermidis. A further 2 mastitis cases were reported in 39 women followed up to 8 weeks postpartum. Four women had elevated milk Na and Na:K without clinical signs of mastitis; three also had reduced milk production. Conclusions: POC testing of milk Na and/or Na:K may offer a useful indicator of breast health. Mastitis may cause an acute reduction in milk production regardless of the presence of culture-positive infection.

Sodium and Potassium Concentrations and Somatic Cell Count of Human Milk Produced in the First Six Weeks Postpartum and Their Suitability as Biomarkers of Clinical and Subclinical Mastitis

The sodium (Na) concentration and the ratio of Na to potassium (K; Na/K) in human milk are used commonly as biomarkers of subclinical mastitis, but limited data exist on their relationship to and ability to predict clinical mastitis. Here, we assessed concentrations of Na, K, Na/K, and somatic cell count (SCC), a mammary health biomarker used in the dairy industry, in milk prospectively collected from both breasts of 41 women over the first 6 weeks postpartum. Although values differed over time postpartum, there were no differences in mean values between breasts. Nearly one-quarter (24%) of participants experienced clinical mastitis. Somatic cell counts >4.76 × 105 cells/mL were most strongly related to development of clinical mastitis in the following week (odds ratio, 7.81; 95% CI, 2.15−28.30; p = 0.002), although relationships were also observed for SCC > 4.00 × 105 cells/mL and Na concentration >12 mmol/L. Estimates of the prevalence of subclinical mastitis in women who never progressed to clinical mastitis differed by biomarker but ranged from 20 to 75%. Despite these findings, positive predictive values (PPV) of the biomarkers for identifying clinical mastitis were low (≤0.34), indicating additional research is needed to identify single biomarkers or composite measures that are highly specific, sensitive, and predictive of clinical mastitis in women.

The Dietary Inflammatory Index Is Associated with Subclinical Mastitis in Lactating European Women

Subclinical mastitis (SCM) is an inflammatory state of the lactating mammary gland, which is asymptomatic and may have negative consequences for child growth. The objectives of this study were to: (1) test the association between the dietary inflammatory index (DII®) and SCM and (2) assess the differences in nutrient intakes between women without SCM and those with SCM. One hundred and seventy-seven women with available data on human milk (HM) sodium potassium ratio (Na:K) and dietary intake data were included for analysis. Multivariable logistic regression was used to examine the association between nutrient intake and the DII score in relation to SCM. Women without SCM had a lower median DII score (0.60) than women with moderate (1.12) or severe (1.74) SCM (p < 0.01). A one-unit increase in DII was associated with about 41% increased odds of having SCM, adjusting for country and mode of delivery, p = 0.001. Women with SCM had lower mean intakes of several anti-inflammatory nutrients. We show for the first time exploratory evidence that SCM may be associated with a pro-inflammatory diet and women with SCM have lower intakes of several antioxidant and anti-inflammatory nutrients.

Oxylipins as Potential Regulators of Inflammatory Conditions of Human Lactation

Chronic low-grade inflammation can be associated with obesity or subclinical mastitis (SCM), which is associated with poor infant growth in low- to middle-income country settings. It is unknown what physiological mechanisms are involved in low milk supply, but our research group has shown that mothers with low milk supply have higher inflammatory markers. Studies investigating oxylipin signaling have the potential to help explain mechanisms that mediate the impacts of inflammation on milk production. Animal studies have reported various elevated oxylipins during postpartum inflammation, mastitis, and mammary involution in ruminant models. Several investigations have quantified oxylipins in human milk, but very few studies have reported circulating oxylipin concentrations during lactation. In addition, there are technical considerations that must be addressed when reporting oxylipin concentrations in human milk. First, the majority of milk oxylipins are esterified in the triglyceride pool, which is not routinely measured. Second, total milk fat should be considered as a covariate when using milk oxylipins to predict outcomes. Finally, storage and handling conditions of milk samples must be carefully controlled to ensure accurate milk oxylipin quantitation, which may be affected by highly active lipases in human milk.

Durable antibody and effector memory T cell responses in breastmilk from women with SARS-CoV-2

Background

Given that only 25% of pregnant women elect to receive a COVID-19 vaccine, maternal SARS-CoV-2 infection remains an important route of conferring protective passive immunity to breastfed infants of mothers who are not vaccinated.

Methods

We enrolled 30 lactating participants between December 2020 and March 2021 who had a positive PCR-test and their first COVID-19 symptoms within the previous 21 days. Participants were asked to provide serial bilateral milk samples at 12 timepoints (~ every 3 days) over a period of 35 days. A second set of samples was collected at least four months after the beginning of the first set. Participants also were asked to provide their dried blood spots and infant stool samples. All samples were tested for receptor-binding domain (RBD)-specific immunoglobulin (Ig)A, IgG, and IgM. Milk samples were assessed for neutralizing ability against the spike protein and four SARS-CoV-2 variants: D614G, Alpha (B.1.1.7), Beta (B.1.351), and Gamma (P.1). Permeability of the breast epithelium was assessed by measuring the sodium to potassium ions (Na:K) in milk. Using flow cytometry, memory CD4 and CD8 T cells (CD45RO+ and CCR7+/-) and mucosal-homing CD4 and CD8 T cells (CD103+) were determined in cells from milk expressed at 35 days and at least 4 months after their first milk donation.

Results

Milk antibodies from SARS-CoV-2 positive participants neutralized the spike complex. Milk from 73, 90, and 53% of participants had binding reactivities to RBD-specific IgA, IgG, and IgM, respectively. In contrast to blood spots, which showed increased levels of IgG, but not IgA or IgM, the COVID-19 response in milk was associated with a robust IgA response. Twenty-seven percent of participants had increased breast-epithelium permeability, as indicated by Na:K ≥ 0.6. The percentage of CD45RO+CCR7- effector-memory T cells in the day ≥120 milk samples was significantly higher than day 35 samples (P< 0.05).

Conclusions

Antibodies in milk from participants with recent SARS-CoV-2 infection and those who recovered can neutralize the spike complex. For the first time we show that breastmilk T cells are enriched for mucosal memory T cells, further emphasizing the passive protection against SARS-CoV-2 conferred to infants via breastmilk.

Mode of Neonatal Delivery Influences the Nutrient Composition of Human Milk: Results From a Multicenter European Cohort of Lactating Women

Background

The effect of the mode of neonatal delivery (cesarean or vaginal) on the nutrient composition of human milk (HM) has rarely been studied. Given the increasing prevalence of cesarean section (C-section) globally, understanding the impact of C-section vs. vaginal delivery on the nutrient composition of HM is fundamental when HM is the preferred source of infant food during the first 4 postnatal months.

Objective

This study aimed to evaluate the association between mode of delivery and nutrient composition of HM in the first 4 months of life.

Design

Milk samples were obtained from 317 healthy lactating mothers as part of an exploratory analyses within a multicenter European longitudinal cohort (ATLAS cohort) to study the HM composition, and its potential association with the mode of delivery. We employed traditional mixed models to study individual nutrient associations adjusted for mother’s country, infant birth weight, parity, and gestational age, and complemented it, for the first time, with a multidimensional data analyses approach (non-negative tensor factorization, NTF) to examine holistically how patterns of multiple nutrients and changes over time are associated with the delivery mode.

Results

Over the first 4 months, nutrient profiles in the milk of mothers who delivered vaginally (n = 237) showed significantly higher levels of palmitoleic acid (16:1n-7), stearic acid (18:0), oleic acid (18:1n-9), arachidic acid (20:0), alpha-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3), docosahexenoic acid (22:6n-3), erucic acid (22:1n-9), monounsaturated fatty acids (MUFA)%, calcium, and phosphorus, whereas the ratios of arachidonic acid/docosahexaenoic acid (ARA/DHA) and n-6/n-3, as well as polyunsaturated fatty acids (PUFA)% were higher in milk from women who had C-sections, in the unadjusted analyses (p < 0.05 for all), but did not retain significance when adjusted for confounders in the mixed models. Using a complementary multidimension data analyses approach (NTF), we show few similar patterns wherein a group of mothers with a high density of C-sections showed increased values for PUFA%, n-6/n-3, and ARA/DHA ratios, but decreased values of MUFA%, 20:1n-9, iodine, and fucosyl-sialyl-lacto-N-tetraose 2 during the first 4 months of lactation.

Conclusion

Our data provide preliminary insights on differences in concentrations of several HM nutrients (predominantly fatty acids) among women who delivered via C-section. Although these effects tend to disappear after adjustment for confounders, given the similar patterns observed using two different data analytical approaches, these preliminary findings warrant further confirmation and additional insight on the biological and clinical effects related to such differences early in life.

Amyloid fibril formation by casein and fatty acid composition in breast milk of mastitis patients

Mastitis can cause changes in the nutrient composition of breast milk, which may be harmful to both newborns and lactating mothers. In this study we preliminarily evaluated amyloid fibrils formation by casein and fatty acids (FA), as well as their potential relation with each other in the breast milk of mastitis patients. Six healthy volunteers and six mastitis patients were recruited from the Maternal and Child Health Care Hospital in Changchun were enrolled. Amyloid fibril content was assessed by thioflavin T fluorescence analysis, transmission electron microscope, circular dichroism, and proton nuclear magnetic resonance. FA contents were measured by gas chromatography. Healthy breast milk contained no amyloid fibrils but inflammatory breast milk did. Several FAs (hendecanoic acid, myristolenic acid, pentadecenoic acid, eicosatrienoic acid) differed significantly between the two groups (p < .05). The concentrations of the eicosatrienoic acid and eleven carbonic acids in the inflammatory groups were lower than those in the healthy groups, but the myristolenic acid and pentadecenoic acid were the opposite trend. Early detection of amyloid fibrils should be performed in lactating mothers with mastitis. Changes in FAs may reflect the importance of abnormal metabolism in amyloid fibril formation. PRACTICAL APPLICATIONS: The work preliminarily clarified the relationship between inflammation, fibril content, and fatty acid (FA) composition in breast milk. Healthy milk contained no amyloid fibril formed by casein but the inflammatory milk did. FAs were also significantly different between the two groups. Thus, an early determination of amyloid fibrils in milk should be considered for lactating women with mastitis to avoid the further malignant development. Additionally, the changes in FAs may reflect the importance of abnormal metabolism and oxidative pathways in amyloid fibril formation in the breast. Therefore, this study provided foundations for further investigation on the association between inflammation, fibril content and FA composition in breast milk.

Interactions between human milk oligosaccharides, microbiota and immune factors in milk of women with and without mastitis

Lactational mastitis is an excellent target to study possible interactions between HMOs, immune factors and milk microbiota due to the infectious and inflammatory nature of this condition. In this work, microbiological, immunological and HMO profiles of milk samples from women with (MW) or without (HW) mastitis were compared. Secretor status in women (based on HMO profile) was not associated to mastitis. DFLNH, LNFP II and LSTb concentrations in milk were higher in samples from HW than from MW among Secretor women. Milk from HW was characterized by a low bacterial load (dominated by Staphylococcus epidermidis and streptococci), high prevalence of IL10 and IL13, and low sialylated HMO concentration. In contrast, high levels of staphylococci, streptococci, IFNγ and IL12 characterized milk from MW. A comparison between subacute (SAM) and acute (AM) mastitis cases revealed differences related to the etiological agent (S. epidermidis in SAM; Staphylococcus aureus in AM), milk immunological profile (high content of IL10 and IL13 in SAM and IL2 in AM) and milk HMOs profile (high content of 3FL in SAM and of LNT, LNnT, and LSTc in AM). These results suggest that microbiological, immunological and HMOs profiles of milk are related to mammary health of women.

Human Milk Antioxidative Modifications in Mastitis: Further Beneficial Effects of Cranberry Supplementation

Mastitis is the inflammation of one or several mammal lobes which can be accompanied by a mammary gland infection, and is the leading cause of undesired early weaning in humans. However, little information exists regarding the changes that this disease may induce in the biochemical composition of human milk, especially in terms of oxidative status. Given that newborns are subject to a significant increase in total ROS burden in their transition to neonatal life and that their antioxidant defense system is not completely developed, the aim of this study was to evaluate antioxidant defense (glutathione peroxidase (GPx), reduced glutathione (GSH), total polyphenol content (TPP), and total antioxidant capacity (TAC)) in milk samples from mothers suffering from mastitis and controls. We also measured the oxidative damage to lipids (malondyaldehyde (MDA)) and proteins (carbonyl group content (CGC)) in these samples. Finally, we tested whether dietary supplementation with cranberries (a product rich in antioxidants) in these breastfeeding mothers during 21 days could improve the oxidative status of milk. GPx activity, TPP, and TAC were increased in milk samples from mastitis-affected women, providing a protective mechanism to the newborn drinking mastitis milk. MDA concentrations were diminished in the mastitis group, confirming this proposal. Some oxidative damage might occur in the mammary gland since the CGC was increased in mastitis milk. Cranberries supplementation seems to strengthen the antioxidant system, further improving the antioxidative state of milk.

MILK LIPIDS AND SUBCLINICAL MASTITIS

This article deals with the process of obtaining quality raw milk by analyzing its lipid composition. The lipid composition of raw milk depends on many factors, among which, first of all, is the species, the composition of the diet and the physiological state of the breast. In recent years, a large amount of data has accumulated on the fluctuations of certain lipid parameters of milk depending on the type, age, lactation, diet, time of year, exercise, animal husbandry technology, physiological state of the lactating organism in general and breast status in particular. Factors of regulation of fatty acid composition of raw milk: genetically determined parameters of quality and safety; fatty acid composition of the diet; synthesis of fatty acids by microorganisms of the digestive tract; synthesis of fatty acids in the breast; physiological state of the breast. The milk of each species of productive animals has its own specific lipid profile and is used in the formulation of certain dairy products to obtain the planned technological and nutritional parameters. Diagnosis of productive animals for subclinical mastitis involves the use of auxiliary (thermometry, thermography, electrical conductivity) and laboratory research methods: counting the number of somatic cells; use of specialized tests; microbiological studies of milk; biochemical studies of milk. The biochemical component in the diagnosis of subclinical forms of mastitis is underestimated. An increase in body temperature implies an increase in the intensity of heat release during the oxidation of substrates, sometimes due to a decrease in the intensity of synthesis of energy-intensive compounds. There are simply no other sources of energy in the body. The situation is the same with certain parts of the metabolism, which are aimed at the development of protective reactions to the etiological factor aimed at the defeat of the breast. That is why the biochemical composition of breast secretions in the absence of clinical signs of mastitis undergoes biochemical changes and the task of scientists is to develop mechanisms for clear tracking of such changes, identification of animals with subclinical forms of mastitis and effective treatment.

Infant Anthropometry and Growth Velocity Before 6 Months are Associated with Breastfeeding Practices and the Presence of Subclinical Mastitis and Maternal Intestinal Protozoa in Indigenous Communities in Guatemala

BACKGROUND

The possibility that maternal health status and breastfeeding practices contribute to growth faltering before 6 mo is underexplored.

OBJECTIVES

This longitudinal study investigated whether indicators of subclinical mastitis (SCM) and breast inflammation, maternal fecal-oral contamination, and/or breastfeeding practices were associated with infant anthropometry or growth velocity before 6 mo.

METHODS

Indigenous Mam-Mayan mother-infant dyads (n = 140) were recruited. Breast milk was collected at early (<6 wk) and established (4-6 mo) lactation when maternal and infant anthropometry were measured. Milk Na:K ratio as an indicator of SCM and concentrations of 4 proinflammatory cytokines were measured. Maternal stool samples were examined for the presence of intestinal parasites including nonpathogenic protozoa (Endolimax nana, Iodamoeba bütschlii, Entamoeba coli, Blastocystis hominis). Questionnaires characterized breastfeeding and hygiene practices. Multiple linear regression identified factors associated with infant growth attainment [weight-for-age z-score (WAZ), length-for-age z-score (LAZ), and head circumference-for-age z-score (HCAZ)] and growth velocity (expressed as change per day from early to established lactation). Multiple logistic regression identified factors associated with increased odds of underweight, stunting, and low head circumference at both lactation stages.

RESULTS

A higher Na:K ratio, individual nonpathogenic protozoa, and specific breastfeeding and hygiene practices were associated with impaired growth before 6 wk and at 4-6 mo in exclusively breastfed infants. Growth velocity for weight was inversely associated with Entamoeba coli but cranial growth was associated positively with Iodamoeba bütschlii whereas feeding colostrum in early lactation was protective and decreased the odds of an HCAZ < -2 SD. Finally, the presence of SCM in early lactation increased the likelihood of both WAZ < -2 SD and LAZ < -2 SD by 6 wk.

CONCLUSIONS

Prevention of SCM can improve early infant weight, but measures that promote the feeding of colostrum and reduce exposure to fecal-oral contamination might be required to minimize infant growth faltering in breastfed infants.

Subclinical Mastitis in Selected Bovine Dairy Herds in North Upper Egypt: Assessment of Prevalence, Causative Bacterial Pathogens, Antimicrobial Resistance and Virulence-Associated Genes

Mastitis is a significant disease affecting dairy cattle farms in Egypt. The current study aimed to investigate the prevalence and major bacterial pathogens causing subclinical mastitis (SCM) in three bovine dairy herds, with a history of SCM, at three Governorates in North Upper Egypt. The antimicrobial resistance profiles and specific virulence-associated genes causing bovine SCM were investigated. One thousand sixty-quarter milk samples (QMS) were collected aseptically from 270 apparently healthy cows in three farms and examined. The total prevalence of SCM was 46% and 44.8% based on California Mastitis Test (CMT) and Somatic Cell Count (SCC), respectively. Bacteriological examination of CMT positive quarters revealed that the prevalence of bacterial isolation in subclinically mastitic quarters was 90.4% (26 and 64.3% had single and mixed isolates, respectively). The most frequent bacterial isolates were E. coli (49.8%), Staphylococcus aureus (44.9%), streptococci (44.1%) and non-aureus staphylococci (NAS) (37.1%). Antimicrobial susceptibility testing of isolates revealed a high degree of resistance to the most commonly used antimicrobial compound in human and veterinary medicine. Implementation of PCR revealed the presence of mecA and blaZ genes in 60% and 46.7% of S. aureus isolates and in 26.7% and 53.3% of NAS, respectively. Meanwhile 73.3% of streptococci isolates harbored aph(3’)-IIIa gene conferring resistance to aminoglycosides and cfb gene. All E. coli isolates harbored tetA gene conferring resistance to tetracycline and sul1 gene conferring resistance to sulfonamides. The fimH and tsh genes were found in 80% and 60%, respectively. A significant association between the phenotypes and genotypes of AMR in different bacteria was recorded. The presence of a high prevalence of SCM in dairy animals impacts milk production and milk quality. The coexistence of pathogenic bacteria in milk is alarming, threatens human health and has a public health significance. Herd health improvement interventions are required to protect human health and society.