Microbiologic Profile of Nipple Swab Culture and its Association With Postoperative Complications in Prosthetic Breast Reconstruction.

BACKGROUND: In breast surgeries, a lactiferous duct leading to lactic glands of breast parenchyma allows direct contamination by normal bacterial flora of the nipple-areola complex. Complete blockage of nipple flora from the intraoperative field is almost impossible. OBJECTIVES: We aimed to analyze the microbiological profile of nipple flora of breast cancer patients who underwent an implant-based immediate breast reconstruction after a total mastectomy, and to evaluate the association of nipple bacterial flora with postoperative complications. METHODS: A retrospective chart review was performed of patients who underwent an implant-based immediate breast reconstruction after a total mastectomy. A nipple swab culture was performed preoperatively. Patient demographics, surgical characteristics, and complications were compared between positive and negative nipple swab culture groups. Microbiological profile data including antibacterial resistance were collected. RESULTS: Among 128 breasts, 60 cases (46.9%) had positive preoperative nipple swab culture results. Staphylococcus epidermidis accounted for 41.4% of microorganisms isolated. A multivariate logistic regression analysis of postoperative complications revealed that the presence of nipple bacterial flora was a risk factor for capsular contracture. Seven cases of postoperative infection were analyzed. In 2 cases (40% of pathogen-proven infection), the causative pathogen matched the patient's nipple bacterial flora, which was methicillin-resistant S. epidermidis in both cases. CONCLUSIONS: Nipple bacterial flora was associated with an increased risk of capsular contracture. Preoperative analysis of nipple bacterial flora can be an informative source for treating clinically diagnosed postoperative infections. More studies are needed to determine the effectiveness of active antibiotic decolonization of the nipple.

Effect of automatic cluster flushing on the concentration of Staphylococcus aureus in teat cup liners.

Automatic flushing of milking clusters between milking events is a control measure aimed at reducing transmission of mastitis pathogens from infectious milk to a subsequently milked cow. We evaluated the effect of flushing with cold water and flushing with water containing peracetic acid (PAA) on the concentration of Staphylococcus aureus in teat cup liners. Thirty-two clusters in a swing-over milking parlor (Dairymaster, Causeway, Ireland) were subjected to a simulated milking with S. aureus-contaminated milk. Sixteen clusters were not flushed (controls), whereas 8 clusters were flushed with cold water (966 ± 32 mL) and 8 clusters were flushed with water containing PAA (200 mL/mL). A random teat cup in each cluster was sampled by rinsing with a phosphate buffer. Teat cup samples were cultured on the day following collection on Baird-Parker plates to determine the concentration of S. aureus. In teat cup samples from control clusters, the mean concentration of S. aureus was 2.8 × 105 cfu/mL. The concentration of S. aureus was zero in teat cup samples from clusters flushed with cold water. In teat cup samples from clusters flushed with water containing PAA, the concentration of S. aureus was in general reduced compared with control clusters, but S. aureus was not removed completely. However, the automatic cluster flushing did not function properly when clusters were flushed with water containing PAA; thus, results reflected the effect of inadequate function rather than the effect of adding disinfectant to the flushing water. Before the main study, we conducted a pilot study to evaluate whether teat cup sampling with swabs and sample analysis with quantitative PCR were appropriate methods for the main study. Specifically, we evaluated the effect of swab sample mass on detection of S. aureus by quantitative PCR in the laboratory, Further, we compared PCR and bacterial culture on detection of S. aureus in a suspension following disinfection of the suspension with PAA. We sampled 20 identical S. aureus suspensions for culture and PCR by swabs before and after disinfection with PAA. Swab sample mass was determined by differential weighing and contributed to 46% of the variation observed in detection of S. aureus by PCR. Following disinfection with PAA, S. aureus remained detectable by PCR, although culturability ceased. Based on these results, we sampled teat cups in the main study with a buffer rinse and quantified S. aureus in the samples by bacterial culture. We concluded that automatic cluster flushing with cold water was effective in removing S. aureus from teat cup liners and that addition of PAA was therefore not necessary.

Noninferiority study evaluating the efficacy of a teat disinfectant containing copper and zinc for prevention of naturally occurring intramammary infections in an automatic milking system.

The aim of this study was to demonstrate the noninferiority of a novel teat disinfectant based on copper and zinc (ZkinCu; Copper Andino, Santiago de Chile, Chile) compared with a previously proven glycolic acid active disinfectant (OceanBlu; DeLaval, Kansas City, MO) as a positive control, with respect to the incidence of new intramammary infections under natural challenge conditions on a commercial robotic dairy farm. This study was conducted in 6 robotic pens of approximately 60 milking cows each. The pens were randomly assigned to 1 of the 2 studied disinfectants. Throughout the 8 wk study, the same pre- and post-milking teat disinfectant was used in each pen. The same milking procedures were used in each robot throughout the study. Pre-milking hygiene consisted of applying the disinfectant (OceanBlu or ZkinCu) with the robotic arm. The same product was applied on the teats after milking. At the beginning of the study, all quarters of all study cows were sampled. In successive samplings (wk 2, 4, 6, and 8), composite milk samples were collected on farm to determine SCC. Once composite SCC results were available (2 d) and based on an SCC of ≥100,000 cells/mL, quarter milk samples underwent bacteriological culture. Clinical mastitis was identified by study personnel. Intramammary infection in biweekly quarter milk samples was determined based on composite SCC levels (≥100,000 cells/mL) and the presence of bacteria. A new IMI was defined as a quarter in which the organism isolated was not present in the previous bacteriological sample, or the previous composite SCC sample was <100,000 cells/mL. Clinical mastitis samples were also considered to be new IMI. The trial was designed as a positive control field trial, in which the objective was to show noninferiority of ZkinCu versus the control (OceanBlu). The overall crude incidences of new IMI for 2 wk at risk were 4.9 and 7.3% for the ZkinCu and OceanBlu groups, respectively. The predominant organisms recovered from quarters with new IMI were Streptococcus uberis, Corynebacterium spp., and coagulase-negative staphylococci in both the ZkinCu and OceanBlu groups. The risk of infection in the OceanBlu group was higher (ß = 0.644; 95% confidence interval = 0.05-1.22). The interaction of treatment by week was not significant. The new IMI rate estimates (95% confidence interval) for ZkinCu and OceanBlu were 1.7% (0.8-2.5) and 3.2% (1.7-4.7), respectively. One novel aspect of this study is that it was one of the first commercial noninferiority trials to evaluate a new pre- and post-milking teat disinfectant in a dairy herd with an automatic milking system. The experimental teat disinfectant ZkinCu, evaluated in this field trial with naturally occurring IMI, showed noninferiority relative to the positive control for the prevention of new IMI. This study was conducted in a herd with an automatic milking system, and the results are applicable to herds with similar characteristics. Additional studies are needed to ensure reproducibility under different management conditions.

Cross-sectional study to identify staphylococcal species isolated from teat and inguinal skin of different-aged dairy heifers.

The purpose of this study was to describe the prevalence and distribution of staphylococcal species on the teat and inguinal skin of dairy heifers across the various stages of the heifer life cycle. The cross-sectional study included 106 Holstein heifers with an age range of 0 d to 27 mo that were selected from 11 different groups, based on housing type and age, on a single dairy operation. A composite swabbing sample including all 4 teats and a second composite sample including both inguinal regions of each heifer were collected using gas-sterilized electrostatic dusters (Swiffers; Procter and Gamble, Cincinnati, OH). Swabbing samples were mixed with 10 mL of sterile saline, agitated, and cultured on mannitol salt agar plates. At 24 h, plates were read and up to 10 staphylococcal colonies were saved for further analysis. Staphylococcal isolates were speciated using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or PCR amplification and partial sequencing of rpoB or tuf. The prevalence of staphylococci was compared between the inguinal and teat regions using the chi-squared or Fisher's exact test, as applicable. Logistic regression models were used to investigate the relationship between a heifer's age (treated as a quantitative continuous variable) and the probability of isolating a given staphylococcal species from a given body site (inguinal region or teats). Overall, the most common species identified were Staphylococcus haemolyticus followed by Staphylococcus chromogenes, Staphylococcus xylosus, Staphylococcus devriesei, and Staphylococcus sciuri. Staphylococcus aureus was more prevalent on the teat than in the inguinal region, whereas Staphylococcus arlettae was more prevalent in the inguinal region than on the teat. All other staphylococcal species were as likely to be found on the teat skin as the inguinal region skin. Isolation from the inguinal and teat skin was associated with age for Staphylococcus agnetis, S. chromogenes, S. devriesei, Staphylococcus equorum, S. haemolyticus, Staphylococcus lentus, S. sciuri, Staphylococcus vitulinus, and S. xylosus. The probability of finding S. chromogenes and S. agnetis on the teat and inguinal region increased with age, whereas the probability of S. devriesei and S. haemolyticus decreased with age. This study provides further insight into the ecology of staphylococcal species involved in heifer mastitis.

Nipple Shields in Transaxillary Breast Augmentation.

BACKGROUND: Infection after breast augmentation occurs in 1.1% to 2.5% of patients. Bacterial contamination of the implants could explain some complications of breast implant surgery, including infection, capsular contracture and even anaplastic large cell lymphoma. Because of the evidence of bacterial spread from the nipple, nipple shields have been proposed as a routine maneuver to avoid contamination of the implants. OBJECTIVE: To determine if nipple shields are useful in transaxillary breast augmentation. METHODS: A culture was obtained from the dressing (nipple shield) in 26 patients with transaxillary incision, and follow-up lasted for 18 months. A retrospective study of patients undergoing breast augmentation between 2008 and 2012 was conducted as well to know our rate of infections. A total of 753 patients between the ages of 18 and 62 years, with a mean age of 34 years, were identified. Of these 753 patients, most underwent surgery using a transaxillary incision (72.5%). The most common placement plane was subfascial (59.2%), and in most cases, an anatomical prosthesis (78%) was used. RESULTS: No cases of infection or capsular contracture were observed in the study group. However, 13.5% of the breasts had positive cultures of swabs taken under the nipple shields. Staphylococcus epidermidis and Enterococcus faecalis were isolated from the nipple culture. Within the retrospective study, we detected 2 cases of acute infection (0.26%) and 5 cases of late infection (0.66%). The acute infections were caused by Staphylococcus aureus. In the late infections, Pseudomonas aeruginosa was isolated in 3 cases, and S. aureus was isolated in 1 case. CONCLUSIONS: Nipple shields did not make any difference for outcomes when using the transaxillary method. Acute infections seem to occur more frequently via the areola route. Late infections seem to have a hematogenous component because an infectious background was present in all cases.

Microbiologic Safety of the Transareolar Approach in Breast Augmentation.

BACKGROUND: In aesthetic breast augmentation, especially by the transareolar approach, there is increasing concern regarding the occurrence of capsular contracture and its potential correlation with intraoperative implant contamination from putative endogenous breast flora of the nipple and lactiferous ducts. However, detectable bacteria cannot be considered synonymous with established resident microflora. OBJECTIVES: The authors sought to elucidate the existence of endogenous breast flora and assess the microbiologic safety of transareolar breast augmentation. METHODS: In this prospective study (BREAST-MF), the authors collected microbiologic samples from the breast skin, ductal tissue, and parenchyma of 39 consecutive female patients who underwent breast procedures in a plastic surgery clinic. Swabs collected pre-, intra-, and postoperatively were processed for bacterial and fungal growth. Positive cultures underwent identification through VITEK and MALDI-TOF, as well as antimicrobial susceptibility testing. RESULTS: Staphylococcus species accounted for 95 of 106 (89.6%) positive results from native breast skin, 15 of 18 (83.3%) positive results from decontaminated breast skin, and 4 of 4 (100%) positive results from the breast parenchyma. Methicillin resistance was present in 26.4% of S. epidermidis, 25.3% of S. hominis, and 71.4% of S. haemolyticus strains. CONCLUSIONS: During transareolar breast augmentation, in the nipple-areola region it is more likely to find bacteria populating the skin, rather than endogenous breast flora, as previously considered. Appropriate preoperative decontamination is essential for minimizing the risk of postoperative infections. LEVEL OF EVIDENCE 3: Risk.

Fluconazole use during breastfeeding.

QUESTION: I have a patient with persistent breast and nipple thrush. Other therapies have failed, so I have decided to treat her with a loading dose of 400 mg of oral fluconazole followed by 100 mg twice daily for at least 2 weeks. Is there any need for her to interrupt breastfeeding during this treatment? ANSWER: Available data regarding fluconazole use during breastfeeding are reassuring. Fluconazole is also used in the treatment of fungal diseases in infants and has a good safety profile. Therefore, there is no need to interrupt breastfeeding when a mother is treated with fluconazole.

Potential application in mercury bioremediation of a marine sponge-isolated Bacillus cereus strain Pj1.

Sponges are sessile marine invertebrates that can live for many years in the same location, and therefore, they have the capability to accumulate anthropogenic pollutants such as metals over a long period. Almost all marine sponges harbor a large number of microorganisms within their tissues. The Bacillus cereus strain Pj1 was isolated from a marine sponge, Polymastia janeirensis, and was found to be resistant to 100 µM HgCl(2) and to 10 µM methylmercury (MeHg). Pj1 was also highly resistant to other metals, including CdCl(2) and Pb(NO(3))(2), alone or in combination. The mer operon was located on the bacterial chromosome, and the volatilization test indicated that the B. cereus Pj1 was able to reduce Hg(2+)-Hg(0). Cold vapor atomic absorption spectrometry demonstrated that Pj1 volatilized 80 % of the total MeHg that it was exposed to and produced elemental Hg when incubated with 1.5 µM MeHg. Pj1 also demonstrated sensitivity to all antibiotics tested. In addition, Pj1 demonstrated a potential for biosurfactant production, presenting an emulsification activity better than synthetic surfactants. The results of this study indicate that B. cereus Pj1 is a strain that can potentially be applied in the bioremediation of HgCl(2) and MeHg contamination in aquatic environments.

Cow teat skin, a potential source of diverse microbial populations for cheese production.

The diversity of the microbial community on cow teat skin was evaluated using a culture-dependent method based on the use of different dairy-specific media, followed by the identification of isolates by 16S rRNA gene sequencing. This was combined with a direct molecular approach by cloning and 16S rRNA gene sequencing. This study highlighted the large diversity of the bacterial community that may be found on teat skin, where 79.8% of clones corresponded to various unidentified species as well as 66 identified species, mainly belonging to those commonly found in raw milk (Enterococcus, Pediococcus, Enterobacter, Pantoea, Aerococcus, and Staphylococcus). Several of them, such as nonstarter lactic acid bacteria (NSLAB), Staphylococcus, and Actinobacteria, may contribute to the development of the sensory characteristics of cheese during ripening. Therefore, teat skin could be an interesting source or vector of biodiversity for milk. Variations of microbial counts and diversity between the farms studied have been observed. Moreover, Staphylococcus auricularis, Staphylococcus devriesei, Staphylococcus arlettae, Streptococcus bovis, Streptococcus equinus, Clavibacter michiganensis, Coprococcus catus, or Arthrobacter gandavensis commensal bacteria of teat skin and teat canal, as well as human skin, are not common in milk, suggesting that there is a breakdown of microbial flow from animal to milk. It would then be interesting to thoroughly study this microbial flow from teat to milk.

Risk of breast implant bacterial contamination from endogenous breast flora, prevention with nipple shields, and implications for biofilm formation.

BACKGROUND: Capsular contracture (CC) is a common complication of breast augmentation that is thought to arise from bacterial contamination and subsequent biofilm formation on the implant. Endogenous breast flora expressed through the nipple may contaminate the sterile field during breast augmentation, acting as a possible source for initiation of biofilm formation. OBJECTIVES: The authors investigate the incidence of nipple bacterial contamination with endogenous breast flora after standard chest wall sterilization during breast augmentation. METHODS: Bacterial contamination of nipples and nipple shields was assessed in a series of 32 consecutive patients presenting for breast augmentation (63 breasts: 31 bilateral procedures and 1 unilateral procedure). After standard sterilization of the chest wall, occlusive nipple shields were applied and breast augmentation was performed. At the conclusion of breast augmentation, the nipple shields were removed and, using the same swab, both the nipple/areolar area and occlusive dressings were cultured. RESULTS: Data from 63 cultured nipples and nipple shields revealed that 22 nipples/nipple shields (34.9%) were positive for bacterial contamination. Three patients, all of whom had negative cultures, developed CC after augmentation. CONCLUSIONS: The exposed nipple is a potential source of implant contamination during breast augmentation. An improved understanding of biofilms and related risk factors for CC can provide surgeons with insights for addressing this common complication. Meticulous hemostasis, use of nipple shields, and submuscular device placement may contribute to a lower incidence of CC.

The role of micro-organisms (Staphylococcus aureus and Candida albicans) in the pathogenesis of breast pain and infection in lactating women: study protocol.

BACKGROUND: The CASTLE (Candida and Staphylococcus Transmission: Longitudinal Evaluation) study will investigate the micro-organisms involved in the development of mastitis and "breast thrush" among breastfeeding women. To date, the organism(s) associated with the development of breast thrush have not been identified. The CASTLE study will also investigate the impact of physical health problems and breastfeeding problems on maternal psychological health in the early postpartum period. METHODS/DESIGN: The CASTLE study is a longitudinal descriptive study designed to investigate the role of Staphylococcus spp (species) and Candida spp in breast pain and infection among lactating women, and to describe the transmission dynamics of S. aureus and Candida spp between mother and infant. The relationship between breastfeeding and postpartum health problems as well as maternal psychological well-being is also being investigated. A prospective cohort of four hundred nulliparous women who are at least thirty six weeks gestation pregnant are being recruited from two hospitals in Melbourne, Australia (November 2009 to June 2011). At recruitment, nasal, nipple (both breasts) and vaginal swabs are taken and participants complete a questionnaire asking about previous known staphylococcal and candidal infections. Following the birth, participants are followed-up six times: in hospital and then at home weekly until four weeks postpartum. Participants complete a questionnaire at each time points to collect information about breastfeeding problems and postpartum health problems. Nasal and nipple swabs and breast milk samples are collected from the mother. Oral and nasal swabs are collected from the baby. A telephone interview is conducted at eight weeks postpartum to collect information about postpartum health problems and breastfeeding problems, such as mastitis and nipple and breast pain. DISCUSSION: This study is the first longitudinal study of the role of both staphylococcal and candidal colonisation in breast infections and will help to resolve the current controversy about which is the primary organism in the condition known as breast thrush. This study will also document transmission dynamics of S. aureus and Candida spp between mother and infant. In addition, CASTLE will investigate the impact of common maternal physical health symptoms and the effect of breastfeeding problems on maternal psychological well-being.

Enzymatic activity, sensitivity to antifungal drugs and Baccharis dracunculifolia essential oil by Candida strains isolated from the oral cavities of breastfeeding infants and in their mothers' mouths and nipples.

Candida strains can cause oral candidosis, as well as nipples candidosis and lead to premature weaning or yeast transmission. The aim of this study was to evaluate 51 Candida isolates obtained from the oral cavities of infants during breastfeeding and mothers' oral cavities and nipples, their enzymatic activity and their sensitivity to amphotericin B, fluconazole and Baccharis dracunculifolia essential oil. Among the studied strains, 96.1% produced phospholipase and 78.4% produced proteinase. The antifungal resistance was only observed among isolates of C. albicans, for which three strains showed a resistant activity to fluconazole and one showed a resistant activity to amphotericin B. All strains were sensitive to B. dracunculifolia essential oil with MIC between 0.2 and 6.25 mg/ml. It was concluded that most of the strains showed significant enzymatic activity and were sensitive to amphotericin B and fluconazole. B. dracunculifolia essential oil inhibited the growth of all strains, including the ones resistant to commercial antifungal agents.

The breast: a clean-contaminated surgical site.

BACKGROUND: Capsular contracture is one of the most common complications associated with breast implants. While the cause of this process has not yet been elucidated, subclinical infection is a likely culprit. OBJECTIVES: The authors assess the hypothesis that a probable source of contamination is endogenous breast bacteria, likely originating in the ducts themselves and most concentrated near the nipple. METHODS: Twenty-five healthy patients presenting for routine reduction mammaplasty were recruited as study participants. Tissue samples were taken intraoperatively from the periareolar, inframammary, and axillary regions of each sampled breast. Specimens were then processed in the microbiology laboratory, and quantitative bacterial counts were obtained. RESULTS: Of the 50 breasts sampled, 19 yielded positive culture results, for a rate of 38%. There was a significant difference in the positive culture rate among all three sites, with increasing quantitative bacterial counts in the axillary, inframammary, and periareolar regions, respectively. The most commonly-identified organisms in this study included various species of Staphylococcus and Propionibacterium acnes, with S. epidermidis being the most common. CONCLUSIONS: The breast harbors significant endogenous bacteria that can become the source of spontaneous or postoperative infection. Positive intraoperative cultures with high quantitative counts suggest that breast tissue harbors more bacteria than normal skin flora. Routine perioperative antibiotic prophylaxis may be suboptimal for the prevention of foreign body seeding in this setting. Furthermore, bacterial concentrations are highest in areas with the most ductal tissue, namely the periareolar region. These findings may be helpful when considering which incision site to select for augmentation mammaplasty.

Mammary candidiasis. A breast infection difficult to handle.

Mammary candidiasis is a disease with significant impact on breast feeding. Early diagnosis and treatment is essential for successful long-term breastfeeding. It constitutes however a significantly rare breast inflammatory entity. A case of a young woman with breast candidiasis properly diagnosed and treated in our clinic is reported.

Raynaud's phenomenon of the nipples: an elusive diagnosis.

Pain and throbbing of the nipples associated with Raynaud's phenomenon often mimics yeast or fungal infections. Breastfeeding mothers with Raynaud's of the nipples are often treated inappropriately for organisms such as Candida Albicans with topical or systemic antifungal agents. This case report describes the eventual diagnosis of Raynaud's phenomenon of the nipples in a breastfeeding mother who was initially treated for yeast.

Association Between Breast Milk Bacterial Communities and Establishment and Development of the Infant Gut Microbiome.

Importance: Establishment of the infant microbiome has lifelong implications on health and immunity. Gut microbiota of breastfed compared with nonbreastfed individuals differ during infancy as well as into adulthood. Breast milk contains a diverse population of bacteria, but little is known about the vertical transfer of bacteria from mother to infant by breastfeeding. Objective: To determine the association between the maternal breast milk and areolar skin and infant gut bacterial communities. Design, Setting, and Participants: In a prospective, longitudinal study, bacterial composition was identified with sequencing of the 16S ribosomal RNA gene in breast milk, areolar skin, and infant stool samples of 107 healthy mother-infant pairs. The study was conducted in Los Angeles, California, and St Petersburg, Florida, between January 1, 2010, and February 28, 2015. Exposures: Amount and duration of daily breastfeeding and timing of solid food introduction. Main Outcomes and Measures: Bacterial composition in maternal breast milk, areolar skin, and infant stool by sequencing of the 16S ribosomal RNA gene. Results: In the 107 healthy mother and infant pairs (median age at the time of specimen collection, 40 days; range, 1-331 days), 52 (43.0%) of the infants were male. Bacterial communities were distinct in milk, areolar skin, and stool, differing in both composition and diversity. The infant gut microbial communities were more closely related to an infant's mother's milk and skin compared with a random mother (mean difference in Bray-Curtis distances, 0.012 and 0.014, respectively; P < .001 for both). Source tracking analysis was used to estimate the contribution of the breast milk and areolar skin microbiomes to the infant gut microbiome. During the first 30 days of life, infants who breastfed to obtain 75% or more of their daily milk intake received a mean (SD) of 27.7% (15.2%) of the bacteria from breast milk and 10.3% (6.0%) from areolar skin. Bacterial diversity (Faith phylogenetic diversity, P = .003) and composition changes were associated with the proportion of daily breast milk intake in a dose-dependent manner, even after the introduction of solid foods. Conclusions and Relevance: The results of this study indicate that bacteria in mother's breast milk seed the infant gut, underscoring the importance of breastfeeding in the development of the infant gut microbiome.

A case-control study of mastitis: nasal carriage of Staphylococcus aureus.

BACKGROUND: Mastitis is a common problem for breastfeeding women. Researchers have called for an investigation into the possible role of maternal nasal carriage of S. aureus in the causation of mastitis in breastfeeding women. METHODS: The aim of the study was to investigate the role of maternal S. aureus nasal carriage in mastitis. Other factors such as infant nasal S. aureus carriage, nipple damage, maternal fatigue and oversupply of milk were also investigated. A case-control design was used. Women with mastitis (cases, n = 100) were recruited from two maternity hospitals in Melbourne, Australia (emergency departments, breastfeeding clinics and postnatal wards). Breastfeeding women without mastitis (controls, n = 99) were recruited from maternal and child health (community) centres and the rooms of a private obstetrician. Women completed a questionnaire and nasal specimens were collected from mother and baby and placed in charcoal transport medium. Women also collected a small sample of milk in a sterile jar. RESULTS: There was no difference between nasal carriage of S. aureus in breastfeeding women with mastitis (42/98, 43%) and control women (45/98, 46%). However, significantly more infants of mothers with mastitis were nasal carriers of S. aureus (72/88, 82%) than controls (52/93, 56%). The association was strong (adjusted OR 3.23, 95%CI 1.30, 8.27) after adjustment for the following confounding factors: income, private health insurance, difficulty with breastfeeding, nipple damage and tight bra. There was also a strong association between nipple damage and mastitis (adjusted OR 9.34, 95%CI 2.99, 29.20). CONCLUSION: We found no association between maternal nasal carriage of S. aureus and mastitis, but nasal carriage in the infant was associated with breast infections. As in other studies of mastitis, we found a strong association between nipple damage and mastitis. Prevention of nipple damage is likely to reduce the incidence of infectious mastitis. Mothers need good advice about optimal attachment of the baby to the breast and access to skilled help in the early postpartum days and weeks.