The role of bacteria in lactational mastitis and some considerations of the use of antibiotic treatment

International Breastfeeding Journal BioMed Central Open Access Research The role of bacteria in lactational mastitis and some considerations of the use of antibiotic treatment Linda J Kvist*†1,2, Bodil Wilde Larsson†2, Marie Louise Hall-Lord†2,3, Anita Steen†4 and Claes Schalén†4 Address: 1Department of Obstetrics and Gynaecology, Helsingborg Hospital, 251 87, Sweden, 2Department of Nursing, Karlstad University, 651 88, Sweden, 3Department of Nursing, Gjovik University College, Norway and 4Department of Clinical Microbiology and Immunology, University Hospital, Lund, Sweden Email: Linda J Kvist* - ; Bodil Wilde Larsson - ; Marie Louise Hall-Lord - ; Anita Steen - ; Claes Schalén - * Corresponding author †Equal contributors Published: 7 April 2008 International Breastfeeding Journal 2008, 3:6 doi:10.1186/1746-4358-3-6 Received: 6 December 2007 Accepted: 7 April 2008 This article is available from: http://www.internationalbreastfeedingjournal.com/content/3/1/6 © 2008 Kvist et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: The role of bacterial pathogens in lactational mastitis remains unclear. The objective of this study was to compare bacterial species in breast milk of women with mastitis and of healthy breast milk donors and to evaluate the use of antibiotic therapy, the symptoms of mastitis, number of health care contacts, occurrence of breast abscess, damaged nipples and recurrent symptoms in relation to bacterial counts. Methods: In this descriptive study, breast milk from 192 women with mastitis (referred to as cases) and 466 breast milk donors (referred to as controls) was examined bacteriologically and compared using analytical statistics. Statistical analyses were also carried out to test for relationships between bacteriological content and clinical symptoms as measured on scales, prescription of antibiotics, the number of care contacts, occurrence of breast abscess and recurring symptoms. Results: Five main bacterial species were found in both cases and controls: coagulase negative staphylococci (CNS), viridans streptococci, Staphylococcus aureus (S. aureus), Group B streptococci (GBS) and Enterococcus faecalis. More women with mastitis had S. aureus and GBS in their breast milk than those without symptoms, although 31% of healthy women harboured S. aureus and 10% had GBS. There were no significant correlations between bacterial counts and the symptoms of mastitis as measured on scales. There were no differences in bacterial counts between those prescribed and not prescribed antibiotics or those with and without breast abscess. GBS in breast milk was associated with increased health care contacts (p = 0.02). Women with ≥ 107 cfu/L CNS or viridans streptococci in their breast milk had increased odds for damaged nipples (p = 0.003). Conclusion: Many healthy breastfeeding women have potentially pathogenic bacteria in their breast milk. Increasing bacterial counts did not affect the clinical manifestation of mastitis; thus bacterial counts in breast milk may be of limited value in the decision to treat with antibiotics as results from bacterial culture of breast milk may be difficult to interpret. These results suggest that the division of mastitis into infective or non-infective forms may not be practically feasible. Daily follow-up to measure the subsidence of symptoms can help detect those in need of antibiotics. Page 1 of 7 (page number not for citation purposes) International Breastfeeding Journal 2008, 3:6 Background Appropriate treatment for inflammatory symptoms of the breast in lactating women has been under discussion in the scientific literature for some time. One reason why consensus has not been reached is that the clinical spectrum of "mastitis" covers a range from focal inflammation with minimal systemic response to septicaemia [1]. According to a review by the World Health Organization (WHO), the incidence of mastitis varies greatly, from 2.6% to 33%, among breastfeeding women [2]. This suggests that due to difficulties in the definition of the term "mastitis" [3], researchers might not have been investigating comparable groups of women. Furthermore, the lack of internationally agreed scales for the measurement of symptoms creates difficulties in the use of meta-analyses. The role of bacterial pathogens in lactational mastitis is unclear [1-4]. In the 1980s, Thomsen et al suggested that levels > 106 cfu/L of pathogenic bacteria in breast milk was an indication for antibiotic treatment since this level, together with leukocytosis was indicative of infection [5,6]. Others have suggested that untreated cases may recover as quickly as treated cases [7] and that bacteriological examination of breast milk may be of limited value [8]. The aims of this study were to compare bacterial species in breast milk of mothers with mastitis and of healthy breast milk donors and to evaluate in relation to bacterial counts, the use of antibiotic therapy, the symptoms of mastitis as measured on scales, number of health care contacts, occurrence of breast abscess, occurrence of damaged nipples and recurrence of symptoms. Methods Study population The case group consisted of 205 women who contacted a breastfeeding clinic in southern Sweden during 2002 – 2004 because of inflammatory symptoms of the breast during lactation and had agreed to join a randomised controlled trial of care interventions [4]; registration number of the RCT is: NCT00405158. The incidence of mastitis in the uptake area was estimated as 6% of the breastfeeding population [4]. Of the 205 women, 192 (94%) had their http://www.internationalbreastfeedingjournal.com/content/3/1/6 breast milk sampled and sent for bacteriological investigation. A follow-up questionnaire inquiring about recurrent symptoms and the women's views on care given was sent by post to the cases, six-weeks following their last contact with the breastfeeding clinic. A total of 176 (84%) returned the questionnaire. The control group consisted of 466 healthy, prospective breast milk donors living in the same geographical area as the case group and studied during the same period of time. According to Swedish recommendations, women with an established lactation who wish to donate breast milk for use in neonatal units are obliged to leave milk for bacterial analysis before being accepted as donors. Ethical considerations Ethical approval for the randomised controlled trial (RCT) was granted by the Committee for Medical Research Ethics, Lund University Hospital, Sweden (protocol number LU 592–00). Two of the authors (CS and AS) are employed at the laboratory where the specimens are tested and therefore had access to the material. After analysis of m (...truncated)