The incidence of neonatal oral candidiasis, or “thrush,” is reportedly 4%.1 The diagnosis of thrush is usually based upon characteristic physical findings, such as a white coating on the newborn’s tongue or inner cheek.2 Although most experts believe that thrush and maternal breast candidiasis usually coexist and that both mother and infant should be treated, the diagnostic criteria for yeast infections of the breast are even less clear. Textbooks describe “incredible pain… feeling like hot cords burning in the chest wall.”3 Others simply describe burning and shooting pain associated with nursing, as well as persistently sore and cracked nipples.4–6 As a result, there are no recent published estimates of the incidence of maternal breast candidiasis in nursing mothers.
The use of antepartum and intrapartum antibiotic prophylaxis has been increasing, with current indications including maternal group B streptococci (GBS) colonization, preterm labor with unknown GBS status, and preterm premature rupture of the membranes. Recent studies report that up to 24% of women receive antibiotic prophylaxis in labor for the indication of GBS prophylaxis.7 Whether the use of intrapartum antibiotic prophylaxis results in significant changes in neonatal microbial flora is not known, although some authors have suggested that the use of intrapartum ampicillin selects for resistant strains of Escherichia coli, particularly in preterm infants.7,8 Other authors suggest that recent increases in antibiotic use have not influenced the incidence of non-GBS early-onset neonatal infections.9 It is also apparent that the use of antibiotics is associated with the development of vaginal candidiasis.10 One case–control study and case reports have suggested that antibiotic use, particularly in the postpartum period, may predispose to nipple candidiasis.5,11 We sought to estimate the contemporary incidence of neonatal thrush and maternal breast candidiasis and whether the use of intrapartum antibiotics was associated with the development of neonatal thrush or maternal breast candidiasis or both in nursing mothers.
PATIENTS AND METHODS
Lactation Services at Memorial Regional Medical Center maintains a database on all mothers who plan to nurse their infants after delivery. Demographic and obstetric data are obtained at delivery, and all nursing mothers are seen by a lactation consultant (L.L. or S.E.) at least once within 24 hours of delivery. Follow-up telephone calls are made to all nursing mothers at 1 week, 1 month, 3 months, and 1 year. Mothers are specifically questioned regarding signs and symptoms of yeast at the 1 week and 1 month telephone calls. A “warm line” is also maintained to answer questions and deal with nursing problems, and calls to this warm line are recorded in the database. For the purposes of this study, the database was reviewed retrospectively.
The diagnosis of neonatal thrush was recorded if the mother reported the diagnosis and if treatment was prescribed by the infant’s pediatrician. The diagnosis of maternal breast candidiasis was made if the mother reported typical symptoms (pain with nursing, cracked and sore nipples) and if treatment had been prescribed by the pediatrician or by the patient’s obstetrician. Only those mother–infant pairs who nursed for at least 1 month and who had at least 1 month of telephone follow-up were included. Mother-infant pairs who developed yeast infections early in the follow-up period and subsequently discontinued nursing before 1 month were included. No cases of yeast infection that occurred more than 30 days after delivery were included, nor were cases included in which treatment was prescribed in the absence of symptoms.
A sample size estimate revealed that 409 subjects would be required to detect a 3-fold increase in neonatal thrush infections, assuming a baseline incidence of 4%, a power of 80%, and an alpha of 0.05, with two thirds of the subjects in the unexposed group. The statistical analysis was performed using SPSS 11.0 (SPSS Inc., Chicago, IL) for the personal computer. A χ2 analysis and Student t test were used for discrete and continuous variables, respectively. A value of P < .05 was considered significant. The study was reviewed and approved as exempt by the Bon Secours Richmond Health System Institutional Review Board.
Between February 1, 2001, and August 31, 2002, 811 nursing mother–infant pairs were seen by Lactation Services at Memorial Regional Medical Center, representing 68% of the 1,195 deliveries occurring during this time period. Four hundred thirty-five (54%) continued to nurse for at least 1 month and had at least 1 month of follow-up. As would be expected in a Level I hospital, very few infants were significantly preterm (< 35 weeks; 2.1%) or low birthweight (< 2,500 grams; 5.1%). One hundred seventy-three (39.8%) received intrapartum antibiotics, a majority (136; 78.6%) for GBS prophylaxis. Thirty-nine (9%) infants had thrush, and 39 (9%) mothers had breast candidiasis (32 pairs with both) in the first 30 days after delivery. Overall, 46 (10.6%) mother–infant pairs had thrush or candidiasis. As shown in Table 1, there were no differences in maternal age, gravidity or parity, or route of delivery between mothers who received intrapartum antibiotics and those who did not. Antibiotic-exposed neonates were slightly younger and lighter, as might be expected due to the increased use of antibiotics in preterm pregnancies. Although statistically significant, these differences are not clinically significant.
Neonates who were exposed to antibiotics were more likely to develop thrush within the first month, although this did not reach statistical significance (12.1% compared with 6.9%; odds ratio [OR] 1.87, 95% confidence interval [CI] 0.97–3.63). There was no difference in the age at which thrush developed when antibiotic-exposed neonates were compared with those who were not exposed (19.1 ± 9.2 compared with 18.8 ± 8.3 days; P = .90).
Mothers who received intrapartum antibiotics were significantly more likely to be diagnosed with breast candidiasis (12.7 compared with 6.5%; OR 2.1, 95% CI 1.08–4.08). Considered as a dyad, antibiotic exposed mother-infant pairs were significantly more likely to develop yeast infections (15.0% compared with 7.6%; OR 2.14, 95% CI 1.15–3.97)
When the Centers for Disease Control and Prevention recently revised its protocol for GBS prophylaxis, they recommended that all women be screened for GBS colonization in the third trimester and given antibiotic prophylaxis during labor if GBS-positive.7 They also advised “continued surveillance of neonatal sepsis caused by organisms other than GBS.”7
Although localized Candida species infections are more of a nuisance than a major health risk, the discomfort and difficulties with nursing associated with these infections have often been cited as a reason that women discontinue nursing.5,6,12 The current recommendation is that, ideally, all women should exclusively nurse their newborn infants for at least 6 months after delivery.13 Developing a neonatal thrush infection, maternal breast candidiasis, or both, in the first month of nursing is unlikely to further this goal.
The limitations of this study are primarily a result of the retrospective nature of the study and the use of a clinical database designed for patient care for the analysis. Additional risk factors for maternal and neonatal yeast infections, such as maternal diabetes and use of antepartum or postpartum antibiotics were not recorded in the database. In addition, the diagnosis of yeast infection was based on signs and symptoms and was not usually confirmed by an examination performed by the study personnel. There is, however, no standard for the diagnosis of neonatal thrush nor for the diagnosis of maternal breast candidiasis. Previous work has revealed that cultures of the breast, breast milk, or both in lactating women with suspected yeast infections has resulted in a high rate of both false-negative and false-positive results.14,15
Further study is needed to confirm and expand upon our findings, in a prospective and tightly controlled fashion. With a larger study population, the differences in neonatal yeast infection might become statistically significant. It would require a sample size of 663 neonates to detect a 2-fold increase (from 7% to 14%) in the incidence of neonatal thrush and would require 1,174 neonates to achieve statistical significance with the increase from 7% to 12% seen in this study. If these findings are confirmed, further investigation into methods to reduce the risk of postnatal yeast infections should be instituted. These methods might include the use of prophylactic maternal oral acidophilus supplementation, an unproven but commonly used homeopathic remedy. Alternatively, prophylactic topical antifungal therapy might be of benefit.
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