Trial design and settings
We performed a controlled parallel randomized and single-blind clinical trial, conducted at the NICU of three public maternity hospitals in São Luís, northeastern Brazil: Hospital of the Federal University of Maranhão (HUMI), Marly Sarney Maternity Hospital (MMS) and Benedito Leite Maternity Hospital (MBL).
Sample
A target sample of 100 patients (including possible losses to follow-up) was calculated considering a 30% difference in the percentage of decolonization between the intervention and control groups, with 80% power and 5% probability of type I error, assuming that percentage of decolonization in the control group is 20% and setting the ratio between groups at 1:1.
Participants
Eligible subjects were singleton neonates, born at the three institutions of the study, weighing 1300 to 1800 g and clinically stable. They had been hospitalized for more than 4 days and their nostrils were colonized by Staphylococcus aureus or coagulase-negative Staphylococcus resistant to methicillin-oxacillin. Mothers were not colonized in their nostrils by these bacteria and did not present skin diseases.
Included infants and hospital participation
A total of 247 (21 from HUMI; 180 from MMS; 46 from MBL) dyads (mother and newborn) were assessed for eligibility from April 2008 to December 2010. The different number of patients assessed for eligibility in the three study hospitals was due to differences in size and number of hospitalizations in these units. Moreover, in the HUMI unit, data collection had to be discontinued because the skin-to-skin position was instituted as routine care, making randomization impossible.
A total of 102 dyads were found to be eligible for the study.
Excluded infants
The remaining 145 newborns were not included in the study, 121 because they were not colonized with MRSA/MRSE and/or because their mothers were colonized with MRSA/MRSE at their first nostrils’ culture. One mother refused to participate and 23 did not participate for other reasons (Figure 1).
We did not include infants below 1300 g because they were often subjected to routine umbilical catheterization. Infants over 1800 g were excluded because they remained, in general, less than four days in the NICU. Those who underwent surgery for congenital problems, ostomy and urethral catheter drainage were not included as well.
Allocation
For allocation of participants, a computer-generated random number list was used. The allocation sequence was concealed by using sealed opaque black envelopes. After identification of each eligible dyad the chief researcher in the presence of the mother in the NICU opened an envelope. Groups were then formed (intervention group, n = 53; control n = 49).
Mothers and researchers were aware of group allocation (intervention or control), whereas the individuals who carried out the bacterial cultures and assessed the results were kept blind to the allocation.
Interventions
Mothers in the study group were instructed to have skin-to-skin contact with their newborns in the NICU twice a day (morning and evening) for 60 minutes, for seven days (including weekends). Adherence to the intervention was verified daily and recorded on sheets. Skin-to-skin contact consisted of placing the infant wearing only a diaper in prone decubitus, upright against his mother's chest, between the breasts. The infant was restrained in position by a strap that tied him/her to his/her mother [18] and was covered with the mother’s clothes. NICU had its temperature maintained at 26 degrees Celsius.
All mothers underwent a routine hand washing procedure before entering the NICU. They did not have their chests scrubbed before skin-to-skin contact. The mother sat in a chair positioned by the side of the infants’ bed. Standing nurses transferred the babies to sitting mothers. A team member who accompanied the intervention monitored infant temperature, heart rate and oxygen saturation to ensure babies’ safety [19,20]. Both groups received routine nursing care such as nutrition, hygiene, bathing and diapering, organization of parents’ visit, breastfeeding and administration of drugs. Mothers were encouraged to touch, breast feed her baby and get him/her as soon as possible in her lap, under staff supervision. Fathers did not hold infants in skin-to-skin contact.
All mothers in the intervention group successfully completed 60 minutes of skin-to-skin contact for just one hour twice a day.
Outcomes
The primary endpoint for testing the efficacy of intervention was colonization status of newborns’ nostrils after 7 days of intervention (decolonization of the infants’ nostril from multi-drug resistant Staphylococcus). Birth weight (measured at birth using digital scales with 5 gram precision), gestational age (according the the last menstrual date), type of delivery (vaginal/cesarean section), sex (male/female), birth weight for gestational age (classified according to Alexander’s curve) [21], 5th min Apgar score and need for resuscitation (at delivery room) and antibiotic use (from birth to the end of data collection) were compared between groups.
Interim analysis and protocol of interruption
No interim analysis was performed. There was no need to interrupt the trial for safety reasons.
Data collection
The material for the first bacterial culture was collected at baseline from both mothers and their newborns by a nasal swab performed on the fourth, fifth or sixth day of hospitalization, by a lab technician using a cotton swab soaked in sterile saline solution that was introduced into the nasal cavity of newborns and their mothers. The results of the culture from the first collection of nasal swabs determined the eligibility of the dyads for randomization.
Decolonization was checked by a second swab collection seven days after the beginning of the intervention. The second culture was collected only from infants. No other site of culture collection was considered in addition to the nostrils. Collected materials were placed in Stuart transport medium and sent to the laboratory for seeding in 5% Agar sheep blood and Brain Heart Infusion (BHI) for 24 to 48 h at 35 °C. Cultures were considered to be positive when Staphylococcus was isolated by the catalase, coagulase and VitekbioMerieux® automated method. Antimicrobial susceptibility testing was performed by Kirby Bauer disc diffusion, following recommendations from the CLSI/2008. For the samples considered to be “methicillin-oxacillin resistant” the E-test was used for confirmation of sensitivity to vancomycin.
All newborns who remained colonized after the second nostril culture, performed 7 days after randomization, were decolonized according to the recommendations of the Hospital Infection Control Committee of each unit at the end of the 7 days.
Statistical analysis
Following CONSORT guidelines, we did not perform a statistical test comparing differences in baseline characteristics because of randomization.
For the analysis of primary outcome, we first applied the Mantel-Haenszel chi-square test for two proportions. In a second analysis we fitted a generalized linear model for the binomial family with a log link to control for possible confounding effects of small for gestational age birth, antibiotic use, need for resuscitation, sex and cesarean delivery. These variables were chosen based on the magnitude of differences in their distributions between the intervention and the control group. A p-value of less than 0.05 was considered statistically significant. All tests were two-tailed. To evaluate the clinical relevance of the outcome we calculated the Number Needed to Treat (NNT). Intention to treat analysis was not performed because there were no losses to follow-up.
Ethical considerations
The study was approved by the Ethics Research Committee of the University Hospital, Federal University of Maranhão, Brazil, under No. 33104-1504/07 on behalf of all three participating hospitals. Each hospital’s director gave institutional permission for the study. All newborns’ mothers read a Plain Language Statement, written in plain, simple language, explaining the purpose, methods, demands, risks and potential benefits of the research and signed a written informed consent form. This trial was registered with ClinicalTrials.gov under number NCT01498133.