Study design and area
This prospective and cross-sectional study was conducted over an 8-month period in 2014 at the Special Care Baby Unit (SCBU) of the University of Abuja Teaching Hospital (UATH). The UATH is a 350-bed tertiary hospital that runs primary and secondary in addition to tertiary health care services. The hospital is in Gwagwalada Area Council of the Federal Capital Territory (FCT), Abuja; North Central region of Nigeria.12 It is the main referral centre for neonatal care in north-central region. UATH has annual deliveries of 2,500 babies and an average annual SCBU admission of 968 babies using the year 2012 records. The SCBU is 30-bedded unit with separate inborn and outborns sections manned by a neonatologist, four senior and junior residents each, six house officers and twenty nurses with further training in neonatology. One thousand, three hundred and twenty-two (1322) newborns were delivered in the center during the study period.
Management overview of neonatal sepsis in UATH
On presentation to the SCBU, historical assessment and detailed physical examination are done. After collection of the relevant samples, the subjects are commenced on empiric antibiotics of amoxicillin/clavulanic acid at 15 mg/kg body weight and gentamicin at 2.5 mg /kg body weight per dose every 12 hours. Necessary changes are made based on clinical response and/or result of blood culture and sensitive test. Sometimes, third generation cephalosporin mostly cefotaxime and ceftazidime are used for severe infections and in babies who presented with relevant clinical features and/or clinical examination suggestive of meningitis. Other supportive measures where necessary are also initiated.
Sample size determination and sampling technique
The sample size was calculated using the Cochrane formula,13 based on a prevalence of neonatal sepsis from a previous,11 a confidence level of 95% and a level of precision estimated to be ± 5% of the assumed prevalence in addition to a non-response rate of 10%. This resulted to a minimum sample size of 331.Consecutive neonates who met the inclusion criteria were enrolled into the study. The inclusion criteria included neonates admitted to the SCBU with features suggestive of sepsis (such as fever, jaundice, lethargy, poor suck etc) and those whose parents/guardians gave consent for enrolment of their newborn in the study. Excluded from this study were newborns with major congenital malformations (this was to avoid mortality not directly linked to sepsis) and neonates who have had administration of antibiotics for more than 24 hours, prior to presentation to the hospital.
Blood and data collection method
All the neonates that were enrolled into the study had their blood specimens drawn for culture before treatment was initiated or latest within 12 hours of admission. The skin over the site of blood collection was cleaned thoroughly with 70% alcohol, allowed to dry and cleaned with Povidone iodine for two minutes before blood sample was collected. Two millilitres of blood were drawn by trained assistants from a peripheral vein. One millilitre was for blood culture, and the other for complete blood count (CBC). A structured questionnaire was used to collect relevant information for each newborn. The questionnaire was pre-tested at Federal Staff Hospital, Jabi in Abuja. It was then analysed for completeness and ease of completing the questionnaire. The neonatal information collected included age, sex, weight on admission, place of delivery, and specific clinical features such as fever, jaundice, hypothermia, hyperthermia, poor skin colour, respiratory distress, feed intolerance, bleeding diathesis, and abdominal distension etc.
Measures and definition of term
- Weight was measured using a standardized Bassinet scale, Salter TM Model 180, made in England, with a sensitivity of 0.05kg and calibrated in 0.1kg. Before placing the baby in the weighing scale, the scale was readjusted to zero each time for a new reading. All clothing was removed including the diaper, in order not to affect the weighing scale reading.
- Length of each baby enrolled in to the study, was measured using inelastic tape measure, by placing the baby on a hard surface, lying supine and the lower limbs fully stretched.
- Occipito-frontal circumference (OFC) was measured using inelastic tape measure. The frontal and occipital bony prominences were identified before measurements were taken using an inelastic tape measure.
- Gestational age of each baby was determined using modified Ballard score.14
- The newborns family’s Socio-economic status was determined using Olusanya’s social economic classification.15
- Neonatal sepsis for the sake of this study was defined as blood stream infection with positive blood culture result.
Blood specimen bottles collected from newborns admitted to the SCBU for probable sepsis were put within one hour of collection into BACTEC 9050 (Becton-Dickinson™ New Jersey, USA) automated system, by a trained dedicated microbiologist to the BACTEC laboratory. It was then monitored for growth by the microbiologist, as flagged by the machine, every 24 hours, for maximum of 5 days, when the bottles were expelled by the automated machine. The BACTEC 9050 system, which accommodates 50 test vials, features an extremely small footprint (only 4 1/4 square feet of tabletop needed, and no external computer required).16
For gram staining procedure, a single colony was picked and emulsified in a drop of normal saline on a clean glass slide and allowed to dry. The slide was then fixed with heat, stained with crystal violet for one minute, followed by procedure mordant with Lugo’s iodine solution for 30 seconds. The slide was then washed with water. The process of decolourisation was carried out with acetone for one to two seconds before washing with water. Counter-staining was with safranin, added for two minute and later washed with water and allowed to air dry. The slide was then examined microscopically. Gram positive bacteria (GPB) were presumed if the identified pathogen appeared dark purple, while a red colour suggested Gram negative bacteria (GNB).
Antimicrobial susceptibility testing was done using modified Kirby-Bauer disc diffusion method,17 using multidisc antibiotics (Oxoid Ltd, Hampshire, UK), as described by the Clinical Laboratory Standards. The degree of inhibition of bacterial growth around the antibiotics in the impregnated discs was noted and the result was reported as sensitive or resistant. For determining sensitivity, the following anti-microbial discs were used; Ampicillin 10 µg, Ceftazidime 30 µg, Augmentin (Amoxicillin 20 µg; Clavulanic acid 10 µg), 30 µg, Vancomycin 30 µg, Cefotaxime 30 µg, Ceftriaxone 30 µg, Gentamicin10µg, ofloxacin 5 µg and Imepenam10µgm.
A complete blood count (CBC) with white blood cell differential count was done for each subject. The complete blood count was processed in the general laboratory of University of Abuja Teaching Hospital. The CBC sample bottle was placed in the BC- 3200 autolizer machine Mindray.™ The machine extracts the required volume of blood for auto analysis and then displayed the result on the monitor. Other investigation done included serum bilirubin estimation for babies with visible jaundice, while serum electrolytes, urea, creatinine and glucose were also evaluated in babies with perinatal asphyxia and neonatal seizures. For the sake of this study, normal white cell count on CBC was defined as cell count between 9–30,000/mm3 (or 9–30 × 109/L). Values above or below this range were considered abnormal.
The raw data were inputted into the Excel spread sheet and analysed using the Statistical Package for Social Sciences (SPSS) version 20 Microsoft USA. Frequency tables were generated for simple proportions and descriptive analysis.