Approval was obtained from the ethics and research committee of the University of Port Harcourt Teaching Hospital and informed consent was obtained from the parent or care givers of the neonates.
A prospective study was carried out in the Special Care Baby Unit (SCBU) of the University of Port Harcourt Teaching Hospital, Rivers State, Nigeria, within a 6 month period from May to November, 2007. All newborns with clinical suspicion or risk factors for sepsis were consecutively recruited into the study. Sepsis was suspected in the presence of clinical features like fever, respiratory distress, poor feeding, jaundice, hypothermia, convulsion, vomiting, irritability, lethargy and abdominal distension. Risk factors for sepsis included outborn delivery, perinatal asphyxia, preterm delivery, prolonged rupture of membranes, maternal peripartum pyrexia and foul smelling amniotic fluid.
Infants of mothers who had intrapartum antibiotics within 1 week of delivery as well as babies with prior antibiotic therapy for present illness before admission into the SCBU were excluded from the study.
C-reactive protein was estimated qualitatively using the Lorne CRP latex kit manufactured by the Lorne laboratories Limited (Great Britain) with catalogue number, 041100. The specific performance characteristics of the Lorne CRP latex reagent was standardized to detect serum CRP levels at or above 6 mg/l, which is considered the lowest concentration of clinical significance. Half a milliliter of venous blood was collected in plain bottles and centrifuged. C-reactive protein was estimated using a drop of undiluted serum placed onto the circle of the agglutination slide with the use of disposable pipettes provided in the kit. One drop of CRP latex reagent was added to the drop of serum and the broad end of the pipette was used to spread the latex reagent over the entire area of the test circle. The agglutination slide was gently tilted backwards and forwards approximately once every two seconds for two minutes. The results were read using the positive and negative controls as reference for agglutination. Visible agglutination of latex particles constituted a positive result which indicated a level of CRP > 6 mg/l while negative result was the reverse. After the results were read, the glass slide was rinsed with distilled water and air dried properly for re-use.
Blood culture was done for all recruited babies using two milliliter of venous blood collected from a peripheral vein after adequate skin preparation and before the commencement of antibiotics. The blood was aseptically introduced into aerobic and anaerobic culture media. The specimens were processed according to standard methods in the microbiology laboratory . Inoculated blood culture media were considered negative if there was no growth after continuous incubation for up to 7 days, subcultures being made each day. Antibiotic sensitivity was done using Kirby-Bauer disc diffusion method .
The results of laboratory investigations and other relevant data such as age, sex, birth weight and gestational age as well as symptoms present and risk factors for sepsis of recruited babies were recorded in a proforma. The results were analysed using the statistical package, SPSS version 14.0. The sensitivity, specificity, positive and negative predictive values of CRP were calculated.