Clinical features of sepsis caused by different types of pathogens in preterm infants

Objective To investigate the clinical features of sepsis caused by gram negative or positive pathogens and funguses in preterm infants.Methods The clinical data of 140 premature infants with sepsis admitted to preterm neonatal intensive care unit of Bayi Children's Hospital from October 2008 to June 2011 were collected and analyzed retrospectively.The clinical features of sepsis caused by different types of pathogens in preterm infants were compared by SPSS 18.0 software.Comparison of measurement data was conducted by one way ANOVA,and comparison between groups was performed by LSD method.Rates among groups were compared by Chi-square test or Fisher's exact test.Results Of 140 preterm infants with sepsis,70 cases were caused by gramnegative bacteria,36 by gram positive bacteria,and 34 by funguses.The top three gram negative sepsis pathogens were Klebsiella pneumonia (55.7 ％,n =39),Escherichia coli (20.0 ％,n =14) and Acinetobacter baumannii (12.9％,n =9).The top three gram positive sepsis pathogens were Staphylococcus epidermidis (36.1％, n =13), Staphylococcus hominis (22.2％, n =8) and Staphylococcus haemolyticus (19.4％,n=7).The top four fungus sepsis pathogens were Candida parapsilosis (44.1％,n=15),Candida albicans (23.5％,n=8),Candida famata (8.8％,n=3)and Cryptococcus laurentii (8.8％,n=3).There were no significant differences in delivery mode,fetal distress, asphyxia, fetal growth restriction, meconium-stained amniotic fluid, maternal infection,hypertensive disorder complicating pregnancy,gestational diabetes mellitus,peripherally inserted central venous catheter,mechanical ventilation before infection,cortical hormon（e） (e)xposure,intraventricular hemorrhage, periventricular leukomalacia, peripheral blood immature-to-total neutrophil ratio,recovery time of platelet,the time of infection onset,fever and hypothermia among the three groups (P＞0.05).While there were differences in gestational age [(30.4 ± 2.3) weeks,(31.0±2.4) weeks and (29.5±1.8) weeks,F=4.317,P=0.015],birth weight [(1512.5±406.0) g,(1563.8±485.4) g and (1328.8±303.2) g,F=3.190,P=0.044],premature rupture of membranes rate [24.3％ (17/70),16.7％ (6/36) and 44.1％ (15/34),X2 =7.241,P=0.034],rate of surgery during neonatal period [12.9％ (9/70),38.9％ (14/36) and 11.8％ (4/34),X2 =10.430,P=0.005],the incidence of lowperfusion [64.3％ (45/70),30.6％ (11/36) and 50.0％ (17/34),X2 =10.922,P=0.004],rate of frequent apnea [67.1％ (47/70),36.1％ (13/36) and 55.9％ (19/34),X2=9.341,P=0.009],incidence of low white blood cell [21.4％ (15/70),8.3％ (3/36) and 32.4％ (11/34),X2=6.267,P=0.042],thrombocytopenia rate [64.3％ (45/70),16.7％ (6/36)and 67.6％ (23/34),X2 =25.576,P=0.000],white blood cell count [(19.9± 17.8) × 109/L,(19.9±14.3) ×109/L and (12.0±8.1)×109/L,F=3.553,P=0.031],platelet count [(159.1±169.1) ×109/L,(311.8±179.7) ×109/L and (121.4±123.4) ×109/L,F=14.140,P=0.000],C-reactive protein [(76.8±70.1) mg/L,(16.6±27.2) mg/L and (31.8±27.5) mg/L,F=17.248,P=0.000],incidence of central nervous system infections [1.4％ (1/70),2.8％ (1/36) and 11.8％(4/34),X2 =5.066,P=0.043],retinopathy rate of premature infants [38.6％ (27/70),50.0％(18/36) and 67.7％ (23/34),X2 =8.780,P=0.012],bronchopulmonary dysplasia rate [8.6％ (6/70),11.1％ (4/36) and 26.5％ (9/34),X2=5.837,P=0.044] and mortality [11.4％ (8/70),0.0％ (0/36) and 2.9％ (1/34),X2 =5.361,P =0.042] among the three groups.Conclusions There are significant differences among sepsis caused by different types of pathogens in risk factors (gestational age,birth weight,premature rupture of membranes and neonatal surgical procedures),clinical manifestations,infection indexes and prognosis in preterm infants.Sepsis caused by gram negative bacilli liked to present shock with obvious increasing of C-reactive protein; and the prognosis is the worst.Central nervous system infection is more common in fungal infection; and the rates of retinopathy of prematurity and bronchopulmonary dysplasia are higher.Sepsis caused by gram positive cocci have mild clinical manifestations and infection indexes variations and better prognosis. Key words: Sepsis; Gram-negative bacteria; Gram-positive cocci; Fungi; Infant,premature