Role of body surface cultures in prediction of sepsis in a neonatal intensive care unit

Late-onset sepsis caused by Gram-negative bacteria in very low birth weight infants: a systematic review

INTRODUCTION

Very low birth weight (VLBW) infants are highly susceptible to late-onset sepsis (LOS). Compared to Gram-positive bacteria, Gram-negative bacteria are less common to cause LOS, but are associated with a more severe clinical manifestation, higher mortality, and increased risk of neonatal morbidity. So far, the clinical picture of late-onset Gram-negative sepsis (LOGNS) in VLBW infants has not been elucidated. An up-to-date and thorough understanding of the clinical picture of LOGNS in VLBW infants is important to optimize current anti-sepsis protocols. Areas covered: Literature published in the last three decades was searched for data on the epidemiology, pathogen profile, risk factors, clinical manifestations, laboratory parameters, mortality, and short-term and long-term morbidity of LOGNS in VLBW infants. Expert opinion: Gram-negative bacteria are major contributors of neonatal morbidity and mortality in VLBW infants with LOS, potentially posing a significant disease burden. Unravelling the pathogen-specific clinical picture of LOGNS and the underlying mechanisms is of particular interest. VLBW infants may differ from more mature neonates in terms of disease burden and clinical course of LOGNS. Epidemiologic studies aided by advanced molecular techniques may help to develop anti-sepsis protocols specialized for VLBW infants, with strategies targeting Gram-negative bacteria.

Routine screening for colonization by Gram-negative bacteria in neonates at intensive care units for the prediction of sepsis: systematic review and meta-analysis

BACKGROUND

At neonatal intensive care units, sepsis due to Gram-negative bacteria is an important cause of morbidity and mortality. The benefits of routine microbiological screening of neonatal body surface to predict and prevent sepsis are controversial.

AIM

To evaluate the prognostic value of neonatal body surface screening for colonization with Gram-negative bacteria for the prediction of late-onset sepsis.

METHODS

A systematic review was performed, including studies of any design that reported data to calculate prognostic accuracy of surface screening for the prediction of late-onset sepsis. Risk of bias was assessed and a meta-analysis performed. Evidence quality was appraised using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.

FINDINGS

Eight studies (all cohort design) were identified as eligible. Studies were performed in six countries in Europe, Asia, and North America and comprised a total of 4829 participants. All studies were at high risk of bias. Pooled sensitivity of body surface screening to predict late-onset sepsis was 41% (95% confidence interval: 17-70), whereas pooled specificity was 56% (34-76) (hierarchical summary receiver operating characteristics (HSROC) model). Subgroup analyses showed higher pooled estimates for specificity but not sensitivity when screening focused on Escherichia coli or Klebsiella pneumoniae. GRADE evidence quality was very low.

CONCLUSION

Limited evidence of very low quality exists regarding the prognostic value of neonatal screening for late-onset sepsis. Carefully planned and conducted prospective studies, including randomized trials, are needed to clarify the potential value of this measure for the prediction and prevention of late-onset sepsis.

Identification of bacteria and potential sources in neonates at risk of infection delivered by Caesarean and vaginal birth

Neonatal gastric aspirates (NGA) are routinely screened in UK hospitals to investigate fetal/neonatal infections associated with cases of adverse pregnancy outcome (APO). The aim of this study was to describe and compare the microbiology of NGA from Caesarean and vaginal deliveries using molecular methods, and to evaluate other possible clinical and non-clinical variables that may have determined the presence of the bacteria in the samples. The value of using NGA and molecular methods to investigate potential pathogens associated with the risk of early infection was also evaluated. Bacteria were identified by a combined molecular approach on the basis of the 16S rRNA gene using both clone analysis and denaturing gradient gel electrophoresis. A total of 43 and 34 different species were identified in the vaginal (n = 121) and Caesarean (n = 119) deliveries, respectively; 26 of the species observed (51 %) were common to both modalities, although usually less prevalent in the Caesarean cases. Multivariate analysis confirmed an association between infection and prolonged rupture of membranes in vaginal deliveries (odds ratio = 5.7, 95 % confidence interval = 1.1-29.0). Various associations between infection and given variables were also shown, including labour, intrapartum antibiotic prophylaxis, and time and place of sample collection. The molecular methods allowed identification of a range of bacteria and potential sources not previously observed in NGA, including possible genito-urinary, gastrointestinal and oral pathogens. NGA represents a valuable sample for investigating potential pathogens associated with APO and the risk of early infection in neonates using molecular methods.

Routine skin cultures in predicting sepsis pathogens among hospitalized preterm neonates in Bangladesh

BACKGROUND

Few studies from developing countries have examined sensitivity, specificity, positive and negative predictive values of routine surface cultures.

OBJECTIVES

The purpose of the study was to determine sensitivity, specificity, and positive predictive value (PPV) of skin cultures among preterm neonates admitted to Dhaka Shishu Hospital, Bangladesh.

METHODS

The study was nested within a prospective, randomized, controlled trial of emollient treatment in Dhaka Shishu Hospital, Bangladesh. A total of 497 preterm infants <33 weeks gestational age and <72 h of chronological age were enrolled, and the sensitivity, specificity, and PPV of skin cultures were analyzed among 3,765 blood-skin culture pairs, wherein the skin culture was obtained within 13 days before the blood culture.

RESULTS

Overall sensitivity, specificity, and PPV were 16, 38, and 5%, respectively. PPV during Klebsiella pneumoniae outbreaks was about 9%, and the inguinal site had the highest PPV (6%) among the three skin sites. Acinetobacter spp.- and K. pneumoniae-specific PPVs were 28 and 23%, respectively. PPV was <2% for Candida spp., Enterobacter spp., and Salmonella spp.

CONCLUSION

Routine skin culture is inefficient in predicting the pathogen responsible for sepsis among premature neonates, even in a developing country setting, where the burden of bacterial infection is relatively high. Skin cultures are also of limited utility during K. pneumoniae outbreaks, and are not recommended.

Impact of surveillance stool culture guided selection of antibiotics in the management of pediatric small bowel transplant recipients

Surveillance stool cultures (SSC) have been used in immunocompromised populations to predict the organisms associated with invasive infections and aid in the selection of empiric antibiotic regimens. To evaluate the utility of this approach in pediatric small bowel transplant (SBT) recipients, we conducted a retrospective review of 33 patients who underwent SBT, 16 of whom had SSC done. In no case was the same organism isolated from SSC and subsequent blood, peritoneal fluid or wound cultures. In the first month post-transplantation, blood cultures were positive in 44% and 35% of patients that had and did not have SSC done, respectively (p = 0.73); peritoneal fluid cultures in 44% and 65% (p = 0.30); and wound cultures in 44% and 24% (p = 0.28). There were no significant differences among both groups in time to first infection, duration of ICU stay following SBT, graft survival or long-term patient survival. We conclude that SSC-guided antibiotic selection does not have a significant impact on the incidence of invasive infections in the first month following SBT or on specific indicators of patient outcome. This suggests that empiric antibiotic regimens should be selected based on clinical presentation and hospital flora and susceptibility patterns.

Infection control practices reduce nosocomial infections and mortality in preterm infants in Bangladesh

OBJECTIVE

The skin is a potential source for invasive infections in neonates from developing countries such as Bangladesh, where the level of environmental contamination is exceedingly high. A randomized controlled trial was conducted from 1998 to 2003 in the Special Care Nursery of a tertiary hospital in Bangladesh to test the effectiveness of topical emollient therapy in enhancing the skin barrier of preterm neonates less than 33 weeks of gestational age. In the initial months of the study, the infection and mortality rates were noted to be unacceptably high. Therefore, an infection control program was introduced early in the trial to reduce the rate of nosocomial infections.

STUDY DESIGN

After a comprehensive review of neonatal care practices and equipment to identify sources of nosocomial infections, a simple but comprehensive infection control program was introduced that emphasized education of staff and caregivers about measures to decrease risk of contamination, particularly hand-washing, proper disposal of infectious waste, and strict asepsis during procedures, as well as prudent use of antibiotics.

RESULTS

Infection control efforts resulted in declines in episodes of suspected sepsis (47%), cases of culture-proven (61%) sepsis, patients with a clinical diagnosis of sepsis (79%), and deaths with clinical (82%) or culture-proven sepsis (50%).

CONCLUSION

The infection control program was shown to be a simple, low-cost, low-technology intervention to reduce substantially the incidence of septicemia and mortality in the nursery.

Outbreak investigation in a neonatal intensive care unit

Outbreaks of healthcare-acquired infection can be devastating in neonatal intensive care units. Neonates are especially susceptible hosts because of prematurity of organ systems, low birth weight, and the use of invasive devices. This article outlines methodologies for infection surveillance and recognition of outbreak events. Principles of infection control in the neonatal intensive care unit are reviewed in reference to an outbreak setting, and a multidisciplinary team approach to developing a plan of action to halt the outbreak and find the source is discussed. Epidemiologic methods for determining the geographical extent and timeline of an outbreak, potential reservoirs or a common source of infection are reviewed.

Prediction of nosocomial sepsis in neonates by means of a computer-weighted bedside scoring system (NOSEP score)

OBJECTIVE

To develop an easy-to-use bedside scoring system, composed of clinical variables, hematologic variables, and risk factors of infection, to predict nosocomial sepsis in neonatal intensive care unit patients.

SETTING

A neonatal intensive care unit in a university hospital, Antwerp, Belgium.

PATIENTS

Over 2 yrs, we analyzed two groups of patients. First, we prospectively studied 104 episodes of presumed nosocomial sepsis in 80 neonates (derivation cohort), and then we retrospectively studied 50 episodes in 39 neonates (validation cohort).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We developed two versions of a scoring system to predict nosocomial sepsis in sick neonates. The first scoring system (NOSEP-1 score) was based on 15 clinical, 12 laboratory, and 17 historical variables potentially connected with infection; the second one (NOSEP-2 score) also included the culture results of central vascular catheters. Based on the odds ratios of all independent variables, an additive and weighted score was developed and validated in a cohort of 39 patients screened for nosocomial sepsis in the same center. The NOSEP-1 score consisted of three laboratory variables (C-reactive protein > or =14 mg/L, thrombocytopenia <150 x 10(9)/L, and neutrophil fraction >50%), one clinical factor (fever >38.2 degrees C [100.8 degrees F]), and one risk factor (parenteral nutrition for > or =14 days). The NOSEP-2 score consisted of the same variables plus catheter-hub and catheter insertion site colonization data. Receiver operating characteristic curve analysis demonstrated good predictor performance of the NOSEP-1 score (area under the curve [Az] = 0.82 +/- 0.04 [SEM]) and NOSEP-2 score (Az = 0.84 +/- 0.04, p < .05). We checked whether a complex computer-generated scoring system (CD-1 and CD-2 scores) based on the original numerical values of the items used in NOSEP-1 and NOSEP-2 would improve the prediction of nosocomial sepsis. The analysis showed the accuracy of bedside NOSEP-1 and NOSEP-2 scores to be comparable with the more cumbersome computer-generated CD-1 and CD-2 scores (receiver operating characteristic curve, Az: CD-1 score = 0.81 +/- 0.04, p = .69, and CD-2 score = 0.86 +/- 0.04, p = .96). Finally, in the validation cohort, we showed that the developed scoring system has a good prediction potential for nosocomial sepsis (Hosmer-Lemeshow goodness-of-fit test, chi2 [19] = 16.34, p > .75).

CONCLUSIONS

The simple bedside scoring system NOSEP-1 composed of C-reactive protein, neutrophil fraction, thrombocytopenia, fever, and prolonged parenteral nutrition exposure provides a valuable tool for early identification of nosocomial sepsis. Its predictive power can be improved by adding central vascular catheter insertion site and hub colonization to the score.