Interpreting positive cultures of endotracheal aspirates: factors associated with treatment decisions in ventilated neonates

Ventilator-Associated Pneumonia in the Neonatal Intensive Care Unit

See Bonus NeoBriefs videos and downloadable teaching slides Intubated infants in the NICU are at risk of developing ventilator-associated pneumonia (VAP), a common type of health care-associated infection. The Centers for Disease Control and Prevention developed guidelines for diagnosing VAP in patients younger than 1 year, which include worsening gas exchange, radiographic findings, and at least 3 defined clinical signs of pneumonia. VAP in infants is treated with empiric antibiotics selected based on local resistance patterns and individualized patient data. Many NICUs have implemented prevention bundles in an effort to decrease VAP by ensuring the cleanest environment for intubated neonates (hand hygiene, sterile handling of equipment), positioning of infants to prevent gastric reflux, and constantly reevaluating for extubation readiness. Although these prevention bundle elements are intuitive and generally low risk, none are based on strong research support. This article reviews the epidemiology, pathogenesis, diagnosis, treatment, and prevention of VAP in NICU patients, focusing on recent evidence, highlighting areas of emerging research, and identifying persistent knowledge gaps.

Lack of utility of tracheal aspirates in the management of suspected pneumonia in intubated neonates

OBJECTIVES

To evaluate the utility of tracheal aspirates in suspected pneumonia in intubated neonates and to measure the burden of antibiotic use associated with a positive tracheal aspirate culture.

DESIGN

Retrospective cohort study between January 2016 and December 2017.

SETTING

A level IV neonatal intensive care unit (NICU).

PATIENTS

Intubated patients with a tracheal aspirate culture.

METHODS

Data on temporally associated clinical measures of illness, laboratory and radiographic testing, and clinical demographic information were analyzed.

RESULTS

Positive tracheal aspirate cultures were associated with lower birth weight and a normal immature to total neutrophil ratio (I/T ratio). Positive tracheal aspirates were not significantly associated with clinical, laboratory, or radiographic markers used in clinical practice to screen for infection. Despite the lack of positive clinical associations, a positive tracheal aspirate culture was associated with increased risk of prolonged antibiotic exposure.

CONCLUSION

These findings suggest that positive tracheal aspirates do not always represent clinical infection and may result in unnecessary antibiotic exposure.

Bacterial colonisation of the endotracheal tube in ventilated very preterm neonates: A retrospective cohort study

AIM

To determine the rate, type and timing of bacterial endotracheal tube (ETT) colonisation in neonates born <32 weeks gestational age (GA); and if bacterial colonisation is associated with chronic lung disease (CLD), septicaemia, length-of-stay or mortality.

METHODS

All intubated newborns born <32 weeks GA were included. Endotracheal aspirates were routinely obtained three times-per-week. Cohort was divided into three colonisation groups: no growth, normal respiratory flora only, significant bacteria. Logistic regression was performed to identify if ETT bacterial colonisation was associated with CLD, septicaemia or mortality. A general linear model was fitted for length-of-stay.

RESULTS

ETT aspirates were sent from 1054 infants: no growth n = 319, only normal respiratory flora n = 357, and significant bacteria n = 378. ETTs became colonised in 70%, most in the first week of life (82%). Most grew normal respiratory flora (642 infants). In those with significant bacteria, 40% grew Gram-negative species; Klebsiella in 34%. Staphylococcus aureus grew in 104 patients. Adjusted odds ratios for CLD (43% of cohort) compared with no growth were, for normal respiratory flora, 0.58 (95% confidence interval (CI) 0.34-0.99) and, for significant bacteria, 0.48 (95% CI 0.24-0.93). With no overall association between colonisation group and CLD in the adjusted model P = 0.07. The odds of septicaemia (10% of cohort) were 4.50 (95% CI 1.98-10.23, P < 0.001) times greater for significant bacteria compared with no growth. No significant associated was found with mortality or length-of-stay.

CONCLUSIONS

Bacterial colonisation of ETTs is common. It is associated with more septicaemia. There was no significant association with CLD, longer admission or mortality.

Neonatal Ventilator Associated Pneumonia: A Quality Improvement Initiative Focusing on Antimicrobial Stewardship

Background and Aims: Neonatal ventilator associated pneumonia (VAP) is a common nosocomial infection and a frequent reason for empirical antibiotic therapy in NICUs. Nonetheless, there is no international consensus regarding diagnostic criteria and management. In a first step, we analyzed the used diagnostic criteria, risk factors and therapeutic management of neonatal VAP by a literature review. In a second step, we aimed to compare suspected vs. confirmed neonatal VAP episodes in our unit according to different published criteria and to analyze interrater-reliability of chest x-rays. Additionally, we aimed to evaluate the development of VAP incidence and antibiotic use after implementation of multifaceted quality improvement changes regarding antimicrobial stewardship and infection control (VAP-prevention-bundle, early-extubation policy, antimicrobial stewardship rounds). Methods: Neonates until 44 weeks of gestation with suspected VAP, hospitalized at our level-III NICU in Lucerne from September 2014 to December 2017 were enrolled. VAP episodes were analyzed according to 4 diagnostic frameworks. Agreement regarding chest x-ray interpretation done by 10 senior physicians was assessed. Annual incidence of suspected and confirmed neonatal VAP episodes and antibiotic days were calculated and compared for the years 2015, 2016, and 2017. Results: 17 studies were identified in our literature review. Overall, CDC-guidelines or similar criteria, requesting radiographic changes as main criteria, are mostly used. Comparison of suspected vs. confirmed neonatal VAP episodes showed a great variance (20.4 vs. 4.5/1,000 ventilator-days). The interrater-reliability of x-ray interpretation was poor (intra-class correlation 0.25). Implemented changes resulted in a gradual decline in annual VAP incidence and antibiotic days from 2015 compared with 2017 (28.8 vs. 7.4 suspected episodes/1,000 ventilator-days, 5.5 vs. 0 confirmed episodes/1,000 ventilator-days and 211 vs. 34.7 antibiotic days/1,000 ventilation-days, respectively). Conclusion: The incidence of suspected VAP and concomitant antibiotic use is much higher than for confirmed VAP, therefore inclusion of suspected episodes should be considered for accurate evaluation. There is a high diagnostic inconsistency and a low reliability of interpretation of chest x-rays regarding VAP. Implementation of combined antimicrobial stewardship and infection control measures may lead to an effective decrease in VAP incidence and antibiotic use.

Special Considerations in Neonatal Mechanical Ventilation

Care of infants supported with mechanical ventilation is complex, time intensive, and requires constant vigilance by an expertly prepared health care team. Current evidence must guide nursing practice regarding ventilated neonates. This article highlights the importance of common language to establish a shared mental model and enhance clear communication among the interprofessional team. Knowledge regarding the underpinnings of an open lung strategy and the interplay between the pathophysiology and individual infant's response to a specific ventilator strategy is most likely to result in a positive clinical outcome.

Preventing ventilator-associated pneumonia in children: an evidence-based protocol

Ventilator-associated pneumonia, the second most common hospital-acquired infection in pediatric intensive care units, is linked to increased morbidity, mortality, and lengths of stay in the hospital and intensive care unit, adding tremendously to health care costs. Prevention is the most appropriate intervention, but little research has been done in children to identify necessary skills and strategies. Critical care nurses play an important role in identification of risk factors and prevention of ventilator-associated pneumonia. A care bundle based on factors, including evidence regarding the pathophysiology and etiology of pneumonia, mechanical ventilation, duration of ventilation, and age of the child, can offer prompts and consistent prevention strategies for providers caring for children in the pediatric intensive care unit. Following the recommendations of the Centers for Disease Control and Prevention and adapting an adult model also can support this endeavor. Ultimately, the bedside nurse directs care, using best evidence to prevent this important health care problem.

Findings of the International Nosocomial Infection Control Consortium (INICC), Part II: Impact of a multidimensional strategy to reduce ventilator-associated pneumonia in neonatal intensive care units in 10 developing countries

Design. Before-after prospective surveillance study to assess the efficacy of the International Nosocomial Infection Control Consortium (INICC) multidimensional infection control program to reduce the rate of occurrence of ventilator-associated pneumonia (VAP). Setting. Neonatal intensive care units (NICUs) of INICC member hospitals from 15 cities in the following 10 developing countries: Argentina, Colombia, El Salvador, India, Mexico, Morocco, Peru, Philippines, Tunisia, and Turkey. Patients. NICU inpatients. Methods. VAP rates were determined during a first period of active surveillance without the implementation of the multidimensional approach (phase 1) to be then compared with VAP rates after implementation of the INICC multidimensional infection control program (phase 2), which included the following practices: a bundle of infection control interventions, education, outcome surveillance, process surveillance, feedback on VAP rates, and performance feedback on infection control practices. This study was conducted by infection control professionals who applied National Health Safety Network (NHSN) definitions for healthcare-associated infections and INICC surveillance methodology. Results. During phase 1, we recorded 3,153 mechanical ventilation (MV)-days, and during phase 2, after the implementation of the bundle of interventions, we recorded 15,981 MV-days. The VAP rate was 17.8 cases per 1,000 MV-days during phase 1 and 12.0 cases per 1,000 MV-days during phase 2 (relative risk, 0.67 [95% confidence interval, 0.50-0.91]; [Formula: see text]), indicating a 33% reduction in VAP rate. Conclusions. Our results demonstrate that an implementation of the INICC multidimensional infection control program was associated with a significant reduction in VAP rate in NICUs in developing countries.