Nia Taylor

High incidence of pulmonary bacterial co-infection in children with severe respiratory syncytial virus (RSV) bronchiolitis

Background: Respiratory syncytial virus (RSV) is the most common cause of viral lower respiratory tract infections (LRTI). Viral LRTI is a risk factor for bacterial superinfection, having an escalating incidence with increasing severity of respiratory illness. A study was undertaken to determine the incidence of pulmonary bacterial co-infection in infants and children with severe RSV bronchiolitis, using paediatric intensive care unit (PICU) admission as a surrogate marker of severity, and to study the impact of the co-infection on morbidity and mortality. Methods: A prospective microbiological analysis was made of lower airways secretions on all RSV positive bronchiolitis patients on admission to the PICU during three consecutive RSV seasons. Results: One hundred and sixty five children (median age 1.6 months, IQR 0.5–4.6) admitted to the PICU with RSV bronchiolitis were enrolled in the study. Seventy (42.4%) had lower airway secretions positive for bacteria: 36 (21.8%) were co-infected and 34 (20.6%) had low bacterial growth/possible co-infection. All were mechanically ventilated (median 5.0 days, IQR 3.0–7.3). Those with bacterial co-infection required ventilatory support for longer than those with only RSV (p<0.01). White cell count, neutrophil count, and C-reactive protein did not differentiate between the groups. Seventy four children (45%) received antibiotics prior to intubation. Sex, co-morbidity, origin, prior antibiotics, time on preceding antibiotics, admission oxygen, and ventilation index were not predictive of positive bacterial cultures. There were 12 deaths (6.6%), five of which were related to RSV. Conclusions: Up to 40% of children with severe RSV bronchiolitis requiring admission to the PICU were infected with bacteria in their lower airways and were at increased risk for bacterial pneumonia.

Gut overgrowth with abnormal flora: the missing link in parenteral nutrition-related sepsis in surgical neonates.

Background and aims: Patients receiving parenteral nutrition are at risk of septicaemia. Intestinal dysmotility and impaired gut immunity due to parenteral nutrition promote bacterial overgrowth. Gut overgrowth with aerobic Gram-negative bacilli (AGNB) impairs systemic immunity. The aim of this study was to determine the potential role of gut overgrowth with AGNB in the pathogenesis of septicaemia related to parenteral nutrition.Methods: A prospective 5 y study of surgical infants less than 6 months of age was undertaken. Surveillance samples of the oropharynx and gut were obtained at the start of parenteral nutrition and thereafter twice weekly, to detect AGNB carriage. Blood cultures were taken on clinical indication only.Results: Two-hundred and eight infants received parenteral nutrition for 6271 days (median 13 days, range 1–512 days). The incidence of AGNB carriage was 42%, whilst the septicaemia rate was 15%. Eighty-four percent of septicaemic infants carried AGNB, whilst 16% never carried AGNB (P<0.005). Carriage developed significantly earlier than septicaemia.Conclusions: The incidence of septicaemia was significantly greater in the subset of abnormal carriers. Although gut overgrowth with abnormal flora reflects illness severity, the fact that it preceded septicaemia implicates AGNB overgrowth, per se, as a contributory factor in the development of septicaemia related to parenteral nutrition. Prevention is unlikely to be successful if it ignores the abnormal flora.

Microbial Gut Overgrowth Guarantees Increased Spontaneous Mutation Leading to Polyclonality and Antibiotic Resistance in the Critically Ill

Polyclonality is defined as the occurrence of different genotypes of a bacterial species. We are of the opinion that these different clones originate within the patient. When infections and outbreaks occur, the terms of polyclonal infections and polyclonal outbreaks have been used, respectively. The origin of polyclonality has never been reported, although some authors suggest the acquisition of different clones from different animate and inanimate sources. We think that the gut of the critically ill patient with microbial overgrowth is the ideal site for the de-novo development of new clones, following increased spontaneous mutation.

Descontaminación digestiva selectiva. ¿Por qué no aplicamos la evidencia en la práctica clínica?

Selective digestive decontamination (SDD) is a prophylactic strategy whose objective is to reduce the incidence of infections, mainly mechanical ventilation associated pneumonia in patients who require intensive cares, preventing or eradicating the oropharyngeal and gastrointestinal carrier state of potentially pathogenic microorganisms. Fifty-four randomized clinical trials (RCTs) and 9 meta-analysis have evaluated SDD. Thirty eight RCTs show a significant reduction of the infections and 4 of mortality. All the meta-analyses show a significant reduction of the infections and 5 out of the 9 meta-analyses report a significant reduction in mortality. Thus, 5 patients from the ICU with SDD must be treated to prevent pneumonia and 12 patients from the ICU should be treated to prevent one death. The data that show benefit of the SDD on mortality have an evidence grade 1 or recommendation grade A (supported by at least two level 1 investigations). The aim of this review is to explain the pathogeny of infections in critical patients, describe selective digestive decontamination, analyze the evidence available on it efficacy and the potential adverse effects and discuss the reasons published by the experts who advise against the use of SDD, even though it is recognized as the best intervention evaluated in intensive cares to reduce morbidity and mortality of the infections.

Is Selective Digestive Decontamination Useful in Controlling Aerobic Gram-Negative Bacilli Producing Extended Spectrum Beta-Lactamases?

AIMS To identify outbreak episodes of either carriage or infection due to extended spectrum beta-lactamases producing aerobic Gram-negative bacilli (AGNB-ESBL); to establish whether AGNB-ESBL, sensitive to tobramycin, become resistant over time; and to evaluate the impact of selective decontamination of the digestive tract (SDD) on abnormal carriage of AGNB-ESBL. DESIGN AND SETTING All children admitted to the pediatric intensive care unit (PICU) over a 12-month period had biweekly surveillance cultures of throat and rectum and diagnostic cultures when clinically indicated. All AGNB were tested for ESBL, and the positive isolates were sent for molecular typing. The PICU uses SDD (parenteral cefotaxime and enteral polymyxin E/tobramycin) to control abnormal carriage. Patients who had at least one AGNB-ESBL were included in the study. RESULTS During the study period, 1,101 children were admitted to the PICU. There were 39 patients (3.5%) with a total of 236 cultures positive for AGNB-ESBL. Twenty-eight patients (2.5%) were carriers, and 11 (1%) had proven infections. Organisms isolated from the first culture were 14 patients with Klebsiella pneumoniae, 8 with Enterobacter cloacae, 7 with Citrobacter freundii, 5 with Klebsiella oxytoca, and 5 with Escherichia coli. In the first sample, 59% of isolates showed tobramycin resistance. Molecular typing confirmed that there were five different strains of K. pneumoniae and that similar strains were not isolated in the same period. CONCLUSIONS SDD is an effective measure to control AGNB-ESBL and to avoid outbreak episodes of either carriage or infection. When tobramycin resistance is found, replacing it with another aminoglycoside based on antibiogram may be more effective in achieving AGNB clearance.

Selective decontamination of the digestive tract in critically ill children: systematic review and meta-analysis.

Objective: We examined the impact of selective decontamination of the digestive tract on morbidity and mortality in critically ill children. Data Sources: We searched MEDLINE, EMBASE, the Cochrane Register of Controlled Trials, and previous meta-analyses. Study Selection: We included all randomized controlled trials comparing administration of enteral antimicrobials in selective decontamination of the digestive tract with or without a parenteral component with placebo or standard therapy used in the controls. Data Extraction: The primary end point was the number of acquired pneumonias. Secondary end points were number of infections and overall mortality. Odds ratios were pooled with the random effect model. Data Synthesis: Four randomized controlled trials including 335 patients were identified. Pneumonia was diagnosed in five of 170 patients (2.9%) for selective decontamination of the digestive tract and 16 of 165 patients (9.7%) for controls (odds ratio 0.31; 95% confidence interval 0.11–0.87; p = .027). Overall mortality for selective decontamination of the digestive tract was 13 of 170 (7.6%) vs. control, 11 of 165 (6.7%) (odds ratio 1.18; 95% confidence interval 0.50–2.76; p = .70). In three studies (n = 109), infection occurred in ten of 54 (18.5%) patients on selective decontamination of the digestive tract and 24 of 55 (43.6%) in the controls (odds ratio 0.34; 95% confidence interval 0.05–2.18; p = .25). Conclusions: In the four available pediatric randomized controlled trials, selective decontamination of the digestive tract significantly reduced the number of children who developed pneumonia.

Nutritional implications of gut overgrowth and selective decontamination of the digestive tract

Patients requiring parenteral nutrition (PN) are at risk of infection. Impaired immunity due to an underlying disease process and/or malnutrition, combined with therapeutic interventions including PN, and the presence of a foreign body, the intravenous catheter, renders them prone to septicaemia (Pun & Reen, 1992). Recent studies suggest that this septicaemia may be primarily due to gut-derived micro-organisms, rather than to external contamination of the intravenous catheter (Kurkchubasche

Selective decontamination of the digestive tract in burn patients: an evidence-based maneuver that reduces mortality.

We would like to thank Dr. Silvestri et al for their comments on selective decontamination of the digestive tract (SDD) in burn patients. Their detailed review of available data in burn patients will prove informative to burn practitioners throughout the world. We agree that multiple SDD trials have indicated benefit in decreasing ventilator-associated pneumonia incidence and reducing mortality in surgical patients, including burns. We have tried to make that point clear in our guidelines. Despite multiple positive SDD trials conducted in Europe and elsewhere, this practice has gained little support in intensive care units (ICUs) in the United States. We believe the deterrents to widespread acceptance of SDD in North America have been 1) heterogeneity of methods for decontamination, 2) inconsistent results in surgical patient populations, and, most importantly, 3) the fear that it will promote emergence and spread of antimicrobial resistant microorganisms. To better understand the impact of systematic antibiotic administration to large patient cohorts, longitudinal ecological ICU studies are also needed to substantiate the efficacy observed in the reported clinical trials. Interestingly, although the recent Dutch multicenter trial demonstrated a decreased incidence of multiresistant organisms on rectal cultures with SDD, its follow-up ecological study in the 13 participating ICUs now reports a twofold increase in the incidence of antibiotic resistance in the intestinal and the respiratory tracts. These findings are consistent with prior studies, indicating major shifts in the microbial ecology of the ICU with SDD. We, thus, believe that our caution against “the prophylactic use of antibiotics in units with high levels of antibiotic resistance” remains justified in light of the aggregate data. We believe the best way to resolve this controversy and impact practice patterns would be a prospective, randomized trial of SDD in burn ICUs recruited from multiple countries.

Selective digestive decontamination reduces ventilator-associated tracheobronchitis

We read with interest the systematic review and metaanalysis on frequency, prevention, outcome and treatment of ventilator-associated tracheobronchitis (VAT) by Agrafiotis et al. We are surprised by the authors’ finding that selective digestive decontamination (SDD) does not prevent VAT (odds ratio [OR]: 0.62, 95% confidence interval [CI]: 0.31e1.26). We believe that an inadequate literature search is the reason for this result. The authors found five randomized controlled trials (RCTs) of SDD including about 800 patients. Remarkably, sixteen years ago Kollef analysed seven RCTs including 1043 patients and

Antibiotic-resistant bacteria and infection in children with cerebral palsy requiring mechanical ventilation.

Introduction: Severe and chronic illness can alter the bacterial flora carried in the oropharynx and gut. There are little data on the bacterial flora of children with chronic neurologic impairment. Objectives: To assess carriage of abnormal bacterial flora, antibiotic-resistant bacteria, infection, and mortality in children with cerebral palsy (CP) admitted for pediatric intensive care. Design: Prospective observational single center cohort study. Setting: Twenty-bed regional pediatric intensive care unit (PICU) in a university-affiliated tertiary referral children’s hospital. Patients: All children with an established diagnosis of CP admitted to PICU and ventilated for four or more days during a 6-yr period. Measurements: Surveillance samples of throat and rectum were taken at admission to PICU and twice a week thereafter. Diagnostic samples were obtained on clinical indication. Main Results: Fifty-three children with a total of 77 admissions were included. Most (90%) of the children with CP had moderate to severe functional limitations. Eighty-nine percent of the children with CP (47/53) carried abnormal bacterial flora/potential pathogens, most frequently Pseudomonas and Klebsiella species. Forty-seven percent (22/47) had antibiotic-resistant bacteria. Thirty-five children (66%) developed 86 infections during their PICU admission. Lower airways and blood were the two most commonly infected sites—Pseudomonas aeruginosa and coagulase-negative Staphylococci, the predominant infecting microorganisms. Sixty-five percent (56/86) of infections were primary endogenous infections, 21% (18/86) exogenous, and 9% (8/86) secondary endogenous. Carriage of abnormal bacterial flora, antibiotic-resistant bacteria, and infection rate was significantly higher than that of children of comparative age without CP ventilated for four or more days on PICU. Nine (17%) of the children with CP died in PICU and 4 of the deaths were infection related. Conclusions: In children with moderate to severe chronic neurologic impairment admitted to PICU, there is a high rate of carriage of abnormal bacteria/potential pathogens, antibiotic-resistant bacteria, and infection.