Discontinuation of Contact Precautions for Methicillin-resistant Staphylococcus aureus in a Pediatric Healthcare System.

BACKGROUND: Many hospitals caring for adult patients have discontinued the requirement for contact precautions (CP) for patients with methicillin-resistant Staphylococcus aureus (MRSA) infection or colonization without reported negative effects. It is not clear whether this experience can be extrapolated to pediatric facilities. METHODS: CP for MRSA were discontinued in all locations except the neonatal intensive care unit at a 3-hospital pediatric healthcare system in September 2019. All hospitalized patients underwent surveillance for LabID healthcare facility-onset MRSA infections. Analysis was done using interrupted time series (ITS) from September 2017 through August 2023 and aggregate before-and-after rate ratios. RESULTS: There were 234 incident healthcare facility-onset MRSA infections during 766 020 patient days of surveillance. After discontinuation of CP for MRSA there was no change in the ITS slope (0.06, 95% CI: -0.35 to 0.47, P = .78) or intercept (0.21, 95% CI: -0.36 to 0.78, P = .47) of the LabID healthcare facility-onset MRSA infection incidence density rate. Additionally, there was no change in the aggregate incidence density rate of these MRSA LabID events (aggregate rate ratio = 0.98, 95% CI: 0.74 to 1.28). MRSA nasal colonization among patients being screened before cardiac surgery did not change (aggregate rate ratio = 0.94, 95% CI: 0.60 to 1.48). The prevalence rate of contact isolation days decreased by 14.0%. CONCLUSIONS: Discontinuation of CP for pediatric patients with MRSA was not associated with increased MRSA infection over 4 years. Our experience supports considering discontinuation of CP for MRSA in similar pediatric healthcare settings in the context of good adherence to horizontal infection prevention measures.

Retrospective Observational Assessment of the Impact of Cefepime Prophylaxis in Neutropenic Pediatric Patients With Acute Myelogenous Leukemia.

BACKGROUND: The potential for cefepime prophylaxis to reduce bloodstream infections (BSIs) in pediatric patients with acute myelogenous leukemia (AML) has been incompletely characterized. METHODS: A retrospective quasi-experimental study of patients under 21 years of age admitted with AML from 2010 through 2018 at two affiliated pediatric tertiary-care hospitals before and after the adoption of routine cefepime prophylaxis for afebrile AML patients during profound neutropenia. RESULTS: The rate of BSIs per 1000 neutropenia days was significantly lower in the prophylaxis group than the baseline group (2.6 vs 15.5, incidence rate ratio [IRR] 0.17, 95% CI 0.09-0.32). Interrupted time-series analysis showed that a sharp reduction in BSIs coincided with the implementation of prophylaxis. Bacteremia with viridans group streptococci was frequent in the baseline group but not observed after adopting prophylaxis. Despite the increased use of cefepime, the rate of cefepime-nonsusceptible BSIs per 1000 neutropenia days decreased (1.6 vs 4.1, IRR 0.40, 95% CI 0.16-0.99). The median number of febrile neutropenia episodes per patient also decreased in the prophylaxis group, as did the proportion of patients admitted to the intensive care unit (ICU) (22/51 (43.1%) vs 26/38 (68.4%); risk difference -25.3%, 95% CI -44.4 to -2.8). A trend was observed toward an increased proportion of patients with Clostridioides difficile infection in the prophylaxis group (10/51 (19.6%) vs 3/38 (7.9%); risk difference 11.7%, 95% CI -3.4 to 29.0). CONCLUSIONS: Cefepime prophylaxis was associated with a significant reduction in BSIs, febrile neutropenia, and ICU admission among pediatric AML patients.

Community Airborne Mold Spore Counts and Invasive Fungal Disease Risk Among Pediatric Hematological Malignancy and Stem Cell Transplant Patients.

BACKGROUND: Patients with hematological malignancies and hematopoietic stem cell transplantation (HSCT) recipients are at risk of developing invasive fungal infections, but the quantitative risk posed by exposure to airborne mold spores in the community has not been well characterized. METHODS: A single-institution, retrospective cohort study was conducted of pediatric patients treated for hematological malignancies and HSCT recipients between 2014 and 2018. Patients with invasive fungal disease (IFD) due to molds or endemic fungi were identified using published case definitions. Daily airborne mold spore counts were obtained from a local National Allergy Bureau monitoring station and tested for association with IFD cases by 0-inflated Poisson regression. Patients residing outside the region or with symptom onset more than 2 weeks after admission were excluded from the primary analysis. RESULTS: Sixty cases of proven or probable IFD were identified, of whom 47 cases had symptom onset within 2 weeks of admission and were therefore classified as possible ambulatory onset. The incidence of ambulatory-onset IFD was 1.2 cases per 10000 patient-days (95% CI, 0.9-1.7). A small excess of ambulatory-onset IFD was seen from July through September, during which period spore counts were highest, but this seasonal pattern did not reach statistical significance (P = .09). No significant association was found between IFD cases and community mold spore counts over intervals from 1 to 6 weeks before symptom onset. CONCLUSIONS: There was no significant association between IFD cases and community airborne mold spore counts among pediatric hematological malignancy and HSCT patients in this region.

Risk Factors for Wound Infections after Deformity Correction Surgery in Neuromuscular Scoliosis.

OBJECTIVE: This study aims to elucidate surgical risk factors in neuromuscular scoliosis (NMS) with respect to wound site infection after spinal fusion. METHODS: A retrospective review was performed of all patients treated surgically for NMS between January 2008 and December 2016 (minimum 6 months' follow-up). A sub-cohort of 60 patients with minimum 2 years of follow-up data was also analyzed. RESULTS: In 102 patients (53 boys and 49 girls), the mean age at surgery was 14.0 years (SD ±2.7). Mean follow-up was 2.53 years (±1.66), and mean time to presentation of infection was 2.14 months (±4.95). The overall perioperative complication rate was 26.5%, with 14.7% of patients developing deep wound infection. Gram-negative bacteria were responsible for 60% of infections; 20% were Gram positive, and 20% involved both types. Pulmonary comorbidities (p = 0.007), pre- to postoperative increase in weight (p = 0.010), exaggerated lumbar lordosis at follow-up (p = 0.008), history of seizures (p = 0.046), previous myelomeningocele repair (p = 0.046), and previous operations (p = 0.013) were significant risk factors for infection. CONCLUSION: Our data suggest that in the pediatric population treated surgically for NMS, wound infection is strongly associated with postoperative increase in body weight, residual lumbar lordosis, pulmonary comorbidity, history of myelomeningocele repair, seizures, and previous operations.

The HtrA protease from Streptococcus pneumoniae digests both denatured proteins and the competence-stimulating peptide.

The HtrA protease of Streptococcus pneumoniae functions both in a general stress response role and as an error sensor that specifically represses genetic competence when the overall level of biosynthetic errors in cellular proteins is low. However, the mechanism through which HtrA inhibits development of competence has been unknown. We found that HtrA digested the pneumococcal competence-stimulating peptide (CSP) and constituted the primary extracytoplasmic CSP-degrading activity in cultures of S. pneumoniae. Mass spectrometry demonstrated that cleavage predominantly followed residue Phe-8 of the CSP-1 isoform of the peptide within its central hydrophobic patch, and in competition assays, both CSP-1 and CSP-2 interacted with HtrA with similar efficiencies. More generally, analysis of ß-casein digestion and of digestion within HtrA itself revealed a preference for substrates with non-polar residues at the P1 site. Consistent with a specificity for exposed hydrophobic residues, competition from native BSA only weakly inhibited digestion of CSP, but denaturation converted BSA into a strong competitive inhibitor of such proteolysis. Together these findings support a model in which digestion of CSP by HtrA is reduced in the presence of other unfolded proteins that serve as alternative targets for degradation. Such competition may provide a mechanism by which HtrA functions in a quality control capacity to monitor the frequency of biosynthetic errors that result in protein misfolding.

Bacteriocin activity of Streptococcus pneumoniae is controlled by the serine protease HtrA via posttranscriptional regulation.

The blp locus of a type 6A strain of Streptococcus pneumoniae encodes a two-peptide bacteriocin, pneumocin MN, which mediates intraspecies competition during mouse nasopharyngeal colonization. This locus is regulated by a quorum-sensing mechanism consisting of a dedicated two-component regulatory system and a peptide pheromone. Like most clinical isolates, this type 6A strain can be separated into opaque and transparent colony variants, each playing a different role during pneumococcal infection. In this study, we show that the blp locus is differentially regulated at the posttranscriptional level in pneumococcal opacity variants. Transparent and opaque variants produce equivalent amounts of blpMNPO transcript when stimulated with a synthetic pheromone, but transparent variants have no pneumocin MN-mediated inhibitory activity while opaque variants produce large zones of inhibitory activity. The differential regulation in opacity variants is driven by the two-component regulatory system CiaRH via its regulation of the serine protease HtrA. Transparent mutants deficient in CiaH or HtrA show increased pneumocin MN-mediated inhibition. In addition, these mutants demonstrate alterations in their dose response to a synthetic peptide pheromone, suggesting that HtrA activity impacts pneumocin MN production at the level of signaling. This, in addition to its known effects on competence, suggests that HtrA is a pleiotropic regulator whose protease activity affects several important bacterial pathways. The complex regulation of pneumocins may allow the pneumococcus to reserve the secretion of active peptides for situations where the benefit of their inhibitory activity outweighs the cost of their production.

An outbreak of Serratia marcescens bacteremia after general anesthesia.

OBJECTIVE: To investigate an outbreak of Serratia marcescens bacteremia among patients after general anesthesia. DESIGN: A case-control study. SETTING: A 304-bed, pediatric teaching hospital. PATIENTS: Twenty-three pediatric patients who developed S. marcescens bacteremia within 2 weeks after general anesthesia between June 15 and September 22, 1999, were compared with 46 age-matched control-patients who had undergone procedures on the same clinical services of the hospital during the same period. RESULTS: Cases were distributed over a wide range of surgical services and were not correlated with exposure to any of the surgical, anesthesia, or nursing staff. Case-patients were significantly more likely than control-patients to have received cefazolin (odds ratio [OR], 11.1; 90% confidence interval [CI90], 1.9 to 24.3) or to have had perioperative placement of a central vascular catheter (OR, 4.2; CI90, 1.2 to 18.8). The timing of the procedures of patients who subsequently developed S. marcescens bacteremia was significantly associated with the shifts of one or more of five operating room technicians (OR, 2.9 to 6.8) who were responsible for preparing intravenous fluids used both to reconstitute perioperatively administered antibiotics and to prime central vascular catheter assemblies. CONCLUSIONS: Our findings are consistent with a pattern of intermittent contamination due to periodic breaches in sterile technique, rather than a point-source of contamination. The unique challenges that such a procedural breakdown presents to an epidemiologic investigation are discussed. This outbreak stresses the importance of providing comprehensive training in antisepsis when multifunctional personnel are incorporated into an operating room work environment.