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.

Healthcare-associated respiratory viral infections after discontinuing universal masking.

In November 2022, our pediatric hospital replaced the requirement for universal masking of all healthcare personnel and visitors in all clinical buildings with a requirement for masking only during patient encounters. Following this change, we observed an immediate, substantial, and sustained increase in healthcare-associated respiratory viral infections.

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.

Contrasting definitions and incidence of healthcare-associated respiratory viral infections in a pediatric hospital.

OBJECTIVE: To determine the difference in the incidence of healthcare-associated respiratory viral infection (HARVI) in a pediatric hospital depending on the definition used. DESIGN: Descriptive historical cohort study. SETTING AND PARTICIPANTS: Patients aged 0-21 years old who were admitted between July 2013 and June 2018 to a 490-bed primary to quaternary-care pediatric hospital serving northern Texas. METHODS: HARVI was defined using microbiologic confirmation, development of new symptoms while hospitalized, and exposure time greater than the minimum incubation period for each specific virus. Events that occurred following the maximum incubation period for that virus were classified as definite, otherwise they were classified as possible. This definition was compared to definitions using alternate timing of onset and symptomatology requirements. Data pertaining to demographics, diagnoses, and illness severity were collected. RESULTS: In total, 498 HARVIs (320 definite and 178 possible) were identified, with an incidence rate of 0.98 per 1,000 patient days (0.63 and 0.35, respectively). Rhinovirus or enterovirus and respiratory syncytial virus were the most identified viruses (58% and 10%, respectively). The median time from admission until HARVI was 10.5 days (interquartile range [IQR], 5-30 days). When alternate definitions were employed, the incidence of HARVI ranged from 0.96 to 2.00 per 1,000 admitted patient days. CONCLUSIONS: HARVI remain a common nosocomial infection in pediatric hospitals and the measured incidence is dependent on the definition used. Because of the endemic and pandemic potential of respiratory viruses, standardized definitions are needed to facilitate intra- and interhospital comparisons.

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.

Transfusion-Transmitted Malaria: Two Pediatric Cases From the United States and Their Relevance in an Increasingly Globalized World.

In non-endemic settings, transfusion-transmitted malaria (TTM) is rare but potentially fatal and becoming more common with globalization. We present two pediatric cases that demonstrate donor screening using questionnaires is subject to error and that TTM should be considered with fever following numerous transfusions in children, particularly sickle cell patients.

Harnessing the Electronic Health Record and Computerized Provider Order Entry Data for Resource Management During the COVID-19 Pandemic: Development of a Decision Tree.

BACKGROUND: The COVID-19 pandemic has resulted in shortages of diagnostic tests, personal protective equipment, hospital beds, and other critical resources. OBJECTIVE: We sought to improve the management of scarce resources by leveraging electronic health record (EHR) functionality, computerized provider order entry, clinical decision support (CDS), and data analytics. METHODS: Due to the complex eligibility criteria for COVID-19 tests and the EHR implementation-related challenges of ordering these tests, care providers have faced obstacles in selecting the appropriate test modality. As test choice is dependent upon specific patient criteria, we built a decision tree within the EHR to automate the test selection process by using a branching series of questions that linked clinical criteria to the appropriate SARS-CoV-2 test and triggered an EHR flag for patients who met our institutional persons under investigation criteria. RESULTS: The percentage of tests that had to be canceled and reordered due to errors in selecting the correct testing modality was 3.8% (23/608) before CDS implementation and 1% (262/26,643) after CDS implementation (P<.001). Patients for whom multiple tests were ordered during a 24-hour period accounted for 0.8% (5/608) and 0.3% (76/26,643) of pre- and post-CDS implementation orders, respectively (P=.03). Nasopharyngeal molecular assay results were positive in 3.4% (826/24,170) of patients who were classified as asymptomatic and 10.9% (1421/13,074) of symptomatic patients (P<.001). Positive tests were more frequent among asymptomatic patients with a history of exposure to COVID-19 (36/283, 12.7%) than among asymptomatic patients without such a history (790/23,887, 3.3%; P<.001). CONCLUSIONS: The leveraging of EHRs and our CDS algorithm resulted in a decreased incidence of order entry errors and the appropriate flagging of persons under investigation. These interventions optimized reagent and personal protective equipment usage. Data regarding symptoms and COVID-19 exposure status that were collected by using the decision tree correlated with the likelihood of positive test results, suggesting that clinicians appropriately used the questions in the decision tree algorithm.

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.

Low Utility of Pediatric Isolator Blood Culture System for Detection of Fungemia in Children: a 10-Year Review.

The use of the Wampole Isolator 1.5-ml pediatric blood culture tube for the detection of fungemia in children was assessed by a 10-year retrospective review at two pediatric hospitals, The Hospital for Sick Children in Toronto, Canada, and the Children's Medical Center of Dallas, Texas. Over this period, a total of 9,442 pediatric Isolator specimens were processed, with yeast or yeast-like organisms recovered in 297 (3.1%) of the specimens (151 [1.6%] unique clinical episodes) and filamentous or dimorphic fungi recovered in 31 (0.3%) of the specimens (25 unique clinical episodes). Only 18 of the 151 clinical episodes of fungemia attributable to yeast were not detected by automated blood culture systems. The majority of isolated yeast were Candida spp., which were usually detected by automated systems, whereas the most common non-Candida yeast was Malassezia furfur, which the automated system failed to detect. Filamentous or dimorphic fungi were detected in 25 episodes, of which only 9 (36%) episodes were deemed clinically significant after chart review, indicating that in the majority of cases (16/25, 64%) fungal isolation represented contamination. In five of the nine clinically significant episodes, the isolated fungus (Histoplasma capsulatum, Coccidioides immitis/posadasii, Fusarium oxysporum, Aspergillus spp., and Bipolaris spp.) was also identified in other clinical specimens. Over the 10-year study period, the use of the pediatric Isolator system, at the discretion of the treating physician, only rarely provided useful clinical information for the diagnosis of fungemia in children, with the exception of M. furfur and possibly endemic mycoses.

Competence in Streptococcus pneumoniae is a response to an increasing mutational burden.

Competence for genetic transformation in Streptococcus pneumoniae has previously been described as a quorum-sensing trait regulated by a secreted peptide pheromone. Recently we demonstrated that competence is also activated by reduction in the accuracy of protein biosynthesis. We have now investigated whether errors upstream of translation in the form of random genomic mutations can provide a similar stimulus. Here we show that generation of a mutator phenotype in S. pneumoniae through deletions of mutX, hexA or hexB enhanced the expression of competence. Similarly, chemical mutagenesis with the nucleotide analog dPTP promoted development of competence. To investigate the relationship between mutational load and the activation of competence, replicate lineages of the mutX strain were serially passaged under conditions of relaxed selection allowing random accumulation of secondary mutations. Competence increased with propagation in these lineages but not in control lineages having wild-type mutX. Resequencing of these derived strains revealed between 1 and 9 single nucleotide polymorphisms (SNPs) per lineage, which were broadly distributed across the genome and did not involve known regulators of competence. Notably, the frequency of competence development among the sequenced strains correlated significantly with the number of nonsynonymous mutations that had been acquired. Together, these observations provide support for the hypothesis that competence in S. pneumoniae is regulated in response to the accumulated burden of coding mutations in the bacterial genome. In contrast to previously described DNA damage response systems that are activated by physical lesions in the chromosome, this pneumococcal pathway may represent a unique stress response system that monitors the coding integrity of the genome.

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.

Competence in Streptococcus pneumoniae is regulated by the rate of ribosomal decoding errors.

UNLABELLED: Competence for genetic transformation in Streptococcus pneumoniae develops in response to accumulation of a secreted peptide pheromone and was one of the initial examples of bacterial quorum sensing. Activation of this signaling system induces not only expression of the proteins required for transformation but also the production of cellular chaperones and proteases. We have shown here that activity of this pathway is sensitively responsive to changes in the accuracy of protein synthesis that are triggered by either mutations in ribosomal proteins or exposure to antibiotics. Increasing the error rate during ribosomal decoding promoted competence, while reducing the error rate below the baseline level repressed the development of both spontaneous and antibiotic-induced competence. This pattern of regulation was promoted by the bacterial HtrA serine protease. Analysis of strains with the htrA (S234A) catalytic site mutation showed that the proteolytic activity of HtrA selectively repressed competence when translational fidelity was high but not when accuracy was low. These findings redefine the pneumococcal competence pathway as a response to errors during protein synthesis. This response has the capacity to address the immediate challenge of misfolded proteins through production of chaperones and proteases and may also be able to address, through genetic exchange, upstream coding errors that cause intrinsic protein folding defects. The competence pathway may thereby represent a strategy for dealing with lesions that impair proper protein coding and for maintaining the coding integrity of the genome. IMPORTANCE: The signaling pathway that governs competence in the human respiratory tract pathogen Streptococcus pneumoniae regulates both genetic transformation and the production of cellular chaperones and proteases. The current study shows that this pathway is sensitively controlled in response to changes in the accuracy of protein synthesis. Increasing the error rate during ribosomal decoding induced competence, while decreasing the error rate repressed competence. This pattern of regulation was promoted by the HtrA protease, which selectively repressed competence when translational fidelity was high but not when accuracy was low. Our findings demonstrate that this organism is able to monitor the accuracy of information used for protein biosynthesis and suggest that errors trigger a response addressing both the immediate challenge of misfolded proteins and, through genetic exchange, upstream coding errors that may underlie protein folding defects. This pathway may represent an evolutionary strategy for maintaining the coding integrity of the genome.

Frequent beneficial mutations during single-colony serial transfer of Streptococcus pneumoniae.

The appearance of new mutations within a population provides the raw material for evolution. The consistent decline in fitness observed in classical mutation accumulation studies has provided support for the long-held view that deleterious mutations are more common than beneficial mutations. Here we present results of a study using a mutation accumulation design with the bacterium Streptococcus pneumoniae in which the fitness of the derived populations increased. This rise in fitness was associated specifically with adaptation to survival during brief stationary phase periods between single-colony population bottlenecks. To understand better the population dynamics behind this unanticipated adaptation, we developed a maximum likelihood model describing the processes of mutation and stationary-phase selection in the context of frequent population bottlenecks. Using this model, we estimate that the rate of beneficial mutations may be as high as 4.8×10(-4) events per genome for each time interval corresponding to the pneumococcal generation time. This rate is several orders of magnitude higher than earlier estimates of beneficial mutation rates in bacteria but supports recent results obtained through the propagation of small populations of Escherichia coli. Our findings indicate that beneficial mutations may be relatively frequent in bacteria and suggest that in S. pneumoniae, which develops natural competence for transformation, a steady supply of such mutations may be available for sampling by recombination.

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.

Severe influenza B myocarditis and myositis.

OBJECTIVE: To report an influenza B infection with associated myocarditis and severe skeletal myositis. DESIGN: Case report. SETTING: Cardiac intensive care unit in a university-affiliated children's hospital. PATIENT: A 4-yr-old girl. RESULTS: The patient was successfully supported with extracorporeal membrane oxygenation for profound myocardial dysfunction and a combination of plasmapheresis and continuous venovenous hemodialysis for rhabdomyolysis and acute renal failure. CONCLUSIONS: This case provides a reminder that patients presenting with viral illness or myoglobinuria accompanied by renal failure, with or without associated myocarditis, may be demonstrating symptoms of influenza B.

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.