Rothia mucilaginosa Infections in Pediatric Cancer Patients.

We performed a retrospective study to determine the epidemiology of Rothia mucilaginosa infections among pediatric cancer patients. Over 20 years, 37 cases were identified; 27% developed complications, but there was no infection-related mortality. All cases were successfully treated with vancomycin.

Multiple NDM-5-Expressing Escherichia Coli Isolates From an Immunocompromised Pediatric Host.

BACKGROUND: Genes conferring carbapenem resistance have disseminated worldwide among Gram-negative bacteria. Here we present longitudinal changes in clinically obtained Escherichia coli isolates from 1 immunocompromised pediatric patient. This report demonstrates potential for antibiotic resistance genes and plasmids to emerge over time in clinical isolates from patients receiving intensive anticancer chemotherapy and broad-spectrum antibiotics. METHODS: Thirty-three isolates obtained over 7 months from 1 patient were included. Clinical data were abstracted from the medical record. For each isolate, studies included phenotypic antibacterial resistance patterns, sequence typing, bacterial isolate sequencing, plasmid identification, and antibiotic resistance gene identification. RESULTS: Sites of isolation included blood, wound culture, and culture for surveillance purposes from the perianal area. Isolates were of 5 sequence types (STs). All were resistant to multiple classes of antibiotics; 23 (69.6%) were phenotypically resistant to all carbapenems. The blaNDM-5 gene was identified in 22 (67%) isolates, all of ST-167 and ST-940, and appeared to coincide with the presence of the IncFII and IncX3 plasmid. CONCLUSIONS: We present unique microbiologic data from 33 multidrug-resistant E. coli isolates obtained over the course of 7 months from an individual patient in the United States. Two E. coli sequence types causing invasive infection in the same patient and harboring the blaNDM-5 gene, encoded on the IncX3 plasmid and the IncFII plasmid, were identified. This study highlights the emergence of multidrug-resistant bacteria on antibiotic therapy and the necessity of adequate neutrophil number and function in the clearance of bacteremia.

Clinical correlation of influenza and respiratory syncytial virus load measured by digital PCR.

Acute respiratory tract infections are a major cause of respiratory morbidity and mortality in pediatric patients worldwide. However, accurate viral and immunologic markers to predict clinical outcomes of this patient population are still lacking. Droplet digital PCR assays for influenza and respiratory syncytial virus (RSV) were designed and performed in 64 respiratory samples from 23 patients with influenza virus infection and 73 samples from 19 patients with RSV infection. Samples of patients with hematologic malignancies, solid tumors, or sickle cell disease were included. Clinical information from institutional medical records was reviewed to assess disease severity. Samples from patients with fever or respiratory symptoms had a significantly higher viral loads than those from asymptomatic patients. Samples from patients with influenza virus and RSV infection collected at presentation had significantly higher viral loads than those collected from patients after completing a course of oseltamivir or ribavirin, respectively. RSV loads correlated positively with clinical symptoms in patients ≤5 years of age, whereas influenza viral loads were associated with clinical symptoms, irrespective of age. Patients receiving antivirals for influenza and RSV had a significant reduction in viral loads after completing therapy. Digital PCR offers an effective method to monitor the efficacy of antiviral treatment for respiratory tract infections in immunocompromised hosts.

Formate acts as a diffusible signal to induce Salmonella invasion.

To infect an animal host, Salmonella enterica serovar Typhimurium must penetrate the intestinal epithelial barrier. This process of invasion requires a type III secretion system encoded within Salmonella pathogenicity island I (SPI1). We found that a mutant with deletions of the acetate kinase and phosphotransacetylase genes (ackA-pta) was deficient in invasion and SPI1 expression but that invasion gene expression was completely restored by supplying medium conditioned by growth of the wild-type strain, suggesting that a signal produced by the wild type, but not by the ackA-pta mutant, was required for invasion. This mutant also excreted 68-fold-less formate into the culture medium, and the addition of sodium formate to cultures restored both the expression of SPI1 and the invasion of cultured epithelial cells by the mutant. The effect of formate was pH dependent, requiring a pH below neutrality, and studies in mice showed that the distal ileum, the preferred site of Salmonella invasion in this species, had the appropriate formate concentration and pH to elicit invasion, while the cecum contained no detectable formate. Furthermore, we found that formate affected the major regulators of SPI1, hilA and hilD, but that the primary routes of formate metabolism played no role in its activity as a signal.