Clinical and Microbiologic Assessment of Cases of Pediatric Community-associated Clostridium difficile Infection Reveals Opportunities for Improved Testing Decisions.

BACKGROUND: Most children with Clostridium difficile infection (CDI) experience community onset of CDI symptoms. METHODS: We retrospectively compared hospital-onset healthcare facility-associated CDI cases to community-associated (CA) CDI cases diagnosed by Cepheid Xpert tcdB polymerase chain reaction (PCR) at an academic children's hospital over a 1-year period. Saved stools from CDI cases additionally underwent anaerobic stool culture and multiplex gastrointestinal pathogen PCR testing. RESULTS: Compared with 25 hospital-onset healthcare facility-associated CDI cases, the 74 CA-CDI cases were more frequently <2 years old (18% vs. 0%, P = 0.034) and less frequently had antibiotic exposure in the past 30 days (26% vs. 88%, P < 0.0001), proton pump inhibitor exposure (16% vs. 36%, P = 0.036) or a gastrostomy tube (11% vs. 32%, P = 0.013). Among children diagnosed with CA-CDI, 19 (26%) had no identified CDI risk factors (immunocompromised; gastrostomy tube; recent antibiotic, proton pump inhibitor or inpatient/outpatient healthcare exposures). Clinical testing for viral pathogens was uncommon among children thought to have CA-CDI. Multiplex PCR testing of saved stool samples failed to identify C. difficile among 23% of cases diagnosed with CA-CDI by the Cepheid Xpert tcdB PCR assay. CDI antibiotic therapy was provided to nearly all patients testing positive by tcdB PCR irrespective of CDI risk factors. CONCLUSIONS: Many children diagnosed with CA-CDI by PCR lack CDI risk factors and have discordant results when additional CDI testing methods are performed, suggesting overdiagnosis of CDI in children with community-onset diarrhea. More selective CDI testing of low-risk pediatric patients is needed to more accurately diagnose CDI and limit unnecessary CDI antibiotic treatment in children.

Multi-center evaluation of the adenovirus R-gene US assay for the detection of adenovirus in respiratory samples.

BACKGROUND: Adenoviruses (AdV) cause a variety of upper and lower respiratory tract infections, with the potential for severe outcomes, especially in persons with immune suppression or other underlying diseases. The ADENOVIRUS US R-gene (AdV R-gene, Argene/bioMérieux) is a FDA cleared real-time PCR assay that utilizes primers and fluorescent probes that target a conserved region of the hexon gene and an internal control DNA. OBJECTIVES: This prospective multi-center study evaluated the clinical performance of AdV R-gene for AdV detection in respiratory specimens from symptomatic patients of all ages. STUDY DESIGN: Nucleic acids from nasopharyngeal washes/aspirates (NPW/A; n=393) and NP flocked swabs (NPS, Copan) (n=1183) were extracted using NucliSENS easyMAG (bioMérieux) and AdV R-gene PCR was performed using the SmartCycler (Cepheid). AdV R-gene results were compared to R-Mix culture (Quidel/Diagnostic Hybrids). For a subset of samples (n=946) AdV R-gene and R-Mix results were also compared to A549 cell culture. RESULTS: In first intention analysis for NPS the AdV R-gene positive percent agreement (PPA), and negative percent agreement (NPA) were 91.7% and 96.2%, respectively, and for NPW/A were 100% and 94.4%, respectively, compared to R-Mix culture. In second intention analysis, discordant samples only were tested with an AdV real-time PCR assay (Viracor-IBT Labs) and amplicon sequencing. For NPS, the sensitivity, specificity, PPV and NPV for AdV R-gene were 98.9%, 100%, 100%, and 99.9%, respectively and for R-Mix culture were 51.7%, 99.7%, 93.8%, and 96.3%, respectively. For NPW/A, the sensitivity, specificity, PPV and NPV for AdV R-gene were 100%, 99.7%, 97.6%, and 100%, respectively, and for R-Mix culture were 52.5%, 100%, 100%, and 94.9%, respectively. Overall, AdV was detected by AdV R-gene and R-Mix in 7.4% and 4.1% NPS, respectively, and in 10.7% and 5.3% NPW/A, respectively. Children 5yr and younger had the highest rates of AdV infections. In a subset of specimens (n=946) the sensitivity of AdV R-gene, R-Mix, and A549 cell culture were 95.0%, 55.4% and 66.3%. CONCLUSIONS: AdV R-gene is sensitive and specific for the detection of AdV in NPW/A and NPS samples. AdV R-gene is simple to use and provides a rapid time to results (within 2.5-3h).

Detection of human parechovirus (HPeV)-3 in spinal fluid specimens from pediatric patients in the Chicago area.

BACKGROUND: The human parechoviruses (HPeV) have recently been recognized as important viral pathogens causing various illnesses including sepsis and meningitis in children. However, data from the United States is limited. OBJECTIVES: To better understand the epidemiology of HPeV in the United States and its role in pediatric disease through detection and typing of the virus in cerebrospinal fluid specimens. STUDY DESIGN: Four hundred and twenty-one spinal fluid samples collected from 373 patients ranging in age from 1 day to 18 years were tested using a real-time reverse transcription-PCR assay. The specimens were originally collected for routine viral and bacterial testing to assist in the diagnosis of meningitis or sepsis. Amplification products of the VP1 region in the virus genome were sequenced to identify the parechovirus type. RESULTS: Ten positive specimens were identified from 10 different patients. All ten samples were typed as HPeV3 and were negative for bacteria by culture, and for enterovirus and herpes simplex virus by PCR. All of the HPeV3-infected patients were young infants ranging in age from 6 to 59 days. Infants in whom HPeV3 was detected had significantly decreased peripheral white blood cell counts. Positive specimens were all from the summer and early fall. CONCLUSIONS: HPeV3 infection of the central nervous system is found in very young infants in certain years during the summer and early fall, and is associated with leukopenia. Real-time RT-PCR is an effective tool for rapid detection of these infections, and could help prevent unnecessary hospitalization and antibiotic use in HPeV infected infants. More widespread use of this tool in diagnosing HPeV infection would aid in further clarifying the prevalence of this disease in the United States.

Analysis and characterization of antiviral drug-resistant cytomegalovirus isolates from solid organ transplant recipients.

The development of cytomegalovirus (CMV) disease and subsequent emergence of drug-resistant strains was examined in a large group of solid organ transplant recipients; drug-resistant CMV was detected in a total of 30 transplant recipients (20 lung, 5 kidney, 4 heart, and 1 liver). Drug resistance was confirmed both phenotypically and genotypically. The sequences of drug-resistant CMV strains from the same patient differed from drug-susceptible baseline sequences only at single sites previously confirmed to confer drug resistance. At least 1 isolate from each patient had a mutation in the UL97 phosphotransferase coding sequence. Mutations in the DNA polymerase gene were found in 6 of 38 sequenced strains. Lung transplant recipients had the highest incidence of drug-resistant virus: of the 30 patients, 28 were CMV-seronegative transplant recipients of CMV-seropositive organs, which strongly supports the premise that drug resistance is most prevalent in that transplant population.