Objectives To establish the optimal parameters for group testing of pooled specimens for the detection of SARS-CoV-2. Methods The most efficient pool size was determined to be five specimens using a web-based application. From this analysis, 25 experimental pools were created using 50 µL from one SARS-CoV-2 positive nasopharyngeal specimen mixed with 4 negative patient specimens (50 µL each) for a total volume of 250 µL. Viral RNA was subsequently extracted from each pool and tested using the CDC SARS-CoV-2 RT-PCR assay. Positive pools were consequently split into individual specimens and tested by extraction and PCR. This method was also tested on an unselected group of 60 nasopharyngeal specimens grouped into 12 pools. Results All 25 pools were positive with cycle threshold (Ct) values within 0 and 5.03 Ct of the original individual specimens. The analysis of 60 specimens determined that 2 pools were positive followed by identification of 2 individual specimens among the 60 tested. This testing was accomplished while using 22 extractions/PCR tests, a savings of 38 reactions. Conclusions When the incidence rate of SARS-CoV-2 infection is 10% or less, group testing will result in the saving of reagents and personnel time with an overall increase in testing capability of at least 69%.

Objectives To establish the optimal parameters for group testing of pooled specimens for the detection of SARS-CoV-2. Methods The most efficient pool size was determined to be 5 specimens using a web-based application. From this analysis, 25 experimental pools were created using 50 microliter from one SARS-CoV-2 positive nasopharyngeal specimen mixed with 4 negative patient specimens (50 microliter each) for a total volume of 250 microliter l. Viral RNA was subsequently extracted from each pool and tested using the CDC SARS-CoV-2 RT-PCR assay. Positive pools were consequently split into individual specimens and tested by extraction and PCR. This method was also tested on an unselected group of 60 nasopharyngeal specimens grouped into 12-pools. Results All 25 pools were positive with Cycle threshold (Ct) values within 0 and 5.03 Ct of the original individual specimens. The analysis of 60 specimens determined that two pools were positive followed by identification of two individual specimens among the 60 tested. This testing was accomplished while using 22 extractions/PCR tests, a savings of 38 reactions. Conclusions When the incidence rate of SARS-CoV-2 infection is 10% or less, group testing will result in the saving of reagents and personnel time with an overall increase in testing capability of at least 69%.

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Cryptosporidium is an enteric pathogen that is transmitted through animal-to-person or person-to-person contact or through ingestion of contaminated water or food. In the United States, Cryptosporidium affects an estimated 750,000 persons each year; however, only approximately 11,000 cases are reported nationally (1,2). Persons infected with Cryptosporidium typically develop symptoms within 2 to 10 days after exposure. Common symptoms include watery diarrhea, abdominal cramps, nausea, vomiting, or fever, which can last 1 to 2 weeks. Cryptosporidiosis is a nationally notifiable disease in the United States. Nebraska presents a unique setting for the evaluation of this pathogen because, compared with other states, Nebraska has a greater reliance on agriculture and a higher proportion of the population residing and working in rural communities. Cryptosporidium species and subtypes are generally indistinguishable using conventional diagnostic methods. Using molecular characterization, Nebraska evaluated the genetic diversity of Cryptosporidium and found a dichotomy in the distribution of cases of cryptosporidiosis caused by Cryptosporidium parvum and Cryptosporidium hominis among rural and urban settings. Characterizing clusters of C. hominis cases revealed that several child care facilities were affected by the same subtype, suggesting community-wide transmission and indicating a need for effective exclusion policies. Several cases of cryptosporidiosis caused by non-C. parvum or non-C. hominis species and genotypes indicated unique animal exposures that were previously unidentified. This study enhanced epidemiologic data by validating known Cryptosporidium sources, confirming outbreaks, and, through repeat interviews, providing additional information to inform cryptosporidiosis prevention and control efforts. During September 2015-December 2017, a total of 630 Cryptosporidium-positive stool specimens were reported to public health agencies by clinical laboratories, which most commonly used culture independent diagnostic testing (CIDT) and enzyme immunoassays (EIAs) for detection; among these 630 positive stool specimens, 149 (24%) were sent to the Nebraska Public Health Laboratory (NPHL), and subsequently to CDC, where genotyping was conducted using nested polymerase chain reaction-restriction fragment length polymorphism analysis and DNA sequencing of the 18S rRNA gene and the gp60 gene (3,4). Epidemiologic data on cases with genotyped and subtyped Cryptosporidium stool specimens were exported

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Salmonella enterica serovar Dublin, which can cause enteritis and systemic infections in humans, has been associated with antimicrobial resistance. Here, we report draft genome sequences of seven multidrug-resistant S. Dublin isolates from human samples. These sequences will contribute to an understanding of pathogenesis and resistance determinants in this serovar.

IntroductionDefinitive vertical transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection has been rarely reported. We present a case of a third trimester pregnancy with fetal distress necessitating cesarean section that demonstrated maternal, placental, and infant infection with the SARS-CoV-2 Alpha variant/B.1.1.7.MethodsCDC's Influenza SARS-CoV-2 Multiplex RT-PCR Assay was used to test for SARS-CoV-2 in a maternal NP swab, maternal plasma, infant NP swab, and formalin-fixed paraffin-embedded (FFPE) placental tissue specimens. Whole genome sequencing (WGS) was performed on maternal plasma, infant, and placental specimens to determine the SARS-CoV-2 genotype. Histopathological evaluation, SARS-CoV-2 immunohistochemistry testing (IHC), and electron microscopy (EM) analysis were performed on placenta, umbilical cord, and membrane FFPE blocks.ResultsAll specimens tested positive for SARS-CoV-2 by RT-PCR. WGS further revealed identical SARS-CoV-2 sequences from clade 20I/501Y.V1 (lineage Alpha/B.1.1.7) in maternal plasma, infant, and placental specimens. Histopathologic evaluation of the placenta showed histiocytic and neutrophilic intervillositis with fibrin deposition and trophoblast necrosis with positive SARS-CoV-2 immunostaining in the syncytiotrophoblast and electron microscopy evidence of coronavirus.DiscussionThese findings suggest vertical transmission of SARS-CoV-2, supported by clinical course timing, identical SARS-CoV-2 genotypes from maternal, placental, and infant samples, and IHC and EM evidence of placental infection. However, determination of the timing or distinction between prepartum and peripartum SARS-CoV-2 transmission remains unclear.

Salmonella enterica subsp. enterica serovar Corvallis is commonly reported in avian populations and avian by-products. We report the draft genome sequence of a multidrug-resistant S. Corvallis strain (NPHL 15376). To our knowledge, this is the first reported case of this serovar isolated from human blood in the United States.