News Scan for Jun 28, 2021

News brief

Chinese study finds lower prevalence of MCR-1 in healthy residents

The prevalence of the colistin-resistance gene MCR-1 in healthy residents of a Chinese city declined following China's ban on colistin as a growth promoter in livestock in 2017, researchers reported today in Clinical Microbiology and Infection. But seafood may be an emerging risk factor for MCR-1 colonization.

In a study led by researchers from the Shenzhen Center for Disease Control and Prevention, 719 healthy volunteers from Shenzhen were recruited from March 2018 through December 2019 to investigate the prevalence of MCR-1, a mobile gene that confers resistance to the last-resort antibiotic colistin, in the human intestine. Researchers collected fecal samples from the volunteers, then conducted whole-genome sequencing to detect the presence of the gene. They also conducted a case-control study to determine risk factors for MCR-1 positivity.

Overall, 56 samples (7.8%) were positive for MCR-1, with the prevalence of MCR-1 significantly higher among volunteers enrolled in 2018 (11.5%) than among those enrolled in 2019 (2.4%). All isolates containing the gene were Escherichia coli. Analysis of risk factors for MCR-1 positivity showed that pork and chicken meat were no longer a risk factor, but a higher intake of seafood (more than 75 grams per day) was associated with a higher risk of MCR-1 carriage (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.05 to 4.52). Increased intake of whole grains (more than 150 grams per day) was associated with a lower risk of MCR-1 carriage (OR, 0.05; 95% CI, 0.004 to 0.58).

The study authors theorize that the significant decline in colistin use in livestock following the 2017 ban resulted in significantly less MCR-1–positive bacteria in animal-derived food. The ban on the use of colistin as a growth promoter came after researchers first identified MCR-1 in Chinese pigs, pork products, and people in 2015. But colistin is still used for treating sick animals in China, and the authors suggest that colistin- and MCR-1–contaminated manure may be getting into waterways and spreading into aquaculture.

"Aquaculture is considered as a significant reservoir and a potential origin of mobile colistin resistance," they wrote. "Hence, a complete surveillance system for antimicrobial resistance in aquatic environment, especially colistin resistance, should be established."
Jun 28 Clin Microbiol Infect study

New 6-case Salmonella outbreak tied to tainted shrimp

Late last week the Centers for Disease Control and Prevention (CDC) announced a new Salmonella Weltevreden outbreak linked to frozen cooked shrimp that has sickened six people in two states.

In interviews with five of the patients, all reported eating shrimp before getting sick. Two patients have been hospitalized for their illnesses, but no patient has died. Nevada has recorded four cases and Arizona two, with symptom onsets ranging from Feb 26 to Apr 25. Sick people range in age from 30 to 80 years, with a median age of 56, and four are female.

The outbreak was detected by the Food and Drug Administration (FDA) when a sample of Avanti Frozen Foods shrimp that was collected for testing at import was found to be contaminated with Salmonella Weltevreden.

"FDA conducted a traceback investigation using purchase records from locations where four sick people bought shrimp. Based on their purchase locations and dates, FDA identified a common shipment of frozen cooked shrimp; a supplier of this shipment was Avanti Frozen Foods," the CDC said.

Avanti Frozen Foods recalled frozen shrimp products on Jun 25, and CDC suggests consumers do not to eat, sell, or serve recalled frozen cooked shrimp supplied by Avanti Frozen Foods.
Jun 25 CDC notice

New Jersey reports first Jamestown Canyon virus case of year

New Jersey recently reported its first Jamestown Canyon virus (JCV) case of the year, which involves a man from Sussex County, a rural southeastern county.

In a statement, the New Jersey Department of Health (NJDH) said the man is in his 60s and tested positive for JCV after experiencing fever and neurologic symptoms in May.

The man's JCV illness is New Jersey's second such case. The first was reported in 2015, also involving a resident of Sussex County.

JCV is a rare mosquito-borne arbovirus that mainly circulates in the Midwest and Northeast, typically in late spring through the middle of fall. Most cases are asymptomatic or mild, but severe cases can lead to encephalitis, meningitis, or death. There are no vaccines or treatments.

The CDC estimates that the United States averages 15 cases a year, though less severe cases are probably underdiagnosed and underreported.
Jun 23 NJDH statement
CDC background information

COVID-19 Scan for Jun 28, 2021

News brief

Point-of-care COVID antibody test is accurate, adaptable, low maintenance

Duke University researchers developed a point-of-care test (POCT) that can detect SARS-CoV-2 antibodies and four other coronaviruses with 100% accuracy, according to initial test results from a small cohort published in Science Advances late last week. The test is called DA-D4 POCT, with DA standing for double-antigen and D4 being the assay platform recently developed to detect Ebola infections 1 day faster than typical polymerase chain reaction tests.

The test uses a polymer brush coating that stops everything but the targeted molecules from attaching to the wet test slide, which can be zoned to delineate different biomarkers. In the case of SARS-CoV-2, it measures antibody responses against the spike protein, the binding domain within the spike protein, and the nucleocapsid protein. Fluorescence intensity of each zone is used to indicate antibody concentration.

Researchers measured the test's accuracy and sensitivity via samples from 31 patients admitted to intensive care for COVID-19, 41 healthy people pre-pandemic, and 18 individuals with seasonal coronaviruses. The test was able to correctly indicate SARS-CoV-2 cases with no false-positives, and further analysis on longitudinal samples from six COVID patients showed seroconversion and antibody kinetics.

"The DA-D4 POCT is a promising platform to supplement existing diagnostic technologies to manage the COVID-19 pandemic because it marries the best attributes of LFAs [lateral flow assays] and ELISAs [enzyme-linked immunosorbent assays]—it is quantitative, easy to use, widely deployable, requires only a single 60-µl drop of blood, and can be performed with minimal user intervention," write the researchers.

"The detector is battery powered and the test doesn't require any power at all, so you can throw the whole thing into a backpack and truly test at the point-of-care with minimal resources," added coauthor Jason Liu in a Duke University press release. He is a PhD student who designed and built the detector.

While this platform may not be used widely for COVID-19 detection, the researchers say its adaptable platform should also be able to be reconfigured to detect immune responses and predict disease outcome.
Jun 25 Sci Adv study
Jun 25 Duke University press release

Childcare closures in pandemic may have affected women more than men

Childcare facility closures due to COVID-19 may have affected US women more than men, according to a research letter late last week in JAMA Network Open.

The researchers looked at 48,920 individuals, 27.2% from states with mandated childcare closures, from January to December 2020 (all closures were rescinded by June 2020). Half were women, and the mean age was 43.3 years. Overall, 165,158 individual-months were tracked.

Data showed employment decreased for both sexes in April 2020, but the likelihood of women being employed was -2.6 percentage points in states during their mandated childcare closures (95% confidence interval [CI], -4.3 to -1.0 percentage points). This association only remained when controlling for households for children younger than 6 (-3.3 percentage points; 95% CI, -6.2 to -0.5 percentage points) and did not hold when the researchers analyzed households with children 11 and older and households with no children.

While Black and Hispanic people saw the largest differences in employment, the researchers note that Hispanic and White people saw the greatest sex-associated differences. Estimates from the interrupted time series model also indicate that men and women both experienced greater hours reduced in states with mandated childcare closures compared with those without (-3.9 and -5.8, respectively, vs -3.5 and -4.3). The researchers add that women in states that had childcare closures had a differential reduction of approximately 1 hour worked, regardless of employment.
Jun 25 JAMA Health Forum study