News Scan for Apr 21, 2021

News brief

Risk factors, mechanisms noted in colistin-resistant Enterobacterales

A study of colistin-resistant Enterobacterales (CORE) isolates from patients in southeast Michigan found that increased age and prior antibiotic receipt were associated with increased risk of CORE colonization or infection, researchers reported today in Open Forum Infectious Diseases.

In the study, one of the first to provide large-scale colistin resistance data on clinical Enterobacterales isolates in the United States, researchers with the University of Michigan and Case Western Reserve University examined routine clinical isolates obtained in single tertiary health system in Ann Arbor from January 2016 through March 2017.

Patients with CORE isolates were matched 1:1 with patients with colistin-susceptible Enterobacterales (COSE) isolates and uninfected control patients, and multivariable logistics regression was used to compare clinical and microbiologic features. The researchers also conducted whole-genome sequencing (WGS) on a subset of CORE isolates.

Of 16,373 tested clinical isolates, 166 (0.99%) were colistin-resistant, representing 103 unique patients. CORE specimens included 45 Enterobacter isolates, 31 Escherichia coli isolates, and 27 Klebsiella pneumoniae isolates. Multivariable analysis of 103 CORE isolates, 103 COSE isolates, and 102 uninfected controls found that antibiotic exposure in the prior 90 days (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.23 to 4.03) and being age 55 and older (OR, 4.06; 95% CI, 2.24 to 7.36) were predictors of CORE. But notably, none of the 103 patients with CORE were exposed to colistin before culture collection. The same factors were also predictors of COSE.

Among the 33 isolates that underwent WGS, several genetic mutations associated with colistin resistance were found; three MCR-1 genes, one MCR-1.1 gene, and four pmrA/B mutations were identified in E coli isolates, and 5 mgrB and pmrA mutations were detected on K pneumoniae isolates. Mechanisms of colistin resistance among Enterobacter isolates could not be determined.

"Further studies are needed to determine the drivers of and determinants of polymyxin resistance among Enterobacterales, including exposure to non-polymyxin antimicrobials," the authors concluded.
Apr 21 Open Forum Infect Dis abstract

H9N2 avian flu virus infects kids in China, Cambodia

China has reported two more H9N2 avian flu infections in humans, both involving children who are from two different provinces, the World Health Organization (WHO) Western Pacific regional office said in its most recent avian influenza update.

One of the patients is a 10-year-old boy from Fujian province whose symptoms began on Feb 28. The investigation found no history of exposure to poultry. The other is a 2-year-old girl from Hubei province who got sick on Feb 7 after she was exposed to backyard poultry.

Both kids recovered after mild illnesses and so far no family clusters have been reported.

Elsewhere, Cambodia reported a H9N2 infection on Apr 2 in a 3-year-old boy, according to an avian influenza update from Hong Kong's Centre for Health Protection (CHP).

So far this year, the WHO's Western Pacific region has reported 12 H9N2 cases, mostly from China. The virus isn't unusual in poultry, and sporadic human infections—which are most common in children—continue to be detected, but with no sustained transmission.
Apr 16 WHO Western Pacific regional office update
Apr 20 Hong Kong CHP report

COVID-19 Scan for Apr 21, 2021

News brief

Study: B117 variant 45% more transmissible than wild-type COVID-19

A study yesterday in Cell Reports Medicine shows the B117 variant, first identified in the United Kingdom in December, is 45% more transmissible than the original, wild-type COVID-19 virus, but Pfizer's mRNA vaccine protected elderly populations against infections caused by the variant.

The study was based on cases documented in Israel from Dec 6, 2020, through Feb 10, 2021. Within 3.5 weeks of detection, B117 was the dominant strain in Israel. But the nation took a three-pronged approach to controlling a spike in cases, including expanded polymerase chain reaction (PCR) testing, focused surveillance in nursing homes, and prioritized vaccination of those 60 years and older with BNT162b2, the two-dose Pfizer-/BioNTech vaccine.

Based on results from 300,000 PCR tests for COVID-19, researchers showed only 5% of the positive results were B117 on Dec 24. By the end of January, that number jumped to 90%, and currently 99.5% of all COVID-19 cases in Israel involve B117.

"To explain this dramatic increase, we compared the R [reproductive] number of the SARS-CoV-2 virus with the R of the British variant. In other words, we posed the question: How many people, on the average, contract the disease from every person who has either variant? We found that the British variant is 45%—almost 1.5 times—more contagious," said lead author Ariel Munitz, PhD, a professor at Tel Aviv University, in a press release.

New cases were rising until 50% of the 60-and-older population received the first dose of the Pfizer vaccine, the authors said. After 2 weeks following the first dose, a significant drop in new cases among the elderly were observed.

The authors concluded that they can expect a drop in cases among at-risk groups once 50% of that population has been vaccinated, even in the face of highly transmissible variants.
Apr 20 Cell Rep Med study
Apr 20 Tel Aviv University press release

Some dietary supplements may cut risk of COVID-19 infection

Use of certain dietary supplements may reduce the risk of testing positive for COVID-19, according to a large observational study of people in the United Kingdom who used a COVID-19 symptom tracking app. UK-based researchers detailed their findings in the latest issue of BMJ Nutrition, Prevention, & Health. Supplements associated with risk reduction included multivitamins, omega-3, probiotics, and vitamin D.

Dietary supplements have the potential to support the immune system, but it's not known which ones are associated with a lower risk of getting sick with COVID-19. Sales of supplements rose steeply during earlier pandemic months.

To explore which ones might be linked to lower levels of infection, the UK team explored data from the 372,720 users of the COVID-19 Symptom Study app, which recorded several measures, including regular use of supplements in May, June, and July 2020 during the United Kingdom's first surge. Of the subscribers, 175,652 took supplements; 67% were women, and more than half were overweight. Overall, 23,521 tested positive for SARS-CoV-2.

Probiotics, omega-3, multivitamins, and vitamin D were associated with a respective reduced risk of 14%, 12%, 13%, and 9%. The associations were seen only in women. The team observed similar patterns for app users from the United States and Sweden. Researchers didn't see associations with other supplements, including vitamin C, zinc, or garlic.

Scientists concluded that though the study was observational and didn't establish a cause, the modest effect they saw was significant, and they called for large clinical trials to guide evidence-based therapeutic recommendation regarding supplement use.
Apr 19 BMJ Nutr Prev Health abstract
Apr 19 BMJ press release