News Scan for May 08, 2019

News brief

Survey finds strong measles vaccine support; Western Pacific cases noted

Despite pockets of vaccine resistance that has led to a surge in measles cases in the United States, a new poll found that 87% of Americans believe the measles virus is dangerous and that 87% believe the vaccine against it is safe.

The poll, conducted by Ipsos on behalf of Thompson Reuters, also found that a similar number (85%) believe that children should be vaccinated against measles unless there are medical reasons for avoiding it. It also found that 77% think children should be vaccinated against the disease even if parents object to vaccinations, with support a little stronger among Democrats (81%) than Republicans (74%).

When asked if they have been vaccinated against measles, 71% said they had, 7% said they hadn't, and 15% didn't know.

The online poll, which included 2,008 US adults, was conducted from Apr 30 to May 2, according to an Ipsos press release. It included 785 Democrats, 666 Republicans, and 378 independents. It has an overall credibility interval of plus or minus 2.5 percentage points.
May 7 Ipsos press release

In an update yesterday on measles activity in the Western Pacific region, the World Health Organization (WHO) noted a resurgence in all of its regions but spotlighted an unusually high number of cases in several Western Pacific countries in which measles had been eliminated. The surge in infections is caused by recent imported cases, the WHO said.

In the Philippines, cases this year have increased 378% compared with the same period in 2018. Australia is reporting higher numbers of cases this year compared with the same period over the last 4 years, and Japan is reporting its largest epidemic in a decade. Malaysia in 2018 experienced an exponential rise—nearly 900%—in measles cases compared with 2013 levels.

Hong Kong reported an airport-linked cluster of 29 cases, and 32 infections in Macao this year include 10 cases in staff from two hospitals. Of 150 cases in South Korea reported since Dec 17, 2018, eight clusters were linked to imported infections.
May 7 WHO measles update


Study: Yellow fever vaccine does not increase dengue severity

A retrospective study today in Travel Medicine and Infectious Disease shows that prior yellow fever (YF) immunization does not increase the risk of subsequent severe dengue infections in a dengue-endemic region of Brazil.

Multiple infections with dengue, unlike other viruses, lead to more severe cases of the disease. Because both yellow fever and dengue are caused by flaviviruses, some have hypothesized that YF vaccination may act as a "first case of dengue" and trigger an antibody-dependent enhancement phenomenon with a subsequent dengue infection.

To conduct the study, researchers looked at the severity of 11,448 lab-confirmed dengue cases reported in Sao Jose do Rio Preto, Brazil, from April 1998 through December 2006, in 7,370 patients vaccinated with the YF vaccine compared with 4,043 patients who did not receive the YF vaccine.

They found no evidence of increased risk for severe dengue in vaccinated patients (odds ratio, 1.00; 95% confidence interval, 0.87 to 1.14).

"Our results suggest that the vaccine against YF does not confer either increased risk or protection against severe dengue," the authors concluded. "These findings contribute towards resolving the controversy surrounding the effect of YF vaccination on the clinical manifestations of dengue fever and thus reassuring health professionals, resident populations, and travelers in areas where dengue and YF are present."
May 8 Travel Med Infect Dis


Health workers with MERS younger, more often female, study finds

An analysis of healthcare workers infected with MERS-CoV found some similarities with other respiratory pathogens, but some differences, including that workers were younger, were female, had fewer comorbidities, and had higher survival rates, according to a study last week in the Journal of Infection and Public Health.

A team from the WHO, the Pasteur Institute, and Saudi Arabia's health ministry performed a retrospective analysis of 2,223 lab-confirmed MERS-CoV (Middle East respiratory syndrome coronavirus) cases reported to the WHO since 2012, of which 415 involved healthcare workers. Five were primary cases, 338 were secondary, 54 were listed as undetermined, and 18 had missing information.

Aside from the other differences, the researchers saw that, when they compared secondary healthcare cases to secondary nonhealthcare cases, the medical workers were more likely to be non-national residents and have asymptomatic infections. "Importantly, no deaths have occurred among healthcare workers with secondary MERS infection since the end of 2015," they wrote.

Younger age and fewer comorbidities might partly explain the lower case-fatality rate, which was 5.8% for health workers compared with 42.8% for non-healthcare workers. Year of infection (2013 to 2018) and having no comorbidities stood out as protective factors against death. The team noted that the decline in deaths since 2013 might reflect improvements in surveillance and infection prevention and control practices.

"Understanding transmission to healthcare workers, preventing infection and improving clinical management of infected healthcare workers will all be critical to further reducing the incidence of secondary infections in healthcare settings," researchers concluded.
May 2 J Infect Public Health abstract

Stewardship / Resistance Scan for May 08, 2019

News brief

MCR-9 gene discovered in Salmonella Typhimurium strain

Researchers from Cornell University have discovered another variant of the mobile colistin-resistance gene MCR, according to a study yesterday in mBio.

The MCR-9 gene was identified in a multidrug-resistant (MDR) Salmonella enterica serotype Typhimurium strain isolated from a patient in Washington state in 2010. The strain was tested for phenotypic resistance to colistin and was found to be sensitive at the 2-milligrams-per-liter (mg/L) European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoint. However, when the MRR-9 gene was cloned and transferred to colistin-susceptible Escherichia coli, it conferred resistance to colistin at levels up to 5 mg/L.

Further analysis revealed that the amino acid sequence of MCR-9 most closely resembled that of the MCR-3 gene, and pairwise comparisons of the predicted protein structures of all MCR genes showed that MCR-9, MCR-3, MCR-4, and MCR-7 share a high degree of similarity at the structural level. A search of the National Center for Biotechnology Information's non-redundant protein sequence database found that MCR-9 was present in multiple genera of Enterobacteriaceae.

Colistin is considered a "last resort" drug for MDR infections.

"These results indicate that mcr-9 has the potential to reduce susceptibility to colistin, up to and beyond the EUCAST breakpoint, and can be found extrachromosomally in multiple species of Enterobacteriaceae, making it a relevant threat to public health," the authors of the study write. "Future studies querying the plasmids that harbor mcr-9 (e.g., transferability, stability, and copy number variation) will offer further insight into the potential role that mcr-9 plays in the dissemination of colistin resistance worldwide."
May 7 mBio study


Study: Carbapenem de-escalation doesn't compromise clinical outcomes

Researchers at a university hospital in Spain report that a carbapenem de-escalation strategy was safe in patients with severe infections, regardless of microbiological results. The findings appeared yesterday in the International Journal of Infectious Diseases.

In the prospective observational study, conducted from August 2013 through July 2014, researchers evaluated the de-escalation strategy in all patients who started treatment with carbapenems at admission for intra-abdominal, respiratory, urinary, skin, or soft-tissue infections. De-escalation was defined as the discontinuation of carbapenems, or substitution with narrower-spectrum agents, during the first 96 hours of treatment. The primary outcomes were in-hospital morality, mortality at 30 days after carbapenem prescription, and infection-related readmission within 30 days.

The study included 1,161 patients, and de-escalation was performed in 667 (57.5%) of these. In the de-escalation group, 54.9% of cultures were positive. After propensity score matching, 30-day mortality was lower (17.4 vs 25.7%, P = 0.036), carbapenem treatment was 4 days shorter (4 vs 8 days, P < 0.001), total antibiotic therapy duration was 2 days longer (12 vs 10 days, P = 0.003) and the length of hospital stay was 5 days shorter (8 vs 13 days, P = 0.008) in the de-escalated patients versus the not-de-escalated patients. In-hospital mortality and 30-day readmission rates did not significantly differ between these groups.

The authors conclude, "Carbapenem de-escalation is a safe strategy that does not compromise the prognosis of severely ill hospitalized patients. There appeared to be no increase in 30-day mortality, 30-day re-admission rate, or length of hospital stay in these patients."
May 7 Int J Infect Dis abstract

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