News Scan for Oct 12, 2016

C diff in dogs
MERS risks
Migrant TB screening
4-strain Flublok OK'd
Salmonella in eggs

Dogs may be a source of community-acquired C difficile infection

A new study in PLoS One suggests that companion animals may be a potential source of community-acquired Clostridium difficile infection (CDI) in humans.

With US dog ownership estimated to be 36%, and a small body of research suggesting that farm animals and companion animals are contributors to community-associated reservoirs for C difficile bacteria, the authors of the study hypothesized that domestic dogs could be a potential source of community-acquired CDI. To determine the prevalence and diversity of C difficile in the dog population, the authors systematically collected and screened 216 canine fecal samples from a single city (Flagstaff, Ariz.), genotyped the C difficile isolates obtained from those samples, and then compared the results to a global database of strains isolated from human CDIs.

The investigators found C difficile isolates in 37 of the 216 samples, for an overall colonization rate of 17.1%, with 10% of those samples containing toxigenic strains that are known to cause human disease.

Whole-genome sequencing identified 44 unique strains within the 37 positive samples representing 12 distinct sequence types. Eleven of these sequence types have also been isolated from human CDIs, and 6 are among the most frequently identified in human infections. While none of the toxigenic strains identified were hyper-virulent, the researchers did identify 4 isolates that carried antimicrobial resistance determinants.

The authors say the results indicate that C difficile types similar to those that cause disease in humans are widespread in dog feces, making dogs a potential source of community-acquired CDI. They suggest future research should include looking at C difficile isolates from humans and dogs within a single household.
Oct 10 PLoS One study


Study says only health workers in close contact with MERS patients at risk

A retrospective cohort study conducted in a hospital in Jeddah, Saudi Arabia, after a 17-case MERS outbreak found that only healthcare workers (HCWs) who had close contact with patients contracted the virus, and their illnesses were mild.

Saudi and US researchers, writing in Emerging Infectious Diseases yesterday, said they recruited every HCW who worked in the intensive care unit (ICU) and emergency department (ED) from Mar 24 through May 3, 2014, when the outbreak of MERS-CoV (Middle East respiratory syndrome coronavirus) occurred. They also recruited HCWs from the neurology unit, which had no known cases.

Of 363 eligible HCWs, 292 (80.4%) were enrolled; 9 of those were excluded from the final analysis because they had no available serum specimens. Testing for MERS-CoV antibodies showed positive results in 20 of 250 HCWs, for an attack rate of 8.0%. The attack rate varied from 11.7% in the ICU to 4.1% in the ED, with none of the 33 HCWs in the neurology unit testing positive.

Radiology technicians had the highest attack rate, at 29.4%, followed by nurses (9.4%), respiratory therapists (3.2%) and physicians (2.4%).

Of the 20 HCWs who tested positive, 3 (15%) were asymptomatic, 12 (60%) had mild illness (hospitalization not required), 2 (10%) had moderate illness (required hospitalization), and 3 (15%) had severe illness (required mechanical ventilation).The most common manifestations of illness among MERS-infected HCWs were muscle pain, fever, headache, and dry cough.

Nineteen of the 20 MERS-positive HCWs reported having been in the same room as or within 2 meters of a patient known to be infected with MERS-CoV. The other HCW shared an automobile with a symptomatic person who subsequently tested positive for MERS-CoV.

The researchers also noted that HCWs who said they always used a mask or N95 respirator had a lower risk for infection than those who didn't, but this association was statistically significant only among those who were in a room in which aerosol-generating procedures were performed.
Oct 11 Emerg Infect Dis study


Pre-screening limits TB spread in migrants moving from high-TB nations

Migrants from countries with high incidence of tuberculosis (TB) who are screened before entry into the United Kingdom pose a negligible risk of spreading infection but are at risk of developing active TB after arrival, according to a study yesterday in The Lancet.

The study looked at 519,955 migrants arriving in the UK on student and settlement visas from 15 high-incidence countries. The migrants were screened for all forms of TB in their countries of origin as part of a pilot pre-entry screening program. All participants were screened for active TB, undergoing a standard chest radiograph and, if radiologic findings were compatible with TB, a sputum test. Those diagnosed as having active TB in their country of origin were denied the medical clearance certificate needed to obtain a visa.

Among the migrants who entered the UK after pre-screening, a total of 1,873 developed TB over the course of the study. Incidence of all forms of TB was lowest in the first year after arrival in England, Wales, and Northern Ireland and then peaked in the fourth year before gradually declining.

Those most at risk for TB were migrants from high-incidence countries, those with chest radiographs that indicated active TB but negative bacteriologic results, and those who had close contact with a TB patient before screening. A secondary analysis using molecular data found that only 35 of 318,983 pre-screened migrants were assumed to be index cases.

The authors say the results indicate that while migrants pose a small public health risk in terms of TB transmission, latent infection—where individuals are infected with Mycobacterium tuberculosis but do not exhibit any symptoms—is a problem that should be addressed. They suggest adding screening for latent infection to the pre-entry screening program or doing it right after migration, with a focus on those migrants from high-incidence countries and those who had chest radiographs compatible with active TB but negative bacteriologic results.
Oct 11 Lancet study

Four-strain Flublock flu vaccine approved by FDA

The US Food and Drug Administration (FDA) has approved a quadrivalent (four-strain) version of Flublok, Protein Sciences Corporation's high-dose flu vaccine, making it the only high-dose quadrivalent vaccine for the US market, the company said in a news release yesterday.

Protein Sciences, based in Meriden, Conn., said that results of a clinical study of 9,000 adults aged 50 and older showed that those receiving Flublok Quadrivalent were over 40% less likely to get cell-culture–confirmed influenza than those receiving a quadrivalent flu vaccine processed using eggs. Both the trivalent and quadrivalent Flublok versions are produced using insect-cell technology and have three times the active ingredient (antigen) of standard vaccines.

The FDA approved Flublok Quadrivalent for adults of any age, but the high antigen content is hoped to especially benefit seniors, whose immune response to vaccines is typically weaker than in younger people.

The newly approved version will be available in prefilled syringes beginning next year, the company said. The trivalent version of Flublok was approved in January 2013, making it the first FDA-approved flu vaccine that uses a baculovirus (an insect virus) expression system and recombinant DNA technology.
Oct 11 Protein Sciences press release


Eggs from small farms bring no guarantee of being Salmonella-free

Salmonella enteritidis is at least as likely to be present in eggs originating from small layer flocks as it is in those from large commercial farms that are subject to federal regulations, according to a study from the Penn State College of Agricultural Sciences presented at a recent veterinary conference.

The researchers bought and tested more than 6,000 eggs in 2015 from 240 randomly selected outlets (eg, farmers markets, roadside stands) supplied by small-layer flocks in 67 Pennsylvania counties. Upon culturing of the shells and egg contents, they found S enteritidis in eggs from 5 (2%) of the selling points (shells, 1; egg contents, 4).

Lead researcher Subhashinie Kariyawasam of Penn State's Animal Diagnostic Laboratory said this is a higher prevalence than that recorded in studies of eggs from large farms (those with more than 3,000 layers). Under the Food and Drug Administration's final egg safety rule, which became effective in July 2010 and aims at reducing S enteritidis contamination, these large farms are required to institute such measures as cleaning and disinfecting between flocks, environmental monitoring of pullet and layer houses, strict rodent control, and continuous testing.

The study findings were presented at the August meeting in San Antonio of the American Veterinary Medical Association and American Association of Avian Pathologists.

Kariyawasam gave a warning to consumers who assume eggs from small growers are safer, saying, "The bottom line is, if you buy your eggs from the small producers, you need to worry about Salmonella just as if you bought eggs produced by large flocks."

He went on to suggest potential solutions: "These findings emphasize the importance of small-producer education on Salmonella enteritidis control measures and perhaps implementation of egg quality-assurance practices to prevent contamination of eggs produced by backyard and other small layer flocks." He also said that people with backyard poultry "need to be aware of the dangers with pet birds—there is a risk to allowing birds to come into the house and children playing with the chickens."
Oct 11 Penn State news release

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