Stewardship / Resistance Scan for Jan 31, 2017

News brief

Study finds resistance genes are abundant in Chinese estuaries

A team of researchers has detected a high abundance and diversity of antibiotic resistance genes in Chinese coastal estuaries, according to a study yesterday in Nature Microbiology.

For the study, researchers tested sediment from 18 estuaries over 4,000 km of coastal China and examined their relationship with bacterial communities, antibiotic residues, and socioeconomic factors. They found a total of 259 resistance genes in the estuary samples, with an average of 118 in each estuary at levels around 1 million resistance genes per gram of sediment. The detected genes conferred resistance to almost all major classes of antibiotics used in humans and animals, the authors said, and represented all major resistance mechanisms, including antibiotic deactivation, efflux pumps, and cellular protection.

The most common resistance genes found at each estuary were multidrug and beta-lactam resistance genes, followed by aminoglycoside and tetracycline resistance genes. Vancomycin resistance genes were found at all estuaries.

When the researchers analyzed antibiotic residues in estuary samples, they found five major antibiotic classes: diaminopyrimidines, tetracyclines, sulfonamides, fluoroquinolones, and macrolides. The concentrations of tetracyclines and macrolides were positively correlated with the total abundance of resistance genes.

Analysis of the relationship between socioeconomic factors and resistance-gene abundance showed that total population, gross domestic product, sewage, and aquaculture production were correlated with the abundance of aminoglycoside, multidrug, and sulfonamide resistance genes.

The authors conclude that anthropogenic activity "appears to be the major driver of abundance and diversity" of resistance genes found in estuaries, and that wastewater streams from municipal sewage treatment and aquaculture are a likely contributor.
Jan 30 Nat Microbiol abstract

Antibiotic use in travelers linked to colonization with MDR bacteria

A new study from researchers in Sweden and Finland has found that antibiotics taken during travel to subtropical regions can predispose travelers to colonization by drug-resistant bacteria with a high rate of co-resistance to other antibiotics.

In the study, which appeared yesterday in Travelers Medicine and Infectious Disease, the researchers analyzed the isolates of 90 people who had contracted extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) while traveling abroad. The 90 participants were part of an earlier investigation, in which the researchers found that taking antibiotics for traveler's diarrhea (TD) increased the risk of colonization by ESBL-PE, particularly when traveling to regions with poor hygiene and weak antibiotic policy (such as South and Southeast Asia). One of the main takeaways of that study was that travelers should be advised against taking antibiotics for mild or moderate TD.

For this study, the researchers were trying to determine what percentage of those isolates were also co-resistant to non-beta-lactam antibiotics, as co-resistance can complicate treatment of ESBL-PE infections. They considered four major risk factors of colonization, including destination, age, TD, and antibiotic use.

Of the ESBL-PE isolates, 53%, 52%, 73%, and 2% were co-resistant to ciprofloxacin, tobramycin, co-trimoxazole, and nitrofurantoin, respectively. The rates were similar among those with TD and without TD. But when they compared the isolates of the travelers who had taken fluoroquinolones (FQs) to those who had taken no antibiotics, they found co-resistance rates for ciprofloxacin were 95% versus 37%, for tobramycin were 85% versus 43%, for co-trimoxazole were 85% versus 68%, and for nitrofurantoin were 5% versus 2%.

"Thus, use of FQs predisposes not only to contracting ESBL-PE strains but, indeed, also to selecting ESBL-PE strains co-resistant to certain clinically important non-beta-lactam antibiotics," the authors write.

"The data reveal that the perils of antibiotic use during travel are even greater than hitherto recognized."
Jan 30 Travel Med Infect Dis study

News Scan for Jan 31, 2017

News brief

US study: Only 0.2% of pregnant women infected with Zika while traveling

A study yesterday in the American Journal of Obstetrics and Gynecology found that 0.2% of US women they screened contracted Zika after traveling to endemic areas while pregnant.

To conduct the study, Dallas researchers screened 14,161 pregnant women for travel to a Zika-affected country from Mar 14 to Oct 1, 2016. Four percent (610) of women reported such travel, and tests showed evidence of possible Zika virus infection in 29 (5.3%), thus the prevalence of asymptomatic or symptomatic Zika virus infection among pregnant women was 2 in 1,000. The vast majority of women (97%) with Zika had traveled to Central America.

Researchers said that none of the 391 babies they analyzed from travel-affected pregnancies showed any signs of Zika infection, microcephaly, or reduced head circumference.

This is one of the first prospective studies to measure risks for pregnant travelers. Babies born to women who contract Zika while pregnant can develop microcephaly, a congenital deformation that leads to small head circumference and developmental problems.
Jan 30 Am J Obstet Gynecol study

Africa CDC officially launches today

African leaders today officially launched the Africa Centres for Disease Control and Prevention (Africa CDC) at its offices in Addis Ababa, Ethiopia, a need identified by the African Union in 2013 with the plan formalized in 2015 in the wake of West Africa's Ebola outbreak in a collaboration between the US CDC and its African counterparts.

In November John Nkengasong, PhD, was named as Africa CDC's first director. Before coming to Africa CDC, he worked in global health for the US CDC for two decades on projects that included HIV and tuberculosis.

In a press release on his appointment, Nkengasong said, "One major lesson learned from the recent Ebola virus disease outbreak is that diseases are a security, economic, and health threat to Africa. The Africa CDC therefore offers a unique possibility to enhance the continent’s capacity to detect and rapidly respond to these threats in order to make Africa secure and safe."

In a recent report on the new center in The Lancet Global Health, Nkengasong and his coauthors said Africa CDC, part of the African Union, will function as a network with five collaborating centers in Egypt, Nigeria, Gabon, Zambia, and Kenya, each with a lab and advanced capacity to rapidly identify common and uncommon pathogens. Africa CDC will lead efforts to promote or strengthen National Public Health Institutes in each member state and closely collaborate with the World Health Organization (WHO) Regional Office for Africa.
Africa CDC Web site
Jan 31 Africa CDC news release
Nov 30, 2016, African Union press release
Jan 17 Lancet Glob Health commentary
Apr 13, 2015, CIDRAP News story "US, African agreement formalizes creation of African CDC"

Cholera outbreak in Somalia tops 2,000 cases

The WHO said in an update posted yesterday that Somalia has reported 930 additional suspected cases of cholera and 6 deaths from Jan 18 to Jan 22.

The new numbers bring the totals in the East African country to 2,236 suspected cases, including 32 deaths. The case-fatality rate is 1.4%.

Last year, the country reported 15,619 suspected cases of cholera, including 531 associated deaths, with a case fatality rate of 3.4%. Cholera, transmitted through tainted drinking water, causes watery diarrhea and fever. It is most dangerous to children under 5 and older people, who can suffer from dehydration after infection.

According to the WHO's update, the organization is working with Somalia's Ministry of Health to organize a mass vaccination campaign using oral cholera vaccines in an effort to halt the transmission of the disease to non-affected areas of the country.
Jan 25 WHO update