Stewardship / Resistance Scan for Jul 26, 2018

News brief

Carbapenem use identified as risk factor for colistin-resistant bacteria

In a paper today in Eurosurveillance, Swiss researchers report that prior exposure to carbapenems was the only risk factor for colonization or infection in patients with colistin-resistant Escherichia coli or Klebsiella pneumoniae.

In the retrospective matched case-control study, researchers at two university-affiliated hospitals in Basel, Switzerland, analyzed more than 10,000 E coli and K pneumoniae isolates collected over a 5-year period for susceptibility to colistin. Forty-two patients (33 with colistin-resistant E coli and 9 with colistin-resistant K pneumoniae) were identified, and they were matched with 126 control patients.

The results showed that baseline characteristics, prior comorbidities, prior exposure to antibiotics, and healthcare settings did not differ between cases and controls. Only two of the patients had previous exposure to colistin. Prior exposure to carbapenems, along with a stay abroad and hospitalization, was found to be associated with colistin resistance. In multivariable analysis, however, only prior exposure to carbapenems remained as a risk factor for colonization with colistin-resistant E coli or K pneumoniae (odds ratio, 5.00).

The authors of the study conclude that the associations between prior carbapenem exposure, as well as the concomitant resistance to quinolones, fosfomycin, and tobramycin identified in the colistin-resistant isolates, suggests that low-grade dissemination of colistin-resistant Enterobacteriaceae in human is mainly fueled by selection pressure occurring in patients exposed to different antimicrobials.

"Our findings suggest that sources of colistin-resistant Enterobacteriaceae may be present in the absence of widespread colistin use in human medicine and that selection pressure constitutes an important driver for the occurrence of colistin-resistant strains in clinical isolates," they write.
Jul 26 Eurosurveill research article

Study finds decline in antifungal use at US hospitals

Researchers with the US Centers for Disease Control and Prevention yesterday reported a small but statistically significant decrease in antifungal use among inpatients at US acute care hospitals.

The study, published in the Journal of Antimicrobial Chemotherapy, looked at data from a nationwide hospital drug database from 2006 through 2012. Over the 7-year period, 2.7% of all inpatients and 7.7% of all intensive care unit (ICU) patients received an antifungal. The overall antifungal days of therapy (DOT) for all study years combined was 35 per 1,000 patient-days, with antifungal DOT in ICUs more than twice as high compared with non-ICUs (73.7 vs. 31.0 DOT/1,000 patient-days). Azoles, primarily fluconazole, were the most frequently used antifungal class, followed by echinocandins.

Multivariable trend analysis showed an 18.2% decrease in overall antifungal use during 2006 through 2012 as measured by DOT, with azole use decreasing by 21% and polyene use decreasing by 47%; echinocandin use rose by 11% from 2006 to 2010, but then declined afterward. Unspecified septicemia, HIV, and antineoplastic therapy were among the top primary diagnosis codes for patients who received antifungal therapy.

The authors of the study say the declines in antifungal use do not necessarily mean that antifungals are being used appropriately, since they were not able to assess appropriateness in the study. Nor does it mean that antifungal stewardship efforts are not needed. They conclude that further monitoring and studies of antifungal use are needed to determine where antifungal stewardship efforts could have the most impact.
Jul 25 J Antimicrob Chemother abstract

Post-hurricane floodwaters found to harbor pathogens, resistance genes

An analysis of floodwaters in the months after Hurricane Harvey hit Texas last summer has found elevated levels of E coli and other pathogens and a higher abundance of antibiotic resistance genes, according to a new study in Environmental Science and Technology Letters.

In the study, researchers from Rice University and Virginia Tech surveyed microbial communities in bayou water, floodwater inside and outside residences, and residual bayou sediment collected post-flood. In two of Houston's major bayous, they found that levels of E coli 3 days post-flood were significantly higher than historic levels, and that immediate post-flood levels of E coli were significantly higher than those measured in samples collected over 2 months after the hurricane.

Six-month monitoring of one of the bayous showed that the relative abundances of two antibiotic resistance genes, sul1 and intI1, were highest immediately after the flood. This likely resulted from the discharge of untreated or partially treated sewage from wastewater treatment plants.

The researchers also found that the abundances of fecal indicator bacteria (E coli and enterococcus) and other pathogenic bacteria (Aeromonas, Klebsiella, Legionella, and Salmonella) were significantly higher in stagnant indoor water (from homes that were closed off more than 1 week) than in street water, bayou water, and open indoor water, while sul1 and intI1 genes in closed indoor waters were more abundant than in street water or bayou water. In addition, pathogenic gene markers were more abundant in floodwater sediment deposited in residential areas and public parks than in deep soil cores, and the pathogen profiles were different from those found in floodwaters and bayou waters.

The authors conclude, "Overall, the epic flooding caused by Harvey temporarily shifted the local microbial landscape, increasing the levels of gene markers for pathogenic bacteria, multiantibiotic resistance, and its extent of dissemination in the flooded areas."
Jul 23 Environ Sci Technol Lett abstract

News Scan for Jul 26, 2018

News brief

WHO details next steps in wake of Ebola outbreak end in DRC

In an update yesterday that came a day after the Democratic Republic of Congo's (DRC's) Ebola outbreak was declared over, the World Health Organization (WHO) said it now considers the risk to the region and the rest of the world as low.

As of Jul 24, the outbreak's total is 54 cases, 38 confirmed by lab tests and 16 classified as probable. Thirty-three deaths were reported in the outbreak that began with the first illness onset in early April.

Earlier this month the DRC's health ministry met with the WHO and its partners to assess the current epidemiologic situation, evaluate progress, and prioritize activities going forward. The group came up with a government-led plan to transition and strengthen emergency response capacities, with steps to take place between August and October. The steps include maintaining lab capacity to detect new cases and provide medical and psychosocial care for survivors and their families.

The WHO said as part of the next phase it will help the health ministry conduct an after-action review to highlight lessons learned and how to leverage resources and knowledge from the outbreak's earlier stages.

Also, the agency recommended three measures to reduce the risk of Ebola transmission in the outbreak area, including using gloves or protective clothing while handling fruit bats, monkeys, or apes, and cooking animal products thoroughly. The other steps include wearing gloves while caring for sick patients at home and male survivors practicing safe sex and hygiene for 12 months after illness onset or until their semen tests negative twice for Ebola virus.
Jul 25 WHO update

Report details lessons learned in mumps outbreaks at Indiana universities

Public health officials who were involved in responding to four mumps outbreaks at universities in Indiana in 2016 described the need for schools to standardize immunization and immunity documentation, according to a report today in Morbidity and Mortality Weekly Report (MMWR).

Through September of that year, the four colleges reported 281 cases, 179 of them in students or staff members and the rest in community members. The cases occurred during a year when 6,366 cases were reported to the US Centers for Disease Control and Prevention (CDC), the highest number of cases in a decade.

At some universities, documentation of two doses of measles, mumps, and rubella vaccination wasn't available, requiring substantial staff time to verify. The authors also reported difficulty implementing policies for excluding susceptible people from classes and other group settings.

Receipt of two doses was documented for nearly 85% of the infected students or staff, and policies on contact exclusion based on vaccination status might not be enough for outbreak control, the team wrote.

Waning immunity after the second dose is thought to be a contributing factor in mumps outbreaks at colleges, and in 2017 the CDC's vaccine advisory group recommended a third dose for people at increased risk in outbreak settings.

Seven vaccination clinics were held at three of the schools, at which 5,273 doses were administered, and the authors said many of the doses were likely third doses. The group noted that that that availability of an outbreak-specific lab testing protocol possibly increased the overall positivity rate of specimens tested at the state lab, which improved case detection.
Jul 26 MMWR report

CDC wraps up probe into Salmonella outbreak linked to precut melon

The investigation into a Salmonella Adelaide outbreak linked to precut melon has ended with 77 cases reported from nine states, the CDC said today.

Since the last update on Jun 19, seven more cases were confirmed, with two more states reporting cases. The latest illness onset was Jul 2. Thirty-six people were hospitalized, but no deaths were reported.

Epidemiologic and trace-back investigations suggest that precut melon supplies by Caito Foods, based in Indianapolis, is the likely source of the outbreak. Before getting sick, most of the outbreak patients interviewed had eaten cantaloupe, watermelon, or a fruit salad mix bought from grocery stores. The company recalled its products, which were distributed in 22 states, on Jun 8.

The Food and Drug Administration (FDA) said in an update today that an investigation with the CDC and state health officials didn't identify a common source of contamination.
Jul 26 CDC final outbreak update
Jul 26 FDA update