Our weekly wrap-up of antimicrobial stewardship & antimicrobial resistance scans
Online platform aims to fill gaps in antimicrobial surveillance
A paper yesterday in the Journal of Infectious Diseases describes a collaborative, Web-based platform for aggregating, analyzing, and disseminating regional antimicrobial resistance information.
The online platform, called ResistanceOpen, is a project of HealthMap, a disease-tracking Web site created by a team of researchers, epidemiologists, and software developers at Boston Children's Hospital. The idea behind ResistanceOpen is to fill gaps in traditional antimicrobial surveillance systems by creating a site that captures the diverse and fragmented antimicrobial data being generated daily by healthcare institutions, laboratories, and regional, national, and international bodies. Resistance data are collected by a team of trained curators for 35 common bacterial species, according to 37 common antimicrobials. Users can type in their location on the site and find resistance data within their region.
"Our ultimate aim is to use this tool to better understand the global burden and geographic distribution of antimicrobial resistance," the authors write.
To test the validity of the aggregated online data, the authors identified and abstracted 845 unique resistance indexes, totaling more than 5 million isolates from 340 unique locations worldwide, and compared the antimicrobial susceptibility data captured for key pathogens (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and antimicrobial combinations with existing national surveillance estimates from the United States and Canada (the two most representative countries).
The authors found that the aggregated resistance values for key pathogens identified during 2013 and 2014 surveillance, when compared with the existing national estimates, demonstrated agreements ranging from 94% to 97%. For the United States, state-specific resistance estimates demonstrated an agreement of 92%. Estimates from inpatient sources tended to match better with national surveillance estimates.
"Our platform for aggregating and disseminating existing but disparate antimicrobial resistance information represents an advance that will permit better situational intelligence, as well as improve antimicrobial stewardship and policy responses to this global problem," the authors write.
Dec 1 J Infect Dis study
Researchers use modeling to estimate fitness of resistant flu strains
A new paper in The Lancet Infectious Diseases describes a mathematical method for estimating the fitness of antiviral-resistant (AVR) flu strains that the authors say can be easily integrated into surveillance systems.
In the paper, US researchers defined the fitness of AVR strains as their reproductive number relative to their co-circulating antiviral-susceptible (AVS) flu strains and developed a simple method for real-time estimation of AVR fitness from surveillance data. The method requires only information on generation time, without other specific details regarding transmission dynamics. The experts then applied this method to two retrospective case studies and one hypothetical case study.
In the first case study, the authors used the method to estimate that the oseltamivir-resistant seasonal influenza A H1N1 strain that emerged in 2007 was 4% more transmissible than its oseltamivir-sensitive predecessor. That finding indicated that even a small fitness advantage is sufficient for an AVR strain to spread to fixation, or evolutionary fitness, within a month.
In the second case study, the authors estimated that the oseltamivir-resistant pandemic influenza A H1N1 strain detected in a large community cluster in Japan during the 2013-14 flu season was 24% less transmissible than an oseltamivir-sensitive strain that emerged at the same.
In the third case study, the authors showed that in the event of large-scale antiviral interventions during an influenza pandemic in which AVR and AVS strains are circulating at the same time, their method can be used to inform optimal use of antivirals in real time by monitoring the intrinsic fitness of the AVR strain and the drug pressure on the AVS strain.
"Timely and accurate estimates of AVR fitness is particularly important in the context of large-scale antiviral intervention during pandemics because the spread of AVR could substantially reduce the effectiveness of antivirals in prophylaxis and treatment of severe infections," the authors write.
Nov 30 Lancet Infect Dis article
Outbreak of drug-resistant Pseudomonas linked to aromatherapy oil
Originally published by CIDRAP News Dec 1.
A paper today in the American Journal of Infection Control describes an outbreak of extensively drug-resistant Pseudomonas aeruginosa (XDR-PA) at an Austrian hospital that the authors believe was likely tied to a bottle of aromatherapy oil shared by the patients.
The outbreak involved 7 of 33 patients admitted to the surgical intensive care unit of the University Hospital at Innsbruck within a month in 2012. The investigation was initiated after an increase in XDR-PA isolates in various clinical specimens among the patients was observed, with investigators looking at relevant patient data, collecting samples from healthcare workers and the hospital environment (washbasins, medical devices, and medical care products), and observing infection control procedures.
Among the 145 environmental samples collected, XDR-PA was present in 6, all of which came from a washbasin and a bottle of aromatherapy oil that was directly applied to the skin of the 7 infected patients. All the XDR-PA strains yielded identical antimicrobial patterns. Molecular typing of all patient isolates and 4 of the environmental samples, all from the same room, revealed an identical genotype.
The investigators hypothesize that the oil was either initially contaminated by a colonized or infected patient, or that backsplash from wash water discharged into basins inside the patients' rooms contaminated the area where the oil and other medical care products were placed. An unopened bottle of the oil tested negative, which ruled out the possibility that the oil was contaminated at the manufacturer's facility.
When healthcare workers stopped discharging the wash water into the basin, discontinued the sharing of aromatherapy oil, and reinforced infection control measures like hand hygiene and environmental disinfection, the transmission of XDR-PA stopped.
The authors say their findings suggest that improper storage and sharing of patient care oil are potential risk factors for nosocomial outbreaks of XDR-PA.
Dec 1 Am J Infect Control study
CDC: 21 ill from multidrug-resistant Salmonella outbreak tied to dairy calves
Originally published by CIDRAP News Nov 28.
At least 21 people in eight states have been sickened by multidrug-resistant Salmonella linked to contact with dairy bull calves in an outbreak dating back to January, the Centers for Disease Control and Prevention (CDC) said today.
Among 19 patients with available information, illness-onset dates range from Jan 11 to Oct 24, and ages vary from less than 1 year to 72, with a median age of 21; 62% of case-patients are female. Eight (42%) of the 19 have been hospitalized, but no deaths have been reported.
Wisconsin has reported 12 of the infections, Minnesota and South Dakota 2 each, and California, Iowa, Idaho, Missouri, and Oklahoma 1 apiece.
"Epidemiologic, traceback, and laboratory findings have linked this outbreak to contact with dairy bull calves purchased from livestock markets in Wisconsin," the CDC said. "Dairy bull calves are young, male cattle that may be raised for meat." All isolates tested were multidrug-resistant Salmonella Heidelberg.
The CDC, which said the outbreak investigation is ongoing, advised people to wash hands thoroughly after touching livestock or their environs, use dedicated clothes, and employ other preventive measures to avoid Salmonella infection.
Nov 28 CDC outbreak notice
Survey highlights resistant Enterobacteriaceae in European hospitals
Originally published by CIDRAP News Nov 28.
A multinational survey of European hospitals is providing the first laboratory-substantiated data on the incidence of carbapenemase-producing Enterobacteriaceae (CPE) across the continent, according to a news release from the European Centre for Disease Prevention and Control (ECDC).
For the European Survey on CPE (EuSCAPE), national laboratories in 36 countries collected the first 10 carbapenem non-susceptible Klebsiella pneumoniae and Escherichia coli clinical isolates from 455 sentinel hospitals, along with 10 susceptible same-species comparator isolates and pertinent patient and hospital information, between November 2013 and April 2014. Analysis of the isolates showed that 850 of 2,301 K pneumoniae samples (37%) and 77 of 402 E coli samples (19%) tested positive for carbapenemase production.
The most frequently detected carbapenemases in K pneumoniae were KPC enzymes, followed by OXA-48-like, NDM, and VIM. In E coli, the most frequently detected carbepenemases were OXA-48-like enzymes, followed by NDM and KPC.
Overall, the results showed that on average in Europe, 1.3 patients per 10,000 hospital admissions had a carbapenemase-producing K pneumoniae or E coli infection, with the highest incidence found in southern and southeastern Europe. In Italy, for example, the rate was 6 patients per 10,000 hospital admissions. In addition, high proportions of K pneumoniae resistant to the last-line antibiotics colistin, fosfomycin, and tigecycline were found in Italy, Romania, Turkey, and Spain. The authors note that this finding could reflect greater use and selection pressure in these countries.
The ECDC says the results "highlight the need to develop a system for public health surveillance of CPE across healthcare systems in Europe" as a tool to inform risk assessment and infection control programs.