Stewardship / Resistance Scan for Feb 18, 2019

Resistant bacteria in farm soil
;
Geographic MRSA risks
;
Readmission after C diff

Resistance genes found in soil 2 years after cattle operation ceases

A new study led by scientists from US Department of Agriculture (USDA) found that antibiotic resistance genes persist in a beef cattle environment even 2 years after cessation of operations.

Writing in PLOS One, researchers from the USDA and Western Kentucky University (WKU) in Bowling Green collected soil samples from both the feedlot and gracing areas of a WKU beef cattle operation before the cattle were removed and then 1 and 2 years after cattle removal. They measured total bacterial populations, total Enterococcus species, integrons, and antimicrobial resistance genes (ARGs) against erythromycin, sulfonamide, and tetracycline.

The investigators noted that concentrations of total bacteria, Enterococcus species, class 1 integrons, and ARGs were higher in the feeding area and around the fence and gate that led to the grazing area but declined gradually followed a gradual decline across the grazing area. They also reported that, although concentrations of total bacteria, Enterococcus species, and ARGs in the feeding area significantly decreased 2 years after cattle removal, their concentrations were still detected, and, again, at higher levels than observed in the grazing area.

The highest concentrations were found around feeding and watering areas.

The authors conclude, "Higher concentrations over two years in the feeding area when compared to the grazing area suggest a lasting effect of confined beef cattle production system on the persistence of bacteria and ARGs in the soil."
Feb 15 PLOS One study

 

Study: Race, household crowding linked to higher risk for CA-MRSA

A study today using geocoded electronic health record (EHR) data to identify risk factors and characterize geographic variations of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) rates in children in Atlanta has found that neighborhoods with higher proportions of black residents, household crowding, and children under the age of 4 have the greatest risk of infection, researchers reported in BMC Infectious Diseases.

The retrospective study looked at children in the Atlanta metropolitan statistical area who were treated for S aureus infection at two hospitals from 2002 through 2010. Children met the case definition if their EHR reported a positive MRSA infection on the first culture test during a single hospitalization. A generalized estimated equations model was developed, and crude and adjusted odds ratios (aOR) were based on S aureus risks.

The researchers measured the risk of S aureus as standardized incidence ratios (SIRs) calculated within aggregated US 2010 Census tracts called spatially adaptive filters, and then created maps that differentiate the geographic patterns of antibiotic-resistant and non-resistant forms of S aureus.

Overall the analysis found 10,642 S aureus cases, with 5,379 MRSA and 5,263 methicillin-susceptible S aureus (MSSA) infections. CA-MRSA rates increased at higher rates compared with non-resistant forms (P = 0.01), and infections more than doubled during the study period, from 23.2% in 2002 to 53.7% in 2006. Black children were almost 1.5 times as likely as white children to have CA-MRSA infections (aOR, 1.58; 95% confidence interval [CI], 1.44 to 1.75, P < 0.0001); this finding persisted at the block group level (P < 0.001) along with household crowding (P < 0.001). Children younger than 4 years also had increased risk for CA-MRSA (aOR, 1.65: 95% CI, 1.48 to 1.83, P < 0.0001).

The spatial analysis showed that CA-MRSA infections encompassed larger areas with higher SIRs compared to non-resistant forms and were found in block groups with higher proportions of black residents (r = 0.517, P < 0.001), younger children (r = 0.137, P < 0.001), and crowding (r = 0.320, P < 0.001). Over 75% of the CA-MRSA cases were found in Fulton and DeKalb counties, which are two of the most densely populated counties in Georgia.

"This study demonstrates how geocoded EHR data can be used to identify areas of excess risk for S. aureus infections, which is important for developing interventions to prevent the spread of antibiotic resistant infectious conditions," the authors of the study write. "These methods can be used to identify specific areas to target public health intervention strategies."
Feb 18 BMC Infect Dis study

 

Hospital readmission common after C difficile infection, study finds

An analysis of nationwide US data has revealed that one in five patients admitted with Clostridioides difficile infection (CDI) is readmitted within 30 days, with almost half because of infections and the leading cause being repeat CDI, according to a study in the American Journal of Infection Control.

The researchers studied details on 38,409 patients admitted to a hospital with a primary diagnosis of CDI, according to 2013 data from the Nationwide Readmissions Database. The mean age was 67.6, 65.0% were women, and 44.7% had two or more comorbidities.

Of the 38,409 patients initially admitted for CDI, 8,198 (21.3%) were readmitted to the hospital within 30 days. Of these, 2,206 (26.9%) were readmitted with CDI as the primary diagnosis, which accounted for 5.7% of all patients initially admitted with CDI. Other leading causes were non–C difficile septicemia (11.6%), congestive heart failure (3.6%), urinary tract infection (3.2%), and diarrhea (2.5%).

Being female and having either renal disease or anemia were associated with increased CDI readmission risk, as was being discharged home versus another healthcare facility.

The authors conclude, "This information may provide a framework for hospitals to develop increased awareness of at-risk populations. Further studies can be aimed at evaluating the role of new therapies on cost and readmission."
Feb 16 Am J Infect Control abstract

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