Stewardship / Resistance Scan for May 22, 2017

Pneumonia antibiotic failure
MDR-TB mortality
MDR Salmonella in poultry

Study: 1 in 4 pneumonia patients fail initial antibiotic therapy

Nearly one in four adult outpatients prescribed antibiotic monotherapy for community-acquired pneumonia (CAP) do not respond to treatment, according to a paper presented at the 2017 American Thoracic Society International Conference.

In the retrospective cohort analysis, researchers examined data on adult outpatients who received antibiotic treatment following an outpatient visit for CAP from 2011 through 2015. To be included in the study, patients were required to have a monotherapy antibiotic prescription claim for a single class of antibiotics (macrolides, fluoroquinolones, beta-lactams, or tetracyclines). Treatment was considered a failure if the patient had their antibiotic prescription refilled, switched to a different antibiotic, visited the emergency room (ER), or was hospitalized within 30 days of the receipt of the initial antibiotic prescription.

Among the 251,947 patients who met the criteria for the study, the mean age was 52.2 years. The majority of patients were prescribed azithromycin (40.3%) and levofloxacin (37.7%). The total antibiotic failure rate was 22.1% (55,741 patients), with 70.7% (39,397) of those patients switching to a different antibiotic, 20.6% (11,493) refilling their initial prescription, 5.4% (3,015) being hospitalized, and 3.3% (1,835) visiting the ER.

A multivariable logistic regression model revealed that diagnosis of pneumococcal pneumonia (p<0.02), older age (p<0.0001), and female gender (p<0.0001) were multivariate predictors of antibiotic failure. Comorbidities associated with higher rates of antibiotic failure included hemiplegia/paraplegia (odds ratio [OR] 1.33), rheumatologic disease (OR 1.28), chronic pulmonary disease (OR 1.25), cancer (1.14), diabetes (OR 1.07), and asthma (OR 1.05). After adjusting for baseline patient characteristics, beta-lactams were associated with the highest antibiotic failure rate (25.7%), followed by macrolides (22.9%), tetracyclines (22.5%), and fluoroquinolones (20.8%).

"Our findings suggest that the community-acquired pneumonia treatment guidelines should be updated with more robust data on risk factors for clinical failure," lead author James McKinnell, MD, an infectious disease specialist with LA BioMed, said in an American Thoracic Society (ATS) press release. In particular, he noted the greater risk of hospitalization for patients over 65. He also warned of the potential hazards of additional antibiotic therapy.

"The additional antibiotic therapy noted in the study increases the risk of antibiotic resistance and complications like C. difficile ("C diff") infection, which is difficult to treat and may be life-threatening, especially for older adults," McKinnell said.
May 21 abstract
May 21 ATS press release


Study finds directly observed therapy reduces mortality in MDR-TB patients

In another paper presented at the 2017 American Thoracic Society International Conference, researchers with the US Centers for Disease Control and Prevention (CDC) report that directly observed therapy (DOT) was associated with a 77% reduction in mortality among patients with multidrug-resistant tuberculosis (MDR-TB).

In an analysis of surveillance data for 3,434 MDR-TB patients treated in the United States from 1993 through 2013, the researchers found that 709 (21%) died during treatment. Among the patients with available data, 34% had an HIV infection, 18% had previous TB disease, and 17% had an additional drug resistance. DOT, a strategy that requires health workers, community volunteers, or family members to record patients taking their medicine, increased from 74% during 1993-2002 to 95% during 2002-2013, while all-cause mortality decreased from 31% to 11% during these periods.

Using Cox proportional hazard models to estimated adjusted hazard ratio (aHR), the researchers determined that older age (aHR 1.15) and reported HIV infection (aHR 7.11) were risk factors for all-cause mortality, while DOT (aHR 0.23) was protective.

"This protective effect may come from DOT alone or from other patient-centered measures, such as transportation assistance or food stamps given along with DOT by TB treatment facilities to improve treatment adherence," lead author Jorge Salinas, MD, said in an ATS press release. "The findings reinforce that all patients with MDR TB should receive DOT and other patient-centered measures to ensure patients complete their treatment."
May 21 abstract
May 21 ATS press release


Extensive multidrug resistance found in Salmonella from Ethiopian poultry

A new study in BMC Infectious Diseases has found extensive multidrug resistance in Salmonella isolates from poultry breeding, multiplication, and distribution centers in Ethiopia.

In the study, researchers from Addis Addaba University took fecal samples and cloacal swabs from chickens at two poultry multiplication centers and a commercial poultry farm, along with bedding samples and hand swabs from poultry workers. Salmonella was isolated in 45 of the 270 fecal samples (16.7%), 36 of 244 cloacal swabs (14.8%), 6 of 17 pooled bedding samples (35.3%), and 3 of 9 hand swabs (33.3%). Of the 45 Salmonella isolates subjected to antimicrobial susceptibility testing, 100% were resistant to at least three antimicrobials, with 93.3% exhibiting resistance to at least eight antimicrobials simultaneously, including all isolates from personnel and poultry bedding.

Interviews with center supervisors revealed that antimicrobials were routinely overprescribed to avoid the undetected spread of pathogens and onset of disease outbreak at the centers. In addition, the authors note the fact that Salmonella prevalence was higher in the bedding samples and hand swabs than in the chicken cloaca demonstrates the poor biosecurity and personnel hygienic practices at the facilities. Given the limited supply of personnel hygiene supplies and poor hand washing practices, hand contamination could lead to self-infection among poultry workers and spread of infection to family members and others.

"We conclude that the poultry breeding, multiplication and distribution centers in Ethiopia, as they currently stand, are a source for the dissemination of pathogens and drug resistant pathogens, at least Salmonella," the authors write.
May 18 BMC Infect Dis study

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