Our weekly wrap-up of antimicrobial stewardship & antimicrobial resistance scans

Study details emergence of drug-resistant Salmonella in Brazilian chicken

An analysis of Salmonella isolates from Brazilian chickens suggests that the introduction of a Salmonella vaccine and increasing antibiotic use by Brazilian farmers has resulted in Salmonellastrains that are more antibiotic resistant but may be less likely to cause human disease, UK and Brazilian researchers reported yesterday in PLOS Genetics.

Brazil is the largest exporter of chicken meat globally, and previous research has found large quantities of chicken meat contaminated with Salmonella being imported into the United Kingdom and European countries from Brazil. To identify the most prevalent Salmonella serovars in chicken meat imported from Brazil and to determine if those strains are contributing to increased cases of food poisoning in the United Kingdom, researchers examined 183 Salmonella genomes from chickens in Brazil, along with 357 Salmonella genomes collected from chickens and chicken meat imported into the United Kingdom, domestic poultry, and UK residents who had confirmed Salmonella infections.

The analysis found that Heidelberg and Minnesota were the most common serovars in Brazilian chickens and in chicken meat imported into the United Kingdom. Comparison with more than 1,200 publicly available genomes of these two serovars in Brazil suggested they emerged in the early 2000s, around the same time the country introduced a Salmonella vaccine for poultry.

In addition, genomes within Heidelberg and Minnesota clades shared resistance genes to sulphanomide, beta-lactam, and tetracycline antibiotics that likely resulted from increased antibiotic use by Brazilian farmers. These genes, the authors suggest, may have enabled Heidelberg and Minnesota to become the dominant Salmonella serovars in Brazilian chickens.

However, UK surveillance data showed no increases in human Salmonella Heidelberg or Minnesota cases, and no spread to domestic poultry.  

"Whilst this poses no immediate health risk to importing countries like the UK, the bacteria were resistant to antimicrobial drugs, and this highlights the importance of taking a 'One Health' approach that sees the connections between the health of people, animals and the environment, especially when assessing global food supply chains," study co-author Alison Mather, PhD, of the UK's Quadram Institute Bioscience said in a journal press release.
Jun 2 PLOS Genet study
Jun 2 PLOS press release

Review finds increased intestinal carriage of multidrug-resistant E coli

Originally published by CIDRAP News Jun 2

An analysis of studies published over the past two decades shows that human intestinal carriage of multidrug-resistant (MDR) Escherichia coli has risen substantially in healthcare and community settings around the world, researchers reported today in JAC-Antimicrobial Resistance.

The review and meta-analysis of 133 studies published from January 2000 through Apr 22, 2021, which included 73,318 patient samples, found that 21.1% of inpatients in healthcare settings and 17.6% of healthy individuals worldwide carried extended-spectrum beta-lactamase (ESBL)-producing E coli in their intestines, which can cause MDR infections that are difficult to treat.

In healthcare settings, the highest carriage rate by World Health Organization (WHO) region was found in the Eastern Mediterranean (45.6%), followed by Southeast Asia (32.9%), Africa (32.4%), and the Western Pacific (24.1%). In community settings, the highest carriage rates were observed in Southeast Asia (35.1%), the Western Pacific (25.3%), Africa (21.4%), and Eastern Mediterranean (20.6%).

Based on an estimation from linear regression analysis, the researchers found that the prevalence of human intestinal ESBL E coli carriage in the healthcare setting more than tripled over the study period, from 7% in 2001 to 2005 to 25.7% in 2016 to 2020, with a 10-fold increase seen in community settings (2.6% to 26.4% during the same period). The researchers also found, based on data from Europe, that fecal ESBL E coli colonization increased with duration of contact/stay in healthcare settings. For example, the prevalence of fecal ESBL E coli colonization in patients who spent more than 48 hours in the hospital was twice that of healthy people who had no contact with a healthcare setting.

"Key relevant health organizations should perform surveillance and implement preventive measures to address the spread of ESBL E. coli in both settings," the study authors concluded.
Jun 2 JAC-Antimicrob Resist study

Testing for carbapenemase production rises at VA hospitals

Originally published by CIDRAP News Jun 2

A study of Veterans Affairs medical centers (VAMCs) found an increase in carbapenemase detection and testing following the release of new guidelines, a team of VA researchers reported today in Antimicrobial Stewardship & Healthcare Epidemiology.

In late 2016, the VA released guidelines that prioritized the identification of carbapenenemase-producing carbapenem-resistant Enterobacterales (CP-CRE). The new guidelines simplified antimicrobial susceptibility testing and recommended polymerase chain reaction (PCR) to identify carbapenemase production in CRE cultures. Knowing whether and what type of carbapenemase enzyme or gene is being produced can provide critical information for clinical care and empiric antibiotic treatment, help guide real-time infection control response, and inform epidemiologic surveillance.

To analyze trends in carbapenemase testing and detection following the release of the guidelines, the researchers analyzed microbiologic and clinical data on VA patients who had CRE-positive cultures from 2013 through 2018.

Overall, the researchers identified 5,778 standard cultures from 3,096 patients at 132 VAMCs that grew CRE. Of these, 1,905 (33.0%) had evidence of molecular or phenotypic carbapenemase testing, and 1,603 (84.1%) of these had carbapenemases detected.

Among the cultures confirmed as CP-CRE, 1,053 (65.7%) had molecular testing for one or more mechanism of carbapenemase production. Almost all testing included the KPC enzyme (1,047; 99.4%), with KPC detected in 914 (87.3%) of 1,047 cultures. The NDM enzyme was found in 585 cultures (55.6%), and OXA-48 was found in 507 (48.1%).

Carbapenemase testing increased over the study period, from 23.5% of CRE cultures in 2013 to 58.9% in 2018, with significant increases in testing observed after the release of the new guidelines. The study authors note, however, that despite the encouraging increase in testing, as of 2018, more than 40% of cultures that grew CRE in all VAMCs and more than 75% of cultures in low-complexity or rural facilities did not have evidence of carbapenemase testing.

"Our study indicates a need to expand carbapenemase testing, to standardize test reporting in microbiology reports, and to support all laboratories in fully implementing national recommendations," they wrote. "Further research in this area could help delineate the most cost-effective strategies to enhance implementation of carbapenemase testing for both VA and private-sector healthcare systems."
Jun 2 Antimicrob Steward Healthc Epidemiol abstract

Decolonization strategy reduces MRSA colonization at multiple body sites

Originally published by CIDRAP News Jun 1

A new analysis of a randomized clinical trial shows that a repeated post-discharge decolonization regimen for methicillin-resistant Staphylococcus aureus (MRSA) carriers reduced MRSA colonization overall and at multiple body sites, researchers reported yesterday in Clinical Infectious Diseases.

The CLEAR (Changing Lives by Eradicating Antibiotic Resistance) Trial was a randomized controlled trial that compared 1,058 patients from hospitals and nursing homes who received MRSA prevention education with 1,058 patients who received education plus a daily, self-administered decolonization regimen of topical chlorhexidine, chlorhexidine mouthwash, and nasal mupirocin over 6 months.

The results of the trial, published in 2019, found that, within a year of discharge, the decolonization regimen reduced MRSA infections by 30% and all-cause infections by 17% compared with education alone. In the new analysis of those results, researchers looked at the efficacy of the regimen on nasal, oropharyngeal, and skin MRSA colonization at 1, 3, 6, and 9 months after randomization.

By 1 month, MRSA colonization was 56% lower in the decolonization group overall compared with the education-only group (odds ratio [OR], 0.44; 95% confidence interval [CI], 0.36 to 0.54), with a similar magnitude of reduction seen on the nares (nostrils; OR, 0.34; 95% CI, 0.27 to 0.42), throat (OR, 0.55; 95% CI, 0.42 to 0.73), and the axilla/groin (OR, 0.57; 95% CI, 0.43 to 0.75). These differences persisted through month 9 except at the wound site, which had a relatively small sample size. Higher adherence to the regimen was associated with lower MRSA colonization.

"These findings demonstrate that a home decolonization strategy is a practical and feasible means to reduce MRSA colonization in the nares, throat, and skin during a time highly vulnerable to infection," the study authors wrote. "The reduction in colonization reinforces the previously reported trial findings of significantly reduced MRSA infections and all-cause infections in the year following discharge and strongly suggests the benefits were driven by reduction in MRSA colonization at multiple body sites."
May 31 Clin Infect Dis abstract

Study suggests meningococcal vaccine may protect against gonorrhea

Originally published by CIDRAP News Jun 1

A matched cohort study published today in Clinical Infectious Diseases suggests that a meningococcal serogroup B vaccine may offer cross-protection against gonorrhea infection.

Using a cohort of teens and young adults in the Kaiser Permanente Southern California healthcare system, researchers with the University of California, Berkeley and the University of Alabama at Birmingham compared gonorrhea infections among recipients of the outer membrane vesical (OMV)-based four-component serogroup B meningococcal vaccine (4CMenB) and recipients of non-OMV-containing polysaccharide-conjugate vaccines targeting serogroups A, C, W and Y (MenACWY).

Recent observational research from Norway and New Zealand has indicated that OMV-based meningococcal vaccines may be protective against Neisseria gonorrhoeae, which is becoming increasingly resistant to the last available oral antibiotic treatment options, and the researchers wanted to see if they could replicate those findings in a setting with distinct epidemiologic circumstances.

Comparing 6,641 recipients of 4CMenB to 26,471 recipients of MenACWY 31 days after index vaccination, the researchers found 27 gonorrhea cases among 4CMenB recipients and 295 among those who received MenACWY only, yielding gonorrhea incidence rates per 1,000 person-years of 2.0 (95% CI, 1.3 to 2.8) for 4CmenB and 5.2 (95% CI, 4.6 to 5.8) for MenACWY.  In multivariable analyses adjusting for potential confounders (including race/ethnicity, prior HIV infection, and sexually transmitted infections in the prior year), gonorrhea rates were 46% lower among recipients of 4CMenB versus MenACWY (hazard ratio [HR], 0.54; 95% CI, 0.34 to 0.86), but chlamydia rates were similar (HR, 0.98; 95% CI, 0.82 to 1.17).

"These results are aligned with prior observational studies and lend support to ongoing randomized controlled trials of the effectiveness of 4CMenB against gonorrhea," the study authors wrote. "As rates of antibiotic-resistant gonorrhea continue to increase in the US and globally, renewed attention to vaccination strategies is paramount to preventing untreatable gonorrhea disease."
Jun 1 Clin Infect Dis abstract

World Health Assembly underscores infection prevention and control

Originally published by CIDRAP News May 31

The World Health Assembly (WHA) last week passed a resolution that aims to make infection prevention and control (IPC) a critical element of addressing healthcare-associated infections (HAIs) and antimicrobial resistance (AMR) and of preparing for infectious disease health emergencies.

The resolution, which provides 13 recommendations to member states, comes on the heels of a WHO report that highlighted the global threat of HAIs and the role that IPC can play in reducing that threat. The report found that 7 of every 100 patients at acute care hospitals in high-income countries, and 15 of 100 in low- and middle-income countries, will acquire at least one HAI during their stay. Mortality was at least two to three times higher among patients with HAIs caused by resistant pathogens.

The recommendations for member states include taking steps to ensure that IPC is a key component of global health preparedness, prevention, and response; acknowledging that clean, high-quality, safe, and affordable medical care should be universally available; taking steps to ensure that science-based IPC programs are implemented, monitored, and updated; ensuring that water, sanitation, and hygiene infrastructures are in place in healthcare facilities; ensuring that IPC programs are integrated and aligned with AMR programs; and encouraging continued investment in IPC research.

The resolution also calls on the WHO director-general to develop a draft global strategy for IPC and to translate the strategy into an action plan.
May 25 WHA draft resolution on IPC

7 of 10 clinicians would prescribe antibiotics for asymptomatic bacteriuria

Originally published by CIDRAP News May 31

A survey of US primary care physicians found that more than 70% would prescribe inappropriate antibiotic treatment for asymptomatic bacteriuria, researchers reported late last week in JAMA Network Open.

The survey, conducted from June 2018 through November 2019, presented four clinical scenarios to primary care clinicians from 30 clinics in Texas, the Mid-Atlantic, and the Pacific Northwest. One of the scenarios was the hypothetical case of a 65-year-old man with asymptomatic bacteriuria. The respondents were asked to indicate whether they would prescribe antibiotics and to estimate the probability that the patient in the scenario had a urinary tract infection (UTI). Study authors also analyzed factors associated with reported increased willingness to prescribe an antibiotic for asymptomatic bacteriuria.

The 551 respondents who answered all the questions included 288 resident physicians, 202 attending physicians, and 61 advanced-practice clinicians. Overall, 392 of 551 (71%) indicated they would prescribe an antibiotic for the patient described in the scenario. On average, respondents who said they would prescribe antibiotics estimated a 90% probability of a UTI.

In multivariable analyses, clinicians with a background in family medicine (OR, 2.93; 95% CI, 1.53 to 5.62) or a high score on the Medical Maximizer-Minimizer Scale (indicating stronger medical maximizing orientation; OR, 2.06; 95% CI, 1.38 to 3.09) were more likely to prescribe antibiotic treatment for asymptomatic bacteriuria. Resident physicians (OR, 0.57; 95% CI, 0.38 to 0.85) and clinicians in the Pacific Northwest (OR, 0.49; 95% CI, 0.33 to 0.72) were less likely to prescribe antibiotics for asymptomatic bacteriuria.

The study authors say the survey results likely reflect knowledge gaps, regional differences in healthcare culture that may influence prescribing of inappropriate antibiotics, and clinician attitudes.

"These findings suggest that the Choosing Wisely campaign recommending against antibiotic treatment for asymptomatic bacteriuria has failed to make an impact in the US and that certain types of clinicians are more likely than others to ignore the guidelines and prescribe antibiotics," they wrote, adding that future interventions to reduce unnecessary treatment for asymptomatic bacteriuria should take clinician culture, attitudes, and cognitive characteristics into consideration.
May 27 JAMA Netw Open study