Stewardship / Resistance Scan for Jun 01, 2022

News brief

Decolonization strategy reduces MRSA colonization at multiple body sites

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

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

News Scan for Jun 01, 2022

News brief

3 doses of same, different vaccines protect against mild, severe COVID-19

Three COVID-19 vaccine doses offer good protection against infection and hospitalization, including those caused by variants of concern—regardless of brand, type, or combination, according to an ongoing meta-analysis published yesterday in BMJ.

Researchers from the Chinese University of Hong Kong searched 38 World Health Organization (WHO) databases each week for studies on the efficacy of regimens using the same (homologous) COVID-19 vaccine or a combination (heterologous) of types, with or without a third dose, starting on Mar 8, 2022.

The analysis included 53 observational studies and randomized controlled trials involving 100,190,476 participants of all ages given a total of 24 different COVID-19 regimens using seven vaccine types.

A three-dose mRNA vaccine regimen was the most effective against both symptomatic and asymptomatic infections, with an estimated effectiveness of 96% (95% credible interval [CrI], 72% to 99%). A combination of two doses of adenovirus vaccines with one dose of mRNA vaccine had an estimated efficacy of 88% (95% CrI, 59% to 97%).

Estimated effectiveness of two doses of the same mRNA vaccine was 99% (95% CrI, 79% to 100%) against severe COVID-19. Three doses of an mRNA vaccine offered the most protection against COVID-19 hospitalization, at 95% (95% CrI, 90% to 97%), but their effectiveness against death was uncertain because of confounding factors and the observational nature of the eight studies reporting deaths.

Subgroup analyses showed that a three-dose vaccine regimen was comparably effective in all age-groups, including people 65 and older, as well as in those with impaired immune systems—even against infections caused by the Alpha and highly transmissible Delta and Omicron variants.

The researchers said they recommend an mRNA vaccine booster to reinforce any primary vaccine regimen. "An mRNA booster can induce a similar level of protection against COVID-19 infections to homologous primary vaccination," they wrote. "A third dose [of] vaccine is needed to prevent COVID-19 variant infections."
May 31 BMJ study

Chest CT shows COVID-19 vaccines protect against pneumonia

According to research published yesterday in the American Journal of Roentgenology, chest computed tomography (CT) scans of adults fully vaccinated against COVID-19 were less likely to show pneumonia frequency and severity during breakthrough infections, compared to unvaccinated patients.

The data came from images collected at the University of Rome from 467 patients with a mean age of 65 who had chest CT scans from Dec 15, 2021, to Feb 18, 2022, while hospitalized for symptomatic COVID-19. In total 216 patients were unvaccinated, 167 were fully vaccinated with the Pfizer vaccine, and 84 were fully vaccinated with the AstraZeneca vaccine. Fully vaccinated was defined as at least 14 days from a second dose.

Only 15% of unvaccinated patients had scans absent of pneumonia, compared with 51% and 29% in patients fully vaccinated with Pfizer and AstraZeneca, respectively.

CT severity scores (CT-SS) also differed among the groups, with unvaccinated scored at an average of 9.7, compared with 5.2 for Pfizer and 6.2 for AstraZeneca).

"The visual observation by radiologic imaging of the protective effect of vaccination on lung injury in patients with breakthrough infections provides additional evidence supporting the clinical benefit of vaccination," the authors concluded.
May 31 AJR Am J Roentgenol study