Infections caused by Salmonella with any antibiotic resistance are associated with more severe clinical outcomes, including hospitalization and death, Centers for Disease Control and Prevention (CDC) researchers reported yesterday in Clinical Infectious Diseases.

Using epidemiologic data from the Foodborne Diseases Active Surveillance Network (FoodNet) and antimicrobial resistance data from the National Antimicrobial Resistance Monitoring System (NARMS), researchers from the CDC's Division of Foodborne, Waterborne, and Environmental Diseases examined outcomes in patients with nontyphoidal Salmonella infections from 2004 through 2018. They compared outcomes for resistant Salmonella infections with those caused by non-resistant Salmonella before and after adjusting for age, state, race/ethnicity, international travel, outbreak association, and isolate serotype or source.

Worse outcomes may involve more than treatment failure

A total of 5,549 FoodNet records were matched with Salmonella isolates from NARMs. Of those isolates, 20% (1,105) had any resistance (defined as resistance to one or more antibiotics), and 8% (469) had clinical resistance (one or more of ampicillin, azithromycin, ceftriaxone, ciprofloxacin, or trimethoprim-sulfamethoxazole).

Patients whose isolates had any resistance were more likely to be hospitalized (31% vs 28%) or have a hospital stay of 3 or more days (20% vs 16%) than patients whose isolates had no resistance. Deaths were rare, but were more common among those with any than no resistance (1.0% vs 0.4%). Outcomes for patients whose isolates had clinical resistance did not differ significantly from those with no resistance.

After adjustment, Salmonella infections with any resistance (adjusted odds ratio [aOR], 1.23; 95% confidence interval [CI], 1.04 to 1.46) and multidrug resistance (aOR, 1.40; 95% CI, 1.12 to 1.75) remained significantly associated with hospitalization. But clinical resistance was not significantly associated with hospitalization.

The study authors say the lack of association between clinical resistance and worse outcomes suggests that factors other than treatment failure, such as strain virulence, strain source, and host factors, may be important.

"Further studies are needed to assess the direct and indirect economic costs attributed to resistant Salmonella and to clarify the role of host and strain factors in determining clinical outcomes," they concluded.

A randomized clinical trial found that nasal mupirocin is more effective than nasal iodophor for reducing Staphylococcus aureus and methicillin-resistant S aureus (MRSA) in intensive care unit (ICU) patients, researchers reported this week in JAMA.

In the cluster-randomized noninferiority trial, investigators randomized 801,668 ICU patients at 137 US hospitals to receive universal decolonization with nasal mupirocin (an antibiotic ointment) plus chlorhexidine gluconate (CHG) bathing or nasal iodophore (an antiseptic) plus CHG bathing.

While a trial conducted from 2009 to 2011 found that universal decolonization with mupirocin and CHG reduced MRSA clinical cultures by 37% and bloodstream infections by 44% in ICU patients, and CHG bathing has been broadly adopted in ICUs, there have been concerns that widespread use of mupirocin could promote resistance in S aureus. Iodophore is considered a potential alternative.

The investigators compared ICU-attributable S aureus cultures, MRSA clinical cultures, and all-cause bloodstream infections in the baseline period—when all hospitals used mupirocin-CHG for universal decolonization—and the intervention period. The noninferiority margin was 10%.

Iodophore inferior to mupirocin

When comparing the two periods, the relative hazard of S aureus clinical cultures was significantly higher by 18.4% for the iodophor-CHG group (hazard ratio [HR], 1.17; 95% confidence interval [CI], 1.12 to 1.23) compared with the mupirocin-CHG group (HR, 0.99; 95% CI, 0.94 to 1.04).

Similarly, MRSA clinical cultures were significantly higher by 14.1% for iodophor-CHG compared with mupirocin-CHG (HR, 1.13 vs 0.99, respectively). For all-cause bloodstream infections, iodophore-CHG was not inferior to mupirocin-CHG (HR, 1.00 vs 1.01, respectively).

This large study confirms that clearing the nose of bacteria prevents infection, and that the choice of product matters.

In addition, when the investigators compared the results from the current trial to the 2009-2011 trial, they found that mupirocin-CHG decolonization remained as effective at reducing S aureus in ICU patients.

"This large study confirms that clearing the nose of bacteria prevents infection, and that the choice of product matters," lead trial investigator Susan Huang, MD, MPH, of the University of California Irvine (UCI), said in a UCI Health press release. "Mupirocin antibiotic ointment remains the best treatment, and serious ICU infections can be avoided by simply giving patients mupirocin for the first five days of an ICU stay along with daily chlorhexidine bathing."

A new meta-analysis of 11 studies reveals a 3.4% estimated prevalence of respiratory syncytial virus (RSV) infection during pregnancy, but with a wide range in estimates, according to a study published yesterday in The Journal of Infectious Diseases.

The analysis comes during a year in which RSV has been the target of new vaccines and monoclonal antibody therapies. Though a mild respiratory illness in most adults, the virus can be severe in infants under 6 months of age, the elderly, and pregnant women.

The meta-analysis, which looked for studies of reparatory illnesses in pregnancy, included 11 studies with pregnant women recruited from 2010 to 2022, for a total of 8,126 patients.

The proportion of pregnant women with respiratory infections who tested positive for RSV ranged from 0.9% in a study in South Africa to 10.7% in a study conducted in Thailand, with a meta-estimate of 3.4% (95% confidence interval [CI], 1.9% to 54%).

Few hospitalizations, no deaths

The estimated incidence rate of prenatal RSV infection was 2.1 (95% CI, 1.3 to 3.0) per 1,000 person-months or 26.0 (95% CI, 15.8 to 36.2) per 1,000 person-years, the authors said.

Hospitalizations were uncommon, and no RSV-associated deaths were observed.

"Hospitalizations were uncommon, and no RSV-associated deaths were observed. Based on limited data from three studies, the odds of stillbirths, miscarriage, low birth weight, and small for gestational age did not differ between pregnant individuals who had antenatal RSV infection compared to those who did not," the authors wrote.

Some studies, however, showed increased odds of preterm delivery in pregnancies affected by RSV (3.6; 95% CI, 1.3 to 10.3).

More studies should be conducted, the authors said, especially as maternal RSV vaccines are rolled out later this year.

The Journal of Infectious Diseases has posted a prospective study showing that 40% of a group of college-aged women in Quebec had human papillomavirus (HPV) infections within 2 years of starting a heterosexual relationship.

A McGill University-led research team tested vaginal samples from 502 women aged 18 to 24 years self-collected at six university clinic visits over 2 years for 36 types of HPV from 2005 to 2011. The women, who had begun a sexual relationship with a man within the past 6 months, also completed questionnaires on sociodemographic factors and sexual behavior.

Persistent HPV infections cause most precancerous cervical lesions and cancers. While most infections in young women resolve, some persist, and a large proportion of "incident" cases in older women are reactivations of previous infections, the study authors said.

Cervical cancer highly preventable with HPV vaccine

By 2 years, new-onset HPV infections were detected in 40.4% of the women. Subgenus 1 infections (43.4%), subgenus 2 (47.1%), and subgenus 3 (46.6%) infections cleared at similar rates per 1,000 infection-months, and infections present at baseline cleared at comparable rates as incident infections.

HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections persist longer than their low oncogenic risk subgenera 1 and 3 counterparts.

"Our analyses of individual HPV types and our HPV-level group analyses provide descriptive natural history estimates for cervical cancer prevention planning," the researchers wrote. "HPV-level analyses did not clearly indicate that high oncogenic risk subgenus 2 infections persist longer than their low oncogenic risk subgenera 1 and 3 counterparts."

They noted that cervical cancer, which made up 3.1% of the global cancer burden in 2020, is highly preventable through the use of the HPV vaccine introduced in 2006. The vaccine "prevents infection with HPV types found in 89.5% of invasive cervical cancers, and molecular HPV testing is an efficacious screening strategy," they wrote.