Study suggests US enteric fever cases won’t respond to ciprofloxacin

News brief Gilnature / iStock An analysis of US enteric fever cases found that most travel-associated cases were not susceptible to the first-line antibiotic treatment, researchers with the Centers for Disease Control and Prevention (CDC) reported this week in JAMA Network Open. Enteric fever, which encompasses both typhoid and paratyphoid fever, is typically transmitted via food or water contaminated with Salmonella Typhi or Paratyphi bacteria and can be deadly if not treated promptly with antibiotics.

Nearly 8 million enteric fever cases occur globally each year, but only a small fraction of those cases (5,700) occur in the United States, and they’re typically linked to travel to countries where typhoid and paratyphoid fever are endemic, such as India and Pakistan. With new patterns of antibiotic resistance emerging globally, particularly in Pakistan , where an extensively drug-resistant (XDR) strain of Salmonella Typhi was identified in 2016, the researchers wanted to analyze US cases for antimicrobial-resistance trends.

“Because resistance can evolve quickly, surveillance is important to detect emerging resistance, track trends, and guide clinical and public health decision-making,” they wrote. Empiric treatment ‘should avoid fluoroquinolones’ Using data from the National Typhoid and Paratyphoid Fever Surveillance system and bacterial samples from the National Antimicrobial Resistance Monitoring System (NARMS), the researchers identified 2,342 enteric fever cases reported from 47 states from 2016 to 2020.

Most patients (81.9%) reported traveling or residing internationally within 30 days of illness onset, with India, Pakistan, and Bangladesh the most common destinations. Of the 1,635 enteric fever isolates that tested through NARMS, 78.4% of the Salmonella Typhi and 94.2% of the Paratyphi isolates were not susceptible to ciprofloxacin, which has been a first-line treatment since the 1980s.

In addition, 5.5% of the Typhi isolates were resistant to ceftriaxone, although it was largely confined to travelers to Pakistan. “These findings suggest that empiric treatment recommendations for enteric fever should avoid fluoroquinolones, as nonsusceptibility has been linked to poorer clinical outcomes,” the authors wrote, adding that treatment of enteric fever should be tailored to antibiotic susceptibility test results and patients’ travel history.

The authors also note that getting vaccinated for typhoid fever prior to travel could help reduce the number of US cases. Maternal RSV vaccination, monoclonal antibody equally effective at protecting infants, study finds News brief Sviatlana Lazarenka / iStock The introduction of the respiratory syncytial virus (RSV) vaccine RSVpreF (Abrysvo) for pregnant women and the long-acting monoclonal antibody nirsevimab (Beyfortus) for newborns in 2023 offered protection for infants against the ubiquitous virus.

RSV is responsible for 3.6 million hospitalizations and about 100,000 deaths in children under 5 years worldwide, per the World Health Organization . A study published last week in JAMA Network Open finds no statistically significant difference between maternal RSVpreF or nirsevimab in protecting infants from RSV infection and hospitalization.

“We did not observe a difference in effectiveness between the [two] products,” wrote the authors, from the Vaccine Study Center the at Kaiser Permanente Northern California Division of Research. “Physicians and expectant parents may continue to choose which protection method to receive based on personal preference or local availability.” Both prevent infection, hospitalization Using a retrospective cohort study, the researchers examined 15,124 matched infants born full term in the Kaiser Permanente Northern California system from either December 3, 2023, to March 30, 2024, or September 29, 2024, to March 15, 2025.

The scientists paired infants with moms who received RSVpreF with infants who received nirsevimab. In total, 146 (0.97%) of the matched infants tested positive for RSV. In the RSVpreF group, 106 of 11,293 (0.94%) had RSV, with seven infants hospitalized.

In the nirsevimab group, 40 of 3,831 (1.04%) tested positive for RSV, with five newborns requiring inpatient treatment. The findings of this study support current national and society guidelines indicating that either maternal RSVpreF or infant nirsevimab should be offered to protect all infants against RSV.

RSVpreF was 69.3% effective against infection and 86.4% against hospitalization. Nirsevimab was 65.2% effective against infection and 73.8% effective against hospitalization. “The findings of this study support current national and society guidelines indicating that either maternal RSVpreF or infant nirsevimab should be offered to protect all infants against RSV,” the authors concluded.