Arguments begin in case over use of medically important antibiotic on citrus trees

News brief

Oral arguments begin today in a lawsuit challenging the US Environmental Protection Agency (EPA) over its approval of the antibiotic streptomycin for use as a pesticide on citrus trees.

The lawsuit, filed in 2021 by a coalition of public interest, environmental health, and farmworker advocacy groups, claims the use of streptomycin is unlawful under the Federal Insecticide, Fungicide, and Rodenticide Act and Endangered Species Act. The groups say the agency failed to ensure that the use of streptomycin to combat citrus greening would not cause unreasonable harm to human health or the environment.

Citrus greening is caused by the bacterium Candidatus Liberibacter asiaticus, which is carried by an insect called the Asian citrus psyllid. Infected trees produce green, small, misshapen fruit and die within a few years. The groups say that more than 650,000 pounds of streptomycin could be used on citrus trees in Florida and California, despite little evidence that it will solve the problem.

The EPA authorized the spraying of streptomycin—labelled as "critically important" to human health by the World Health Organization—in 2018 after 2 years of review, despite concerns expressed by the Centers for Disease Control and Prevention, the Food and Drug Administration, and members of Congress. In addition to worries about the effect on citrus workers, insects, and mammals that forage in treated fields, there are concerns that spraying streptomycin in citrus trees could select for antibiotic-resistant bacteria in the environment.

"Medically important antibiotics should be reserved for a doctor's toolkit, not agricultural fields," Allison Johnson, a senior attorney with the Natural Resources Defense Council (NRDC, one of the petitioners in the case), said in a press release. "Misuse and overuse of these precious medicines are known to exacerbate the growing health threat posed by antibiotic-resistant infections."

The case is being heard by the Ninth Circuit Court of Appeals.

Our underwriters

Federal biosecurity panel proposes tighter pathogen research oversight

News brief

An outside expert panel that advises the National Institutes of Health (NIH) on biosecurity issues on Jan 20 issued draft recommendations that would tighten oversight of potentially dangerous pathogens, which the group will discuss in a meeting on Jan 27.

In February 2022, the NIH asked the National Science Advisory Board for Biosecurity (NSABB) to look at existing federal policies on oversight of federally funded research on potential pandemic pathogens and to review government policies on dual-use research (DURC). The NSABB formed two working groups to tackle the reviews, and they published a preliminary report in September.

Among the findings, they said current definitions of potential pandemic pathogens and enhanced versions of them are too narrow, focusing too much on "highly transmissible" and "highly virulent." The experts said current definitions could overlook some research that involves the creation, transfer, or use of pathogens with enhanced potential to trigger a pandemic.

Regarding DURC, the report says government policies have strengthened oversight, but the current framework covers just a small fraction of life sciences research.

The NIH said the review wasn't done in response to concerns that SARS-CoV-2 may have come from a lab, according to the Washington Post. However, the report emphasizes that increased transparency regarding the review process is needed to build public trust in the government's oversight process.

Over the past decades, the NSABB has played a key role in advising the government about its oversight of federally funded pathogen research, tapping it in 2012 to make recommendations about publishing controversial H5N1 avian flu gain-of-function (GOF) studies and in 2016 to provide more clarity on assessing and funding GOF studies.

Vaccinated pregnant women less prone to serious Omicron COVID

News brief

Overall, moderate to severe COVID-19 disease (MSCD) was rare among pregnant Italian women infected with the Omicron variant but was nearly three times more likely in those who received no vaccine doses during pregnancy, finds a study published late last week in Clinical Microbiology and Infection.

The study, led by researchers from the National Centre for Disease Protection and Health Promotion in Rome, enrolled 1,069 pregnant COVID-19 patients who received at least one vaccine dose during pregnancy (considered protected) and 1,078 infected pregnant women who were either unvaccinated or received one or two vaccine doses before pregnancy (unprotected) and tested positive at 22 or more weeks' gestation.

Participants were hospitalized within 7 days of infection from Jan 1 to May 31, 2022. Of all women, 96.4% were admitted to give birth or for obstetrical reasons, and 3.6% were admitted for COVID-19. Eight of the latter group were severely ill, while 12 were moderately ill, and 58 had mild disease.

Higher rate of preterm birth, C-section

MSCD was rare (1.9%) but occurred in 2.8% of unprotected women. Compared with vaccinated women, unprotected participants were more often younger, had symptoms, were foreign-born, and had less education.

Other risk factors for MSCD were chronic conditions (odds ratio [OR], 2.86) and being born in Asia (OR, 3.05). More preterm and caesarean births occurred among MSCD patients than among the mildly ill (32.0% vs 8.4% and 52.0% vs 31.6%, respectively).

Of the 41 MSCD patients, 27 of 29 unprotected women were unvaccinated, and two received two doses before pregnancy. Among the 12 protected women, three received a booster dose, and nine had two doses, one each before and during pregnancy. Seven of eight severe illnesses and one maternal death occurred among unprotected participants.

MSCD patients delivered a greater proportion of babies admitted to a neonatal intensive care unit, probably owing to their higher rate of preterm birth.

Of the 41 MSCD patients, 27 of 29 unprotected women were unvaccinated, and two received two doses before pregnancy.

"Transplacental transfer of maternal antibodies following SARS-CoV-2 vaccination during pregnancy can protect the mother and neonate throughout the first six months of life," the authors wrote.

Resistant H pylori infections linked to use of antibiotics for COVID-19

News brief

Antibiotic treatments for Heliobacter pylori infections showed lower-than-accepted eradication rates in patients previously treated for COVID-19, according to the results of a randomized trial published last week in BMC Infectious Diseases.

In the trial, conducted in Egypt from Mar 21, 2021, to Sep 30, 2021, investigators enrolled 270 patients with newly diagnosed H pylori infections who had been treated for COVID-19 more than 3 months before enrollment. The patients were randomized to receive the first-line treatment of clarithromycin, esomeprazole, and amoxicillin or the alternative regimen of levofloxacin, esomeprazole, and amoxicillin. H pylori is the main causative organism of chronic gastritis, peptic ulcer disease, and gastric carcinoma.

A total of 116 patients in the clarithromycin group and 117 patients in the levofloxacin group were assessed. The eradication rates in the intention-to-treat and per-protocol analyses were 55.56% and 64.66%, respectively, in the clarithromycin arm and 64.44% and 74.36%, respectively, in the levofloxacin arm. While the eradication rate using levofloxacin was higher than that of the clarithromycin-based regimen, the difference did not reach statistical significance, and both regimens had an unacceptable rate of eradication.

Although they did not document which type of antibiotics the patients had been treated with for COVID-19, the investigators suggest the extensive use of azithromycin (which has cross-resistance with clarithromycin) and levofloxacin to treat COVID-19 patients may have resulted in the accumulation of mutations in H pylori—a bacterium present in 50% to 75% of the world's population—that confer resistance.

They say the findings should "raise the alarm" about the impact that widespread antibiotic use for COVID-19, particularly during the first year of the pandemic, has had on antibiotic resistance. "This rising resistance can adversely impact the costs of H. pylori treatment and increase the risk of H. pylori related diseases," they wrote. "Further studies enrolling a larger number of patients with molecular and genetic testing are needed to elucidate the exact mechanism of antibiotic resistance of H. pylori in such patients."

More Salmonella cases reported in outbreak tied to pet bearded dragons

News brief
Bearded dragon
Frank Paul Silye / Flickr cc

A pair of Salmonella outbreaks linked to pet bearded dragons, first announced in October, has sickened at least nine more people in five more states, the Centers for Disease Control and Prevention (CDC) said in a Jan 20 update.

The added cases bring the total to 32 infections from 20 states. Ten people have been hospitalized, and no deaths have been reported. The outbreaks involve two Salmonella serotypes: Vitkin (12 cases) and IIIb 61:z52:z53 (20 cases).

Of the sick people, 47% were children. Of the 25 people interviewed, 16 had contact with a pet bearded dragon before they got sick. The latest illness onset was Nov 20.

Among the Salmonella Vitkin infections, investigators are still working to determine if there is a common supplier. Four patients bought their pets from different stores. In the Salmonella IIIb 61:z52:z53 outbreak, public health officials from Utah and Colorado have identified the outbreak strain from a sick person's bearded dragon and its habitat. Patients bought their pets from different stores, and efforts are still under way to identify a common supplier. Sequencing from 30 patient samples predicted resistance to ciprofloxacin, though most people recover without antibiotic treatment.

Pet bearded dragons have been linked to several past Salmonella outbreaks, including one announced in January 2022 involving Salmonella Uganda that sickened 56 people from 26 states. The CDC urges people to wash their hands after handling bearded dragons and to avoid kissing or snuggling with them.

This week's top reads