In its weekly update on COVID-19 today, the World Health Organization (WHO) said cases dropped 76% over the last 28 days, compared to the previous 28 days, with deaths down 66% over the same period. The WHO included caveats that the numbers are underestimates due to reduced testing and delays in reporting.

Cases declined in all world regions, and deaths fell in all regions except the Eastern Mediterranean.

In its variant update, the WHO said Omicron recombinants, mostly XBB.1.5, make up a growing proportion and are at 41.5%, up from 18.7% in the first half of January. XBF, added a few weeks ago as a variant under monitoring, makes up an estimated 1.2% of sequenced samples.

In a separate report, an updated assessment of XBB.1.5 from the WHO's technical advisory group on SARS-CoV-2 evolution said the subvariant is likely to fuel an increase in cases, given strong evidence of higher transmissibility and moderate-strength evidence of immune evasion. So far, XBB.1.5 doesn't appear to pose an additional public health risk over other currently circulating Omicron lineages, the group said.

Seeking EUA for 4th vaccine dose in preschoolers

In other COVID developments, Pfizer and BioNTech announced today that they have submitted an application for emergency use authorization (EUA) for their bivalent COVID vaccine as a fourth (booster) dose in kids younger than 5 who have already received their primary series.

The vaccine is already authorized as the third dose of a three-dose primary series for kids in the age-group.

The Centers for Disease Control and Prevention (CDC) yesterday declared its investigation into a multistate Salmonella outbreak tied to alfalfa sprouts over, but it added 48 cases and five affected states since its previous outbreak notice in late December, for a total of 63 cases in eight states, with 10 people hospitalized.

The Salmonella Typhimurium outbreak has been linked to sprouts sold by SunSprout Enterprises, of Omaha, Nebraska. On December 29, 2022, SunSprout recalled four lots of raw alfalfa sprouts.

Of 50 case-patients interviewed, 35 (70%) reported eating alfalfa sprouts. And 8 of them confirmed they had bought SunSprout brand alfalfa sprouts from their local grocery store.

Illness-onset dates vary from December 2, 2022, to February 2, 2023. Outbreak patients range in age from less than 1 year to 83 years, with a median age of 42, and 61% are female.

"The true number of sick people in this outbreak was likely much higher than the number reported, and the outbreak may not have been limited to the states with known illnesses," the CDC said. "This is because many people recover without medical care and are not tested for Salmonella."

Nebraska reported the most cases, 26, followed by South Dakota (13), Missouri (9), Iowa (6), and Kansas (6). Arizona, New Hampshire, and Oklahoma each confirmed 1 case.

A new report from the United Kingdom's Health Security Agency (HSA) shows the rate of bloodstream infections (BSIs) caused by Enterococcus has increased in England year over year since 2012.

According to the report, the overall rate of Enterococcus spp. bacteremia was 15.9 per 100,000 population in 2021, up from 14.1 per 100,000 in 2020 and 9.6 per 100,000 in 2012. Rates ranged from 12.5 per 100,000 in the North East of England to 18.8 in the South West, with all regions of the country showing an increase from 2020 to 2021.

The report suggests the increase in Enterococcus spp. bacteremia rates could be linked to the increased number of patients admitted to intensive care units (ICUs) during the pandemic and the subsequent risk of ICU-acquired bacteremia. But it also notes that rates of bacteremia from other pathogens, such as Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae, declined from 2019 to 2021.

The highest rates of Enterococcus spp. bacteremia were observed in the elderly, with men over 75 having a significantly higher rate than women (106.4 per 100,000 vs 39.8 per 100,000). Men had higher rates in all age groups compared with women, except among those aged 15 to 44 years.

The most frequently identified Enterococcus species from blood cultures in 2021 was Enterococcus faecium (44.5%), followed by E faecalis (40.5%). Antimicrobial resistance in E faecalis bacteremia remained rare in 2021, at around 2% to ampicillin/amoxicillin, vancomycin, and teicoplanin and 1% to linezolid. Resistance of E faecium to teicoplanin increased from 19.5% in 2020 to 22.1% in 2021, while resistance to linezolid increased from 1.3% to 1.9%. Resistance of E faecium to ampicillin/amoxicillin remained high, at 92%.

"The switch from E. faecium becoming the more dominant species in England could have significant treatment implications in light of higher resistance rates compared to those seen in E. faecalis BSI," the report states.

An analysis of municipal and hospital wastewater in Japan found a high number of multidrug-resistant Escherichia coli strains, with significantly more found in the municipal wastewater, researchers reported last week in the Journal of Global Antimicrobial Resistance.

In the study, researchers with Yamagata University and Tohuko University School of Medicine sampled wastewater from a municipal wastewater treatment plant and a hospital in the city of Sendai twice a month from February 2019 to February 2020. 

Over the study period, 279 and 37 strains of ESBL-EC were isolated from municipal and hospital wastewater, respectively.

A previous study by the group in the same city had detected higher levels of antibiotic-resistant bacteria (ARB) in municipal wastewater than hospital wastewater, which demonstrated the feasibility of using municipal wastewater to monitor for ARB in healthy populations.

The aim of this study was to investigate the levels of extended-spectrum beta-lactamase–producing E coli (ESBL-EC) in the wastewater and to further characterize the isolated strains of ESBL-EC using antibiotic susceptibility testing and multi-locus sequence typing (MLST).

Over the study period, 279 and 37 strains of ESBL-EC were isolated from municipal and hospital wastewater, respectively. All 316 isolates were resistant to ampicillin and cefotaxime and susceptible to imipenem and tigecycline, and 98.1% possessed bla_CTX-M genes, with bla_CTX-M-9 detected most frequently (62.3%). Six isolates from municipal wastewater and one from hospital wastewater contained multiple bla_CTX-M genes.

MLST revealed a higher diversity of sequence types (STs) in isolates from the municipal wastewater than in those from the hospital wastewater, but E coli ST131—an epidemic ESBL-EC strain that has caused multidrug-resistant urinary tract infections worldwide—was the most common ST in both types of wastewater.

"These results support our hypothesis that monitoring municipal wastewater can effectively obtain comprehensive information about the strains of this clinically important ARB circulating in the study area, some of which may cause human infections in the future," the study authors wrote.