The Centers for Disease Control and Prevention (CDC) yesterday declared its investigation into a multistate Salmonella outbreak tied to organic and cage-free brown eggs over after 134 people fell ill and 1 died.

The outbreak has grown by 55 cases and three affected states since the CDC first reported the event on June 6. Ten states have confirmed cases. The death, in a patient from California, is also new.

Eggs from August Egg Company, of Hilmar, California, have been implicated. On June 6 the company recalled 1.7 million eggs that were distributed in California and Nevada from February 3 to May 15, with sell-by dates ranging from March 4 to June 4. The eggs were sold under various brand names across multiple stores, including Walmart, Safeway, and Save Mart.

Scientists with the Food and Drug Administration collected samples for testing at cage-free laying houses used by August Egg Company. Three of those samples tested positive for Salmonella, and whole-genome sequencing showed that they matched the Salmonella strain that sickened patients.

People started getting sick in February

Outbreak patients ranged in age from 1 to 90 years, with a median age of 46. About 59% were female and 85% White.

Of the 41 case-patients that officials interviewed, 37 (90%) reported eating eggs. In addition, state health officials identified illness clusters at multiple restaurants, all of which served eggs.

People started getting sick with the outbreak strain from February 24 to June 6. Of the 112 people with available information, 38 (34%) were hospitalized. By far the most cases were in California (109), followed by Arizona (8).

"The true number of sick people in this outbreak was likely much higher than the number reported, and this outbreak may not have been limited to the states with known illnesses," the CDC said.

An increase in uptake of routine childhood vaccines among US children over 15 years was associated with a decrease in antibiotic prescriptions and antibiotic-treated sinus infections, according to an ecological study published today in Antimicrobial Stewardship & Healthcare Epidemiology.

Using de-identified commercial claims data, researchers from Merck and Analysis Group Inc. analyzed uptake of four pediatric vaccines recommended by the Centers for Disease Control and Prevention for children aged 5 years and younger: the 7- or 13-valent pneumococcal conjugate vaccine, Haemophilus influenzae type b (Hib) vaccine, diphtheria-tetanus-acellular pertussis (DTaP) vaccine, and influenza vaccine. Vaccination status was assessed annually from 2000 through 2019, and children were categorized based on receipt of all 4 vaccines, 1 to 3 vaccines, or no vaccines. 

The primary outcomes were antibiotic prescriptions for any reasons and five respiratory tract infections that commonly result in antibiotic prescriptions: otitis media (ear infection), pharyngitis, pneumonia, sinusitis, and viral respiratory infections. 

Antibiotic prescriptions nearly cut in half

Data from 6.7 million children showed that vaccine uptake more than doubled over the study period, from 32.5% of children receiving one dose of the four vaccines in 2004 (the first year all 4 vaccines were recommended) to 66.8% in 2019. The proportion of unvaccinated children fell from 8.4% in 2004 to 2.5% in 2019. At the same time, overall antibiotic prescriptions decreased from 1.89 to 1.01 per person-year from 2000 through 2019, and the rate of overall antibiotic prescriptions decreased by 46.6%. The greatest reduction in comparison to 2000 was seen in macrolides (73.3%) and broad-spectrum antibiotics (57%). 

Antibiotic-treated respiratory tract infections declined from 2.43 to 1.61 episodes per person-year, with the largest decreases in sinusitis (64.7%) and pharyngitis (39.8%). The incidence of overall antibiotic-treated respiratory tract infections decreased by 33.8% in 2019 compared with 2000.

"Although causality cannot be inferred due to the ecological study design, the observed trends are consistent with the notion that reducing vaccine-preventable diseases may decrease antibiotic use," the study authors wrote. "While various factors besides vaccination may also play a role, future prospective cohort studies using longitudinal patient-level data are warranted to validate this association."

• Though H5N1 avian flu detections in US dairy cattle have tailed off over the past few months, sporadic positives continue to be reported, including a new detection in a herd from California, the state's first since early June, the US Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) confirmed today. The new positive from California raises the national total to 1,075 herds in 17 states.
• Wastewater detections of SARS-CoV-2 crept up from very low to the low level last week, the US Centers for Disease Control and Prevention (CDC) reported today. Though virus activity remains low across the nation this summer, the region with the highest levels continues to shift and is now the West. In the previous week it was the South.
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