A new study from Kazakhstan highlights just how diverse Salmonella enterica can be. Among the 20 isolates examined, researchers identified 10 serovars and 11 genetic types, while their susceptibility to antibiotics varied. What does this mean for infection control? The question is particularly important in light of recent salmonellosis outbreaks — from the recall of nearly 19 million eggs in the United States to 51 confirmed cases in Salekhard, Russia.
Scientists in Kazakhstan examined 20 Salmonella enterica isolates preserved in the National Collection of Microorganisms. The researchers wanted to understand how diverse these bacteria are and whether they respond to antibiotics in the same way. The findings are important not only for Kazakhstan, but for all Central Asian countries, where shared food supply chains and cross-border trade can create opportunities for the spread of antibiotic-resistant bacteria.
The diversity was notable: among the 20 isolates, researchers identified 10 serovars and 11 genetic types. But the antibiotic susceptibility tests were even more revealing. Even bacteria belonging to the same serovar and the same genetic type could respond differently to the same drug.
The researchers used serotyping and MLST (multilocus sequence typing), a method that helps determine the genetic type of a bacterium. Put simply, they were trying to answer two questions: what kind of bacterium is it, and how does it respond to different antibiotics?
The tests covered 13 antibiotics. The absence of a measurable zone of growth inhibition was most frequently observed with ampicillin and the trimethoprim–sulfamethoxazole combination — in both cases, this was observed in 10 of the 20 isolates. For cefepime and lomefloxacin, a growth-inhibition zone was observed for all of the bacteria tested.
The authors, however, make an important clarification: the absence of a growth-inhibition zone does not automatically mean that the bacterium is resistant to the drug. This study examined the bacteria’s phenotypic response. The researchers did not specifically analyze the genes responsible for antibiotic resistance. That would require a separate genomic study.
Therefore, the findings cannot be extrapolated to all Salmonella strains in Kazakhstan. The study included only 20 archival isolates, specifically selected from the collection rather than collected as part of national epidemiological surveillance. The authors explicitly note that the study does not allow them to estimate the prevalence of antibiotic resistance or the frequency of different serovars in the country.
However, the research demonstrates an important point: knowing the name of the bacterium alone is not enough to predict how it will respond to an antibiotic. This is why effective salmonellosis control requires a combination of laboratory testing, genetic characterization of bacteria, and epidemiological surveillance.
In the United States, nearly 19 million eggs were recalled in August 2026 after being linked to a Salmonella Enteritidis outbreak. The U.S. Food and Drug Administration (FDA) classified the recall as Class I, the highest risk level. The outbreak was associated with 98 illnesses across 17 states, and 26 people were hospitalized.
The investigation traced the outbreak back to products from a single company. Salmonella was also detected on farms in Texas, and whole-genome sequencing of some samples showed that they matched the strain associated with the outbreak.
This is an important example of how modern laboratory methods can do more than simply detect a bacterium: they can help link it to a specific outbreak and identify a likely source of contamination.
In Salekhard, salmonellosis was confirmed in 51 people after they consumed ready-to-eat food delivered by a food delivery service. Among those affected were 18 children. Public health authorities launched anti-epidemic measures, and a criminal investigation was opened into the provision of services that failed to meet safety requirements.
However, the information currently available does not provide enough evidence to determine exactly at which stage Salmonella entered the ready-to-eat food. The contamination could have occurred through raw ingredients, storage, preparation, packaging, or at another point in the food chain.
This is the key difference between the two cases. In the United States, laboratory data helped link the detected bacterium to a specific outbreak. In Salekhard, illnesses were identified first, while the circumstances and source of the infection have yet to be established.
For the food safety system, this distinction is critical: the earlier contamination is detected and the more precisely its source can be identified, the greater the opportunity to stop the spread of infection.
There is another scenario — when a dangerous bacterium is detected before it causes illness.
In August, a batch of Vitasia Asian Style Wok Spice Mix was recalled in the United States after routine testing detected potential Salmonella contamination. At the time of the recall, no illnesses associated with the product had been reported.
At first glance, this may seem like just another food recall. But from a public health perspective, this is precisely the kind of outcome a food safety system should strive for: detecting a threat before the product reaches consumers and causes illness.
And this is where all the cases discussed in this article come together. The study from Kazakhstan shows how diverse Salmonella bacteria can be and how differently they may respond to antibiotics. In the United States, modern laboratory methods help link a bacterium to a specific outbreak. In Salekhard, authorities were already dealing with dozens of people who had fallen ill. And the spice recall demonstrates that the most effective form of control is one that works before people start getting sick.
When it comes to Salmonella, the best outcome is not a successfully investigated outbreak — it is an outbreak that was prevented from happening in the first place.
This material was prepared by the Regional Environmental Centre for Central Asia (CAREC) as part of the regional “One Health in Central Asia” programme, with the support of the World Bank.
Shoira Toirova
PR Specialist, One Health Program»