Background and Aim: Escherichia coli, a commensal intestine bacterium of vertebrates, is widely distributed in the environment and indicates the microbiological quality of food products in relation to coliforms. In addition, virulent strains, particularly E. coli O157:H7, cause outbreaks of toxic infections caused by consuming dairy products. Because food safety studies regarding E. coli have not been conducted in Central Asia, this research aimed to study the characteristics of contamination, microbiological and genotypic properties, and resistance to antimicrobial agents of E. coli strains that contaminate various types of commercialized cheeses originating from Kazakhstan. Materials and Methods: In retail outlets, 207 samples of three types of cheese produced by 22 industrial and eight small enterprises in the central, eastern, southern, and northern regions of Kazakhstan were selected in 2020–2023. E. coli contamination was examined using standard microbiological, mass spectrometric, and molecular genetic methods. The discodiffuse European Committee on Antimicrobial Susceptibility Testing method was used to test the resistance of the identified E. coli isolates (65/207; 31.4%) to 20 antibacterial drugs. The Shiga toxin-producing E. coli (VT1 and VT2) and E. coli O157:H7 (eae) genes were investigated in all E. coli isolates using multiplex polymerase chain reaction. Results: An average of 31.4% samples of commercial Kazakhstani cheeses of various types were found to be contaminated with E. coli in almost all geographical regions of Kazakhstan, regardless of the productivity of the dairy enterprises. Soft cheeses produced by small farms (80% of samples) packaged at the retail site (100%) were the most contaminated with E. coli. The microbiological index (colony-forming unit/g) was unsatisfactory and unsuitable in 6.2% of such cheese samples. For the first time in Central Asia, the enteropathogenic strain E. coli O157:H7 was detected in 0.5% of cheese samples. E. coli isolates from cheese samples were resistant to 65% of antibacterial drugs and contained resistance genes to β-lactams, sulfonamides, and quinolones groups. At the same time, 25% of the E. coli isolates were multi-resistant to three or more antimicrobial agents. Conclusion: The high level of contamination caused by multi-antibiotic resistant E. coli strains, including pathogenic pathogens, poses a risk to public health and highlights the need for further research on the monitoring and control of coliform enteropathogens in food products. Keywords: antibiotic resistance, Escherichia coli O157:H7, Kazakhstan cheese, microbial contamination.

Background and Aim. Feline leukemia virus (FeLV) is one of the most important retroviral pathogens in domestic cats, causing immunosuppression, anemia, lymphoma, and leukemia. FeLV exists in two forms: exogenous (exFeLV), which is infectious and horizontally transmitted, and endogenous (enFeLV), which is inherited as integrated proviral sequences. Differentiating between these forms is essential for accurate epidemiological assessment and diagnostics, since enFeLV sequences can interfere with molecular assays and lead to false-positive results. This study aimed to evaluate the prevalence of endogenous FeLV sequences in domestic cats in Astana and to determine whether exogenous FeLV was actively circulating in this population. Materials and Methods. A total of 203 whole-blood samples from domestic cats were collected during routine veterinary examinations, and genomic DNA was extracted using a modified Kanai method. Two independent real-time PCR systems were employed: primers targeting the conserved env region to detect enFeLV, and primers specific to the U3 region of the long terminal repeat (LTR) to identify exFeLV. Amplifications were performed on the CFX96 Touch platform, and samples with quantification cycle (Cq) values <40 were interpreted as positive. Results. Of the 203 analyzed samples, 197 (97%) were positive for enFeLV sequences, confirming the widespread presence of endogenous retroviral elements in the genome of cats, while no amplification was detected with U3-specific primers, indicating the absence of active exFeLV infection. The Cq values for enFeLV-positive samples ranged from 11.24 to 37.04, reflecting variability in proviral copy number among individuals. These findings demonstrate that enFeLV is nearly ubiquitous among domestic cats in Astana, while no evidence of exFeLV circulation was detected. Conclusion. The results underscore the importance of using U3-LTR specific assays to reliably differentiate endogenous from exogenous forms of FeLV and to avoid false-positive diagnoses. Further studies should focus on monitoring potential recombination events between enFeLV and exFeLV, evaluating the expression of endogenous loci, and assessing their role in disease pathogenesis.

Background and Aim. Equine salmonellosis-associated abortion remains an important infectious disease of horses, with significant implications for reproductive health and horse breeding. Salmonella enterica subsp. enterica serovar Abortusequi is recognized as one of the etiological agents associated with abortion in mares and may persist within affected horse populations. This study is aimed to characterize and identify an S. Abortusequi isolate recovered from pathological material obtained from an aborted equine fetus in the Aiyrtau District of the North Kazakhstan Region through comprehensive assessment of its morphological, cultural, biochemical, and serological characteristics, and to determine its antimicrobial susceptibility profile.Materials and Methods. A pure bacterial culture was obtained through sequential subculturing followed by the selection of colonies exhibiting characteristic morphological features. Identification of the isolate was performed using an integrated approach based on morphological, cultural, biochemical, and antigenic characteristics. Cellular morphology and staining properties were examined by light microscopy, while cultural characteristics were evaluated based on growth patterns and colony morphology on selective and differential diagnostic media. Biochemical activity was assessed using standard diagnostic tests. The antigenic profile of the isolate was determined by slide agglutination with polyvalent and monoreceptor diagnostic antisera specific for Salmonella O- and H-antigens. Species-level identification was additionally confirmed by matrix-assisted laser desorption/ionizationtime-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility was assessed against 12 antimicrobial agents using the disk diffusion method, with results evaluated based on the diameters of bacterial growth inhibition zones.Results. The recovered isolate exhibited morphological, cultural, and biochemical characteristics consistent with the genus Salmonella, including Gram-negative, motile, rod-shaped cells, facultative anaerobic growth, characteristic colony morphology on selective and differential media, and hydrogen sulfide (H2S) production. Biochemical testing demonstrated glucose fermentation with acid and gasproduction, absence of lactose and sucrose fermentation, negative indole and urease reactions, and positive citrate utilization. Serological analysis revealed specific agglutination with O:4 (O-IV) and O:12 (O-XII) diagnostic antisera, assigning the isolate to Salmonella serogroup B; the antigenic formula was determined as 4,12:-: n,x, consistent with Salmonella enterica subsp. enterica serovar Abortusequi. Identification was additionally supported by MALDI-TOF MS analysis. Antimicrobial susceptibility testing showed inhibition zone diameters ranging from 26 to 41 mm, with the largest zones observed for imipenem (41 mm), ofloxacin (40 mm), and ceftriaxone (38 mm), followed by amoxicillin/clavulanic acid and norfloxacin (35 mm each), cefoxitin (34 mm), co-trimoxazole and tobramycin (32mm each), ampicillin (31 mm), gentamicin (30 mm), azithromycin (27 mm), and tetracycline (26 mm).Conclusion. Comprehensive assessment of the morphological, cultural, biochemical, serological, and mass spectrometric characteristics enabled identification of the isolate recovered from pathological material of an aborted equine fetus as S. Abortusequi. Disk diffusion testing demonstrated growth inhibition zone diameters ranging from 26 to 41 mm across the panel of 12 antimicrobial agents tested. These findings provide a phenotypic characterization of the S. Abortusequi isolate and describeits antimicrobial susceptibility profile, contributing to the laboratory characterization of this pathogen associated with equine abortion.

Background and Aim. This article presents the results of a study on the effectiveness of extruded feed containing a formulation of symbiotic bacteria on the performance of catfish production and its meat quality as assessed by veterinary and sanitary indicators. The study aimed to develop extruded feed based on a symbiotic formulation and to determine the effectiveness of the feed on the production of clary catfish meat. Materials and Methods. Experimental work was carried out on the platform of the International Scientific Research center “Fisheries” and S.Seifullin Kazakh Agrotechnical Research University (S. Seifullin KATRU). In total, 135 kg of feed was used to feed young African clary catfish at a rate of 30 g per fish per day over 40 days. The fish were divided into two pools, with 100 individuals in each group. To assess the effectiveness of feed, a weekly total catch of the two pools was carried out to determine the mass of fish. To determine the Fulton fatness coefficient (kc), 20 fish were measured from each group. Veterinary and sanitary assessments of fish meat were carried out using generally accepted organoleptic and physico-chemical research methods. Results. On the 40th day, a significant difference was observed in all weight gain indicators on day 40: the mean fish weights were 570 ± 17.8 and 565 ± 18.2 g in the Control and Experimental groups, respectively (P < 0.01). Indeed, the chemical composition of meat improved in terms of the mass fractions of protein and fat: the mass fraction of protein was 16.22 and 17.38% for the Control and Experimental groups, respectively, and 3.90 and 4.90% for the mass fraction of fat. Conclusion. The novelty of this research is to develop extruded feed based on a symbiotic formulation and to determine the effectiveness of the feed on the production of clary catfish meat. One formulation of extruded feed with a symbiotic was obtained. The effect of symbiotic feed on the productive performance of the African catfish has been studied. A veterinary and sanitary assessment was carried out to determine the nutritional value of fish meat. All indicators of the amino acid, vitamin, and mineral composition of fish meat in both groups were normal.