OXIDATIVE STRESS MARKERS

Street-vended foods provide affordable nutrition for many urban populations but often serve as vehicles for food-borne pathogens capable of causing systemic health effects. This study investigated the effects of pathogens isolated from street-vended foods on the hematological parameters and oxidative stress markers of Wistar rats. Bacteria isolated from street-vended foods were obtained for this study and identified using molecular (polymerase chain reaction) technique. Thereafter, isolates were screened for phenotypic virulence characteristics (biofilm formation, haemolysin and gelatinase production) using standard techniques. Twenty-five wistar rats weighing 169.40g-175.01g were used. Enumeration and isolation of feed samples was done using serial dilution and pour plate techniques. After one week acclimatization, rats were randomly selected into five equal groups (control, W1,W2, X1 and X 2). Rats were experimentally infected with different concentrations (0.06ml and 0.1ml) of Escherichia coli (PX395408) and
Klebsiella pneumoniae (PX395409). After infection, changes in the weight of rats were determined weekly. Following sacrifice, blood and tissue samples were obtained for hematology and histopathological examination. The results revealed that E. coli exhibited β-hemolytic activity, was positive for biofilm formation, and negative for gelatinase production, while K. pnuemoniae showed γ-hemolytic activity and was negative for both biofilm and gelatinase production. The total heterotrophic bacterial counts of feed samples ranged from 5.35±0.07 to 6.90±1.56×10⁵ cfu/g, with isolates including Citrobacter spp and Klebsiella spp. The initial body weight of rats ranged from 169.00 ± 13.90 g to 175.00 ± 10.40 g, while the control group weighed 170.61 ± 4.90 g. After infection, the control rats gained weight steadily (189.35 ± 12.52g), whereas infected rats showed weight reduction, ranging from 125.76 ± 11.95 g to 145.02 ± 28.94 g, indicating systemic infection. Hematological analysis revealed that the control rats maintained normal values except for slightly higher white blood cell counts compared to infected groups. Rats infected with E. coli (0.06 mL) recorded higher red blood cell (RBC) and hemoglobin (HGB) levels than the control, while platelet (PLT) counts significantly increased in K. pneumoniae-infected rats, particularly in the high-dose group (1315±546). Significant differences (p<0.05) were observed in mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) values, while other parameters showed no significant differences (p>0.05). Oxidative stress markers revealed that K. pneumonia infected rats exhibited elevated superoxide dismutase (SOD) and malondialdehyde (MDA) levels, indicating oxidative damage, whereas catalase (CAT) and glutathione peroxidase (GPx) activities were significantly increased in all infected groups. These findings demonstrate that E. coli and K. pnuemoniae from street-vended foods can induce hematological alterations, oxidative stress, and weight loss in Wistar rats, underscoring the need for improved food hygiene and stricter safety regulations.