Natural spices used for culinary purposes in Nigeria: vendor practices, bacterial contamination, and antimicrobial susceptibility patterns

Abstract

Introduction The increasing demand for natural spices used for culinary purposes in Nigerian local markets has raised concerns about the potential contamination of these products by harmful microorganisms. This study investigated natural spices used for culinary purposes in Nigeria by assessing vendor practices, bacterial con-tamination, and antimicrobial susceptibility patterns. Methods A cross-sectional design was employed, with a sample of 267 vendors selected from a population of 800 spice sellers via stratified random sampling. Samples of commonly sold natural spices, including cloves, cinnamon, turmeric, rosemary, basil, and others, were collected for microbiological analysis. Standard microbiological techniques were used to isolate and identify the bacteria present, followed by antimicrobial susceptibility testing via the disc diffusion method. Results The results revealed that common storage practices include open air (40%) and covered containers (32%). Handling was mostly done with bare hands (45%), and only 15% used gloves. While 60% of vendors practice hygiene, only 15% receive training on spice handling. The quality control was performed primarily through visual inspection (50%). The viable count of 1.2 × 10 4 cfu/g, a coliform count of 5.0 × 10 2 cfu/g indicates relatively low contamination and a bacterial count of 3.4 × 10 3 cfu/g suggests a fairly high bacterial presence. Cinnamon, on the other hand, presented the lowest levels of bacterial contamination, with a TVC of 0.1 × 10 4 cfu/g, a coliform count of 1.0 × 10 2 cfu/g and a bacterial count of 1.5 × 10 3 cfu/g, further indicating that cinnamon is less prone to microbial growth. Turmeric had the highest microbial loads, with a TVC of 3.4 × 10 4 cfu/g, a coliform count of 8.0 × 10 2 cfu/g, and a bacterial count of 4.0 × 10 3 cfu/g. The presence of various bacteria, including species of Escherichia coli and Staphylococcus aureus , among others, was revealed. Antimicrobial susceptibility testing revealed that S. aureus exhibited significant resistance to penicillin, whereas E. coli presented resistance to common antibiotics such as ampicillin and tetracycline. Discussion These findings suggest the presence of potential antimicrobial-resistant bacteria in natural spices, indicating the need for improved hygiene practices among spice vendors.