Proximate Analysis and Occurrence of Antibiotic Resistant Escherichia coli in Street Vended Ready to Eat Edible Larvae of Rhynchophorus phoenicis in Port Harcourt, Nigeria
Authors: Igbonezu Victor Nzube , Eruteya Onoriode Christian , Uguomore Edmond Osi , Umezurike Kingsley Chimuanya , Okonkwo Philip Onyelukachukwu 
Published: August 2024

Rhynchophorus phoenicis, known as the African palm tree larva weevil or edible worm, is a popular edible insect in southern Nigeria and other African countries. These larvae, by-products of oil palm and palm trees, are consumed roasted or boiled and are known for their nutritional and medicinal properties. In Nigeria, they are widely sold along highways in states like Bayelsa, Delta, Edo, Imo, Rivers, and the upper Cross River basin. Preparation methods include consuming them raw, boiled, fried, smoked, or in stews and soups. Typically, the larvae are washed, skewered, sprinkled with salt and pepper, and grilled. They are juicy and have a taste reminiscent of Torzo or cow intestines.
Despite their popularity, edible worms pose safety and health concerns due to contamination and the emergence of antimicrobial-resistant bacteria. The indiscriminate use of antimicrobials in animals and humans has led to the development of resistant microorganisms, including multidrug-resistant Escherichia coli, which has been increasingly reported in food poisoning outbreaks. There is limited data on the incidence and antibiotic resistance of Escherichia coli in ready-to-eat foods in Nigeria, prompting this study.
The study aimed to determine the proximate composition, occurrence, and antibiotic-resistant pattern of Escherichia coli from edible larvae (Rhynchophorus phoenicis). Objectives included determining the proximate composition of the larvae, the occurrence of Escherichia coli in them, and their antibiotic susceptibility pattern.
Fifty ready-to-eat food samples of edible larvae were randomly collected from hawkers. These samples, often partially exposed and poorly packaged, were transported to the microbiology laboratory for analysis. Sterilized glassware and media were used, including Nutrient Agar, Eosin Methylene Blue (EMB) Agar, and Mueller Hinton Agar. Samples were diluted using peptone water, and bacteriological determination involved homogenizing 25 grams of the sample in 225 ml of peptone water, followed by serial dilutions. Aliquots were inoculated on EMB Agar plates, and incubated at 37°C for 24 hours, and colonies were counted and recorded as colony-forming units per gram (cfu/g). Isolates were identified using standard microbiological methods and biochemical tests.
Proximate analysis revealed moisture (35.49%), carbohydrate (6.01%), protein (20.73%), ash (1.25%), lipid (22.3%), and fiber (14.23%) content. Bacterial counts ranged from 8.1 x 10^7 to 6.34 x 10^8 cfu/g, with the highest count at the Checkpoint sample and the lowest at Elele-Alumini. Of the 27 isolates, 15 (55.56%) were confirmed as E. coli, with 18.52% of samples exceeding the acceptable microbiological limit (≥10^7 CFU/g). Antibiotic susceptibility tests showed all isolates resistant to augmentin, penicillin, cephalosporin, and ofloxacin, with 46.67% resistance to sulfamethoxazole and streptomycin.