Lesser Wax Worm Larvae, Achroia Grisella as An Animal Model for Staphylococcus Aureus Infection

Abdul Razak, Noralia (2021) Lesser Wax Worm Larvae, Achroia Grisella as An Animal Model for Staphylococcus Aureus Infection. [Project Paper] (Submitted)

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Abstract

Staphylococcus aureus Infection is quite prevalent in animals and humans. Numerous animal models for bacterial infection have been developed, but there is always a lack of a thorough description of the infection mechanism. The non-mammalian model organism: Galleria mellonella larvae have been widely used as an alternative model for microbial infection study but not Achroia grisella. The lesser wax moth, A. grisella shares the same life history as the greater wax moth, G. mellonella. Consequently, they hold benefits such as reasonable price, readily available, requiring no special laboratory equipment, and short life-cycle which are great for large-scale research. Plus, the innate immune response of the larvae is highly similar to that of vertebrates. Objective: This study aims to assess the activity of A. grisella larvae upon Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible Staphylococcus aureus (MSSA) infections. Methodology: In the study, the last instar larvae (3-4 weeks of age) were used. For the infection route, intra haemocoelic injection through the skin was applied. The larvae were evaluated by the health index scoring system within five days after infection, which measures the health status of the larvae by assigning scores according to four key observations: mobility of the larvae, formation of cocoons, melanization and survival. Each waxworm's overall health index score was computed by assigning a numerical value to each observation and averaging the scores. Using the Kaplan–Meier method, the survival data was plotted, and the log-rank test was then used to compare the groups. Results: The survival percentage for PBS-injected larvae is 40% after five days post-infection. In contrast, MRSA- and MSSA-infected wax worms have higher survival percentages ranging from 70% to 80% at doses above 1.0 x 109. The surviving larvae transform to complete cocoon and moth stages throughout an additional one-week observation. Discussion: The death of PBS-uninfected, MRSA- and MSSA-infected larvae might be due to two reasons: the physical trauma experienced during the administration of the inoculum and melanization which occurred at the injection site of the larvae body (<3 spots on a beige wax worm). As the survival rate of both MRSA- and MSSA-infected larvae are quite similar, the potency of both bacteria might be the same. Conclusion: Hence, to appropriately vindicate the concept of MRSA and MSSA pathogenesis, we suggest more in-depth research towards the influence of experimental design on the wax worm larvae.

Item Type:	Project Paper
Faculty:	Faculty of Medicine and Health Science
Depositing User:	Ms. Nor Safa'aton Saidin
Date Deposited:	22 Aug 2023 07:08
Last Modified:	22 Aug 2023 07:08
URI:	http://psaspb.upm.edu.my/id/eprint/1083

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