Acanthamoeba is a free-living protozoa which causes serious ocular problem. Acanthamoeba keratitis is becoming more prevalent amongst contact lens wearers and it can cause loss of vision and blindness if not treated properly. The objective of this research is to determine the effectiveness of gentamicin against six Acanthamoeba spp. isolates, of which three were clinical isolates (HS 6, HKL 95, HTH 73) and three environmental isolates (SMAL 7, SMAL 8, TTT 9). Cyst suspension from the chosen isolates were exposed to gentamicin. After 48 hours of incubation at temperature of 30°C and 37ºC, each mixture was filtered and filtration membrane was put onto non-nutrient agar laid with Escherichia coli. The agar plates were incubated for three days at 30oC and 37oC and the plates were examined daily until day 14 to look for the presence of Acanthamoeba trophozoites under inverted microscope. The presence of trophozoites indicated the ineffectiveness of gentamicin. Gentamicin was found to be effective against Acanthamoeba cysts from all the test strains at both incubation temperatures. The minimum cysticidal concentration (MCC) mean value of gentamicin was 0.193 mg/mL at 30oC and 0.229 mg/mL at 37oC. So, we concluded that gentamicin has cysticidal potential towards Acanthamoeba.

Introduction: Acanthamoeba is an ubiquitous free-living protozoa which causes serious ocular problems. Acanthamoeba keratitis is becoming more prevalent amongst contact lens wearers. The disease can cause loss of vision and blindness if not treated properly. The objective of this research is to study the sensitivity of six Acanthamoeba spp. isolates, of which three were from the clinical isolates (HKL 95, HTH 40 and HS 6) and the remaining three from environmental isolates (TTT 9, TL 3 and SMAL 8) to antimicrobial agents. Methods: The antimicrobial agents chosen for this purpose were polyhexamethylene biguanide and chlorhexidine. Cyst suspensions from the chosen isolates were exposed to PHMB and chlorhexidine respectively. After 48 hours incubation time at 30°c,each mixture was filtered and filtration membrane was put onto non-nutrient agar laid with Escherichia coli. The agar plates were incubated for three days at 30°c and examined daily until day 14 to detect the presence of Acanthamoeba trophozoites under the inverted microscope. The presence of thropozoites indicated the ineffectiveness of the antimicrobial agents. Results: Both of the antimicrobial agents tested were found to be effective against Acanthamoeba cysts from all the test starins. Polyhexamethylene biguanide gave minimum cysticidal concentration (MCC) mean value of 2.848mg/mL while chlorhexidine showed MCC mean value at a concentration of 3.988mg/mL. Conclusion: It can be concluded that the Acanthamoeba were sensitive to polyhexamethylene biguanide and chlorhexidine.

Rhipicephalus (Boophilus) microplus serves as an important ectoparasite of livestock and a vector of several pathogens resulting in diseases, subsequently affecting the agricultural field as well as the economy. The extensive use of synthetic acaricides is known to cause resistance over time and therefore a much safer, effective and environmentally friendly alternative to overcome tick infestation should be implemented. Larval immersion tests (LIT) were done to evaluate the effects of Citrus hystrix (Family: Rutaceae) and Cymbopogon citratus (Family: Poaceae) essential oils (EOs) for their individual and combined (1:1) acaricidal activity against the cattle tick. Results showed that LC50 and LC90 values in 24 and 48 hours for Cit. hystrix EO were 11.98% and 24.84%, and 10.95% and 21.71% respectively. LC50 and LC90 values for Cym. citratus EO were 1.21% and 6.28%, and 1.05% and 6.12% respectively. The mixture of EOs from two plants in 1:1 ratio (Cit. hystrix 50%: Cym. citratus 50%) was found to exhibit antagonistic effect (synergistic factor < 1). The 24 hours and 48 hours LC50 and LC90 values for combined EOs were 1.52% and 2.84%, and 1.50% and 2.76% respectively. Individual and combined essential oils were subjected to qualitative analysis using gas chromatography-mass spectrometry (GC-MS) to screen the chemical components present in EOs. Our results showed that the combination of Cit. hystrix and Cym. citratus at 1:1 ratio resulted in an antagonistic effect and the use of Cym. citratus alone is more toxic to R. (B.) microplus, making it a better alternative to chemical based acaricide.