Acanthamoeba is a free living protozoa that can cause keratitis and granulomatous amoebic encephalitis. Physiological characteristics of this amoeba are found to have a medical importance and related to the pathogenic potential of the organism. This study was carried out to investigate the physiological characteristic from the aspect of temperature tolerance. Six Acanthamoeba strains from three clinical isolates (HSB 1, HKL 48 and HKL 95) and three environmental isolates (PHS 2, PHS 11 and PHS 15) were used in this study. Test was done by culturing cysts at 30°C, 37°C and 42oC for two weeks and the ability of cysts to change to trophozoites were observed. The result showed all strain was able to change to trophozoites at 30°C and 37oC. However, no trophozoites were observed at 42oC. This indicate that there is a similarity in the physiological trait of strains from both isolates are the same and strains from the environment are able to show the pathogenic potential thus capable of causing infection to human.

This study was carried out to isolate Acanthamoeba spp. from various aquatic environments in Peninsular Malaysia. A total of 160 samples were collected with 140 samples using direct swab method and 20 samples using water collection method with 500 ml sterile Schott bottle. The swab samples were taken from water tap (50), sink (50), and swimming pool (40) while the water samples were from seawater. Swab samples were inoculated directly onto non-nutrient agar (NNA) seeded with heat-killed Escherichia coli using aseptic technique. Water samples were first filtered through a 0.45μm pore size membrane before the membrane was transferred aseptically onto NNA plate seeded with heat-killed E. coli. All plates were incubated at 30°C and examined daily for the presence of Acanthamoeba spp. up to 14 days after incubation before being declared negative. Overall, 20% samples were positive for the presence of Acanthamoeba. Positive isolation of Acanthamoeba spp. from sink and swimming pool were 20% and 30%, respectively. All three groups of Acanthamoeba genus in cyst form could be found from the collected samples.

Acanthamoeba is a free living protozoa that can cause keratitis and granulomatous amoebic encephalitis. Physiological characteristics of this amoeba are found to have a medical importance in which it can be related to the pathogenicity potential of the organism. This study was carried out to investigate the physiological characteristics of survivability during axenization. Six Acanthamoeba strains from three clinical isolates (HSB 1, HKL 48 and HKL 95) and three environmental isolates (PHS 2, PHS 11 and PHS 15) were used in this study. Axenization test was done by treating cysts with hydrochloric acid (3%) and Page saline containing Gentamicin (100 μg/ml). Cysts were then cultured into PYG enrich media, incubated at 30oC and the presence and proliferation of trophozoites of Acanthamoeba were observed. This study showed that PHS 15, HSB 1, HKL 48 and HKL 95 could be axenized but they have poor proliferation rate in PYG enrich media. The result showed that the difference between both clinical and environmental isolates was observed in two strains; PHS 2 and PHS 11. This indicates that there is a possibility that the physiological traits of strains from both isolates are the same and strains from the environment are able to show the pathogenic potential and capable of causing infection to human.

Acanthamoeba is a free-living amoeba that has been identified to cause Acanthamoeba keratitis and granulomatous amoebic encephalitis. Their physiological characteristics can be related to pathogenic potential which have a medical importance. This study was carried out to investigate the value of minimum cysticidal concentration of chlorine against them. Acanthamoeba strains tested were from clinical isolates from hospitals (HSB 1, HKL 48 and HKL 95) and environmental isolates (PHS 2, PHS 11 and PHS 15). The minimum cysticidal concentration of chlorine was determined by dilution process using 12 wells microtitre plate starting with 2500 ppm. 100 μl cyst suspensions standardized at 105/ml were pipetted into all wells and incubated overnight at 30°C. Cysts were then washed using Page saline and cultured on non nutrient agar overlaid with Escherichia coli. The presence of trophozoites was then observed. The lowest concentration able to prevent trophozoites formation was noted as the minimum cysticidal concentration. Minimum cysticidal concentration test showed the same concentration of 156 ppm (156 μg/ml) chlorine solution was needed to kill all cysts of Acanthamoeba isolates. This indicates that the physiological traits of environmental and clinical isolates are the same. Isolates from the environmental specimens are also able to show the pathogenic potential similar to clinical specimens, thus capable of causing disease to human.

if not treated. This study was therefore performed to evaluate the effectiveness of eyedrop antibiotics on eight Acanthamoeba spp. isolates, of which four were clinical isolates and the remaining four from the environment. Three different eyedrop antibiotics (neomycin, ciprofloxacin and gentamicin) currently available in the market and ready for use were tested. Cyst suspension from all strains were tested against eyedrop antibiotics, respectively. After 48 hours of incubation period, the solutions were filtered and the filtered membranes were put onto non-nutrient agar lawn with E. coli. Bab 3 The plates were examined daily for Acanthamoeba trophozoites under inverted microscope until day 14. Neomycin, ciprofloxacin and gentamicin were found to be effective against Acanthamoeba spp. cysts for all test strains.

This study was carried out to observe thermotolerance ability of Acanthamoeba spp. A total of 32 Acanthamoeba spp. isolates obtained from water taps, sinks, swimming pools and sea water were used. Trophozoites of Acanthamoeba spp. were inoculated onto non-nutrient agar (NNA) seeded with heat-killed Escherichia coli using aseptic technique and incubated for 14 days at 30°C to obtain the cyst. The cysts were subcultured onto new agar plates for thermotolerance test at 37°C and 42°C. The plates were observed until 96 hours after incubation for excystation of Acanthamoeba before being declared negative. Overall, 81.25% of samples were able to excyst at 37°C while 37.5% were able to excyst at 42°C. Thermotolerant Acanthamoeba is associated with high pathogenicity potential.