EVALUATION OF BLOOD PRESERVATION METHODS IN THE PERFORMANCE OF THE WHO IN VITRO MICRO TEST FOR PLASMODIUM FALCIPARUM IN THE FIELD
BY: MIROTOSHI IWAGAMI, NAO TAGUCHI, RAY U. ANGLUBEN, ALEYLA S. ESCUETA, ELENA A. VILLACORTE, PILARITA T. RIVERA, SHIGEYUKI KANO, AND SHIN-ICHIRO KAWAZU
IN VITRO DRUG SUSCEPTIBILITY TESTING OF PLASMODIUM FALCIPARUM MUST BE CONDUCTED IMMEDIATELY AFTER COLLECTING A SAMPLE OF THE PATIENT'S BLOOD; OTHERWISE THE PARASITES MAY WEAKEN AND THE CULTURE FAIL. COLLECTING BLOOD SAMPLES FROM INDIVIDUALS IN AREAS FAR FROM THE FIELD STATION OR CLINIC WHERE IN VITRO TESTING IS CONDUCTED REQUIRES A RELIABLE METHOD OF SAMPLE PRESERVATION DURING THE TRANSPORTATION. WE EXAMINED AND COMPARED THREE DIFFERENT METHODS USED TO PRESERVE BLOOD SAMPLES IN ENDEMIC AREAS IN THE PHILIPPINES. THE THREE METHODS ARE AS FOLLOWS: THE ON-SITEMETHOD (TEST IS CONDUCTED SOON AFTER THE BLOOD SAMPLING), FLASK CULTURE METHOD (SAMPLE IS TAKEN TO THE LABORATORY IN A CULTURE FLASK WITH MEDIUM) AND EDTA TUBE METHOD (SAMPLE IS TAKEN TO THE LABORATORY IN A BLOOD COLLECTION TUBE). THE WHO IN VITRO MICROTEST FOR SUSCEPTIBILITY OF P. FALCIPARUM TO CHLOROQUINE WAS PERFORMED USING ANAEROPACK SYSTEM AND A PORTABLE THERMOSTAT INCUBATOR. EVALUATION OF THE THREE METHODS WAS BASED ON SCHIZONT MATURATION, EASE OF HANDLING, AND RISK OF CONTAMINATION DURING THE TEST. THE ON SITE AND FLASK CULTURE METHODS, BUT NOT THE EDTA TUBE METHOD, WERE EFFECTIVE FOR KEEPING THE PARASITES VIABLE. FURTHERMORE, SCHIZONT MATURATION APPEARED BETTER WITH THE FLASK METHOD THAN WITH THE ON-SITE METHOD, ESPECIALLY IN THE CONTROL WELLS (DUG-FREE WELLS). IN ADDITION, IT WAS EASIER TO PERFORM THE FLASK METHOD THAN THE ON-SITE METHOD. NO CONTAMINATION WAS OBSERVED USING ANY METHODS. THE RESULTS OF THE STUDY SUGGEST THAT THE FLASK CULTURE METHOD IS THE MOST EFFECTIVE AND USEFUL WAY TO PRESERVE THE BLOOD SAMPLES FOR THE IN VITRO TEST, AND MOREOVER, THAT IT AIDS IN PROVIDING DETAILED FIELD EVIDENCE OF DRUG-RESISTANT MALARIA.
IN VITRO DRUG SUSCEPTIBILITY TESTING OF PLASMODIUM FALCIPARUM MUST BE CONDUCTED IMMEDIATELY AFTER COLLECTING A SAMPLE OF THE PATIENT'S BLOOD; OTHERWISE THE PARASITES MAY WEAKEN AND THE CULTURE FAIL. COLLECTING BLOOD SAMPLES FROM INDIVIDUALS IN AREAS FAR FROM THE FIELD STATION OR CLINIC WHERE IN VITRO TESTING IS CONDUCTED REQUIRES A RELIABLE METHOD OF SAMPLE PRESERVATION DURING THE TRANSPORTATION. WE EXAMINED AND COMPARED THREE DIFFERENT METHODS USED TO PRESERVE BLOOD SAMPLES IN ENDEMIC AREAS IN THE PHILIPPINES. THE THREE METHODS ARE AS FOLLOWS: THE ON-SITEMETHOD (TEST IS CONDUCTED SOON AFTER THE BLOOD SAMPLING), FLASK CULTURE METHOD (SAMPLE IS TAKEN TO THE LABORATORY IN A CULTURE FLASK WITH MEDIUM) AND EDTA TUBE METHOD (SAMPLE IS TAKEN TO THE LABORATORY IN A BLOOD COLLECTION TUBE). THE WHO IN VITRO MICROTEST FOR SUSCEPTIBILITY OF P. FALCIPARUM TO CHLOROQUINE WAS PERFORMED USING ANAEROPACK SYSTEM AND A PORTABLE THERMOSTAT INCUBATOR. EVALUATION OF THE THREE METHODS WAS BASED ON SCHIZONT MATURATION, EASE OF HANDLING, AND RISK OF CONTAMINATION DURING THE TEST. THE ON SITE AND FLASK CULTURE METHODS, BUT NOT THE EDTA TUBE METHOD, WERE EFFECTIVE FOR KEEPING THE PARASITES VIABLE. FURTHERMORE, SCHIZONT MATURATION APPEARED BETTER WITH THE FLASK METHOD THAN WITH THE ON-SITE METHOD, ESPECIALLY IN THE CONTROL WELLS (DUG-FREE WELLS). IN ADDITION, IT WAS EASIER TO PERFORM THE FLASK METHOD THAN THE ON-SITE METHOD. NO CONTAMINATION WAS OBSERVED USING ANY METHODS. THE RESULTS OF THE STUDY SUGGEST THAT THE FLASK CULTURE METHOD IS THE MOST EFFECTIVE AND USEFUL WAY TO PRESERVE THE BLOOD SAMPLES FOR THE IN VITRO TEST, AND MOREOVER, THAT IT AIDS IN PROVIDING DETAILED FIELD EVIDENCE OF DRUG-RESISTANT MALARIA.