Latar Belakang: Metode PCR dapat digunakan untuk mengidentifikasi DNA suatu organisme. ldentifikasi gen 18S rRNA sudah hanyak dipakai untuk mempelajari sejumlah organisms eukariot seperti tanaman, hewan dan protozoa termasuk Cryptosporidium sp. Penelitian terdahulu pada anak batita di daerah kumuh dan rawan banjir di Jakarta yang dideteksi secara mikroskopis dengan pcwarnaan modifikasi tahan 838111 (MTA), didapatkan prevalensi 2,l% yang rendah dibandingkan negara berkembang lain yang keadaan lingkungan dan populasinya mirip Indonesia. Deteksi Cryptosporidium sp. secara molekular di feses dengan PCR memungkinkan diagnosis lebih akurat dan cepat. Tujuan: mengembangkan metode PCR :mink deteksi gen ISS rRNA Cryptosporidium sp. pada feses yang disimpan dalam larutan kalium bikromat 2,5% selama 1 bulan. Metode: sejumlah 188 sampel feses yang disimpan dalam larutan kalium bikromat dikonsentrasikan dengan teknik air-eter, selanjutnya dilakukan ekstraksi DNA terhadap konsentrat dan sebagian lagi dipulas dengan MTA. Amplifikasi DNA Cryptosporidium terhadap gen 18S rRNA dilakukan dengan program PCR iangsung, siklus 39 kali. Hasil: pemeriksaan dengan metode MTA konsentrasi didapatkan sembilan sampel positif (4,8%) sedangkan dengan PCR didapatkan 65 sampel positif (34,6%). Kesimpulan: Larutan kalium bikromat dapat dipakai untuk penyimpanan ookista Cryptosporidfwn sp. tanpa mempengaruhi hasil PCR maupun mikroskopis.

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Background: PCR method can be used to characterize an organism DNA. Identification of 18S rRNA gene has been widely used to study eukaryotes like plants, animals and protozoa such as Cryptosporidium sp. Previous study on Cryptosporidium sp. in children under tluee years old in a slum area in Jakarta, detected by direct modiiied acid fast (MAF) showed 2.1% prevalence, which was unexpectedly much lower than other developing country with similar enviromnent and study population. Detection of Cryptosporidium sp. by molecular technique, PCR will offer more accurate and efficient diagnosis.

Objective: develop PCR method to detect Cryptosporidium sp. 18S rRNA gene of stool from stools preserved in potassium dichromate solution for 13 months.

Methods: There were l88 stool samples which have been kept in 2.5% potassium dichromate for 13 months. These samples were concentrated by water-ether technique, extracted the DNA and stained by MAF. Amplihcation of Cnprosporidium sp. ISS rRNA gene was using direct PCR for 39 cycles.

Result: of samples with MAF has found 9 positive (4,8%) and samples with PCR has presented 65 positive (34,6%).

Conclusion: Potassium dichromate solution can be used to preserve oocysts of Cryptosporidium sp since it does not interfere the PCR and microscopic examination result.