[Rapid pathogens diagnosis of infected keratitis and endophthalmitis using two steps polymerase chain reaction].

OBJECTIVE: To establish a rapid diagnosis technique of the pathogens of infected keratitis and endophthalmitis.
METHODS: Fifty-one corneal scraping, tear and 16 vitreous specimens were obtained from 67 cases of infected keratitis and endophthalmitis. Multiplex polymerase chain reaction (MPCR) was performed to differentiate the genes of bacteria, fungi and HSV using their own universal primers. Special-primers PCR were carried out for MPCR positive specimens to detect the genes of common bacteria and fungi respectively. The results were compared with microbe culture and clinical diagnosis.
RESULTS: In 67 clinical samples, 52 (77.6%) were positive at least one kind of pathogen by MPCR (two positive pathogens were 8 cases). SPCR revealed that 7 bacteria (25.0%) out of 28 bacteria positive specimens were Staphylococcus aureus, Streptococcus pneumoniae, Pseudomonas aeruginosa. Eight fungi (53.3%)of 15 fungi positive specimens was Candida, Aspergillus, Fusarium. The culture positive rates were 31.3% (21 cases), among them 1 case was found positive for two pathogens. MPCR positive rate was statistically higher than the rate that in culture (chi(2) = 13.50, P < 0.005). The kinds of bacteria and fungi of SPCR positive were as the same as bacteria and fungi of culture positive. Consistency of clinical diagnosis and experimental evidences of infected keratitis was 54.8%. The time for microbe culture needs 72 to 96 hours, but MPCR and SPCR needs 8 hours.
CONCLUSION: Two steps PCR is rapid, sensitive method to detect the pathogens of infected keratitis and endophthalmitis.