Comparison of the sensitivity of microscopy and culture in the laboratory diagnosis of intestinal protozoal infection.

Concentration of protozoal cysts from faeces by the formol-ether method and faecal culture on Robinson's medium were studied to determine their diagnostic value among patients attending a sexually transmitted diseases clinic in Edinburgh. Of 450 men studied Entamoeba histolytica and Giardia lamblia were identified in the faeces of 10.7 and 5.1% respectively. Thirty (81.1%) of 37 men with E histolytica and 11 (47.8%) of 23 men with G lamblia infections would not have been identified if formol-ether concentration had not been undertaken. Culture of faeces in Robinson's medium led to the detection of a further 11 men with amoebiasis. Oocysts of Cryptosporidium spp were not identified in faecal samples from 130 men.