title: Evaluation of the optimal number of faecal specimens in the diagnosis of cryptosporidiosis in AIDS and immunocompetent patients.
abstract: This study determines the optimal number of faecal samples that should be examined in order to minimize the occurrence of false-negative results in the diagnosis of cryptosporidiosis using routine techniques. A total of 23,023 faecal samples from 10,870 patients submitted for parasitological examination were processed by the formalin-ethyl acetate concentration technique and stained using a modified Ziehl-Neelsen method. Cryptosporidiosis was diagnosed in 232 patients (2.13%), 44 of whom were infected by HIV, the prevalence rate in this population group being 15.54%. The increase in the number of diagnoses obtained by the examination of n and (n-1) specimens was evaluated statistically. This study found that three is the optimal number of faecal samples that should be examined when cryptosporidiosis is suspected in immunocompetent patients; whereas, only two samples are required for diagnosing this protozoosis in AIDS patients.
authors.affiliation: Servicio de Microbiología y Parasitología, Hospital Clínico Universitario, Zaragoza, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Clavel
authors.forename: A C
authors.initials: AC
authors.lastname: Arnal
authors.forename: E C
authors.initials: EC
authors.lastname: Sánchez
authors.forename: M
authors.initials: M
authors.lastname: Varea
authors.forename: F J
authors.initials: FJ
authors.lastname: Castillo
authors.forename: I
authors.initials: I
authors.lastname: Ramírez de Ocáriz
authors.forename: J
authors.initials: J
authors.lastname: Quílez
authors.forename: J
authors.initials: J
authors.lastname: Cuesta
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000469:parasitology*; D000818:Animals; D003457:Cryptosporidiosis / Q000150:complications / Q000175:diagnosis*; D003458:Cryptosporidium / Q000302:isolation & purification*; D005188:False Negative Reactions; D005243:Feces / Q000469:parasitology*; D006801:Humans; D016867:Immunocompromised Host; D009894:Opportunistic Infections / Q000469:parasitology*; D010270:Parasite Egg Count; D012680:Sensitivity and Specificity