Diagnostic Yield of a PCR Assay in Focal Complications of Brucellosis

Abstract

In order to evaluate the diagnostic yield of a PCR assay for patients with focal complications of brucellosis, we studied by PCR and by conventional microbiological techniques 34 nonblood samples from 32 patients with different focal forms of brucellosis. The samples from patients with brucellosis were paired to an equal number of control samples from the same locations of patients whose illnesses had different etiologies. Thirty-three of the 34 nonblood samples (97%) from the brucellosis patients were positive by PCR, whereas Brucella spp. were isolated from only 29.4% of the conventional cultures. For 11.4% of the patients, the confirmatory serological tests were either negative or showed titers below the diagnostic range. Two patients (6.2%) from the control group, both with tuberculous vertebral osteomyelitis, had a positive PCR result. The brucella PCR of blood from these two patients was also positive, and the two strains of Mycobacterium tuberculosis isolated were analyzed by the brucella PCR, with no evidence of amplification. These results show that the PCR assay is far more sensitive than conventional cultures, and this, coupled with its speed and reduction in risk to laboratory workers, makes this technique a very useful tool for the diagnosis of focal complications of brucellosis.

Challenges of Establishing the Correct Diagnosis of Outbreaks of Acute Febrile Illnesses in Africa: The Case of a Likely Brucella Outbreak among Nomadic Pastoralists, Northeast Kenya, March–July 2005

“…In this investigation, there was no significant difference in the IgM and IgG ELISA titers, except for specimens from three patients, two of whom had IgM titers several-folds higher than IgG suggestive of acute infection; the other positive IgG and IgM results that were the same or within one-fold titer of each other are difficult to interpret, especially in light of the fact that IgM declines faster than IgG following acute infection. 19 Although polymerase chain reaction is sensitive for Brucella , [20][21][22][23][24] it is expensive, susceptible to false positives, and still not validated for direct use on blood specimens. 20 Human leptospirosis has been documented in several parts of Kenya through clinical studies in the 1970s including isolation of leptospires from patients, which is definitive, and surveys in the 1960s.…”

“…19 Although polymerase chain reaction is sensitive for Brucella , [20][21][22][23][24] it is expensive, susceptible to false positives, and still not validated for direct use on blood specimens. 20 Human leptospirosis has been documented in several parts of Kenya through clinical studies in the 1970s including isolation of leptospires from patients, which is definitive, and surveys in the 1960s. [25][26][27] However, these did not include the arid northeastern region where this outbreak occurred and no recent data exists for this region.…”

Exceptionally high titres in atypical presentation of occult epididymo-orchitis due to brucellosis

“…Molecular techniques, if available, play an important role in providing the confirmatory evidence (Morata et al, 2001;Romero et al, 1995) but in cases where these methods are unavailable, primary isolation of Brucella in culture is still the conventional gold standard. In the present case, we attempted culture from both blood and pus samples, of which only the pus sample yielded growth of Brucella.…”

Diagnóstico Serológico (Rosa De Bengala) Y Molecular (Pcr) De Brucelosis en Humano

“…La PCR es una prueba con alta sensibilidad y especificidad, sin embargo un resultado negativo no excluye la presencia de la enfermedad (Morata et al, 1999;2001a;2001b). Por otro lado la PCR no provee información diferencial entre una enfermedad activa, porque la técnica no puede diferenciar entre ADN a partir de organismos vivos o muertos.…”