In this study we compared two polymerase chain reaction (PCR) methods using either 16S ribosomal RNA (rRNA) or 23S rRNA gene primers for the detection of different Leptospira interrogans serovars. The performance of these two methods was assessed using DNA extracted from bovine tissues previously inoculated with several bacterial suspensions. PCR was performed on the same tissues before and after the formalin-fixed, paraffin-embedding procedure (FFPE tissues). The 23S rDNA PCR detected all fresh and FFPE positive tissues while the 16S rDNA-based protocol detected primarily the positive fresh tissues. Both methods are specific for pathogenic L. interrogans. The 23S-based PCR method successfully detected Leptospira in four dubious cases of human leptospirosis from archival tissue specimens and one leptospirosis-positive canine specimen. A sensitive method for leptospirosis identification in FFPE tissues would be a useful tool to screen histological specimen archives and gain a better assessment of human leptospirosis prevalence, especially in tropical countries, where large outbreaks can occur following the rainy season.

We set a method targeting 16 rRNA gene consisting in a single polymerase chain reaction of 40 cycles which is specific for pathogenic leptospira. Negative polymerase chain reaction results were observed with nonpathogenic Leptospira (serovar patoc) and other bacteria species. By this method a survey on a population of autochthon swine herds had been conducted in Sicily particularly on kidney samples of slaughtered animals and on urine samples from live animals. The analysis showed that a prevalence of leptospira up to 40 % can be observed on these animals. Results on other bovine and ovine herds from the same province in Sicily showed a lower prevalence.

Se fijó un método que apuntó al gen del rRNA 16S, que consistió en una sola reacción en cadena de la polimerasa de 40 ciclos que es específica para leptospiras patógenas. Los resultados negativos de la reacción en cadena de la polimerasa fueron observados en leptospiras no-patogénicas (serovar patoc) y en otras especies de bacterias. Un estudio en una población de manadas de cerdos autóctonos en Sicilia se realizó por este método, particularmente en muestras de riñón de animales sacrificados y en muestras de orina de animales vivos. El análisis demostró una prevalencia de leptospiras de 40 % en estos animales. En otra manada de bovinos y ovinos, en la misma provincia de Sicilia, se encontró una baja prevalencia.

It was carried out a comparison on two reference Leptospira strains DNA between different extraction methods and two polymerase chain reaction protocol. The DNA was quantified and serial dilutions were tested by polymerase chain reaction. The results showed difference in terms of recovery and sensitivity between this methods.

Se realizó una comparación entre diferentes métodos de extracción y 2 protocolos de reacción en cadena de la polimerasa en 2 ADN de cepas de Leptospira de referencia. El ADN se cuantificó y se probaron diluciones seriadas mediante la reacción en cadena de la polimerasa. Los resultados mostraron diferencias en términos de recuperación y sensibilidad entre estos métodos.