Microbiological and Molecular Investigation of Clinically Suspected Caseous Lymphadenitis Cases in Goats

Abstract

Chronic suppurative lymphadenitis characterized by abscess formation is of economic significance in sheep and goats. It is principally caused by Corynebacterium pseudotuberculosis (caseous lymphadenitis, CLA) and Staphylococcus aureus subsp. anaerobius. Pus samples from superficial lymph nodes of 33 (4.38 %) out of 752 adult Sirohi goats showing clinical lesions similar to CLA were collected for laboratory investigations. Sixteen (48.48 %) bacterial isolates from pus were identified as C. pseudotuberculosis, 12 (36.36 %) as catalase-negative S. aureus subsp. anaerobius while samples from 5 cases were negative. The polymerase chain reaction (PCR) assays targeting putative oligopeptide/dipeptide ABC transporter, nicotinamide adenine dinucleotide phosphate oxidoreductase coenzyme F420-dependent and proline iminopeptidase genes of C. pseudotuberculosis when carried out directly on the DNA extracted from pus were positive in the same 16 goats. All the C. pseudotuberculosis isolates were also found to be positive for these genes in the PCR. Isolates of S. aureus subsp. anaerobius were found to be positive for 16S rRNA and nuclease (nuc) gene PCR. The present study shows the incidence of CLA as 4.38, 2.12 and 2.12 % based on the clinical, bacterial culture and direct PCR assay on pus samples, respectively. The incidence of abscess disease due to S. aureus subsp. anaerobius was 1.59 %. The three gene PCR assay developed in the study was found to be specific and rapid than the bacterial culture in detecting bacteria directly in the pus samples and can be applied for the diagnosis and control strategy of CLA.