Confirmation that PCR can be used to identify NAD-dependent and NAD-independent Haemophilus paragallinarum isolates

Abstract

75 bacteria tentatively identified as H. paragallinarum, 8 identified as Ornithobacterium rhinotracheale and 13 identified as nicotinamide adenine dinucleotide (NAD)-independent Pasteurella spp. were isolated from chickens with respiratory infection in various provinces in South Africa. The isolates were characterized by conventional biochemical and serological methods. A polymerase chain reaction (PCR) assay specific for H. paragallinarum was used to identify the cultures directly from colonies. The PCR assay gave positive results for all isolates that were identified by conventional methods as H. paragallinarum, irrespective of whether they were NAD-dependent (43 isolates) or NAD-independent (32 isolates). The 8 isolates that were identified by conventional methods as O. rhinotracheale and the 13 isolates identified as various Pasteurella spp. gave negative results in the PCR assay. It is concluded that colony PCR is a rapid method for uniquely identifying NAD-dependent and NAD-independent strains of H. paragallinarum and distinguishing them from other bacteria, such as O. rhinotracheale and Pasteurella spp.