Investigation of infection with Campylobacter jejuni in a man with hypogammaglobulinaemia using PCR-single-stranded conformational polymorphism (PCR-SSCP) typing

This study investigated several episodes of infection of Campylobacter jeju ni in an immunocompromised male with hypogammaglobulinaemia, presenting wit h diarrhoea and bacteraemia over a 16-month period, by employing three phen otyping and four genotyping schemes, including the single-stranded conforma tional polymorphism (SSCP) technique to establish if infection was reinfect ion or persistent infection. Four isolates from blood culture and two faeca l isolates of Campylobacter jejuni were obtained from the patient by direct selective plating on Skirrow Selective agar. Isolates were characterised a t the sub-species level by Penner serology, Preston biotyping, Preston phag e-typing, as well as E3CJC2 restriction fragment length polymorphism (RFLP) , 16S ribo-typing, flagellin (flaA) RFLP and single-stranded conformational polymorphism (SSCP) analyses. Phenotyping and genotyping sub-species analy ses demonstrated that the patient was infected with at least two different strains of Campylobacter jejuni, i.e. one strain that persisted throughout the 16-month period and another strain that was transient suggesting reinfe ction from a different source. SSCP analysis was the most discriminatory of all the typing schemes examined and demonstrated an altered genotype of th e persistent strain, whereby there were subtle modifications to the hyperva riable regions of the flaA gene. Overall, as SSCP examines the hypervariabl e region of the flaA gene and as this technique can detect point mutations, differences between SSCP banding patterns may represent markers and thus e xamine mutations that occur under immune selection, thereby permitting the C. jejuni to evade the host immune response. In conclusion, this study desc ribes the novel use of SSCP genotyping of C. jejuni and demonstrated that t his method is a highly discriminatory technique which may be beneficial in outbreak characterisation, but which is not suitable to examine the clonal patterns of C. jejuni over a long period of time.