Investigation of Virulence Genes in Campylobacter Species Isolated from Patients with Acute Diarrhea

Acute gastroenteritis is one of the most common infectious diseases worldwide. This disease causes child deaths and economic losses in developing countries. Campylobacter spp. is the most common cause of gastroenteritis in both adult and pediatric patients. Although the disease typically presents as common diarrhea, in some cases, it can lead to severe complications and even death. This study aimed to identify Campylobacter species isolated in stool samples from patients admitted to the hospital with gastroenteritis complaints and to investigate their virulence genes using polymerase chain reaction (PCR). In order to determine the frequency of Campylobacter species, 850 stool samples were taken from patients suspected with gastroenteritis. For the isolation of Campylobacter, the stool samples were inoculated on modified charcoal cefoperazone deoxycholate agar and incubated at 42 °C for 48-72 hours in a microaerophilic atmosphere. Gram staining, catalase, and oxidase tests were applied for Campylobacter suspected colonies. During the macroscopic examination, the stool consistency, presence of mucus and leukocytes were evaluated. DNA isolation was performed from freshly grown colonies according to the commercial QIAampDNA mini kit (Qiagen, Germany) protocol. Identification of the species and the presence of virulence genes were studied by PCR. The 816 bp long C412F and C1228R primer pair specific to the 16S rRNA gene for the molecular identification of Campylobacter isolates were used. The specific 735 base pair (bp) long HipO1 and HipO2 primer pair, targeting the hippurase gene of Campylobacter jejuni was used. 500 base pair long CC1 and CC2 primers specific to the asperkinase gene of Campylobacter coli were used. In our study, Campylobacter spp. growth was detected in 122 of the 850 samples. 107 (87.7%) of the positive samples were taken from the patients at the outpatient clinic, while 15 (12.3%) were taken from patients in the ward. The highest rate of positivity was among children aged 0-5, with 39.4% (48 cases). By using PCR, 106 of the Campylobacter species were identified as C.jejuni, 11 as C.coli and five as Campylobacter spp. The ciaB gene was found in 102 (83.6%) of the Campylobacter strains; the dnaJ gene was found in 93 (76.2%); the cdtC gene was found in 106 (86.8%); and the cdtA gene was found in 115 (94.2%) strains. cdtb, pldA, and cadF genes were detected as follows: 110 (90.1%), 85 (69.6%), and 110 (90.1%), respectively. When examining the distribution of virulence genes by species, it was observed that the cadF gene was present in all C.coli strains, while the cdtA and ciab genes were detected in all five Campylobacter spp. strains. All genes were detected as positive in 68 of the C.jejuni isolates, three of the C.coli isolates and one of the Campylobacter spp. strains. The data obtained in this study showed that the frequency of Campylobacter is high in patients with acute gastroenteritis. As a result of this study, it is believed that this study will assist clinicians in their approach to Campylobacter infections.