Comparison Between Serological and Molecular Identification of Vibrio Cholera

Abstract

Cholera, caused by the bacterium Vibrio Cholerae, remains a critical global health issue, leading to significant morbidity and mortality. Traditional identification methods, primarily serological techniques, have been the standard for decades; however, the advent of molecular techniques has transformed pathogen detection, offering improved sensitivity and specificity. This study aims to systematically compare serological and molecular methods for identifying V. cholerae, focusing on their sensitivity, specificity, time efficiency, cost-effectiveness, and reliability across various sample types and conditions. Methods: Data were collected from 150 samples (100 clinical isolates from patients with cholera-like symptoms and 50 environmental samples) in Baghdad during 2022. The study employed various identification methods: traditional culture, serological tests (slide agglutination and coagglutination), conventional PCR, and real-time PCR. Biochemical tests were conducted for presumptive identification, and molecular techniques targeted specific virulence genes (ompW, ctxA, rfbO1). Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using culture results as the gold standard. Statistical analyses were performed using SPSS version 25.0. Results: The study found that culture detected 115 positive cases, while serological tests identified 112 (slide agglutination) and 110 (coagglutination) positives. Conventional PCR showed 118 positives, and real-time PCR outperformed all methods with 120 positives. The sensitivity and specificity of the methods were as follows: slide agglutination (95% sensitivity, 92% specificity), coagglutination (94.8% sensitivity, 91.8% specificity), conventional PCR (98.3% sensitivity, 98.7% specificity), and real-time PCR (99.1% sensitivity, 99.3% specificity). The presence of virulence genes was significantly higher in clinical isolates compared to environmental samples. Statistical analysis revealed strong agreement between molecular methods and culture results, with Cohen's kappa coefficients indicating very strong agreement for PCR methods. Discussion: The results demonstrate that molecular methods, particularly real-time PCR, significantly outperform traditional serological techniques in identifying V. cholerae. Molecular methods offer high sensitivity and specificity due to their detection of certain genetic markers. On the other hand, higher positivity rates in clinical isolates strengthen some confirmation of effective cholera management that focuses more effective identification. And although molecular methods depend on more advanced equipment and technical know-how, their speedesse critical for clinical applications. Finally, this study showed that molecular methods, and especially real-time PCR, exhibit much better performance than classical serologic methods for the identification of Vibrio Cholerae, with sensitivities and specificities that reach over 99%. Although molecular methods provide rapid and accurate results, they may not be practical because of higher costs and the need for technical expertise particularly in low-resourced settings. Thus, the use of high-throughput clinical laboratories with real-time PCR as the preferred method for pathogen identification is recommended as it offers a high level accuracy with a reduced time to result Nevertheless, serological techniques must continue to play an important advantage in limited-resource settings with periodic confirmation by molecular techniques for important samples. A combination strategy of both diagnostic tests for environmental surveillance is recommended. This is only the start; standardized protocols for testing and regional networks to distribute testing kits will allow testing to continue to improve, which will no doubt lead to better cholera surveillance and control measures around the world.