Community-acquired Atypical Bacterial Pneumonia among Sudanese: A Serological and Molecular Studies

Abstract

Atypical pneumonia caused by bacterial pathogens, accounts for 40% of all cases of community-acquired pneumonia. Classical microbiological identification techniques cannot provide an efficient means of diagnosis of the causative organisms. Recently, other diagnostic techniques such as serological tests and singleplex Polymerase Chain Reaction (PCR) assays have been developed. This study was conducted during the period 2013-2016 to investigate community-acquired atypical bacterial pneumonia as well as to determine the prevalence of the disease among Sudanese population. A total of 400 patients (242 males and 158 females) were enrolled in this study. The patients were grouped according to their age into 13 to 30 years, 31 to 60 years and 61 to 91years. The mean age of patients was 42.1 years. Sputum and blood specimens were collected from each patient attended four major hospitals in Khartoum State, including Omdurman Teaching Hospital, AL-Shaab Teaching Hospital, Bahry Teaching Hospital and Abu Anja Teaching Hospital. The causative agents were characterized by serological tests using Enzyme Linked Immunosorbent Assay (ELISA) for M. pneumoniae, Indirect Immunofluorescence Antigen IIFA (IgM) for C. pneumoniae and Indirect Immunofluorescence Antigen IIFA (IgM, IgA and IgG) for L. pneumophila then confirmed by molecular technique using singleplex PCR. Sequencing of target gene was carried out in Macrogen (Korea). Similarities and phylogenetic analysis were compared with published data. The serological tests results revealed that 125 (31.3%) were positive, while the rest 275 (68.7%) were negative. Of the positive 50 (12.5%) were L. pneumophila, 43 (10.8%) were C. pneumoniae and 32 (8.0%) were M. pneumoniae. The PCR technique showed 175(43.9%) were positive and 225(56.1%) were negative. Of the positive 69 (17.3%) were C. pneumoniae, followed by L. pneumophila 57(14.3%), and M. pneumoniae 49(12.3%). Sequences analysis showed the similarities of identified isolates in gene-bank database were vary from 92% to 100%. Statistical analysis of the results showed that the atypical pneumonia prevalence among patients attended different hospitals was insignificant (p= >0.05) as well as gender (p= >0.05). The analysis also showed significant prevalence among age group 31-60 years old (p=< 0.05). The comparison between serological test and molecular techniques in detection of atypical pneumonia was found significant (p= 0.000). The study concluded that the prevalence of atypical pneumonia is high among males than females and it is high in the age group 31 to 60 years old. Although PCR technique was found more accurate than serological techniques, but diagnosis of atypical pneumonia using serological techniques is highly recommended in the absence of PCR facilities.