ORIGINAL ARTICLE Capsular genotype and lipooligosaccharide locus class distribution in Campylobacter jejuni from young children with diarrhea and asymptomatic carriers in Bangladesh Z. Islam 1 & S. K. Sarker 1 & I. Jahan 1 & K. S. Farzana 1 & D. Ahmed 1 & A. S. G. Faruque 2 & P. Guerry 3 & F. Poly 3 & A. P. Heikema 4 & H. P. Endtz 1,4,5 Received: 21 October 2017 /Accepted: 27 November 2017 # Springer-Verlag GmbH Germany, part of Springer Nature 2017 Abstract Campylobacter jejuni-related diarrheal diseases is one of the major health issues among young children (0–59 months old) in low- income countries. Monitoring of the capsular (capsule polysaccharide, CPS) types of virulent C. jejuni strains in regions where the disease is endemic is of great importance for the development of a customized capsule-based multivalent vaccine. Therefore, we aimed to determine the prevalence of CPS genotypes among C. jejuni strains isolated from young children with enteritis (n = 152) and asymptomatic carriers matched by age, sex, and residence defined as the control group (n = 215) in Bangladesh. CPS genotyping was performed using a newly established multiplex polymerase chain reaction (PCR) method and lipooligosaccharide (LOS) locus classes (A–E) were characterized using PCR as well. We identified 24 different CPS genotypes among the 367 isolates. Four prevalent capsular types, HS5/31 complex (n = 27, 18%), HS3 (n = 26, 17%), HS4A (n = 10, 7%), and HS8/17 (n = 10, 7%) covered almost 50% of the strains from enteritis patients and 43% of the isolates from controls. In combination, the CPS genotype and LOS class was not discriminative between cases and controls. Dominant capsular types previously identified in C. jejuni strains isolated from patients with Guillain–Barré syndrome in Bangladesh were rarely detected in strains isolated from the young children. A similar distribution was evident among enteritis- and control-related strains when comparison was done between CPS types and LOS classes. This is the first systematic study presenting the distribution of CPS genotypes of C. jejuni strains isolated in Bangladesh from children with diarrhea and controls, with capsular genotypes HS5/31 complex, HS3, HS4A, and HS8/17 being prevalent in both. In conclusion, systematic studies are required to develop a multivalent capsule-based vaccine for children in low-income countries. Introduction Campylobacter jejuni is one of the most frequent pathogens causing bacterial gastroenteritis throughout the world [1–3]. The symptoms of campylobacteriosis include watery to bloody diarrhea, abdominal complaints, headache, and fever [2, 4]. Furthermore, long-term sequelae have been associated with C. jejuni infection, including Guillain–Barré syndrome (GBS) [5], reactive arthritis [6], and irritable bowel syndrome (IBS) [7]. Early structure analysis revealed capsule polysac- charide (CPS) in Campylobacter species [8, 9], which was further evident by a genomic study in C. jejuni [10]. CPS of C. jejuni is a potent component that modulates the invasion of intestinal epithelial cells [11, 12]. This gave rise to the idea to develop a globally relevant capsule-conjugated vaccine to pre- vent campylobacteriosis [13]. The epidemiology of the global burden of enteritis in children aged 5 years or younger, caused by Campylobacter infection, varies geographically [14]. Low- income countries such as Bangladesh have a high burden of pediatric diarrheal disease, with the higher incidence rates of child mortality than the developed world [15]. Contaminated water supplies, inadequate sanitation, and nutritional deficien- cy contribute to this high disease burden [16]. CPS-based * Z. Islam zislam@icddrb.org 1 Laboratory Sciences and Services Division, International Centre for Diarrhoeal Disease Research (icddr,b), GPO Box-128, Dhaka 1000, Bangladesh 2 Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, (icddr,b), Dhaka, Bangladesh 3 Naval Medical Research Center, Silver Spring, MD, USA 4 Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, The Netherlands 5 Fondation Mérieux, Lyon, France European Journal of Clinical Microbiology & Infectious Diseases https://doi.org/10.1007/s10096-017-3165-7