Citation: Sultana, S.; Parvin, R.; Parvin, M.S.; Islam, M.T.; Bari, A.S.M.; Chowdhury, E.H. Prevalence of Methicillin and β−Lactamase Resistant Pathogens Associated with Oral and Periodontal Disease of Children in Mymensingh, Bangladesh. Pathogens 2022, 11, 890. https://doi.org/10.3390/ pathogens11080890 Academic Editor: Lawrence S. Young Received: 3 July 2022 Accepted: 2 August 2022 Published: 9 August 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). pathogens Article Prevalence of Methicillin and β-Lactamase Resistant Pathogens Associated with Oral and Periodontal Disease of Children in Mymensingh, Bangladesh Sharmin Sultana 1 , Rokshana Parvin 1 , Mst. Sonia Parvin 2 , Md. Taohidul Islam 2 , Abu Saleh Mahfuzul Bari 1 and Emdadul Haque Chowdhury 1, * 1 Departmentof Pathology, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh 2 Population Medicine and AMR Laboratory, Department of Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh * Correspondence: emdad001@yahoo.com Abstract: Oral and periodontal diseases (OPD) is considered one of the main problems of dentistry worldwide. This study aimed to estimate the prevalence of oral and periodontal pathogenic bac- teria along with their antimicrobial resistance pattern in 131 children patients aged between 4–10 years who attended in Mymensingh Medical College Hospital during October 2019 to March 2020. OPD pathogens were identified through isolation, cultural and biochemical properties, and nucleic acid detection. The isolates were subjected to antimicrobial susceptibility to 12 antibiotics commonly used in dentistry. In addition, the isolates were analyzed molecularly for the presence of six virulence and three antibacterial resistance genes. Five pathogens were identified, of which Staphylococcus au- reus (S. aureus) (49%) and S. salivarius (46%) were noticed frequently; other bacteria included S. mutans (16.8%), S. sobrinus (0.8%) and L. fermentum (13.7%). The virulence genes—clumping factor A (clfA) was detected in 62.5% isolates of S. aureus, and gelatinase enzyme E (gelE) gene was detected in 5% isolates of S. salivarius, while other virulence genes were not detected. All the tested isolates were multidrug-resistant. The overall prevalence of MDR S. aureus, Streptococcus spp. and L. fermentum was 92.2%, 95.1% and 100%, respectively. It was observed that a high proportion of isolates were found resistant to 5–8 antibiotics. A majority of S. aureus, Streptococcus spp., and L. fermentum isolates tested positive for the β−lactamase resistance genes blaTEM and cfxA, as well as the methicillin resistance gene mecA. Phylogenetically, the resistance genes showed variable genetic character among Bangladeshi bacterial pathogens. In conclusion, S. aureus and S. salivarius were major OPD pathogens in patients attended in Mymensingh Medical College Hospital of Bangladesh, and most were Beta- lactam and methicillin resistant. Keywords: OPD pathogens; virulence genes; β−lactamase resistant; methicillin resistant; pediatric patient 1. Introduction Oral and periodontal disease (OPD) is one of the most prevalent diseases in the world, causing significant morbidity, particularly among children [1]. The human oral flora encompasses over 700 microorganisms, 50% of them being uncultivable microbes [2]. Bacteria, fungi, protozoa and other ecological community of biofilm cling to various surfaces of the mouth cavity to make up the oral flora [3,4]. Some of these microorganisms, mostly bacterial species, are associated with human diseases in certain conditions [5– 7]. Various species of the genus Streptococcus, Staphylococcus, Lactobacillus, Enterococcus, Corynebacterium, Veillonella and Bacteroids are predominant bacteria in the human oral cavity. Mutans group Streptococci (Streptococcus mutans and Streptococcus sobrinus), mittis group Streptococci (Streptococcus sanguinis, Streptococcus oralis, and Streptococcus gordonii) and Pathogens 2022, 11, 890. https://doi.org/10.3390/pathogens11080890 https://www.mdpi.com/journal/pathogens