Modern Taxonomy and Classification of Anaerobic Bacteria

Abstract

Anaerobic bacteria (AB) are a heterogeneous group of microorganisms belonging to several genus and being gram-positive and gram-negative cocci, bacilli, spiral and branched forms. These bacteria grow only under anaerobic conditions and are sensitive to toxic action of oxygen. Over the past 20 years the advances in molecular technologies led to multiple changes in taxonomy and classification of AB. According to the modern classification morphologically similar AB may belong not only to different families and even orders, but also to different classes. In contrast, one family may comprise closely related grampositive and gram-negative anaerobic cocci and bacilli. Classification of AB isolated from the various human body sites and clinical specimens includes multiple species that represent 81 genders and 26 families. Majority of AB are the facultative pathogens that may cause non-specific suppurative infections at different sites.