Chapter 16: Mycoplasma

Mycoplasma bacteria represent a fundamental departure from conventional prokaryotic architecture, relying on a sterol-enriched cell membrane to provide structural support and protection rather than the rigid peptidoglycan layer characteristic of most bacterial species. The absence of this cell wall has profound implications for bacterial physiology, morphology, and clinical treatment. A critical clinical consequence explored in this chapter is the intrinsic resistance these organisms display toward beta-lactam antibiotics, including penicillin and its derivatives, since these drugs specifically target peptidoglycan synthesis in cell walls. This mechanism of antibiotic resistance differs fundamentally from acquired resistance mechanisms and represents a structural vulnerability in antimicrobial therapy strategies. The chapter details clinically significant species and their associated pathologies, including Mycoplasma pneumoniae, which causes atypical respiratory infections commonly known as walking pneumonia, characterized by gradual symptom progression and lower respiratory involvement. Additionally, the chapter addresses urogenital pathogens such as Mycoplasma genitalium and Ureaplasma urealyticum, which are responsible for sexually transmitted infections and related complications. Understanding these organisms requires recognizing how their membrane composition substitutes for missing cell wall components, how this structural difference explains their resistance to cell wall synthesis inhibitors, and how conventional diagnostic and treatment approaches must be modified accordingly. The chapter establishes why standard antibiotic protocols prove ineffective and contextualizes these bacteria within broader discussions of atypical bacterial pathogens and emerging antibiotic resistance challenges in clinical microbiology.