MICRO PARA Lec (Part 10) - WALL-LESS Microorganisms

Mycoplasma

• Smallest, free-living organisms in nature and self-replicating on laboratory media

• Highly pleomorphic because they lack cell wall

• Bounded by a triple layered “unit membrane” that contains a sterol

• Completely resistant to penicillin

• Glucose – source of energy

• Poorly stain in gram staining

Pathogenesis of Mycoplasma

• Many pathogenic mycoplasmas have flask-like or filamentous shapes with polar tip structures

o P1 adhesin of M. pneumoniae

o MgPa adhesin of M. pneumoniae

• Mycoplasma attach to the surfaces of ciliated and non-ciliated cells

Mechanisms of Mycoplasma Interaction

• Direct cytotoxicity through the generation of hydrogen peroxide and super oxide

• Antigen-antibody reactions by chemotaxis

• Competition or depletion of nutrients

Mycoplasma pneumoniae

• It is prominent cause of (atypical) pneumoniae, especially in persons 5 – 10 years.

• Transmission via respiratory droplets

Clinical Findings of Mycoplasma pneumoniae

• Incubation period – 1 to 3 weeks

• Clinical representation – malaise, fever, headache, sore throat, and non-productive cough

• Chest x-rays shows pulmonary infiltrates

• Walking pneumonia

• Extrapulmonary manifestations

o Erythema multiforme

o CNS involvement, including meningitis, meningoencephalitis, and mono- and polyneuritis

o Myocarditis

o Pericarditis

o Arthritis

o Pancreatis

Treatment for Mycoplasma pneumoniae

• Tetracycline, macrolides, fluroquinolones

Mycoplasma hominis

• Colonies may have a typical fried egg appearance on agar

• Causes pelvic inflammation disease (PID),nongonococcal urethritis (NGU), pyelonephritis, post-partum fever, and salpingitis

Ureaplasma urealyticum

• It requires 10% urea for growth.

• Causes nongonococcal, nonchlamydial urethritis in men

• Lung diseases of premature low birth weight infants

Mycoplasma genitalium

• Diseases caused by Mycoplasma genitalium are as follows:

o Acute and chronic nongonococcal urethritis in men

o Cervicitis, endometritis, salpingitis, and infertility in women