THE BACILLI OF MEDICAL IMPORTACE
Gram negative bacilli • Comprises a large group of nonspore-forming bacteria. • Highly diverse in metabolism and pathogenicity • Inhabitants of large intestine, some are zoonotic, some are adapted to the human respiratory tract and still others live in soil and water. • Containing endotoxin
Aerobic Gram-Negative Nonenteric Bacilli • • • •
Pseudomonas ( opportunistic) Brucella and Francisella( Zoonotic) Bordetella ( human pathogen) Legionella ( human pathogen)
Pseudomonas(PSEUDOMONADS) • free-living bacteria ,primarily in soil, seawater, and fresh water. • Colonize plants and animals • Polar flagellum • Oxydase positive • Catalase positive • Not ferment carbohydrates • Most of the obtain energy through oxidative metabolism • Produce green, brown, red, or yellow pigments
Pseudomonas aeruginosa • Common inhabitants of soil and water • Intestinal resident in about 10% of normal people • Frequent contaminants of ventilators, intravenous solutions and anesthesia equipments. • Typical opportunist
Pseudomonas aeruginosa • Predisposing conditions: Debilitating illness, immunosupressant medicaiton or IV injection Virulence factors: Exotoxins, slime layer resistant to phagocytosis, various enzymes that degrades host tissue, endotoxin
Most common nosocomial infections • Severe burns • Neoplastic diseases • Cystic fibrosis Complications: Pneumonia UTI, Otitis, abscesses and corneal diseases Pseudomonas septicemia: Endocarditis, meningitis, bronchopneumonia
• More virulent in premature infants and neonates. • Outbreaks of skin rashes, UTI and external ear infections from community hot tubs and swimming pools in healthy people.
Identification • Grape like odor • Blue pus ( Pyocyanin) • Culture on common media such as: blood agar, MaCconky agar, eosin-methylene blue agar and pseudomonas flourescenc agar
treatment • Multi drug resistant • Third generation cephalosporins, aminoglycosides, carbincillin, polymyxin,quinolones and monobactams(Aztreonam)
