بسم الله الرحمن الرحيم 1 1 1

Head of Medical Microbiology Department Gram Negative Bacilli Dr. Manal El Said Head of Medical Microbiology Department

Head of Medical Microbiology Department Pseudomonas Dr. Manal El Said Head of Medical Microbiology Department

Pseudomonas aeruginosa Diseases Wound infection UTI Pneumonia Sepsis. Nosocomial infections, especially in burn patients and those with cystic fibrosis. Causes endocarditis in intravenous drug users.

Pseudomonas aeruginosa Habitat and Transmission Characteristics Aerobic gram-negative rods. Non–lactose-fermenting. Pyocyanin (blue-green) pigment production. Oxidase-positive Habitat and Transmission Habitat is environmental water sources. Inhabits the skin, upper respiratory tract & colon. Transmission is via water aerosols, aspiration & fecal contamination.

Pseudomonas aeruginosa Pathogenesis Endotoxin is responsible for fever and shock associated with sepsis. Produces exotoxin A inactivates EF-2. Pili and capsule mediate attachment and inhibit phagocytosis, respectively. Glycocalyx-producing strains predominate in chronic infections in cystic fibrosis patients. Severe burns & neutropenia are predisposing factors

Pseudomonas aeruginosa Laboratory Diagnosis Gram-stained smear and culture. Non–lactose-fermenting colonies on MacConkey's agar. . Oxidase-positive.

Pseudomonas aeruginosa Laboratory Diagnosis TSI agar shows an alkaline slant and an alkaline butt because the sugars are not fermented.

Pseudomonas aeruginosa Treatment Antibiotics must be chosen on the basis of antibiotic sensitivities because resistance is common. Anti-pseudomonal penicillin & aminoglycoside are used. Resistance is mediated by a variety of plasmid-encoded enzymes, e.g., β  -lactamases & acetylating enzymes.

Pseudomonas aeruginosa Prevention Disinfection of water-related equipment in the hospital Handwashing, Prompt removal of urinary and intravenous catheters. There is no vaccine.

Burkholderia cepacia & Stenotrophomonas maltophilia Gram-negative rod resembling P. aeruginosa. Important cause of chronic infections in patients with cystic fibrosis.

Acinetobacter They are gram-negative coccobacillary rods They found in soil & water They can be part of normal flora. They are opportunistic pathogens that colonize patients with compromised host defenses.

Acinetobacter

Acinetobacter Acinetobacter baumannii causes disease in a hospital setting associated with respiratory therapy equipment & indwelling catheters. Sepsis, pneumonia & urinary tract infections are the most frequent manifestations. A baumannii is antibiotic resistant & some isolates are resistant to all known antibiotics.