Batterjee Medical College

Batterjee Medical College

Dr. Manal El SaidDr. Manal El Said

Gram Negative Bacilli

Head of Medical Microbiology Department

Batterjee Medical College

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

Pseudomonas

Batterjee Medical College

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.

Batterjee Medical College

Pseudomonas aeruginosa

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.

Batterjee Medical College

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

Batterjee Medical College

Laboratory Diagnosis

• Gram-stained smear and culture.

• Non–lactose-fermenting colonies on MacConkey's agar. .

• Oxidase-positive.

Pseudomonas aeruginosa

Batterjee Medical College

Laboratory Diagnosis• TSI agar shows an alkaline slant and an alkaline butt

because the sugars are not fermented.

Pseudomonas aeruginosa

Batterjee Medical College

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

Batterjee Medical College

Prevention

• Disinfection of water-related equipment in the hospital

• Handwashing,

• Prompt removal of urinary and intravenous catheters.

• There is no vaccine.

Pseudomonas aeruginosa

Batterjee Medical College

•Gram-negative rod resembling P. aeruginosa.

• Important cause of chronic infections in patients

with cystic fibrosis.

Burkholderia cepacia & Stenotrophomonas maltophilia

Batterjee Medical College

• 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

Batterjee Medical College

Acinetobacter

Batterjee Medical College

• 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.

Acinetobacter