Non-Fermentative Gram-Negative Bacilli Flashcards

Vocabulary flashcards covering non-fermentative Gram-negative bacilli, focusing on Pseudomonas aeruginosa characteristics, virulence factors, laboratory identification, and antimicrobial resistance mechanisms.

Non-Fermentative Gram-Negative Bacilli

Gram-negative bacilli that cannot catabolize glucose and therefore do not ferment glucose, though catabolism of other carbohydrates is not excluded.

Gram-Negative Bacilli Classification

The breakdown of Gram-negative bacilli into Nonfastidious (Fermenters $63\%$, Nonfermenters $20.3\%$) and Fastidious groups (Hemophilic $13\%$, Fermenters and nonfermenters $1\%$, Anaerobes $3\%$).

Pseudomonas aeruginosa

A motile, oxidase-positive Gram-negative rod and strict aerobe that grows at $42\,^\circ\text{C}$, produces a grape-like odor, and acts as an opportunistic pathogen causing nosocomial infections.

Pseudomonas aeruginosa Pigments

Pigments produced by P. aeruginosa, including Pyocyanin (blue-green), Pyoverdine (yellow-green fluorescent), Pyorubin (red-brown), and Pyomelanin (black).

Pyocyanin

A blue-green pigment produced by Pseudomonas aeruginosa that oxidizes and reduces other molecules, causing the death of competitive microbes or host cells.

Exotoxin A

A virulence factor produced by Pseudomonas aeruginosa that inhibits polypeptide elongation, leading to tissue necrosis.

Exoenzyme S

An extracellular product of Pseudomonas aeruginosa that induces T-cell apoptosis.

Otitis Externa

An ear infection also known as swimmer's ear, commonly caused by Pseudomonas aeruginosa.

ESKAPE Pathogens

A group of critical multidrug-resistant pathogens comprising Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.

Pseudomonas aeruginosa Resistance Mechanisms

Resistance features categorized into Intrinsic resistance (low outer membrane permeability, efflux pump overexpression, $\beta$-lactamases), Adaptive resistance (continuous antibiotic exposure, environmental stress), and Acquired resistance (horizontal gene transfer, mutation).

Structural Virulence Factors of Pseudomonas aeruginosa

Cellular structures including a single flagellum, Type IV pili, non-pilus adhesins, Outer Membrane Proteins (OMPs), Lipopolysaccharide (LPS), Type 3 Secretion System (T3SS), and an alginate/mucoid exopolysaccharide biofilm layer.

Ventilator-Associated Pneumonia (VAP)

A serious hospital-acquired pneumonia commonly seen in ICU patients on mechanical ventilation, frequently caused by Pseudomonas aeruginosa.

Nonfastidious Nonfermenters

A category of nonfastidious Gram-negative bacilli accounting for $20.3\%$ of isolates, which includes Pseudomonas spp. and Acinetobacter spp.

Colistin

An antibiotic agent used to treat multidrug-resistant (MDR) and extensively drug-resistant (XDR) infections caused by non-fermenters like Pseudomonas aeruginosa and Acinetobacter spp.