Acinetobacter_flashcards
What are the main characteristics of Acinetobacter baumannii?
Gram-negative coccobacillus, nonmotile, oxidase-negative, strictly aerobic, resists decolorization in Gram stain
What type of infections is Acinetobacter baumannii commonly associated with in hospitals?
Ventilator-associated pneumonia (VAP), bloodstream infections (BSI), urinary tract infections (UTI), wound infections
How is Acinetobacter baumannii primarily transmitted in healthcare settings?
Contact with contaminated surfaces, medical equipment, healthcare workers’ hands, environmental reservoirs like ventilators
Why is Acinetobacter baumannii considered a significant hospital pathogen?
Exhibits multidrug resistance (MDR), survives on dry surfaces for long periods, forms biofilms on medical devices
What are the key resistance mechanisms of Acinetobacter baumannii?
Carbapenem-hydrolyzing enzymes (OXA-type beta-lactamases), modified porin channels, overactive efflux pumps, biofilm formation
Which antibiotics are typically ineffective against Acinetobacter baumannii?
Ceftriaxone, cefotaxime, cefuroxime (3rd generation cephalosporins), moxifloxacin (fluoroquinolone), kanamycin (aminoglycoside)
What are the last-resort treatment options for multidrug-resistant Acinetobacter infections?
Polymyxins (e.g., colistin) due to nephrotoxicity, carbapenems (except for ertapenem)
What is the Difficult-to-Treat Resistance (DTR) definition for Pseudomonas aeruginosa, and why is it relevant to Acinetobacter?
DTR is defined as non-susceptibility to multiple primary antibiotics, indicating extreme resistance; Acinetobacter exhibits similar resistance patterns
What environmental sources harbor Acinetobacter species in hospitals?
Soil, environmental surfaces, medical equipment (ventilators, catheters), healthcare workers’ hands
Which carbapenem antibiotics are used for Acinetobacter infections, and which one is ineffective?
Effective: meropenem, imipenem-cilastatin; Ineffective: ertapenem
What are biofilms, and why are they significant in Acinetobacter infections?
Biofilms are bacterial communities that adhere to surfaces, creating a barrier against antibiotics and immune response, enhancing Acinetobacter persistence and resistance
What are the clinical implications of Acinetobacter’s resistance mechanisms?
Resistance mechanisms reduce treatment options, requiring toxic last-resort antibiotics like polymyxins
Why is strict infection control important in preventing Acinetobacter outbreaks?
Acinetobacter can survive on dry surfaces and spreads easily, making hygiene and disinfection critical
How does Acinetobacter’s modification of porin channels contribute to its resistance?
Modified porin channels limit antibiotic entry, increasing resistance, especially to beta-lactams
What is the role of OXA-type beta-lactamases in Acinetobacter baumannii’s resistance profile?
OXA-type beta-lactamases hydrolyze carbapenems, contributing to resistance against powerful antibiotics for gram-negative infections
