Acinetobacter baumannii

Acinetobacter baumannii is a non-fermenting, oxidase-negative, gram-negative coccobacillus that can appear as a diplococcus on Gram stain, sometimes mistaken for Neisseria species. It is an opportunistic pathogen associated with hospital-acquired infections, especially in immunocompromised, critically ill, or mechanically ventilated patients. Common infections include ventilator-associated pneumonia, bacteremia, catheter-associated UTIs, wound infections (notably in combat-related trauma, earning it the nickname 'Iraqibacter'), and meningitis (rare, post-neurosurgical).

It survives well in hospital environments (desiccation-resistant), persisting on surfaces, medical devices, and healthcare workers' hands, facilitating outbreaks. As one of the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species), it exemplifies the growing threat of antimicrobial resistance. Resistance mechanisms include efflux pumps, porin loss, and production of beta-lactamases (including carbapenemases like OXA-type enzymes), leading to multidrug-resistant (MDR) and even pandrug-resistant (PDR) strains.

Treatment is challenging; options include carbapenems (if susceptible), colistin, tigecycline, or combination therapy for MDR/XDR strains. Infection control practices (hand hygiene, environmental cleaning, contact precautions) are critical for prevention given its capacity for nosocomial spread.