Acinetobacter spp

Gram Stain

• Gram negative coccobacilli - nonfermenter (aerobic)

Clinical Significance

These organisms are widely distributed in the environment. They may be part of normal flora of the skin, conjunctiva, pharynx, urethra, and vagina.

Although they can represent colonization in patients who have received broad spectrum antibiotics, they are associated with nosocomial infections (pneumonia, bacteremia, CAPD peritonitis, meningitis, septic arthritis, osteomyelitis, cellulitis, conjunctivitis, wound, and urinary tract infections).

Usual Susceptibility Pattern

Acinetobacter often exhibit multiple resistances. They should always be considered resistant to amoxicillin +/- clavulanate, as well as 1st and 2nd generation cephalosporins. They are inherently resistant to ertapenem, trimethoprim (not sulfamethoxazole), and fosfomycin.

Aminoglycoside (especially gentamicin) and quinolone resistance is common.

Multiple beta-lactamases (chromosomal and plasmid) can result in broad beta-lactam resistance, including carbapenems.

Doxycycline and colistin often retain activity but resistance has been reported.