Achromobacter spp

Gram Stain

• Gram negative straight bacilli - nonfermenter (aerobic)

Clinical Significance

These organisms are found in a variety of environmental and water sources.  They may be part of the human gastrointestinal tract.

They are considered to have a low pathogenic potential and rarely cause human infections.

Patients who have received broad spectrum antibiotics (especially 3rd generation cephalosporins and quinolones) may become colonized with these organisms. They are relatively common colonizers in bronchiectasis patients and spread within cystic fibrosis populations has been reported.

Nosocomial infections include bacteremia, septicemia in febrile neutropenia / hematologic malignancies, endocarditis, prosthetic joint infections, medical device related infections, post-operative and post-traumatic wounds, pneumonia (especially ventilator associated and cystic fibrosis patients), neonatal meningitis, peritonitis, septic arthritis, biliary tract infections, chronic otitis media, ophthalmic (conjunctivitis/keratitis), and urinary tract infections.

Usual Susceptibility Pattern

These organisms typically exhibit resistance to beta-lactam agents, including penicillins, amoxicillin-clavulanate, cefazolin, cefotaxime/ceftriaxone, cefixime, aztreonam, and ertapenem.

They are usually susceptible to anti-pseudomonal beta-lactams such as piperacillin-tazobactam, imipenem, and meropenem (susceptibility to ceftazidime is variable).  Elevated MICs to imipenem and meropenem have been reported as well as frank resistance as a result of carbapenemases.

They are usually susceptible to TMP/SMX (sulfamethoxazole component) but often resistant to quinolones.

They have inherent resistance to aminoglycosides and trimethoprim, and exhibit elevated MICs to colistin.