Multi-drug resistant Acinetobacter baumannii bacteria inside biofilm, computer illustration. A. baumannii is a Gram-negative, oxidase negative, aerobic, coccobacillus. It has always been naturally resistant to multiple antibiotics. It can be especially resistant to penicillin and chloramphenicol. It causes various nosocomial infections, including, skin and wound infections, pneumonia, meningitis, septicaemia, urinary tract infection and endocarditis. It is commonly found in soil, water, sewage, and normal skin and gastrointestinal tract flora. It is the most frequently encountered species in the clinical laboratory. Species found in soil can colonize root nodule systems and oxidize the hydrogen produced by nitrogen fixing bacteria. The illustration shows morphology of Acinetobacter such as short rods and sometimes long filamentous cells.