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outbreaks of human disease (Brauers et al., 2005; Joly-Guillou, 2005; Murray et al.,
2007).
1.3.2 Laboratory Diagnosis:
Morphologically, Acinetobacter are aerobic, non motile Gram-negative coccobacilli
and are usually found in diploid shape or chains of different length. They are strictly
aerobic and grow simply on all common media at temperatures from 20 to 30 o C for
most strains, the optimum temperature for this bacterium at 33-35 o C (Winn et al.,
2006). They are oxidase-negative, catalase-positive, indole-negative and nitrate-
negative. Furthermore, the initial clue in recognising these bacteria is the appearance
of tiny (1.0x 0.7 µm) diplococci with the Gram stain (Koneman et al., 1997).
Colonies appear smooth, opaque, sometimes mucoid and slightly smaller than those
of members of the family Enterobacteriaceae on blood agar. Most strains appear
colourless, slightly pink or lavender in colour on MacConkey agar due to lactose
oxidation (Engelkirk 2007). The genus of Acinetobacter can be therefore subdivided
into two groups. Acinetobacter that are able to oxidise glucose are called
saccharolytic, with those that are unable called asaccharolytic (Engelkirk 2007).
Most glucose-oxidizing non-haemolytic clinical strains are A. baumannii, most
glucose-negative non-haemolytic ones are A. lwoffii, and most haemolytic ones are
A. haemolytic (Murray et al., 2007).
1.3.3 Clinical features of Acinetobacter infections:
Acinetobacter species particularly Acinetobacter baumannii, can cause many clinical
disorders, including pneumonia, secondary meningitis, bacteraemia, wound
infections in burn patients and UTI. They are also isolated from skin, throat and
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