Editing Acinetobacter (section)

== Identification ==
Identification of ''Acinetobacter'' species is complicated by lack of standard identification techniques. Initially, identification was based on phenotypic characteristics such as growth temperature, [[colony morphology]], growth medium, carbon sources, gelatin hydrolysis, glucose fermentation, among others. This method allowed identification of ''A. calcoaceticus–A. baumannii'' complex by the formation of smooth, rounded, mucoid colonies at 37&nbsp;°C. Closely related species could not be differentiated and individual species such as ''A. baumannii'' and ''Acinetobacter'' genomic species 3 could not be positively identified phenotypically.{{citation needed|date=August 2022}}

Because routine identification in the clinical microbiology laboratory is not yet possible, ''Acinetobacter'' isolates are divided and grouped into three main complexes:{{citation needed|date=August 2022}}
* ''Acinetobacter calcoaceticus-baumannii complex'': glucose-oxidising nonhemolytic (''A. baumannii'' can be identified by OXA-51 typing)
* ''Acinetobacter lwoffii'': glucose-negative nonhemolytic
* ''Acinetobacter haemolyticus'': [[Hemolysis (microbiology)|hemolytic]]

Different species of bacteria in this genus can be identified using fluorescence-lactose-denitrification to find the amount of acid produced by [[metabolism]] of [[glucose]]. The other reliable identification test at genus level is chromosomal DNA transformation assay. In this assay, a naturally competent tryptophan [[auxotrophic]] mutant of ''Acinetobacter baylyi'' (BD4 trpE27) is transformed with the total DNA of a putative ''Acinetobacter'' isolate and the transformation mixture is plated on a brain heart infusion agar. The growth is then harvested after incubation for 24 h at 30&nbsp;°C, plating on an ''Acinetobacter'' minimal agar (AMA), and incubating at 30&nbsp;°C for 108 h. Growth on the AMA indicates a positive transformation assay and confirms the isolate as a member of the genus ''Acinetobacter''. ''E. coli'' HB101 and ''A. calcoaceticus'' MTCC1921T can be used as the negative and positive controls, respectively.<ref>{{cite journal | last1 = Rokhbakhsh-Zamin | first1 = F. | last2 = Sachdev | first2 = D.P. | last3 = Kazemi-Pour | first3 = N. | last4 = Engineer | first4 = A. | last5 = Zinjarde | first5 = S.S. | last6 = Dhakephalkar | first6 = P.K. | last7 = Chopade | first7 = B.A. | year = 2012 | title = Characterization of plant growth promoting traits of Acinetobacter species isolated from rhizosphere of Pennisetum glaucum | journal = J Microbiol Biotechnol | volume = 21 | issue = 6| pages = 556–566 | doi = 10.4014/jmb.1012.12006 | pmid = 21715961 }}</ref>

Some of the molecular methods used in species identification are repetitive extragenic palindromic sequence-based PCR, ribotyping, pulsed field gel electrophoresis (PFGE), random amplified polymorphic DNA, amplified fragment length polymorphism (AFLP), restriction and sequence analysis of tRNA and 16S-23S rRNA gene spacers and amplified 16S ribosomal DNA restriction analysis (ARDRA)<!-- ? [1] -->. PFGE, AFLP, and ARDRA are validated common methods in use today because of their discriminative ability.<!-- [2,3]. --> However, most recent methods include multilocus sequence typing and multilocus PCR and electrospray ionization mass spectrometry, which are based on amplification of highly conserved housekeeping genes and can be used to study the genetic relatedness between different isolates.<ref>Antibiotic resistance is a major risk factor for epidemic behavior of Acinetobacter baumannii. ''Infect Control Hosp Epidemiol'' 2001; 22:284–288.</ref>