Resistance towards antimicrobial drugs have posed a serious threat to mankind. Acinetobacter baumannii, a nosocomial pathogen have been spotted to hold a bunch of drug resistant genes which serves as an armour to escape from antimicrobial drugs commonly used for treatment. The present study describes the tetracycline resistant phenotype encountered in A. baumannii and its evolutionary relatedness with other bacterial species. A small subset of genome sequence from Acinetobacter sp. was probed to assess the frequency of tetracycline-resistant phenotype by in silico amplification. Further, the protein sequences of PCR-positive genes were subjected to multiple sequence alignment, to deduce the phylogenetic relationship across several other bacterial species. The tet(B) gene was found to occur in a greater frequency (42.1%) followed by tet(A) (10.5%), among eleven different tet genes analysed. The tet(A) gene was found in strains harbouring plasmids and tet(B)was observed in plasmid-bearing strains as well as one strain devoid of plasmids. Multiple sequence alignment and phylogenetic analysis of the protein sequences revealed an evolutionary closeness of tet(A) and tet(B) from A. baumannii to E. coli and P. stuartii respectively. A basic understanding on the molecular mechanisms underlying drug-resistant phenotype would eventually lead to the assessment of new drug targets. An evolutionary analysis of proteins encoding drug resistance might be useful to target closely related pathogens which enable the discovery of broad spectrum drugs targeting multiple pathogens.