The present invention provides oligonucleotide probes that are specific for nucleic acid characteristic of a target sequence of 16s ribosomal rna (rrna) in prokaryotes from the genus acinetobacter and pseudomonas. The probes can be employed in a method to identify nucleic acid characteristic of the 16s rrna in samples, and particularly, in clinical isolates of gram non-enterobacteriaceae bacteria from the genus acinetobacter and pseudomonas. The invention also relates to a diagnostic kit comprising the probes for carrying out the inventive method