![]() These features can be used for their presumptive identification in the routine diagnostic laboratory. baumannii is saccharolytic, acidifies most carbohydrates and demonstrates the rapid production of acid from 1% and 10% lactose. ![]() ![]() They have been grouped as Acinetobacter calcoaceticus-Acinetobacter baumannii complex. baumannii, Acinetobacter genomic species 3 and Acinetobacter genomic species 13TU that have an extremely close relationship and are difficult to distinguish from each other by phenotypic tests alone. Among these are species Acinetobacter calcoaceticus, A. More than 25 genomospecies have been recognised by DNA-DNA hybridisation within the genus and seven have been given formal species name. Classified under the family Moraxella More Detailsceae, this genus includes Gram-negative coccobacilli that are non-motile, oxidase negative and resistant to penicillin. Few commonly encountered clinically important non fermenters other than Pseudomonas are high lighted in this article.Īs evidenced by our data in the special article in this issue, and most other studies, the most common non- Pseudomonas non-fermenter recovered from clinical specimens is Acinetobacter. The list of NFGNB is endless and beyond the scope of this article. Among these are 16s rRNA gene sequencing and DNA array (oligonucleotide array) technique that have been described as reliable and rapid method for identification of clinically significant Non-fermenting Gram negative bacilli (NFGNB). Molecular identification techniques are emerging as alternate for phenotypic identification methods. Identification by conventional phenotypic methods can be difficult and time consuming. However, studies investigating the performance of the commercial identification system have shown contradictory results. These may include manual or commercial kit/automated identification systems, such as API 20NE, Remel N/F, Vitek 2, Microscan Walkaway, the Sensititre AP80 system, the Phoenix system. Most clinical microbiology laboratories rely mainly on the phenotypic methods of identification. Commercial kit systems that are available for use are not only expensive but also often have low accuracy for identification of certain strains. Many species are slow growing and biochemically weak or inert and requires considerable experience to interpret equivocal results. Many of the conventional culture media are not suitable for identification and quality control of media may be difficult. Most species are infrequently encountered and therefore, the laboratory personnel may not be familiar with many of the non-fermenters. This is compounded by the factors that contribute to the difficulties in identifying them in the routine clinical microbiology laboratory. Taxonomic confusion prevails as there is a continuous revision and many of the identified strains have no designated species assigned. Published studies from various centres quote varied isolation rates of non-fermenters ranging from 2.18% to 45.9%. Non-fermenters account for 15% of all bacterial isolates from a clinical microbiology laboratory. Emerging challenges of multi-drug resistance, both intrinsic and acquired among them is of serious concern to the treating physician. ![]() However, they have now emerged as important healthcare associated pathogens as they have made their niche in the hospital environment. Being ubiquitous in nature, they were disregarded as probable contaminants, when isolated in the laboratory. Non-fermenters are a heterogenous group of Gram-negative bacilli that are aerobic, non-sporing, either do not use carbohydrates as a source of energy or degrade them through metabolic pathways other than fermentation. Non-fermenting Gram-negative bacilli (NFGNB) other than Pseudomonas. ![]()
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