Acinetobacter Strain KUO11TH, a Unique Organism Related to Acinetobacter pittii and Isolated from the Skin Mucus of Healthy Bighead Catfish and Its Efficacy Against Several Fish Pathogens

The bacterial strain KU011TH was isolated from the skin mucus of healthy bighead catfish. The strain is a Gram-negative coccobacillus that is nonmotile, aerobic, catalase positive, oxidase negative, and nonhemolytic. Sequence analyses of the housekeeping genes 16S rRNA, gyrB and rpoB indicate that this strain is a new member of the Acb complex of the genus Acinetobacter and is closely related to Acinetobacter pittii and Acinetobacter lactucae. In addition, the genome relatedness-associated ANIb (<95–96%) and in silico DDH (<70%) values clearly supported the new member of the genus Acinetobacter and the Acb complex. The genome of the strain KU011TH was approximately 3.79 Mbp in size, comprising 3619 predicted genes, and the DNA G+C content was 38.56 mol%. The major cellular fatty acids were C18:1ω9c, C16:0, C16:1, C20:2, C18:2ω6c and C18:1ω9t. The whole-genome sequences and phenotypic, phylogenetic, and chemotaxonomic data clearly support the classification of the strain KU011TH as a new member in the genus Acinetobacter which is closest to A. pittii. Additionally, the new bacterial strain exhibited strong activity against a broad range of freshwater fish pathogens in vitro.

Colistin resistance in Acinetobacter baumannii isolated from critically ill patients: clinical characteristics, antimicrobial susceptibility and outcome

Background: Acinetobacter baumannii (AB) is increasingly becoming a clinically relevant organism due to the rising number of associated nosocomial infections. The therapeutic options are extremely minimal because of its ability to develop resistance to all available antimicrobials, including colistin (CST). Data on the clinical and microbiological characteristics of colistin-resistant A. baumannii infections remain scarce to date.Methods: In this prospective study, clinical isolates of colistin resistance among Acinetobacter strain was evaluated from the database of Microbiology Laboratory of King Khalid University Hospital, Saudi Arabia.Results: In a total of 142 patients with 136 Acinetobacter isolates, Acintobacter baumannii was the predominant serotype 73% of the isolates and Acinetobacter lwoffii constituted 27% of the isolate .There was 8.5% colistin resistant isolates with colistin E-test MIC >4. The clinical characteristics were determined for colistin resistant Acinetobacter baumannii. All patients were critically ill and 64% of them were hositalized in the Intensive Care Unit (ICU). All patients have been previously given antibiotics. Other associated clinical characteristics included; morbid obesity and sleeve gastrectomy (21 %), mechanical ventilation and central venous catheter (50%). High mortality rate was found(28%).Conclusion: There is an increase of colistin resistance among clinical isolates of Acinetobacter baumannii causing serious infections especially in critically ill patients.Keywords: Acinetobacter baumannii, colistin resistance, clinical characteristics.

A Taxonomically Unique Acinetobacter Strain with Proteolytic and Hemolytic Activities Recovered from a Patient with a Soft Tissue Injury

A taxonomically unique bacterial strain,Acinetobactersp. A47, has been recovered from several soft tissue samples from a patient undergoing reconstructive surgery owing to a traumatic amputation. The results of 16S rRNA,rpoB, andgyrBgene comparative sequence analyses showed that A47 does not belong to any of the hitherto-known taxa and may represent an as-yet-unknownAcinetobacterspecies. The recognition of this novel organism contributes to our knowledge of the taxonomic complexity underlying infections caused byAcinetobacter.

Production of 6-Phenylacetylene Picolinic Acid from Diphenylacetylene by a Toluene-Degrading Acinetobacter Strain

ABSTRACT Several strategies for using enzymes to catalyze reactions leading to the synthesis of relatively simple substituted picolinic acids have been described. The goal of the work described here was to synthesize a more complex molecule, 6-phenylacetylene picolinic acid [6-(2-phenylethynyl)pyridine-2-carboxylic acid], for use as a potential endcapping agent for aerospace polymers. We screened 139 toluene-degrading strains that use a variety of catabolic pathways for the ability to catalyze oxidative transformation of diphenylacetylene. Acinetobacter sp. strain F4 catalyzed the overall conversion of diphenylacetylene to a yellow metabolite, which was identified as a putative meta ring fission product (2-hydroxy-8-phenyl-6-oxoocta-2,4-dien-7-ynoic acid [RFP]). The activity could be sustained by addition of toluene at a flow rate determined empirically so that the transformations were sustained in spite of the fact that toluene is a competitive inhibitor of the enzymes. The overall rate of transformation was limited by the instability of RFP. The RFP was chemically converted to 6-phenylacetylene picolinic acid by treatment with ammonium hydroxide. The results show the potential for using the normal growth substrate to provide energy and to maintain induction of the enzymes involved in biotransformation during preliminary stages of biocatalyst development.