Molecular Detection of blaOXA -type Carbapenemase Genes and Antimicrobial Resistance Patterns among Clinical Isolates of Acinetobacter baumannii.

Acinetobacter baumannii is a bacterium found in most places, especially in clinics and hospitals, and an important agent of nosocomial infections. The presence of class D enzymes such as OXA-type carbapenemases in A. baumannii is proven to have a key function in resistance to carbapenem. The aim of the current study is to determine the blaOXA -type carbapenemase genes and antimicrobial resistance among clinically isolated samples of A. baumannii. We assessed 100 clinically isolated specimens of A. baumannii from patients in intensive care units of educational hospitals of Hamadan, West of Iran. The A. baumannii isolates' susceptibility to antibiotics was performed employing disk diffusion method. Multiplex polymerase chain reaction was used to identify the bla OXA-24-like , bla OXA-23-like , bla OXA-58-like , and bla OXA-51-like genes. The bla OXA-23-like , bla OXA-24-like , and bla OXA-58-like genes' prevalence were found to be 84, 58, and 3%, respectively. The highest coexistence of the genes was for bla OXA-51/23 (84%) followed by bla OXA-51/24-like (58%). The bla OXA-51/23- like pattern of genes is a sort of dominant gene in resistance in A. baumannii from Hamadan hospitals. The highest resistance to piperacillin (83%) and ciprofloxacin (81%) has been observed in positive isolates of bla OXA-23-like . The A. baumannii isolates with bla OXA-58-like genes did not show much resistance to antibiotics. Based on the results of the phylogenetic tree analysis, all isolates have shown a high degree of similarity. This study showed the high frequency of OXA -type carbapenemase genes among A. baumannii isolates from Hamadan hospitals, Iran. Thus, applying an appropriate strategy to limit the spreading of these strains and also performing new treatment regimens are necessary.

Fruit wrapping kraft coated paper promotes the isolation of actinobacteria using ex situ and in situ methods.

Designing novel isolation methods could enhance the diversification of the available bacterial strains to biotechnology. In this study, the new ex situ and in situ cultivation methods are introduced for the isolation of actinobacteria. In the ex situ experiments, the soil suspension was spread on the isolation media located above some ordinary papers in immediate contact with the slurry of soil substrate and incubated for 16 weeks. The paper was wholly immersed in the cave soil for in situ cultivations, and the containers were buried under layers of soil in Hampoeil cave for 10 weeks. Fruit wrapping kraft coated paper, with 68.8% recovery of isolates, was a better choice in isolation of actinobacteria than other studied filter paper. Based on the molecular identification results, 19% of the isolates obtained from the in situ cultivation method had less than 98.5% similarity to known taxa of actinobacteria and potentially may represent new species. In contrast, in the standard cultivation method, 1.3% of the isolates had less than 98.5% similarity 16Sr RNA gene. This data shows that the introduced cultivation method is a promising technique for isolating less culturable or new actinobacteria.

A Study on actinobacterial diversity of Hampoeil cave and screening of their biological activities.

Caves are oligotrophic, dark and less-explored environments and are considered as sources of promising microbial strains in biotechnology. Hampoeil Cave is located in massive dolomite with thin bedded limestone in northwestern of Iran. In an isolation and screening program, various samples from soil, water, floor, wall and ceiling of Hampoeil cave and its invertebrates were collected. Four various treatments and 10 different isolation media were used for the isolation of the actinobacteria. Screening of the isolates for antimicrobial activity against 10 bacteria and fungi, 5 hydrolytic enzymes production and resistance to 5 heavy metals have been performed. Among 33 various samples, 76 actinobacteria from various genera, including Streptomyces, Micromonospora, Micrococcus, Kocuria and Corynebacterium were isolated. Eighty percent of the strains had one of the studied hydrolytic enzyme activity. At least one type of antimicrobial activity was seen in 25.3% of the isolates. Resistance to one metal or more was seen in 26.32% of the isolates. The ratio of rare-actinobacteria in the oligotrophic samples to enriched samples is 20% more than Streptomyces. Percentage of strains with the highest activity in esterase, amylase, DNase, protease or lipase activity that were isolated from organic-rich environmental samples were 100, 100, 100, 82 and 82%, respectively. Also, 26.32% of the actinobacterial isolates resisted to heavy metals. It was concluded that Hampoeil cave is a good source in finding cave-living actinobacteria potent in producing hydrolytic enzymes and bioremediation.