Comparison of the Virulence Potential of Acinetobacter Strains from Clinical and Environmental Sources

Several Acinetobacter strains have utility for biotechnology applications, yet some are opportunistic pathogens. We compared strains of seven Acinetobacter species (baumannii, Ab; calcoaceticus, Ac; guillouiae, Ag; haemolyticus, Ah; lwoffii, Al; junii, Aj; and venetianus, Av-RAG-1) for their potential virulence attributes, including proliferation in mammalian cell conditions, haemolytic/cytolytic activity, ability to elicit inflammatory signals, and antibiotic susceptibility. Only Ah grew at 102 and 104 bacteria/well in mammalian cell culture medium at 37°C. However, co-culture with colonic epithelial cells (HT29) improved growth of all bacterial strains, except Av-RAG-1. Cytotoxicity of Ab and Ah toward HT29 was at least double that of other test bacteria. These effects included bacterial adherence, loss of metabolism, substrate detachment, and cytolysis. Only Ab and Ah exhibited resistance to killing by macrophage-like J774A.1 cells. Haemolytic activity of Ah and Av-RAG-1 was strong, but undetectable for other strains. When killed with an antibiotic, Ab, Ah, Aj and Av-RAG-1 induced 3 to 9-fold elevated HT29 interleukin (IL)-8 levels. However, none of the strains altered levels of J774A.1 pro-inflammatory cytokines (IL-1β, IL-6 and tumor necrosis factor-α). Antibiotic susceptibility profiling showed that Ab, Ag and Aj were viable at low concentrations of some antibiotics. All strains were positive for virulence factor genes ompA and epsA, and negative for mutations in gyrA and parC genes that convey fluoroquinolone resistance. The data demonstrate that Av-RAG-1, Ag and Al lack some potentially harmful characteristics compared to other Acinetobacter strains tested, but the biotechnology candidate Av-RAG-1 should be scrutinized further prior to widespread use

Isolation of Mycobacterium malmoense in the island of Crete, Greece

Mycobacterium malmoense was isolated from a broncho-alveolar lavage sample of a 73-year-old cancer (small cell lung carcinoma) patient in Crete, representing the first reported case of this pathogen in Greece. The isolate was considered to be a colonizer and the patient did not receive any antimycobacterial treatment while he received chemotherapy to which he responded favourably. No signs of pulmonary infection were noted during the course of his disease. This case provides evidence of the ubiquitous nature of this mycobacterial species, believed until recently to favour cooler climates. We, therefore, propose that the index of suspicion for this pathogen should be raised particularly in patients with underlying immunodeficiency, cancer and chronic lung disease, irrespective of the geographic location

Use of loop-mediated isothermal amplification of DNA for the rapid detection of Mycobacterium tuberculosis in clinical specimens

Loop-mediated isothermal amplification (LAMP) is a recently developed molecular method that has been successfully implemented in the detection of Mycobacterium tuberculosis in clinical specimens. LAMP has several advantages, such as rapidity, high sensitivity, ease of application and cost-effectiveness. As a result, it is anticipated that its use for the detection of M. tuberculosis is likely to become widespread, especially in low-resource countries. The present review aimed to present this method and all of the available information on its implementation in the detection of M. tuberculosis in clinical specimens