The pathogenesis of catheter-associated urinary tract infection

Catheter-associated urinary tract infection (CAUTI) remains one of the most common types of hospital-acquired infections. Further progress in the prevention of CAUTI requires a better understanding of its pathogenesis. Bacteria may enter the bladder through contamination of the tip during insertion with the flora of the distal urethra or from bacteria ascending the outside or the inside of the catheter. Residual urine in the bladder of catheterised patients increases the risk of bacteriuria. During the process of infection, bacteria need first to adhere to the epithelial cells of the urinary tract and/or the surface of the catheter. They will then develop into biofilms on the catheter surface and are resistant to the immune system and antibiotics. Catheters by themselves may cause immediate physical damage to the bladder epithelium; they may be toxic and also cause inflammation. Bacteria can also damage the epithelium and cause inflammation and the combination of both may be synergistic in producing symptoms in the patient. Most episodes of catheter-associated bacteriuria are asymptomatic but it is not known why some patients are symptomatic and others are not. Further research into the pathogenesis of CAUTI needs to be carried out. A suggestion for the prevention of CAUTI is the use of catheters with an additional eye-hole beneath the balloon to prevent residual urine in the bladder or to remove the tip and balloon altogether, with the additional benefit of having no tip to cause damage or inflammation to the bladder epithelium.

Comparison of the sterilising activities of the nitroimidazopyran PA-824 and moxifloxacin against persisting Mycobacterium tuberculosis

OBJECTIVES

To measure the bactericidal activity of the nitroimidazopyran PA-824 against Mycobacterium tuberculosis, strain H37Rv, in the three Hu/Coates models of bacterial persistence, in comparison with the activity of moxifloxacin (MXF), a drug shown to be likely to shorten treatment in current clinical trials.

METHODS

The bactericidal activity of a wide range of PA-824 and MXF concentrations was tested against a 100-day static, starved, anaerobically-adapted culture in Model 1. In Models 2 and 3, rifampicin (RMP) 100 mg/ml was added to the 100-day culture for 5-7 days and bactericidal activities against surviving tolerant bacilli were tested by addition of the test drugs after removal of RMP in Model 2, and during exposure to RMP in Model 3.

RESULTS AND DISCUSSION

PA-824 exhibited little bactericidal activity at low concentrations up to 1.25 microg/ml in each of these models, but high concentrations of >or=10 microg/ml showed considerable bactericidal activity, sufficient to kill all bacilli in Model 3, and appreciably greater than with MXF. However, as PA-824 is 94% plasma bound, concentrations of free drug sufficient to reach the zone of high bactericidal activity may not be obtained in cavities of pulmonary tuberculosis.

The TB structural genomics consortium: a resource for Mycobacterium tuberculosis biology

The TB Structural Genomics Consortium is an organization devoted to encouraging, coordinating, and facilitating the determination and analysis of structures of proteins from Mycobacterium tuberculosis. The Consortium members hope to work together with other M. tuberculosis researchers to identify M. tuberculosis proteins for which structural information could provide important biological information, to analyze and interpret structures of M. tuberculosis proteins, and to work collaboratively to test ideas about M. tuberculosis protein function that are suggested by structure or related to structural information. This review describes the TB Structural Genomics Consortium and some of the proteins for which the Consortium is in the progress of determining three-dimensional structures.