Blood Pressure Cuff as a Potential Vector of Pathogenic Microorganisms A Prospective Study in a Teaching Hospital

Objective.

To investigate the potential role of blood pressure (BP) cuffs in the spread of bacterial infections in hospitals.

Design.

A comprehensive, prospective study quantitatively and qualitatively evaluating the bacterial contamination on BP cuffs of 203 sphygmomanometers in use in 18 hospital units from January through March 2003.

Setting.

A university hospital with surgical, medical, and pediatric units.

Results.

A level of contamination reaching 100 or more colony-forming units per 25 cm2was observed on 92 (45%) of inner sides and 46 (23%) of outer sides of 203 cuffs. The highest rates of contamination occurred on the inner side of BP cuffs kept in intensive care units (ICUs) (20 [83%] of 24) or on nurses' trolleys (27 [77%] of 35). None of the 18 BP cuffs presumed to be clean (ie, those that had not been used since the last decontamination procedure) had a high level of contamination. Potentially pathogenic microorganisms were isolated from 27 (13%) of the 203 BP cuffs: 20 of these microorganisms wereStaphylococcus aureus, including 9 methicillin-resistant strains. The highest rates of contamination with potentially pathogenic microorganisms were observed on cuffs used in ICUs and those kept on nurses' trolleys. For 4 patients with a personal sphygmomanometer, a genetic link was found between the strains isolated from the BP cuffs and the strains isolated from the patients.

Conclusions.

The results of this survey highlight the importance of recognizing BP cuffs as potential vectors of pathogenic bacteria among patients and as a source of reinfection when dedicated to a single patient, emphasizing the urgent need for validated procedures for their use and maintenance.

[Molecular identification of species within the Mycobacterium tuberculosis complex using regions of difference]

The differentiation within the Mycobacterium tuberculosis complex (MTBC) based on phenotypic methods is long and does not give an unambiguous result in every case whereas the advance in genetic knowledge leads to new views. Thus, regions of difference (RD), that seem to characterize the species of the MTBC, have been identified. Amplification methods, targeted on these zones, have been developed then. The study of four regions (RD1, RD5, RD9, RD10) has been done on 64 isolates formerly identified thanks to phenotypic methods. Genotypic results confirm phenotypic identifications except in one case. This strain initially identified as M. tuberculosis and isolated from a Gabonese patient, corresponds, according to genotypic identification, to M. africanum. Since phenotypic characterization of M. africanum is difficult, this method would allow to accurately determine the true prevalence of this specie. Moreover, the study of RD10 doesn't seem to be informative. The amplification of only two RD, RD1 and RD9 carries out the identification of all M. tuberculosis and M. bovis BCG isolates. M. bovis and M. africanum will be then identified thanks to RD5. Thus, this easy and rapid method of identification of the major species of MTBC seems to be appropriated for a routine use.