In some hospitals, initial outbreaks of infection have been supplanted by endemicity of the ESBL-producing organisms (20, 223, 246, 334). This may lead to increased patient mortal- ity when antibiotics inactive against ESBL producers are used (358). As a consequence, when a significant proportion of gram-negative isolates in a particular unit are ESBL producers, empirical therapy may change towards use of imipenem, quin- olones, or þ-lactam/þ-lactamase inhibitor combinations. In some centers this has been associated with emergence of re- sistance in Pseudomonas aeruginosa, Acinetobacter baumanii, and in ESBL-producing organisms themselves (246, 334). Con- trol of endemic ESBL producers is difficult, and may only be possible after significant nursing and medical reorganization, at substantial financial cost (223, 334).Therefore, control of the initial outbreak of ESBL-produc- ing organisms in a hospital or specialized unit of a hospital is of critical importance (Table 1).The initial stages of the infection control program in a hos- pital or unit which has not previously been affected by ESBLs should therefore include (i) performance of rectal swabs to delineate patients colonized (but not infected) with ESBL pro-ducers, (ii) evaluation for the presence of a common environ- mental source of infection, (iii) a campaign to improve hand hygiene, and (iv) introduction of contact isolation for those patients found to be colonized or infected (294).Although common environmental sources of infection have rarely been discovered, when they are recognized their impact on arresting an outbreak of infection with a multiresistant organism can be dramatic. Three examples of such an inter- vention have been described in the context of controlling out- breaks of infection with ESBL-producing organisms. Gaillot(132) found that contaminated gel used for ultrasonography was contaminated with ESBL-producing organisms. Replace- ment of this gel quickly curtailed the outbreak. Branger (57) found that a poorly maintained bronchoscope was colonized with ESBL-producing organisms and could be linked to respi- ratory tract infections with the same strain. Repair and proper maintenance of the bronchoscope stopped nosocomial trans- mission of the organism. Finally, Rogues (346) found coloni- zation of four of 12 glass mercury thermometers with ESBL- producing Klebsiella pneumoniae and axillary colonization with the same strain in two patients. Disinfection of the thermom- eters curtailed the outbreak.Contact isolation implies use of gloves and gowns when contacting the patient. Several studies have documented that this practice alone can lead to reduction in horizontal spread of ESBL-producing organisms. However, compliance with these precautions needs to be high in order to maximize the effec- tiveness of these precautions. Furthermore, we recommend that patients who have gastrointestinal tract colonization as well as those with frank infection should undergo contact iso- lation. It has been noted that standard methods of hand wash- ing, screening for colonization, and patient isolation may not always be effective in controlling outbreaks of ESBL-producing organisms (230). Macrae and colleagues (230) were forced to close a ward tempoararily in order to adequately control an outbreak which had been unresponsive to conventional mea- sures.
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