JOURNAL REVIEWS

Arrow PM, Garcia-Houchins S, Neagle MB, et al. An outbreak of bloodstream infections arising from hemodialysis equipment. J Infect Dis 1998; 178:783-791.

The authors traced an outbreak of 29 cases of bloodstream infection by 16 pathogens to contaminated equipment at two chronic hemodialysis centers. Consequences of the outbreak included 21 hospital admissions and removal of 23 dialysis catheters. An epidemiologic investigation comparing case patients with uninfected controls showed that risk was significantly associated with having a catheter for vascular access and receiving treatment on one heavily contaminated dialysis machine.

Culture studies and mock trials showed that bloodstream pathogens were present in a recently installed, commercially marketed attachment for disposal of spent priming saline. Pathogens could enter blood line tubing directly or indirectly during dialyzer priming and tubing assembly.

The outbreak demonstrates the hazard posed by microbial reservoirs in hemodialysis settings and underscores the need for well-designed equipment and practices. The authors emphasize the following points:

• In the design of hemodialysis equipment, special attention should be directed to the handling of dialysate waste, which contains balanced salts, bicarbonate, dextrose, and post-membrane organic solutes. This solution can support the growth of bacteria.

• When new equipment is introduced, dialysis staff should be educated about design, operation, maintenance, and potential hazards.

• Better education about asepsis is needed to stimulate a more critical assessment of procedures and equipment in dialysis centers. It is noteworthy in this outbreak and others that dialysis personnel did not recognize when blood lines were being contaminated by contact with a nonsterile environment.

• Heightened asepsis is especially important in this era of common use of venous catheters for dialysis. It appears that catheters amplify the risk that persistent bloodstream infection will result when small numbers of microorganisms are inadvertently introduced during hemodialysis.

Girou E, Pujade G, Legrand P, et al. Selective screening of carriers for control of methicillin-resistant Staphylococcus aureus (MRSA) in high-risk hospital areas with a high level of endemic MRSA. Clin Infect Dis 1998; 27:543-550.

Screening patients for methicillin-resistant Staphylococcus aureus (MRSA) carriage is controversial, but may prove useful in certain settings, the authors report.

They evaluated the efficacy of screening patients as part of a control program in a 26- bed medical intensive care unit (ICU) of a university hospital with a high level of endemic MRSA.

"Our study shows that in an environment with a high level of endemic MRSA, screening for MRSA carriage during admission to high-risk areas allows early identification of a large proportion of all patients with MRSA," they report.

Control measures included isolation and barrier precautions, skin decolonization with chlor hexidine of patients from whom MRSA was recovered, and mupirocin treatment of nasal carriers of MRSA. Of 3,686 patients admitted during a four-year period, 44% were screened, which occurred during admission for 38%. Overall, MRSA was recovered from 293 (8%) of the patients. There were 150 imported cases and 143 ICU-acquired cases, of which 51% and 41% respectively were first identified through screening.

In the absence of a screening program, at least one-third of all carriers would have remained undetected, and an additional one-third would have been ignored for several days, thus likely increasing the risk for cross-transmission, they report. The authors found that more than 80% of MRSA carriers were identified by nasal swab cultures, while about 15% had carriage at other sites.

"Our study confirms recent observations that, in the current epidemiological setting of many hospitals having endemic MRSA on the one hand and the growing pressure for early hospital discharge with the accompanying increasing circulation of colonized patients across health care institutions and within the community on the other hand, many patients colonized with MRSA can be admitted to high-risk acute-care areas. In such settings, screening for early identification of carriers, which can be targeted to selected high-risk groups, appears warranted."