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Etiology

Cephalosporin use was associated with increased risk for nosocomial Enterococcus faecalis bacteremia

ACP J Club. 1994 Jan-Feb;120:23. doi:10.7326/ACPJC-1994-120-1-023


Source Citation

Pallares R, Pujol M, Peña C, et al. Cephalosporins as risk factor for nosocomial Enterococcus faecalis bacteremia.A matched case-control study. Arch Intern Med. 1993 Jul 12;153:1581-6.


Abstract

Objective

To determine if the use of second- and third-generation cephalosporins is a risk factor for nosocomial enterococcal bacteremia (NEB).

Design

Blinded case-control study.

Setting

A teaching hospital in Spain.

Participants

Patients with clinical evidence of NEB identified from laboratory records. NEB was confirmed by ≥ 2 positive blood cultures for Enterococcus faecalis, or 1 positive blood culture and isolation of the organism from an infected site, or 1 positive blood culture with no other source of infection evident. The infection was considered nosocomial if it appeared > 72 hours after admission. Each patient with NEB was matched with another hospitalized patient based on age within 10 years, date of admission within 2 years, sex, hospital service, at least the same number of days in the hospital, primary diagnosis, and similar operative procedure. 207 patients had NEB, and 156 were matched for analysis. 114 pairs were men. Matching was blinded to cephalosporin use. Mean age for patients in both groups was 56 years.

Assessment of risk factors

Computerized medical records were abstracted for use of urinary catheters, intravenous lines, mechanical ventilation, and antibiotic agents.

Main outcome measure

Univariate and multivariate analyses to calculate odds ratios (ORs) for the association between risk factors and NEB.

Main results

27 pairs of patients had malignant neoplasms; 28 had liver, biliary tract, or gastrointestinal disorders; 40 had cardiac or lung diseases; 18 had neurologic disorders; 33 had multiple trauma; and 10 had other diseases. Univariate analysis showed that NEB was associated with the presence of a urinary catheter (OR 3.8, 95% CI 2.0 to 7.1, P < 0.001), mechanical ventilation (OR 2.6, CI 1.4 to 4.7, P < 0.01), previous antibiotic treatment (OR 3.6, CI 1.9 to 6.6, P < 0.001), and the use of second- and third-generation cephalosporins (OR 5.1, CI 2.6 to 9.7, P < 0.001). NEB was not associated with intravenous lines, other β-lactam antibiotics, aminoglycosides, or other classes of antibiotics. Multivariate analysis showed that only cephalosporin use (OR 4.8, CI 2.3 to 9.8, P < 0.001) and urinary catheter use (OR 3.6, CI 1.7 to 7.4, P < 0.001) increased the risk for NEB.

Conclusion

The use of second- and third-generation cephalosporins and the use of urinary catheters were independently associated with an increased risk for nosocomial enterococcal bacteremia in hospitalized adults.

Source of funding: Fondo de Investigaciones Sanitarias from the National Health Service, Madrid, Spain.

For article reprint: Not available.


Commentary

Bloodstream infections with gram-positive bacteria have increased among hospitalized patients (1). Nosocomial infections are often multifactorial in origin. The introduction of a new antibiotic may sufficiently alter the microbial environment of the hospital so that infection with uncommon pathogens becomes more prevalent. The authors suspected this problem when they observed an increase in NEB in their hospital when cephalosporin use was increasing. Second- and third-generation cephalosporin use occurred for at least 2 days during the 2 weeks before bacteremia developed. The lack of association between NEB and use of other antimicrobial agents or use of vascular catheters reflects differences in antimicrobial activity and in the effectiveness of case-control matching for this variable, respectively.

This study should be used to reinforce 2 important points: First, antimicrobial therapy should have a rational basis. The finding that NEB was associated with cephalosporin use does not mean that these agents should be avoided. Rather, broad spectrum antibiotics such as cephalosporins should be used judiciously in order to avoid the unnecessary selection of pathogenic organisms, including resistant bacteria. The use of third-generation cephalosporins is not only associated with enterococcal bacteremia but is also a risk factor for the nosocomial acquisition of vancomycin-resistant enterococci (2, 3). Second, recent antibiotic therapy should be considered when choosing treatment for a new infection. When nosocomial bacteremia is suspected in patients receiving cephalosporins, enterococci should be considered as a potential pathogen.

Patrick J. Brennan, MD
University of PennsylvaniaPhiladelphia, Pennsylvania, USA


References

1. Banerjee SN, Emori TG, Culver DH, et al. Secular trends in nosocomial primary bloodstream infections in the United States 1980-1989. Am J Med. 1991;91(Suppl 3B):86S-9S.

2. Tornieporth NG, Roberts RB, John J, Hafner A, Riley LW. Risk factors associated with vancomycin-resistant Enterococcus faecium infection or colonization in 145 matched case patients and control patients. Clin Infect Dis. 1996 Oct;23:767-72.

3. Morris JG Jr, Shay DK, Hebeden JN, et al. Enterococci resistant to multiple antimicrobial agents, including vancomycin. Establishment of endemicity in a university medical center. Ann Intern Med. 1995;123:250-9.