Clinical Case Study
Paenibacillus macerans pseudobacteremia resulting from contaminated blood culture bottles in a neonatal intensive care unit*

https://doi.org/10.1067/mic.2001.111535Get rights and content

Abstract

Paenibacillus species are gram-positive, rod-shaped, spore-forming aerobes that are abundant in nature and closely related to Bacillus. Between June 24 and June 30, 1999, 8 neonates in our neonatal intensive care unit had positive blood cultures for Paenibacillus macerans. This cluster of positive blood cultures with an unusual pathogen suggested a pseudoepidemic. Investigation revealed that the most likely etiology of the pseudobacteremia was environmental contamination of the rubber stoppers in blood culture bottles. This was confirmed by environmental sampling and simulated inoculation studies. This pseudobacteremia outbreak highlights the importance of adhering to well-established methods for blood culture collection and ongoing infection control surveillance. (AJIC Am J Infect Control 2001;29:126-9)

Section snippets

Background and investigation

Northwestern Memorial Hospital is a 708-bed academic medical center with a level III neonatal intensive care unit (NICU). The NICU is geographically separate from the remainder of the medical center and consists of a central nurses’ station surrounded by 5 distinct nurseries. Between June 24 and June 30, 1999, 8 neonates had positive blood cultures for P macerans (Table 1).

. Isolation of P macerans in blood cultures

Patient No.Date of collectionNurseryBottle typeNo. positive/No. cultured
16/24/99B

Results

During the pseudobacteremia period, all blood isolates from 8 patients were identified as P macerans. None of the neonates was infected with this organism as determined by lack of fever or leukocytosis. However, because of their very low birth weights and the report of a positive blood culture, all were empirically started on antimicrobial therapy.

The results of environmental cultures are detailed in Table 2.

. Results of environmental cultures revealing growth of P macerans and Bacillus spp

SampleEmpty Cell

Discussion

Bacillus species may be associated with invasive bloodstream infections, especially in neonates or patients with impaired host defenses.1 Therefore, it is necessary to distinguish true bacteremia from pseudobacteremia particularly in these high-risk patients. The prompt recognition of pseudobacteremia is critical to avoid the unnecessary use of antimicrobial agents and to prevent a delay in the diagnostic evaluation of the patient’s clinical syndrome.9 Empiric antimicrobial therapy is often

References (11)

  • DJ Weber et al.

    Clinical significance of Bacillus species isolated from blood cultures

    South Med J

    (1989)
  • F Bert et al.

    Brain abscess due to Bacillus macerans following penetrating periorbital injury

    J Clin Microbiol

    (1995)
  • D. Maki

    Through a glass darkly—nosocomial pseudoepidemics and pseudobacteremias

    Arch Intern Med

    (1980)
  • DL Church et al.

    Investigation of a Streptococcus viridans pseudobacteremia epidemic at a university teaching hospital

    Infect Control Hosp Epidemiol

    (1989)
  • MK York

    Bacillus species pseudobacteremia traced to contaminated gloves used in collection of blood from patients with ac- quired immunodeficiency syndrome

    J Clin Microbiol

    (1990)
There are more references available in the full text version of this article.

Cited by (0)

*

Reprint requests: Gary A. Noskin, MD, Division of Infectious Diseases, Northwestern University Medical School, 215 E Huron—Feinberg 16-704, Chicago, IL 60611.

View full text