2006 OPEN FORUM Abstracts
THE ASSOCIATION OF MECHANICAL VENTILATION AND RALSTONIA COLONIZATION/INFECTION IN THE USA BY META-ANALYSIS
Jonathan B. Waugh, PhD, RRT, RPFT; Amit Gaggar, MD; Wesley Granger, PhD, RRT. University
of Alabama at Birmingham, Birmingham, AL.
Introduction: A recent FDA Preliminary Public Health Notification reported Ralstonia spp.
had been cultured from a respiratory gas administration device at several
hospitals (first reported October 2005 in CDC Morbidity and Mortality Weekly
Report).1 Ralstonia
species are gram-negative bacilli that are commonly found in the environment
but rarely reported in the hospital setting. Ralstonia strains have traditionally exhibited low virulence in
humans.1 We performed a secondary analysis of published clinical
reports of Ralstonia to determine if
being on mechanical ventilation (MV) had an influence on how many colonizations
converted to infection (symptomatic).
Methods: We performed a meta-analysis of published multiple incidences of Ralstonia cultured in patients with
respiratory infections in the USA (through July 2005). The treatment group was
patients on MV and the control group consisted of patients not on MV. We
developed two different analyses; one for colonization with Ralstonia and the other for infection
with Ralstonia.
Results:
Colonization with Ralstonia:
| Study Name | Odds Ratio | 95% Lower CI | 95% Upper CI | Percent Weight |
| MMWR 1983 | 34.48 | 2.09 | 586.04 | 8.73 |
| MMWR 1998 | 10.32 | 4.23 | 25.22 | 87.80 |
| Burns et al | 125.25 | 1.30 | 11219.63 | 3.47 |
| Average | 12.51 | 5.41 | 28.8805 | 100.00 |
Infection with Ralstonia:
| Study Name | Odds Ratio | 95% Lower CI | 95% Upper CI | Percent Weight |
| MMWR 1983 | 1.00 | 0.020 | 50.89 | 24.03 |
| Timm et al | 1.49 | 0.029 | 76.82 | 23.96 |
| Labraca et al | 72.67 | 4.36 | 1211.39 | 33.26 |
| Burns et al | 201.00 | 1.65 | 24543.34 | 18.75 |
| Average | 12.38 | 0.96 | 159.05 | 100.00 |
The wide 95% confidence
intervals are due to the fact that these studies have small numbers. The
overall average from combining all the studies is the statistic of interest.
Conclusions: 1. Patients on MV have a
12.5 times increased chance of becoming colonized with Ralstonia. 2. Since the overall average 95% CI for infection had an
odds ratio which crosses one, there is not enough evidence to conclude an
increased rate of infection with MV. 3. Respiratory infection due to known
positive cultures of Ralstonia
in the USA was rare enough to make comparative analysis difficult (11 cases out
of a total of 632 patients or 1.74%). That rate may be biased by reporting only
positive cultures during periods of a Ralstonia outbreak. That, plus the use of small control
groups relative to a much larger clinical cohort, indicates a small clinical
impact of Ralstonia
colonizations for mechanically ventilated patients.
REFERENCE:
1. MMWR
2005:54(41);1052-1053.