Automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis

doi:10.1016/S0161-6420(99)00178-5

Ophthalmology

Volume 107, Issue 4, April 2000, Pages 685-690

Presented in part at the 2nd International Conference on Ocular Infections, August, 1998, Munich, Germany.

https://doi.org/10.1016/S0161-6420(99)00178-5 Get rights and content

Abstract

Purpose

Contamination of automated surgical equipment is a potential source of postoperative endophthalmitis. The effect of disinfecting the unsterile vacuum control manifold (VCM) on contamination of the aspiration fluid was studied.

Design

Comparative prospective microbiologic contamination study.

Specimens and controls

The 37 aspiration fluid specimens studied or examined consisted of 25 from three automated evacuation systems equipped with an internal VCM (experimental groups) and 12 from one system equipped with a modified external VCM (control group). In addition, the tubings of two internal VCMs were investigated.

Methods

We investigated aspiration fluid specimens from routine cataract and vitrectomy operations performed with automated evacuation systems. After tracing the source of contamination to the internal VCM, the system was modified, creating an external VCM with the possibility for disinfection, and the study was continued. Whereas no sterilizing rinsing procedures were applied to the hidden internal VCM, the modified external VCM was regularly rinsed and filled overnight with 70% isopropanol. All samples were collected under sterile conditions, centrifuged, and cultured for bacterial growth on blood agar and MacConkey agar for 24 to 48 hours at 37°C. The samples of the two internal VCMs were cultured for fungi as well.

Main outcome measures

Bacterial growth was quantified, and bacteria and fungi were isolated and identified according to standard microbiologic procedures.

Results

In all aspiration fluid specimens from internal VCM-systems, 2+ to 4+ bacterial growth was found. Pseudomonas-related genera (Stenotrophomonas maltophilia, 17x; Comamonas acidovorans, 8x;Chryseomonas spp., 3x), Agrobacterium radiobacter (13x), Flavobacterium spp. (3x), and Micrococcus luteus (7x) were found most frequently. The tubing of the two VCMs contained biofilms exhibiting several of these bacteria and fungi. All specimens from the modified external VCM-system remained sterile. There was a significant difference with regard to the frequency of contamination of the aspiration fluid between the experimental and control groups (chi-square: P = 0.0001).

Conclusions

The technical modification described herein allows facile hygienic measures, by which contamination of aspiration fluid by the VCM can be eliminated, which otherwise can be a significant source of contamination.

Section snippets

Materials and methods

In the summer of 1997, we prospectively investigated a total of 37 aspiration bags from routine and uneventful vitrectomies and cataract operations performed by five different surgeons. In parallel, we searched for possible mechanisms of contamination of the aspiration fluid. After the source of contamination was tracked down to the internal VCM, the automated system was modified, creating an external VCM that can be disinfected. To substantiate our hypothesis and to confirm the efficacy of the

Results

In the aspiration fluid from the machines with internal VCMs, 4+ bacterial growth was observed in 13 of the 25 cases, 3+ in 11 cases, and 2+ in 1 case (Fig 5). By contrast, all 12 samples from the machine with an external VCM (control group) remained sterile. Statistical analysis showed 100% contamination of aspiration fluid in machines with an internal VCM in contrast to 0% in the machine with the external VCM (chi-square: P = 0.0001). Details of the microbiologic cultures are shown in Table 1

Discussion

In 25 of 25 intraocular operations performed with three approximately 1-year-old irrigation/aspiration systems, we found severe contamination of the aspiration fluid by several ubiquitous bacteria, including M. luteus, S. maltophilia, C. acidovorans, Chryseomonas spp., F. meningosepticum, and A. radiobacter. It is noteworthy that S. maltophilia and A. radiobacter were among the three most frequently isolated species in all three experimental groups. These bacteria are widely distributed in the

Acknowledgements

The authors thank the Max-von-Pettenkofer-Institute for Hygiene and Medical Microbiology of the Ludwig-Maximilians-University of Munich for identification of the bacteria. We also thank Michael Brown, of the University of Würzburg, Germany, for carefully reading the manuscript.

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Automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis1

Abstract

Purpose

Design

Specimens and controls

Methods

Main outcome measures

Results

Conclusions

Section snippets

Materials and methods

Results

Discussion

Acknowledgements

Ophthalmology

Ophthalmology

Infect Dis Clin North Am

J Cataract Refract Surg

J Cataract Refract Surg

Am J Ophthalmol

Endophthalmitis

Automated surgical equipment requires routine disinfection of vacuum control manifold to prevent postoperative endophthalmitis¹