Cataract extraction is a commonly performed operation in the United
States, with 1.3 million procedures performed annually. Postoperative endophthalmitis
is a potentially devastating complication, with an incidence of approximately
0.1% to 0.3%.1,2 We report
herein an evaluation of an outbreak of postoperative endophthalmitis.
This outbreak was investigated by the North Carolina Statewide Program
for Infection Control and Epidemiology. Patient cultures were performed in
a hospital microbiology laboratory. Environmental cultures were processed
as follows. Medication vials and water samples were processed by filtration
using a disposable filter (MSI Savur Analytical filter; Osmonics, Minnetonka,
Minn) placed on either sheep blood or D/E-neutralizing agar. Fluids too viscous
for filtration (eg, Keri Lotion) were plated directly onto suitable media.
Environmental surfaces (eg, sink drains) were cultured using a sterile swab
premoistened with trypticase soy broth and then plated directly onto appropriate
To determine the relatedness of Pseudomonas aeruginosa isolates, we performed pulsed-field gel electrophoresis using standard
The North Carolina Statewide Program for Infection Control and Epidemiology
was notified on October 14, 1999, about a cluster of cases of postoperative
endophthalmitis. Preliminary data obtained via telephone revealed that 5 of
7 patients who underwent a cataract extraction with phacoemulsification and
implantation of an intraocular lens on October 11, 1999 (outbreak day), had
developed postoperative endophthalmitis (Table 1). Patients were seen postoperatively with severe pain in
the involved eye, conjunctival hyperemia, and decreased visual acuity.
Clinical Characteristics of Patients Who Underwent Cataract
Extractions on the Outbreak Day*
All infected patients had undergone cataract extraction in the right
eye, and all noninfected patients had undergone cataract extraction in the
left eye (P = .048, 2-tailed Fisher exact test).
All cataract procedures were performed using automated phacoemulsification
with a phacomachine (AMO Diplomax; Allergan Inc, Irvine, Calif) that used
a peristaltic pump, followed by implantation of a Starr foldable silicone
intraocular lens. All patients received 0.3% ofloxacin drops, 3 times per
Following notification of this outbreak, we recommended that no additional
operations be performed. Multiple environmental cultures were obtained on
days 9 and 14 after the outbreak (Table
2). The P aeruginosa isolates from 4 patients
and 3 environmental sites were compared using pulsed-field gel electrophoresis
(Figure 1). All patient isolates
and the strain isolated from the phacoemulsifier's internal tubing were identical.
The strains of P aeruginosa isolated from the scrub
sink and its drain were identical, but differed by multiple bands from the
Results of Environmental Cultures
Pulsed-field gel electrophoresis
of Pseudomonas aeruginosa isolates. The sources of
the isolates in each lane are as follows: 1, λ ladder; 2, patient 5
(outbreak strain a); 3, patient 5 (outbreak strain a); 4, patient 5 (outbreak
strain a); 5, unrelated patient isolate (strain b); 6, patient 3 (outbreak
strain a); 7, patient 8 (outbreak strain a); 8, patient 8 (outbreak strain
a); 9, patient 6 (outbreak strain a); 10, right scrub sink (strain c); 11,
interior tubing of the phacoemulsifier (outbreak strain a); 12, unrelated
environmental isolate (strain d); 13, unrelated environmental isolate (strain
d); and 14, scrub sink drain (strain c).
The fluid pathways of the phacoemulsifier are shown in Figure 2A. The outflow tubing is connected via a T fitting to a
pressure transducer and air valve system that is housed within the machine
(Figure 2B). Using methylene blue,
we investigated conditions that might lead to retrograde flow from the internal
tubing to the handpiece. Disrupting the sealed connection of the internal
tube from the pressure transducer was effective in producing almost immediate
reflux that reached the handpiece within 2 minutes.
A, Schematic view of the fluid
channels of the phacoemulsifier. BSS indicates balanced salt solution; AV,
air valve; P, peristaltic pump; and W, waste disposal container. Tubing to
the right of the "case" is within the interior of the machine. B, The internal
tubing of the phacoemulsifier. S indicates pressure sensor; T, internal tubing;
F, filter; and V, air valve.
Postoperative endophthalmitis is a potentially devastating complication
of cataract surgery, with an incidence of 0.08% to 0.30%.1,2
Multiple P aeruginosa–related outbreaks of
postoperative endophthalmitis following cataract extraction are linked to
use of contaminated multidose vials or irrigating solutions and to an intrinsically
contaminated intraocular lens; recently, 2 European outbreaks were linked
to use of a contaminated phacoemulsifier.3,4
We demonstrated that all infecting strains of P aeruginosa were identical by pulsed-field gel electrophoresis. Patient 1's culture
did not yield P aeruginosa, but only the aqueous
humor was cultured. In patients with endophthalmitis, cultures of the aqueous
humor are less sensitive than cultures of the vitreous. We believe that the
additional organisms cultured from patient 3 represented contaminants.
We believe that the phacoemulsifier was the source of this outbreak.
All patients who underwent an operation on their right eye developed infection,
while all patients who underwent an operation on their left eye were uninfected.
The operating room was set up in such a way that the phacoemulsifier was placed
on the patient's right side. Thus, when the left eye was operated on, the
tubing for the phacoemulsifier was stretched more taut. This may have led
to gravity backflow of contaminated fluid during operations on the right eye
and might explain the significantly different infection rates between left
and right eyes.
Contamination of the internal tubing of 3 different models of phacoemulsifiers
that used a peristaltic pump was first demonstrated in 1986.5
Under certain vacuum settings, air was introduced into the aspiration catheter
from the machine, and during this venting process, previously sequestered
fluids in the machine could be regurgitated back into the aspiration catheter,
resulting in potential transmission of pathogens. de Kasper and colleagues6 investigated the contamination rates of automated
evacuation systems equipped with an internal vacuum control manifold compared
with a system equipped with a modified external vacuum control manifold that
was sterilized between patients; 2+ to 4+ bacterial growth was found in all
specimens from the internal vacuum control manifold system. They emphasized
that "the observed contamination of intraocular surgery machines is not related
to a specific company but must be attributed to the technical constituent
of an inbuilt and inaccessible internal vacuum control manifold that exists
in a wide variety of types of automated intraocular surgery machines of several
Using methylene blue, we demonstrated the possibility of retrograde
flow when the internal tubing was disconnected from the transducer. Although
the machine would not pass normal preoperative checks with this malfunction,
it seems plausible that a small leak might have a similar or intermittent
result, and the machine could still pass the check yet lead to retrograde
flow. This might occur with a leak at one of the fittings, a small defect
in the transducer, or an intermittently sticking air valve.
To our knowledge, this represents the third outbreak of postoperative
endophthalmitis due to P aeruginosa linked to use
of a contaminated phacoemulsifier and the first report from North America.
All manufacturer's recommendations regarding machine maintenance were followed.
These 3 outbreaks linked to a contaminated phacoemulsifier suggest that this
device may need to be redesigned to reduce the likelihood of contamination
or that additional disinfection methods may need to be routinely used.
None of the authors has any financial interest in the company that manufactured
the phacoemulsifier described in this article.
We thank Marlene Durand, MD, for reviewing the manuscript.
Corresponding author and reprints: David J. Weber, MD, MHA, MPH,
University of North Carolina at Chapel Hill, Campus Box 7030, Burnett-Womack,
Room 547, Chapel Hill, NC 27599-7030 (e-mail: firstname.lastname@example.org).
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1986;12158- 161Google ScholarCrossref
A Automated surgical equipment requires routine disinfection of vacuum
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