Defining the Public Health Impact of Drug-Resistant Streptococcus
pneumoniae - Report of a Working Group
Appendix - Laboratory-Based Surveillance System
Appendix
Components and operation of the laboratory-based surveillance
system
Definitions
The proposed surveillance system is intended to monitor
only
invasive pneumococcal infections and their antimicrobial
susceptibility patterns. For this system, invasive
pneumococcal
infection refers only to meningitis and bacteremia
identified by
isolation of S. pneumoniae from cerebrospinal fluid (CSF)
or blood,
respectively. The system is not intended to monitor
isolates
obtained from respiratory secretions. Although information
from
respiratory isolates may be useful, the large number of
sputum
specimens routinely collected from patients who have
pneumonia
would likely overwhelm a surveillance system initially.
Addition of
surveillance for respiratory isolates might be considered
in the
future, depending upon ease of implementing surveillance,
available
resources, and expected utility. The following definitions
have
been approved by the Council of State and Territorial
Epidemiologists (CSTE) for drug-resistant Streptococcus
pneumoniae
(DRSP) surveillance:
Confirmed case
A confirmed case of invasive DRSP is defined as either
meningitis or bacteremia in which S. pneumoniae
cultured from
CSF or blood is identified as nonsusceptible (using
National
Committee for Clinical Laboratory Standards {NCCLS}
methods and
breakpoints) to antimicrobial drugs currently approved
for
treating pneumococcal infections.
When oxacillin disk screening is the only antimicrobial
susceptibility method used, the antimicrobial
susceptibility
profile cannot be definitely determined. For these
instances, a
probable case definition is needed.
Probable case
To obtain data from laboratories that perform only
oxacillin
screening, a probable case definition has been made. A
probable
case of invasive DRSP is defined as either meningitis
or
bacteremia in which S. pneumoniae cultured from CSF or
blood is
identified as nonsusceptible by oxacillin screening
(i.e., zone
size less than or equal to 19 mm) and no further
antimicrobial
susceptibility testing has been performed.
Reporting
Laboratories will be required to report probable or
confirmed cases
of DRSP to their state health departments in a line-listed
manner
to include the patient's date of birth or age, the anatomic
site of
specimen collection, the date of specimen collection, the
antimicrobial susceptibility pattern, and unique
identifiers for
the laboratory and the specimen. The patient's first and
last name
also will be required at the state level; however, CDC will
not
have personal identifiers. Measures will be taken to
protect
sensitive health information. Current reporting software
supports
the capability to encrypt names, allowing personal
identifiers to
be removed. Having the encrypted name along with laboratory
and
specimen identifiers allows duplicate reports to be
identified. To
reduce duplicate reporting of isolates from the same
episode of
clinical illness, isolates from the same patient will not
be added
to the surveillance database if the specimen submission
date is
within 10 days of a previous report.
To determine the incidence and prevalence of DRSP, the
total number
of invasive site isolates tested (i.e., denominator data)
must be
determined. Denominator data will be essential for
providing
relevant clinical information to physicians and other
health-care
providers (see Goal III, Objectives C and D). For
laboratories with
computerized data management, all invasive site isolates
can be
reported in the same manner as previously described.
Laboratories
unable to provide data easily in this manner should report
aggregate denominator data monthly; data would include the
total
number of invasive site isolates tested by age group (less
than 6
years of age, 6-17 years, and greater than or equal to 18
years of
age) and anatomic collection site (i.e., CSF or blood).
The data being collected for surveillance may be readily
available
from the computerized records of many laboratories. This
information may be imported from laboratory computer files
into a
currently available standardized database format, which may
be
either transmitted electronically or sent by mailed
diskette to the
state health departments and subsequently to CDC. Ideally,
computerized laboratories would be able to provide data
output in
Health Level Seven (HL7) standard format, or in a
compatible
standard format, for transmission to the state health
department,
where the data could be retrieved by compatible software.
HL7 is
being used increasingly as a standard for coding and
electronically
transmitting hospital and laboratory data, and its
continued use as
a standard should be encouraged by CDC, CSTE, and
Association of
State and Territorial Public Health Laboratory Directors
(ASTPHLD).
These HL7 standards and specifications should be made
readily
available to laboratory information systems (LIS) vendors
and large
national reference laboratories.
Initially, the system would be piloted in selected cities.
Ultimately, it is intended to be a comprehensive,
population-based
system for U.S. laboratories certified in accordance with
the
Clinical Laboratories Improvement Amendment (CLIA) of 1988,
including hospital laboratories, commercial laboratories,
and state
public health laboratories.
Data management and dissemination
Data will be stored in three locations: the laboratory data
repository, state health departments, and CDC.
State-specific
information regarding DRSP prevalence will be maintained at
the
respective state health departments and will be used to
provide
regular feedback of regional data to hospitals,
laboratories, and
clinicians (see Goal III, Objective C). Data merged from
multiple
laboratories will be periodically transmitted
electronically to
state health departments and CDC. These data will be
compiled to
determine DRSP prevalence data by state and to provide a
quarterly
national summary report (see Goal III, Objective D). State
health
departments will have the ability to restrict certain data
fields,
such as personal identifiers, before sending data to CDC.
The
quarterly results of the merged surveillance information
will be
published in journals accessible to laboratorians and
clinicians.
Data presented in a graphic format will reflect regional
variations
and temporal changes.
Phases of implementation
The surveillance system will be implemented in four phases:
pilot,
addition of laboratories in the pilot community, expansion to
other
laboratories, and nationwide laboratory participation.
Phase 1. Pilot study
Two laboratories in New Jersey (one in Camden County and
one in
Middlesex County) have been identified for participation.
These
counties are the site of a vaccine demonstration study
currently
being conducted with CDC assistance. Both laboratories
provide
services to large academic centers and have agreed to
participate
in the pilot phase of the implementation of the
surveillance
system. These and other laboratories in New Jersey have
been
participating in surveillance of methicillin-resistant
Staphylococcus aureus (MRSA), vancomycin-resistant
enterococcus
(VRE), and DRSP through a traditional surveillance
mechanism that
uses paper report forms. Implementing the pilot phase in
New Jersey
allows for introduction of electronic reporting in an
environment
where reporting is already required and familiar to
laboratories.
A review of the computer capabilities and laboratory
practices of
the two participating laboratories was performed in early
January
1995. Initial site visits were made to introduce the
hospitals to
the electronic surveillance system. During a trial period
after the
initiation of the pilot, data will be collected and
electronically
transmitted to the state health department. Software will
be
available at the state level for analysis and for
transmission to
CDC. After the data are transmitted to CDC at the end of
the first
month of collection, the system will be evaluated and
improved.
Phase 2. Addition of laboratories in the pilot community
In Phase 2, laboratories in the same counties as the two
pilot
laboratories will be added to the surveillance system.
Phase 2
should begin approximately 90 days after initiation of
Phase 1.
Laboratories will be evaluated for participation in the
following
manner:
Laboratory survey
Through a mailed questionnaire, laboratories in the
pilot area
will be surveyed to determine the methods used for
susceptibility testing of pneumococcal isolates and to
determine the level of computer capability in the
laboratory.
Assessment of laboratories
Laboratories capable of participation in the pilot
should meet
the following criteria:
Perform pneumococcal susceptibility testing by
using NCCLS
interpretive standards,
Enter and report laboratory data by using
computers,
Have a laboratory software package capable of being
translated to a database software through
downloaded ASCII
text, Health Level 7 standard format, or a
comparable
standard format,
Have a personal computer (at least a 386 processor)
with a
modem (greater than or equal to 2400 bps), capable
of
running PHLIS (Public Health Laboratory Information
System)
version 3.1, and
Have personnel available and willing to implement
the pilot
study.
Laboratories meeting the criteria will be involved in
Phase 2.
Those laboratories not yet capable of electronic
reporting will
be encouraged to enhance their present system to
participate in
later phases. In the two pilot sites, 19 laboratories
are
expected to participate.
Implementation and evaluation
Data from the participating laboratories will be
transmitted to
the state health department at least once a month. At
the end
of each 30-day period, the state health department will
transmit the data to CDC. The system will be evaluated
and
improved.
Phase 3. Expansion of surveillance to other laboratories
During Phase 3, laboratories in communities that have
ongoing
population-based pneumococcal studies will be enrolled.
These
studies may be CDC-sponsored emerging infections programs
or other
surveillance projects. Implementing surveillance in
communities
that have ongoing studies will enable comparisons to be
made
between the new, electronic, laboratory-based surveillance
and the
present standard for surveillance. Four to seven states are
expected to have communities participating. When the
surveillance
is established within those communities with ongoing
pneumococcal
studies, expansion to include all laboratories within the
state
will begin. Implementation of Phase 3 is expected by late
1996.
Phase 4. Nationwide laboratory participation
Laboratories will be added to the surveillance system, with
an
estimated participation of 70% of clinical laboratories
nationwide
by 1998. Expansion of the surveillance system to include
other
laboratory-reportable illnesses is expected. The system
proposed in
the strategy is intended to utilize software and data
transmission
standards to allow coordination with other systems for
reporting.
System attributes
The proposed surveillance system is intended to simplify data
reporting
by using information that is currently being collected in many
laboratories. The system is flexible because the software used
to
manage and transmit the data will be able to accommodate other
laboratory reportable diseases in the future. The system
facilitates
timely feedback to the laboratories and health departments
because
incidence of DRSP can be determined using the software both in
the
laboratory and in the health department.
IV. Utility
The surveillance system is intended to provide public health
officials,
clinicians, and health-care providers with data that can be
used to
prevent and control DRSP infections. In addition, the DRSP
surveillance
system is intended to be a model for the introduction of
electronic,
laboratory-based reporting of communicable diseases. Inherent
in the
implementation and maintenance of the surveillance system is
the
ability to change the components or the focus of surveillance
to
respond to results of new studies and emerging problems. Given
the
dynamic nature of DRSP, predicting the rate at which resistance
to
antimicrobial drugs will increase communitywide and nationwide
is
difficult. Surveillance may be scaled back and performed at
selected
sites when geographic and temporal variations in DRSP incidence
are no
longer apparent.
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