LABORATORY SERVICES AT THE COMMUNICABLE DISEASE CENTER

There are certain limitations to the availability of the laboratory services at the Communicable Disease Center. These laboratories act only as a national reference or consultative facility and accept specimens only from the State public health laboratories. Acceptance of diagnostic specimens from private individuals or institutions is not authorized. Specimens which cannot be examined locally should be sent to the State laboratory where they may be processed or, if the requested service is not available at the State level, the State laboratory director may then forward either the original specimen or the pure culture from it to the Communicable Disease Center. However, certain services available at CDC are of value in epidemic situations only and submission of single cultures from isolated cases would serve no useful purpose. Requests for serotyping of Group A streptococci and phage typing of salmonella, shigella or staphylococci from such cases serve to illustrate the point.

The volume of specimens submitted for virological examination has increased to the point where it is impossible for CDC to examine routine specimens and, at the same time, provide the support needed for development of virological facilities within the State laboratories and assist the States in the solution of their epidemiologic problems. Since assistance to the States in the above matters is of major importance and a basic responsibility of CDC, the resources of CDC virology laboratories must be directed to these ends. In the future the Laboratory Branch will limit its acceptance to specimens having epidemiologic implications.

Because virology is still a rapidly developing science, diagnostic problems may occasionally arise which will require assistance from the CDC laboratories even though the case has no immediate clear-cut epidemiological implication. In such instances, the State laboratory director should consult with the Chief of the Virus Reference Unit at the Communicable Disease Center.

From the viewpoint of the practicing physician, this policy should work no hardship as most virologic diagnosis is retrospective and of little or no value in the treatment of the individual patient.

I. PROCEDURE FOR COLLECTION, PREPARATION, AND SHIPMENT OF DIAGNOSTIC SPECIMENS

A. General Instructions

1. Basic Principles

There are certain basic principles involved in obtaining and submitting diagnostic specimens which must not be violated without compelling reasons.

a.

b.

Specimens submitted for isolation and identification of the etiologic agent.

(1) Obtain specimens as early as possible in the illness

(2) Preserve viability of suspected viruses and rickettsiae by storage and shipment in dry

ice

(3) Ship pure cultures of aerobic bacteria or
fungi as non-refrigerated agar cultures

(4) Submit anaerobes as stab cultures

Specimens submitted for serological examination
(1) Collect blood and serum samples in sterile
tubes and maintain sterility in handling

(2) With a few exceptions, paired specimens are
desirable in all instances and mandatory in
suspected viral infections. Since a rise in
antibody titer is a more reliable diagnostic
sign than the mere presence of antibodies, the
first specimen should be collected as early
after onset as possible and the second, two
or three weeks later.

(3)

Do not permit whole blood to freeze under any circumstances

2. Infectious Diagnostic Specimens

Rapid transport of infectious diagnostic specimens is of vital importance in communicable disease control. Fortunately, there are no regulations in effect which might hamper such movement providing the rigid Postal Regulations which pertain to the preparation of the specimen for shipment are met.

The Communicable Disease Center defines infectious
diagnostic specimens as:

a. All specimens of human or animal excreta, secreta,
tissue, tissue fluids, or hair which contain or
are suspected of containing the live causative
agent of a human disease or an animal disease
transmissible to man, and which are shipped or
mailed to a diagnostic or research laboratory
for isolation and identification of the etiological
agent.

Pure cultures or concentrated isolates or
vectors of etiological agents shipped from
the isolating or collecting laboratory to
a specialty laboratory for identification
and typing, or further research, or both.

Pure cultures of known etiological agents
which are used as reference cultures or as
antigens in diagnostic laboratory procedures.

Identification of Specimens

a.

b.

Identify individual specimen tubes or con-
tainers by encircling them with typed or
pencilled legends on adhesive tape. Give
patient's name, type of specimen, and date
of collection. This is particularly impor-
tant with clear fluids and paired sera. Ink,
ball-point pen, wax, or indelible pencil should
not be used because they become illegible.

A legible copy of a list of the specimens giving identifying name or number, date obtained, and tests desired should be included with the shipment.

4. Packaging of Specimens

Good packaging not only protects the specimen in
transit but the personnel handling it in case of
breakage.

a.

NEVER MAIL INFECTIOUS SPECIMENS IN PETRI PLATES.

b. NEVER ENCLOSE DRY ICE IN HERMETICALLY SEALED
CONTAINERS.

A safe packaging procedure which complies with
Public Health Service Regulations and the require-
ments of the Universal Postal Union is as follows:

a.

b.

Enclose the specimen in a bottle or tube of
thick glass sealed with a rubber or paraffin-
treated corkage. Bottles are preferred because
of greater shock resistance but heavy-walled
tubes are acceptable if properly packed. Closure
by fusion is also acceptable.

Place the glass container in an air- and water-
tight tin, using vermiculite, sawdust, or other
suitable material for insulation.

Pack the can in a cardboard container with
crumpled newspaper or other shock-resisting
insulating material and wrap for shipment.

Individual tubes must be shipped in containers
providing sufficient space for shock-absorbing
material all around the tube. If several
tubes are packed in the same can, they must
be individually wrapped in soft paper or cloth
to provide adequate cushioning between the
tubes.

Screw-cap tubes are not recommended because leakage frequently occurs, particularly when outside pressure decreases during air transportation.

Bottles recommended for specimens are hard glass serum bottles of two ml. or larger capacity.

When screw-capped jars are used for shipping
larger specimens, it must be ascertained that
the resilient cap lining permits air- and
fluid-tight closure and the corkage or cap is
secured in place with a metal collar or adhesive
tape. Gas-forming cultures of yeast are an
exception to this rule.

Useful tin cans for shipment of bottles or multiple specimens are either regular #3 household cans or pressure-sealed paint cans. The former are sealed by roll crimping the lid, using a home-canning device for this purpose. The latter have the advantage of not requiring a crimping device. The larger size paint cans are practical for large quantity shipments and may be used as outer containers as required by the Convention of The Universal Postal Union.

Shipment of Specimens

a. Mark shipments "Perishable," "Packed in dry ice,' "Refrigerated biologic materials," "Fragile," or with some other suitable designation. Standard labels should be used if availabe.

b.

For long distances, ship all specimens by air mail or air express. Air freight should not be used when speed of transport is essential. If possible, determine that the shipment is given priority over nonperishable items.

B.

6.

c.

d.

e.

Avoid delay by addressing shipments to the
laboratory unit involved, e.g., "Virus Reference
Unit," "Enteric Bacteriology Unit," etc.

Shipment of specimens should be timed so they
will not arrive at the laboratory on or just
before a weekend or holiday, to avoid possible
deterioration.

In some localities, surface mail or express may
be faster than air transport; but in any case,
the most rapid method should be used.

to all shippers of diagnostic materials whether poten-
tially pathogenic or not. In fact, it is most important
in the latter case since in-transit damage to laboratory
specimens has involved blood for serologic tests or
urine for chemical examination - free of pathogenic
organisms. Thus, if spillage occurs so as to injure
or damage mail, equipment, or personnel, the shipper
may face prosecution even though there be no question
of hazard from an infectious agent. The value of
meticulous packaging with sufficient absorbing material
around the specimen to absorb any leaking fluid extends
well beyond the major concern of preventing accidental
infection.

Bacteriological, Mycological, and Parasitological Specimens

For the purpose of this Manual, the significant difference
between primary specimens and already cultured bacteria and
fungi is that primary specimens are usually shipped intrastate
only, whereas most shipments to CDC or other out-of-State
reference laboratories consist of pure cultures. The same
general rules and principles covering handling and shipment
of pure cultures also apply to specimens obtained from the
patient.

1. Bacterial Specimens

Agar slant or stab cultures, using freshly prepared
media free of excess moisture, are most practical.
Stab cultures for anaerobes are best. If the bacteria
have low shipping tolerance (such as Neisseria), fresh
and relatively heavy growths either on blood agar or
semisolid cystine-trypticase-soy agar should be forwarded.
The semisolid agar must not be so soft that it will "run"