DIRECTOR: Mary Jane Ferraro, Ph.D., M.P.H. x6-3612
CO-DIRECTOR: Eric Rosenberg, M.D. x4-7519
ASSOCIATE DIRECTOR: John Branda, M.D. x6-3611
The Microbiology Laboratories are divided into Bacteriology, Susceptibility
Testing, Mycology, Mycobacteriology, Parasitology, Virology, Serology,
and Molecular Diagnostics. Specimens are accepted for accessioning and
processing for all divisions 24 hours/day.
Hours of Full Service Operation
24 hours for accessioning and processing of specimens.
Anaerobes, Molecular Diagnostics, Mycology, Mycobacteriology,
Parasitology, Serology, and Virology
For information or special test requests call x6-3613 during the above
hours. For after-hour emergency assistance call the Clinical Pathology
Resident for Microbiology (beeper #2-1826).
Specimens submitted to the Microbiology Laboratories must be labeled
with patient’s name and unit number and bagged according to Infection
Control Standard Precaution protocols. The requisition should be firmly
attached to the outside of the specimen transport bag and be filled in
with the following information:
1. Patient Name
2. Patient Unit Number
3. Patient Location (i.e., in-house, clinic or physician to whom report
is to be sent if private patient).
4. Telephone extension of ordering care unit or physician.
5. Type or source (anatomic site) of specimen.
6. Type of culture requested (i.e. routine, fungal, TB, viral, etc.)
7. Ordering Physician
8. Diagnosis and/or specific organism sought.
9. Date and time of collection.
10. Specific organism sought.
Because they may contain viable micro-organisms, specimens should be
delivered to the laboratory as soon as possible after collection. Specimens
are accepted for all divisions 24 hours.
Ambulatory patients requiring specimens for parasite examination should
be directed to the Ambulatory Lab #2 in the Wang Ambulatory Care Center
(WACC), 2nd Level for specimen collection instructions and assistance.
Fresh stool specimens for O&P arriving in laboratory after 4 p.m.
will be preserved for processing the next working day.
Respiratory specimens from cystic fibrosis patients (including post-transplant
patients) must be labeled "CF" to receive appropriate specimen
processing and workup.
Criteria for Refusal of Specimens
For the purpose of providing useful diagnostic testing, the Microbiology
laboratories consider it an obligation to refuse specimens under the following
1. Patient's name and unit number are not provided.
2. Name on specimen differs from that on the requisition.
3. Specimen type is not that indicated on the requisition.
4. Specimen is one or more days old.
5. Specimen type is not indicated.
6. Test requested is not available in the Microbiology Lab.
7. Quantity is not sufficient.
8. Quality of specimen is questionable.
9. Improperly sealed or leaking container.
10. Specimen is received in fixative or in improper fixative
11. Time or date of collection is not indicated.
12. Excessive delay in receiving specimen for anaerobic culture.
13. Method of collection is not acceptable for anaerobic culture and
14. Stool specimens from patients hospitalized >3 days.
15. Whole blood specimens for molecular diagnostics testing received
>6 hours after collection.
Specimens that have been refused are held in the laboratory for 48 hours
and will be processed only after consultation with the laboratory supervisory
personnel by the requesting physician. Specimens which are unacceptable
for any of the above reasons, which have been collected by invasive procedures,
or which might necessitate recalling an outpatient for recollection will
usually be processed with a notation on the report indicating why the
specimen is unacceptable. Interpret results of such cultures carefully.
Preliminary and final times listed for individual cultures indicate the
earliest times for availability of results. Positive cultures may require
additional time for identification or susceptibility testing of isolates.
The lab will call results to the requesting area in accordance with the
MGH Critical Values Policy
NOTES ON MICROBIOLOGY
LABORATORY RESULTS (December 2009)
1. PRELIMINARY RESULTS – All culture results are preliminary unless
marked “FINAL.” Preliminary results may be changed, modified,
deleted, or augmented after further observation, incubation, or testing
2. ROUTINE CULTURES AND “NORMAL FLORA”:
3. ANTIMICROBIAL SUSCEPTIBILITY TESTING
Susceptibility testing of aerobic pathogens is performed by either the
Kirby-Bauer disk diffusion method or an automated, rapid system (Vitek
AMS), depending upon identification of the organism and reliability of
the applicable methods. Anaerobic susceptibility testing is available
after consultation with the laboratory. Results of susceptibility testing
are interpreted into 3 categories (Susceptible, Intermediate, Resistant),
using standardized criteria. The intermediate category for a drug indicates
an equivocal result and this drug should generally not be relied on for
single agent therapy except perhaps of urinary tract infections. Certain
organisms are screened for beta-lactamase production before susceptibility
results are reported.