S. Condon and C. C. Ginocchio. North Shore – LIJ Health System Laboratories, Lake Success, NY.
INTRODUCTION AND AIMS OF THE STUDY
Successful laboratory diagnosis of bacterial infections depends on key factors such as
specimen selection, collection and the rapid transport of the specimen to the
laboratory. In general, it is not recommended to store specimens for bacterial culture
for more than 24 hours. Swabs collected from sources suspected of containing
environmental sensitive organisms such as Neisseria gonorrhoeae and Streptococcus
pneumoniae should never be refrigerated.
The use of the most appropriate specimen transport device is critical for the preservation,
isolation and recovery of fastidious, pathogenic bacteria.
This quantitative study compared the performance of two culture transport systems, the
Copan Transystem Swab (TS) and the Copan ESwab (ES) (Copan Diagnostics, Inc.,
Corona, CA). The Copan Transystem Swab contains a polyurethane foam sponge
that is soaked with a liquid transport media such as Stuarts. The ESwab is a new
unique nylon flocked swab with a 1 ml vial of liquid Amies media.
RESULTS: Figures 3-6:
100
Figure 1: TranSwab (TS)
Figure 2: ESwab
60
TS-RT
40
ES-4C
20
ES-RT
% Recovery
120
Haemophilus influenzae
100
TS-4C
80
TS-RT
60
ES-4C
40
RT-48
40C-24
40C-48
N. gonorrhoeae
6.6
0
1.6
0
H. influenzae
59.0
15.9
71.2
24.9
S. pyogenes
88.5
34.4
84.0
68.6
S. pneumoniae
21.7
1.4
121.1
62.2
RESULTS: Table 2: ESwab Results (% Recovery)
RT-24
RT-48
40C-24
40C-48
N. gonorrhoeae
13.8
0
87.5
9.0
H. influenzae
101.1
60.2
61.3
50.8
S. pyogenes
90.8
72.5
70.7
69.2
S. pneumoniae
90.8
72.5
70.7
69.2
CONCLUSIONS
ES-RT
I. The ES showed better recovery of: H. influenzae at RT-24, RT-48 and 4oC-48;
S. pyogenes at RT-48; S. pneumoniae at RT-24, RT-48, compared to the TS.
0
24 hr
100
RT-24
Transwab
ESwab
48 hr
20
% Recovery
II. Specimen preparation:
I. A saline suspension of each sample was made equivalent to a 0.5 McFarland
standard (108 cfu/ml).
II. Four 10-fold dilutions were made using 2.5 ml test suspension added to 22.5
ml saline.
III. The final working concentrations (104, 105, 106 cfu/ml) were used to inoculate
the TS and the ES swabs by applying 100 μl of each dilution to the swabs and
letting the swabs absorb the liquid for 10 seconds.
IV. TS and ES swabs were placed at the appropriate temperatures (RT, 4oC) and
then plated at specified time intervals (0, 24, 48 hr).
V. The TS swabs were inoculated directly onto appropriate media by streaking the
swabs over the entire agar surface, rotating the swabs to ensure that all
surfaces of the swabs equally contact the surface of the media. The ES swabs,
in liquid transport media, were vortexed for 20 seconds. A 100 μl aliquot of the
suspension was removed using a pipette and was dispensed onto the surface
of the agar. A sterile spreader was used to uniformly spread the inoculum over
the agar surface.
VI. Both TS and ES swab systems were tested in triplicate.
VII.Plates were incubated at 35OC CO2 environment for all organisms.
VIII.Results were calculated by taking an average of the colony counts from
triplicate tests.
TS-4C
80
24 hr
48 hr
II. TS was slightly better for the recovery of S. pneumoniae, S. pyogenes and H.
influenzae at 4oC-24.
Streptococcus pneumoniae
TS-4C
80
60
TS-RT
40
ES-4C
20
ES-RT
III. At 4oC-24, ES was significantly better and at RT-24 slightly better for the
recovery of N. gonorrhoeae than TS. There was no recovery of N.
gonorrhoeae with either TS or ES at RT-48, although there was marginal
recovery with ES at 4OC-48.
IV. Results for S. pyogenes RT-24 and 4oC-48, S. pneumoniae 4oC-48 were
comparable for TS and ES.
V. In conclusion, the ES system was able to maintain overall higher levels of
growth than the TS system.
VI. The ESwab can also be used for gram stains and for other testing platforms.
0
24 hr
140
REFERENCES
48hr
Streptococcus pyogenes
TS-4C
120
% Recovery
I. Samples tested included:
I. Organisms: Neisseria gonorrhoeae ATCC 43069, Streptococcus pneumoniae
ATCC 6305, Streptococcus pyogenes ATCC 19615 and Haemophilus
influenzae ATCC 10211.
N eisseria gonorrhoeae
0
This study:
1. Evaluated four fastidious aerobic bacteria, Streptococcus pneumoniae, Haemphilus
influenzae, Neisseria gonorrhoeae and Streptococcus pyogenes, for viability by
comparing two different swab transport systems held at different temperatures (4O C,
room temperature [RT]) and for different time intervals (24 hr, 48 hr).
2. Determined the quantitative colony counts at each time interval and temperature.
MATERIALS AND METHODS
RESULTS: Table 1: Transwab Results (% Recovery)
The mean number of bacteria recovered per time point and temperature were
expressed as a % of the mean number of bacteria recovered at time 0. The results
for TS versus ES were as follow for temperature and time.
% Recovery
ASM 2007
C-363
Comparison of the Copan Transystem Swab and the Copan ESwab for the Preservation
and Recovery of Fastidious Bacteria
100
TS-RT
80
60
ES-4C
40
ES-RT
20
I. Miller, J.M.C., 1999. Specimen Management in Clinical Microbiology Samples.
ASM Press. .pg 9-11.
II. Isenberg, H., Schoenknecht, F., von Graevenitz, A. 1979. Cumitech 9. Collection
and Processing of Bacteriological Specimens. ASM Press. pg.1-6.
III. Hindiyeh,M., Accevedo, V., Carroll, K. 2001. Comparison of Three Transport
Systems (Starplex Star Swab II , the New Copan VI-Pak Amies Agar Gel Collection
and Transport Swabs, and BBL Port- A- Cul) for Maintenance of Anaerobic and
Fastidious Aerobic Organisms. JCM 39:377-380.
ACKNOWLEDGEMENT
Copan Diagnostics, Inc., Corona, CA for supplying swabs for this study.
0
24 hr
48 hr