Direct isolation of Francisella spp. from environmental samples.
OBJECTIVE
To develop a selective medium for isolation of F. tularensis, F. novicida and F. philomiragia from environmental samples.


RESULTS
A selective media, cysteine heart agar with 9% chocolatized sheep blood, containing polymyxin B, amphotericin B, cyclohexamide, cefepime and vancomycin (CHAB-PACCV) was developed and evaluated for growth of Francisella spp. No differences were observed in recovered colony forming units (CFUs) for F. tularensis, F. novicida and F. philomiragia on CHAB-PACCV vs nonselective CHAB. Growth of non-Francisella species was inhibited on CHAB-PACCV. When environmental samples were cultured on CHAB and CHAB-PACCV, only CHAB-PACCV allowed isolation of Francisella spp. Three new Francisella strains were isolated directly from seawater and seaweed samples by culture on CHAB-PACCV.


CONCLUSIONS
CHAB-PACCV can be used for direct isolation of Francisella spp from environmental samples.


CONCLUSIONS
Francisella spp. show a close association with environmental sources. Future utilization of CHAB-PACCV for isolation of Francisella spp. directly from environmental samples should prove valuable for investigating outbreaks and human infections attributed to environmental exposure.
Petersen
J M
JM
Bacterial Diseases Branch, Division of Vector-Borne Infectious Diseases, National Center for Zoonotic, Vector-Borne and Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80522, USA. nzp0@cdc.gov
Carlson
J
J
Yockey
B
B
Pillai
S
S
Kuske
C
C
Garbalena
G
G
Pottumarthy
S
S
Chalcraft
L
L
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D003470:Culture Media / Q000032:analysis / Q000378:metabolism; D046508:Culture Techniques / Q000379:methods*; D004783:Environmental Microbiology; D005603:Francisella / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism; D010802:Phylogeny
D000900:Anti-Bacterial Agents; D003470:Culture Media