Identification of lysine positive non-fermenting gram negative bacilli (Stenotrophomonas maltophilia and Burkholderia cepacia complex).
BACKGROUND
The Burkholderia cepacia complex (BCC) and Stenotrophomonas maltophilia are closely related groups of non-fermenting gram-negative bacilli (NFGNBs) having a similar spectrum of infections ranging from superficial to deep-seated and disseminated infections. Identification of these lysine decarboxylase-positive NFGNBs lags behind in most Indian laboratories. A simplified identification scheme was devised for these two pathogens that allowed us to isolate them with an increasing frequency at our tertiary care institute.


METHODS
A simple five-tube conventional biochemical identification of these bacteria has been standardized. In the beginning, some of the isolates were confirmed from the International B. cepacia Working group, Belgium. Molecular identification and typing using recA polymerase chain reaction-restriction fragment length polymorphism was also standardized for BCC. For short-term preservation of BCC, an innovative method of preserving the bacteria in Robertson's cooked medium tubes kept in a domestic refrigerator was developed.


RESULTS
Thirty-nine isolates of BCC isolates were obtained from various specimens (30 from blood cultures) and 22 S. maltophilia (13 blood cultures and 9 respiratory isolates) were isolated during the year 2007 alone.


CONCLUSIONS
BCC and S. maltophilia can be identified with relative ease using a small battery of biochemical reactions. Use of simplified methods will allow greater recognition of their pathogenic potential and correct antimicrobials should be advised in other clinical laboratories and hospitals.
Gautam
V
V
Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India. r_vg@yahoo.co.uk
Ray
P
P
Vandamme
P
P
Chatterjee
S S
SS
Das
A
A
Sharma
K
K
Rana
S
S
Garg
R K
RK
Madhup
S K
SK
Mahajan
M
M
Sharma
M
M
D015373:Bacterial Typing Techniques / Q000379:methods* / Q000592:standards; D042602:Burkholderia cepacia complex / Q000302:isolation & purification* / Q000378:metabolism; D002262:Carboxy-Lyases / Q000378:metabolism*; D016172:DNA Fingerprinting / Q000379:methods / Q000592:standards; D004269:DNA, Bacterial / Q000235:genetics; D016905:Gram-Negative Bacterial Infections / Q000175:diagnosis* / Q000382:microbiology; D006801:Humans; D007194:India; D016133:Polymerase Chain Reaction / Q000379:methods / Q000592:standards; D012150:Polymorphism, Restriction Fragment Length; D011309:Preservation, Biological / Q000379:methods; D011938:Rec A Recombinases / Q000235:genetics; D020615:Stenotrophomonas maltophilia / Q000302:isolation & purification* / Q000378:metabolism
D004269:DNA, Bacterial; D011938:Rec A Recombinases; D002262:Carboxy-Lyases; C021520:lysine decarboxylase