protocol to enhance the staining of Campylobacter, Helicobacter,
and Brucella.
Perhaps the most frequently encountered fastidious bacteria
are the members of the HACEK group as the aetiological
agents for subacute bacterial endocarditis. As noted above, in
the vast majority of cases, these organisms are isolated with
standard blood culture techniques without the need for special
protocols or procedures. This is also generally true for Brucella
spp., Campylobacter spp., and Francisella spp., but is not true for
all fastidious bacteria.
Abiotrophia and Granulicatella are usually detected with
automated blood culture instruments, but do not grow well
on standard, unsupplemented solid media, as they require
pyridoxal or cysteine for growth. This can be accomplished by
co-cultivation with staphylococci, by the use of pyridoxalimpregnated
disks placed on the surface of standard blood agar
plates, or by the use of specially supplemented or enriched
media.
The yield of standard blood culture media for the cultivation
of Bartonella spp. is typically low. Special techniques, including
lysis centrifugation methods and/or serological investigations,
are thus indicated for the diagnosis of BSI caused by Bartonella
spp.
Legionella spp. require buffered charcoal yeast extract
(BCYE) for optimal growth. Recovery of Legionella can be
achieved by subculturing standard blood culture medium that
has been incubated according to the standard protocol for
5 days into BCYE, or by utilizing BCYE in conjunction with
lysis centrifugation methods. A detailed description of all of the
special techniques required for the culture of other rarely
encountered fastidious organisms (e.g. Helicobacter and Leptospira)
is beyond the scope of this review, and has been
provided elsewhere [12].