Washing sputum serves to get rid of saliva and unwanted mucus and other
rubbish you do not want to culture.
Transfer sputum to petri dish.
Pour some saline in two other petridishes.
Pick pus-like bits from the sputum, using inoculating loop or needle (some
people use what's called a "prepareernaald", literally "preparation
needle", can cut tough bits).
Transfer this into first saline dish en move it gently through the saline,
sometimes a bit harder, using the loop or needle. The lid of the dish is
used as a fake safety-shield. A safety cabinet should be used. But
near-sighted people always bang their heads if they want to check what they
Transfer to second saline dish and repeat.
Some labs make a wet slide with coverslip to check for the presence of
large epithelial cells. If present, a new part of the sample is tried.
Clever boys and girls don't need to go through that trouble, they choose
the good bits.
Small bits of washed sputum are plated and smeared on slide for Gram.
It is the normal procedure in Holland for processing sputum (not for
Anaerobic cultures for the reasons you mentioned.
A personal experience: I have had episodes of pneumococcal sinusitis myself
(not work-related!!). In the Gram beautiful cocci, perfectly shaped, large
capsule?? how do you call it?. Enough to expect the plates dripping with
mucoid colonies next day. No way. Tiny green specks, not even looking like
pneumococci (would miss them in sputum). But the anaerobic plate !!!!! No
drips, but the best school example for a fresh Pneumococcus.
> How does someone "wash" sputum? I've never heard of this or done this
> (has mental picture of scrubbing, hanging out to dry, etc., :-) :-) -
> sorry couldn't resist). Do you plate sputum specimens anaerobically to
> enhance the growth of the S. pneumo? One of my previous employers used
> to put the CNA plate anaerobically for the first 24 hours to make the
> mucoid strains more obvious.
>> Judy Dilworth, M.T. (ASCP)
>> lamb wrote:
>> > ............. We wash purulent bits of sputum in saline to remove
> > saliva etc. and then culture aerobically and anaerobically.
> > Loes