Once in the Lab...
The blood culture bottles have arrived safely (see earlier blog) and are loaded on an automated incubator, which uses that barcode you now know not to peel off! How long it takes to signal positive depends on the type of organism, some take longer than others. Routinely negative blood cultures are destroyed after 5 days. That is really unhelpful if your patient has a slow growing microorganism or possible infective endocarditis. Did you write those details on the request form? If you did then the blood cultures will be incubated for up to 14 days.

The clinical details also help the laboratory decide how to safety process the blood cultures after they have signalled positive. So if you forgot to add the possibility of a high risk specimen e.g. typhoid or paratyphoid, you risk exposing the biomedical scientist handling the positive culture to a potential pathogen...blood-borne viruses, tuberculosis, shigellosis, salmonellosis, E.coli O157, Neisseria meningitidis, brucellosis, etc. Surely, being too busy to add these clinical details is negligent to your colleagues in the laboratory?

Bacteria like to colonise warm moist sites with poor blood supply and hence a poor immune response. They especially like broken areas of skin such as ulcers and lacerations.

Broken areas of skin are not sterile. Wounds should be colonised with relatively harmless bacteria like the Coagulase-negative Staphylococci, Coryneform bacteria (Diptheroids) and Propionibacterium spp. This normal process prevents more dangerous bacteria from getting in and causing infections such as Staphylococcus aureus and the Beta-haemolytic Streptococci. It is therefore really important that we only treat breaks in the skin when infections have occurred, rather than trying to prevent them occurring.

Anyone listening to the radio or watching television this week will be aware that it is National Meningitis Awareness Week. The aim of this is to highlight the risks to health posed by meningitis, and the symptoms and signs of the disease. 
 
The Meningitis Research Foundation provides excellent material for both patients and healthcare professionals about meningitis and I would recommend you look at their website http://www.meningitis.organd the test yourself case histories in the document “doctor’s in training” http://www.meningitis.org/assets/x/50156. The earlier meningitis is diagnosed and treated the better the outcome, so Meningitis Awareness Week is definitely a good thing BUT should meningitis really be compared to meningococcal sepsis?! 

At the beginning of a recent medical student teaching session I was asked by a student why he should bother learning normal flora because what he really needed
to know was what causes infections. This is a particularly common and understandable approach from students but misses the significance of the most fundamental principle of microbiology or in fact medicine. If you do not know what is normal, how do you recognise abnormal? I smile inwardly and count to ten before going on to explain the importance of this often overlooked bit of knowledge.