The culture of organisms direct from the blood
stream can be a useful diagnostic aid; however, it does require meticulous aseptic sampling techniques and usually large volumes
of broth into which the sampled blood is placed, which can be difficult in the field and for transportation to your laboratory.
Most anticoagulants are bacteriostatic or bactericidal to at least some bacteria. For this reason and for easy safe transportation
PALS recommend the use of OXOID 1.5 isolator tubes.
Bacterial invasion of the blood stream can occur by three main routes:
Bacteraemia This can occur commonly and can be of no clinical
significance such as during dental extractions, but can go on to form more serious conditions such as Bacterial endocarditis.
It can also be an integral part of some infectious processes such as typhoid fever. Bacteraemia is characterised by few organisms
which can be killed by the hosts own defence mechanisms or with minimal prophylactic cover. Bacteraemia is a common finding
in reptilian patients.
Septicaemia This is a rapid overwhelming infection which
without antibiotic treatment results in death. It is usually one of three types: a) PRIMARY – usually caused by extremely virulent organisms e.g.
Coliforms b) SHOCK COMPLICATIONS – either from invasive
injuries or any trauma/surgery which involves any part of the alimentary tract.
c) IMMUNOSUPPRESSION –
this occurs during medical treatment such as chemotherapy where immune mechanisms are disturbed and opportunistic infections
may result.
Pyaemia Pyaemia is a serious condition characterised
by severe toxaemia. Organisms escape into the blood stream in the form of small aggregates known as micro-emboli. This results
in either Pyaemic abscesses or septic infarction possibly following on from Bacterial endocarditis.
Specimen Collection ISOLATOR 1.5 tubes are intended for the collection
of small volume 1.5mls of blood and to be used specifically for the isolation of micro organisms. The tube contains agents
which lyse white and red blood cells and block coagulation releasing free organisms and should be kept at room temperature.
On reaching the laboratory they are cultured on to routine agars.
We would advise taking three
samples over hourly periods and the clinical significance of any micro organisms isolated should be determined by a veterinarian
taking in to account the patients history, clinical status, repetition of cultures and any other pertinent laboratory findings,
such as an elevated granulocyte count. Toxic activity or bacteria being engulfed by the leucocytes add further weight to the
diagnosis of septicaemia.
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