Blood Culture

Blood culture: many thought must be put in mind when designing or adopting a reliable method, such thought are

      The volume of the blood, it should be born in mind that high volume of blood faster high growth of colonies and therefore result in higher isolation rate of bacteria.

Air growth condition of the microorganism should be born in mind either the organism is aerobic or anaerobic microorganism.

The presence of natural bacterial in the blood and other some chemotherapeutic agent on this point the blood must need neutralization in case of bactericidal activity in the blood, sodium polyanethanol sulphonate (sps) should be used to neutralize the bactericidal in the blood, but care should be taken because when the substance is used more 0.0025% will resist the growth of the organism that may occur. The function to prevent the clothing of blood that may take place due to bactericidal agent. In terms of chemotherapeutic antibiotic that may be present in the blood due to chemotherapy. The neutralization of these antibiotic in the blood can be treated by adding antichemotherapeutic agent such as if penicillin is present then add penicillinase, in case of sulphamide p-amino obenzoic acid should be added e.t.c.

One of the major challenge faced in the laboratory is the contamination of the blood culture by either when collecting blood from the patient or apparatus used for culture contaminate the blood sample, at these point sterilization by disinfecting the point at which the blood is collected from patient body. Sterilization of inoculation size and the necessary apparatus need for the culturing.

The appropriate media should be employed for blood culture. E.g typtic soy broth or brain hart infusion  broth are widely considered for cultivation of aerobic organism, while fluid thioglycollate medium is sometimes recommended for anaerobic microorganism.

Diffusion ratio is one of the important of blood to media to be considered. A greater ratio more than 1:5 is considered to be more disadvantageous in blood culture.

Design of blood culture system: any apparatus design for blood culture must have a significant space in other to contain the media and the blood, and also permit adequate mixing of blood after collection. The cap of the culture bottle must have entry door which will make it easy for sterilization and cleaning and the container must be conducive for aerobic and anaerobic micro-organism cultivation and permit out flow of gas that may be generated by bacteria during cultivation of the bacteria. The easier blood culture system made up of a bottle of accurate culture medium with cap made up hole which permit the ejaculation of the blood. After the inoculation there are two ways of examining the organism, either by visual detection or subculture of the colony growth on the solid medium.

With advance research there was modification of the above explanation for detection of  bacteria. These modification was originated by a man called ‘casleneda’, he incorporated liquid and solid media into one bottle. The solid media was a slope of nutrient ager. Liquid is added to these media after the solidification has taken place. These was an alternative for subculture. The battle is bend to a slope side and liquid phase of growth is seen on the nutrient ager slope. The risk of contaminating these culture is directly reduced because there is no need to open the bottle for subculture.