Blood cultures: Nursing

A 70-year-old male client arrives at the emergency department after his wife noticed he developed a fever; fatigue; and a productive cough that have been worsening over the past few days. His medical history is significant for chronic obstructive pulmonary disease, or COPD; and on physical assessment, he has warm, flushed skin, tachypnea, and crackles in the lung bases. The healthcare provider suspects bacteremia secondary to pneumonia, so a blood culture is ordered. Okay, so normally blood is considered sterile, meaning in a healthy state, there are no pathogens floating around. Our bodies have various defenses in place to maintain this healthy state like the skin, which acts as a protective barrier; the mucociliary escalator in the bronchi, which moves mucus and pathogens up and away from the lungs; epithelial cells that line the urinary tract, which are highly impermeable to pathogens; and of course the immune system, which fights pathogens and removes them from the body.

Now, sometimes a pathogen is able to gain access to the blood if our defensive mechanisms are compromised, like with breaks in the skin, inefficient mucociliary clearance, or when urinary tract epithelial cells are outnumbered by pathogens. Pathogens can also enter the blood if a client is immunosuppressed, like in HIV or cancer. All right, so blood culture is obtained to detect the presence of pathogens, like bacteria or fungi, in the blood when there’s a history of conditions that can predispose a person to an infection; when there are signs and symptoms of infection like leukocytosis, fever, or chills; or if a client has a known infection, like pneumonia, cellulitis, or a urinary tract infection. The blood culture results are reported by the lab as the amount of growth after a specific number of days. A positive blood culture is an indication of bacteremia or septicemia.

All right, let’s look at the nursing care you’ll provide for a client with suspected bacteremia. Priorities of nursing care are to assist in identifying and treating the underlying cause. First, prior to administering any antimicrobials, draw blood cultures using strict aseptic technique to reduce contamination of the samples. Obtain venous blood from two different sites using an aerobic and anaerobic media culture at each site. Keep in mind that obtaining samples from two different sites is essential, because if one sample grows bacteria but the other one doesn’t, it’s likely that the bacteria in the first culture is from a contaminant, like bacteria from the skin, and not the infecting organism. However, when both cultures grow the infecting organism, this indicates that the client has bacteremia caused by the organism growing in the culture.