Question

A client has a severe bacterial infection. Which of the following would be expected on the client's complete blood count \((\mathrm{CBC})\) with differential? a. WBC 8,500 , lymphocytes \(45 \%\) b. WBC 15,000 , segmented neutrophils \(50 \%\) c. WBC 25,000 , band neutrophils \(20 \%\) d. WBC 20,000 , segmented neutrophils \(58 \%\)

Short answer

The expected CBC with differential for a client with a severe bacterial infection would be (c) WBC 25,000, band neutrophils 20%, indicating a severe immune response with the presence of immature neutrophils.

Step-by-step solution

Understand the context of the problem

A severe bacterial infection typically causes the body to respond by increasing the production of certain types of white blood cells (WBC), particularly neutrophils. The total white blood cell count usually elevates beyond the normal range (4,500 to 11,000 WBCs per microliter of blood), and a shift in the distribution of white blood cell types is often seen, with an increase in the proportion of neutrophils.

Review the CBC results

Analyze the provided complete blood count (CBC) results to determine which one indicates an elevated white blood cell count and a proportionally high percentage of a type of neutrophil. A significant elevation in WBC count and an increase in neutrophils (either segmented or band) is suggestive of an acute bacterial infection response.

Identify the abnormal CBC result consistent with a severe bacterial infection

Compare the given options and identify which one reflects both an elevated white blood cell count and an increased proportion of neutrophils. Band neutrophils are immature neutrophils that are released into the bloodstream when there is a significant infection. An elevated band count (known as bandemia) can indicate a severe infection and a demand for new neutrophils that is higher than the supply of mature cells.

Select the answer

From the provided options, select the one that corresponds to the expected changes in the CBC with differential during a severe bacterial infection, taking into account both total WBC count and the percentage of neutrophils.

Key concepts

Complete Blood Count (CBC)

A Complete Blood Count (CBC) is a common blood test that helps detect a wide range of disorders, including infections, anemia, and other diseases. It provides a snapshot of one's overall health and offers critical information about the various cells present in someone's blood. The CBC measures several components, including white blood cells (WBC), red blood cells (RBC), hemoglobin (Hb), hematocrit (Hct), and platelets.

In the context of an infection, attention is often focused on the white blood cell count. An increased WBC count can indicate that the body is fighting an infection or is under stress. By performing a differential alongside the CBC, healthcare providers can delve deeper to understand the specific types of white blood cells involved and their relative proportions. This can help pinpoint the nature of the infection—whether bacterial, viral, or another cause—and guide appropriate treatment.

White Blood Cells (WBC)

White blood cells, also known as leukocytes, serve as the body's primary immune defense against infections. They are formed in the bone marrow and circulate in the bloodstream and lymphatic system. There are several types of WBCs, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each type has a particular function in the body's immune response.

When an infection is present, the body typically increases the production of WBCs to fight off the invading pathogens. The total WBC count is a key indicator of immune activity, with ranges typically between 4,500 and 11,000 WBCs per microliter of blood. A count above the normal range can suggest an ongoing fight against an infection, while counts outside this range in either direction may indicate a host of potential health concerns that require further investigation.

Neutrophils

Neutrophils are the most abundant type of white blood cells and are one of the body's first lines of defense against infection. They target and destroy bacteria and fungi that invade the body. Neutrophils are a key component of the pus that forms at an infection site and are often responsible for the initial phase of inflammation.

There are two types of neutrophils that are important in diagnosing infections: segmented neutrophils (also known as segs or polymorphonuclear leukocytes) and band neutrophils. Segmented neutrophils are mature white blood cells, ready to fight infections, while band neutrophils are immature cells. The presence of a high number of band forms, a condition known as 'left shift' or 'bandemia,' may indicate that the body is producing an increased number of neutrophils to combat a severe infection.

Bacterial Infection

Bacterial infections occur when harmful bacteria enter the body and start multiplying, potentially leading to illness. The body responds to this threat by increasing the production and deployment of white blood cells to the affected area. Symptoms of a bacterial infection can vary widely depending on the location and severity of the infection but often include fever, inflammation, and fatigue.

In the context of a CBC, an elevated white blood cell count, especially an increase in neutrophils, is a strong indicator of a bacterial infection. Increased numbers of band neutrophils usually signify a particularly acute bacterial infection where the demand for neutrophils has risen so significantly that the bone marrow begins to release immature cells into the bloodstream. Medical intervention with antibiotics is typically required to control and eliminate bacterial infections.