Which of the following is most often recommended to prevent infection for a patient with neutropenia?

Neutropenia caused by intrinsic defects in myeloid cells or their precursors is uncommon, but when present, the most common causes include

• Chronic idiopathic neutropenia

• Congenital neutropenia

Chronic benign neutropenia is a type of chronic idiopathic neutropenia in which the rest of the immune system appears to remain intact; even with neutrophil counts < 200/mcL (< 0.2 × 109/L), serious infections usually do not occur, probably because neutrophils are sometimes produced in adequate quantities in response to infection. It is more common in women.

Severe congenital neutropenia (SCN, or Kostmann syndrome) is a heterogenous group of rare disorders that are characterized by an arrest in myeloid maturation at the promyelocyte stage in the bone marrow, resulting in an absolute neutrophil count of < 200/mcL and significant infections starting in infancy. SCN can be autosomal dominant or recessive, X-linked, or sporadic. Several genetic abnormalities that cause SCN have been identified, including mutations affecting neutrophil elastase (ELANE/ELA2), HAX1, GFI1, and the G-CSF (granulocyte colony-stimulating factor) receptor (CSF3R). Most patients with SCN will respond to chronic growth factor therapy, but hematopoietic stem cell transplantation Hematopoietic Stem Cell Transplantation Hematopoietic stem cell (HSC) transplantation is a rapidly evolving technique that offers a potential cure for hematologic cancers ( leukemias, lymphomas, myeloma) and other hematologic disorders... read more may need to be considered for poor responders. SCN patients have an increased risk of developing myelodysplasia Myelodysplastic Syndrome (MDS) The myelodysplastic syndrome (MDS) is group of clonal hematopoietic stem cell disorders typified by peripheral cytopenia, dysplastic hematopoietic progenitors, a hypercellular or hypocellular... read more or acute myeloid leukemia Acute Myeloid Leukemia (AML) In acute myeloid leukemia (AML), malignant transformation and uncontrolled proliferation of an abnormally differentiated, long-lived myeloid progenitor cell results in high circulating numbers... read more

Cyclic neutropenia is a rare congenital granulocytopoietic disorder, usually transmitted in an autosomal dominant fashion and usually caused by a mutation in the gene for neutrophil elastase (ELANE/ELA2), resulting in abnormal apoptosis. It is characterized by regular, periodic oscillations in the number of peripheral neutrophils. The mean oscillatory period is 21 ± 3 days. Cycling of other blood cells is also evident in most cases.

Benign ethnic neutropenia occurs in members of some ethnic groups (eg, some people of African, Middle Eastern, and Jewish descent). They normally have lower neutrophil counts but do not have increased risk of infection. In some cases this finding has been linked to the Duffy red blood cell antigen; some experts think neutropenia in these populations is related to protection from malaria Malaria Malaria is infection with Plasmodium species. Symptoms and signs include fever (which may be periodic), chills, rigors, sweating, diarrhea, abdominal pain, respiratory distress, confusion... read more .

Neutropenia can also result from bone marrow failure due to rare congenital syndromes (eg, cartilage-hair hypoplasia syndrome, Chédiak-Higashi syndrome Chédiak-Higashi Syndrome Chédiak-Higashi syndrome is a rare, autosomal recessive syndrome characterized by impaired lysis of phagocytized bacteria, resulting in recurrent bacterial respiratory and other infections and... read more , dyskeratosis congenita, glycogen storage disease type IB, Shwachman-Diamond syndrome, warts, hypogammaglobulinemia, infections, myelokathexis [WHIM] syndrome). Neutropenia is also a feature of myelodysplasia Myelodysplastic Syndrome (MDS) The myelodysplastic syndrome (MDS) is group of clonal hematopoietic stem cell disorders typified by peripheral cytopenia, dysplastic hematopoietic progenitors, a hypercellular or hypocellular... read more , where it may be accompanied by megaloblastoid features in the bone marrow, and of aplastic anemia Aplastic Anemia Aplastic anemia is a disorder of the hematopoietic stem cell that results in a loss of blood cell precursors, hypoplasia or aplasia of bone marrow, and cytopenias in two or more cell lines ... read more

Secondary neutropenia can result from use of certain drugs, bone marrow infiltration or replacement, certain infections, or immune reactions.

The most common causes include

• Drugs

• Infections and immune reactions

• Marrow infiltrative processes

Drug-induced neutropenia is one of the most common causes of neutropenia. Drugs can decrease neutrophil production through toxic, idiosyncratic, or hypersensitivity mechanisms; or they can increase peripheral neutrophil destruction through immune mechanisms. Only the toxic mechanism (eg, with phenothiazines) causes dose-related neutropenia.

Severe dose-related neutropenia occurs predictably after cytotoxic cancer drugs or radiation therapy due to suppression of bone marrow production.

Idiosyncratic reactions are unpredictable and occur with a wide variety of drugs, including alternative medicine preparations or extracts, and toxins.

Hypersensitivity reactions Drug Hypersensitivity Drug hypersensitivity is an immune-mediated reaction to a drug. Symptoms range from mild to severe and include rash, anaphylaxis, and serum sickness. Diagnosis is clinical; skin testing is occasionally... read more are rare and occasionally involve antiseizure drugs (eg, phenytoin, phenobarbital), methimazole, or propylthiouracil. These reactions may last for only a few days or for months or years. Often, hepatitis Overview of Acute Viral Hepatitis Acute viral hepatitis is diffuse liver inflammation caused by specific hepatotropic viruses that have diverse modes of transmission and epidemiologies. A nonspecific viral prodrome is followed... read more , nephritis, pneumonitis, or aplastic anemia Aplastic Anemia Aplastic anemia is a disorder of the hematopoietic stem cell that results in a loss of blood cell precursors, hypoplasia or aplasia of bone marrow, and cytopenias in two or more cell lines ... read more

Immune-mediated drug-induced neutropenia, thought to arise from drugs that act as haptens to stimulate antibody formation, usually persists for about 1 week after the drug is stopped. It may result from aminopyrine, clozapine, propylthiouracil and other antithyroid drugs, penicillin, or other antibiotics.

Immune defects can cause neutropenia. Neonatal isoimmune neutropenia can occur with fetal/maternal neutrophil antigen incompatibility associated with transplacental transfer of IgG antibodies against the newborn’s neutrophils (most commonly to HNA-1 antigens). Autoimmune neutropenia can occur at any age and may be operative in many cases of idiopathic chronic neutropenia. Testing for antineutrophil antibodies (immunofluorescence, agglutination, or flow cytometry) is not always available or reliable.

Chronic secondary neutropenia often accompanies HIV infection Human Immunodeficiency Virus (HIV) Infection Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more

Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more

Symptoms and Signs of Neutropenia

Neutropenia is asymptomatic until infection develops. Fever is often the only indication of infection. If neutropenia is severe, typical signs of focal inflammation (erythema, swelling, pain, infiltrates) may be muted or absent. Focal symptoms (eg, oral ulcers) may develop but are often subtle. Patients with drug-induced neutropenia due to hypersensitivity may have a fever, rash, and lymphadenopathy as a result of the hypersensitivity.

Some patients with chronic benign neutropenia and neutrophil counts < 200/mcL (< 0.2 × 109/L) do not experience many serious infections. Patients with cyclic neutropenia or severe congenital neutropenia tend to have episodes of oral ulcers, stomatitis, or pharyngitis and lymph node enlargement during severe neutropenia. Pneumonias and septicemia often occur.

The first priority is to determine whether an infection is present. Because infection may be subtle, physical examination systematically assesses the most common primary sites of infection: mucosal surfaces, such as the alimentary tract (gums, pharynx, anus); lungs; abdomen; urinary tract; skin and fingernails; venipuncture sites; and vascular catheters.

If neutropenia is acute or severe, laboratory evaluation must proceed rapidly.

Cultures are the mainstay of evaluation. At least 2 sets of bacterial and fungal blood cultures are obtained from all febrile patients; if an indwelling IV catheter is present, cultures are drawn from the catheter and from a separate peripheral vein. Persistent or chronic drainage material is also cultured for bacteria, fungi, and atypical mycobacteria. Mucosal ulcers are swabbed and cultured for herpes virus and Candida. Skin lesions are aspirated or biopsied for cytology and culture. Samples for urinalysis and urine cultures are obtained from all patients. If diarrhea is present, stool is evaluated for enteric bacterial pathogens and Clostridioides (formerly Clostridium) difficile toxins. Sputum cultures are obtained to evaluate for pulmonary infections.

Imaging studies are helpful. Chest x-rays are done on all patients. A chest CT may also be necessary in immunosuppressed patients. CT of the paranasal sinuses may be helpful if symptoms or signs of sinusitis (eg, positional headache, upper tooth or maxillary pain, facial swelling, nasal discharge) are present. CT scan of the abdomen is usually done if symptoms (eg, pain) or history (eg, recent surgery) suggests an intra-abdominal infection.

Next, mechanism and cause of neutropenia are determined. The history addresses family history, presence of other disorders, all drugs, other preparations, and possible toxin exposure or ingestion.

If no obvious cause is identified (eg, chemotherapy), the most important test is

• Bone marrow examination

Bone marrow examination determines whether neutropenia is due to decreased marrow production or is secondary to increased cell destruction (determined by normal or increased production of the myeloid cells). Bone marrow examination may also indicate the specific cause of the neutropenia (eg, aplastic anemia Aplastic Anemia Aplastic anemia is a disorder of the hematopoietic stem cell that results in a loss of blood cell precursors, hypoplasia or aplasia of bone marrow, and cytopenias in two or more cell lines ... read more

Further testing, such as flow cytometry and T-cell receptor gene rearrangement for the LGL syndrome, may be needed to determine the cause of neutropenia, depending on the diagnoses suspected. In patients at risk of nutritional deficiencies, levels of copper Acquired Copper Deficiency Copper is a component of many body proteins; almost all of the body’s copper is bound to copper proteins. Copper deficiency may be acquired or inherited. (See also Overview of Mineral Deficiency... read more , folate Folate Deficiency Folate deficiency is common. It may result from inadequate intake, malabsorption, or use of various drugs. Deficiency causes megaloblastic anemia (indistinguishable from that due to vitamin... read more , and vitamin B12 Vitamin B12 Deficiency Dietary vitamin B12 deficiency usually results from inadequate absorption, but deficiency can develop in vegans who do not take vitamin supplements. Deficiency causes megaloblastic anemia, damage... read more are determined. Testing for the presence of antineutrophil antibodies is done if immune neutropenia is suspected. Differentiation between neutropenia caused by certain antibiotics and infection can sometimes be difficult. The white blood cell count just before the start of antibiotic treatment usually reflects the change in blood count due to the infection.

Patients who have had chronic neutropenia since infancy and a history of recurrent fevers and chronic gingivitis should have white cell counts with differential done 3 times/week for 6 weeks, so that periodicity suggestive of cyclic neutropenia can be evaluated. Platelet and reticulocyte counts are done simultaneously. In patients with cyclic neutropenia, eosinophils, reticulocytes, and platelets frequently cycle synchronously with the neutrophils, whereas monocytes and lymphocytes may cycle out of phase.

Molecular genetic testing for ELANE and other genes is appropriate when congenital causes are considered.

Suspected infections are always treated immediately. If fever or hypotension is present, serious infection is assumed, and empiric, high-dose, broad-spectrum antibiotics are given IV. Regimen selection is based on the most likely infecting organisms, the antimicrobial susceptibility of pathogens at that particular institution, and the regimen’s potential toxicity. Because of the risk of creating resistant organisms, vancomycin is used only if gram-positive organisms resistant to other drugs are suspected.

Indwelling vascular catheters can usually remain in place even if bacteremia is suspected or documented, but removal is considered if infections involve S. aureus, Bacillus, Corynebacterium, or Candida or another fungus or if blood cultures are persistently positive despite appropriate antibiotics. Infections caused by coagulase-negative staphylococci generally resolve with antimicrobial therapy alone. Indwelling Foley catheters can also predispose to infections in neutropenic patients, and change or removal of the catheter should be considered for persistent urinary infections.

If cultures are positive, antibiotic therapy is adjusted to the results of sensitivity tests. If a patient defervesces within 72 hours, antibiotics are continued for at least 7 days and until the patient has no symptoms or signs of infection. When neutropenia is transient (such as that following myelosuppressive chemotherapy), antibiotic therapy is usually continued until the neutrophil count is > 500/mcL (> 0.5 × 109/L); however, stopping antimicrobials can be considered in selected patients with persistent neutropenia, especially those in whom symptoms and signs of inflammation have resolved, if cultures remain negative.

Fever that persists > 72 hours despite antibiotic therapy suggests

• A nonbacterial cause

• Infection with a resistant species

• Superinfection with a 2nd bacterial species

• Inadequate serum or tissue levels of the antibiotics

• Localized infection, such as an abscess

Neutropenic patients with persistent fever are reassessed every 2 to 4 days with physical examination, cultures, and chest x-ray. If the patient is well except for the presence of fever, the initial antibiotic regimen can be continued, and drug-induced fever should be considered. If the patient is deteriorating, alteration of the antimicrobial regimen is considered.

For afebrile patients with neutropenia, antibiotic prophylaxis can be considered although alterations in the bacterial microbiome may slow bone marrow recovery (1 Treatment reference Neutropenia is a reduction in the blood neutrophil count. If it is severe, the risk and severity of bacterial and fungal infections increase. Focal symptoms of infection may be muted, but fever... read more ). Treatment with fluoroquinolones (levofloxacin, ciprofloxacin) is used in some centers for patients who receive chemotherapy regimens that commonly result in neutrophils ≤ 100/mcL (≤ 0.1 × 109/L) for > 7 days. Prophylaxis is usually started by the treating oncologist. Antibiotics are continued until the neutrophil count increases to > 1500/mcL (> 1.5 × 109/L). Also, antifungal therapy can be given for afebrile neutropenic patients at higher risk of fungal infection (eg, after hematopoietic stem cell transplantation Hematopoietic Stem Cell Transplantation Hematopoietic stem cell (HSC) transplantation is a rapidly evolving technique that offers a potential cure for hematologic cancers ( leukemias, lymphomas, myeloma) and other hematologic disorders... read more , intensive chemotherapy for acute myeloid leukemia Acute Myeloid Leukemia (AML) In acute myeloid leukemia (AML), malignant transformation and uncontrolled proliferation of an abnormally differentiated, long-lived myeloid progenitor cell results in high circulating numbers... read more

Myeloid growth factors (ie, granulocyte colony-stimulating factor [G-CSF]) are widely used to increase the neutrophil count and to prevent infections in patients with severe neutropenia (eg, after hematopoietic stem cell transplantation and intensive cancer chemotherapy). They are expensive. However, if the risk of febrile neutropenia is ≥ 30% (as assessed by neutrophil count < 500 mcL [< 0.5 × 109/L], presence of infection during a previous cycle of chemotherapy, associated comorbid disease, or age > 75), growth factors are indicated. In general, most clinical benefit occurs when the growth factor is administered beginning about 24 hours after completion of chemotherapy. Patients with neutropenia caused by an idiosyncratic drug reaction may also benefit from myeloid growth factors, particularly if a delayed recovery is anticipated. The dose for G-CSF (filgrastim) is 5 to 10 mcg/kg subcutaneously once a day, and the dose for pegylated G-CSF (pegfilgrastim) is 6 mg subcutaneously once per chemotherapy cycle.

Glucocorticoids, anabolic steroids, and vitamins do not stimulate neutrophil production but can affect distribution and destruction. If acute neutropenia is suspected to be drug- or toxin-induced, all potentially etiologic agents are stopped. If neutropenia develops during treatment with a drug known to induce low counts (eg, chloramphenicol), then switching to an alternative antibiotic may be helpful.

Saline or hydrogen peroxide gargles every few hours, liquid oral rinses (containing viscous lidocaine, diphenhydramine, and liquid antacid), anesthetic lozenges (benzocaine 15 mg every 3 or 4 hours), or chlorhexidine mouth rinses (1% solution) twice a day or 3 times a day may relieve the discomfort of stomatitis with oropharyngeal ulcerations. Oral or esophageal candidiasis is treated with nystatin (400,000 to 600,000 units oral rinse 4 times a day; swallowed if esophagitis is present), clotrimazole troche (10 mg slowly dissolved in the mouth 5 times a day), or systemic antifungal drugs (eg, fluconazole). A semisolid or liquid diet may be necessary during acute stomatitis or esophagitis, and topical analgesics (eg,viscous lidocaine) may be needed to minimize discomfort.

In some patients with accelerated neutrophil destruction caused by autoimmune disorders, corticosteroids (generally, prednisone 0.5 to 1.0 mg/kg orally once a day) can increase blood neutrophils. This increase often can be maintained with alternate-day G-CSF therapy.

Splenectomy has been used in the past to increase the neutrophil count in some patients with splenomegaly and splenic sequestration of neutrophils (eg, Felty syndrome); however, because growth factors and other newer therapies are often effective, splenectomy should be avoided in most patients. Splenectomy can be considered for patients with persistent painful splenomegaly or with severe neutropenia (ie, < 500/mcL [< 0.5 × 109/L]) and serious problems with infections in whom other treatments have failed. Patients should be vaccinated against infections caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae before splenectomy because splenectomy predisposes patients to infection by encapsulated organisms.

• 1. Yan H, Baldridge MT, Yang KY: Hematopoiesis and the bacterial microbiome. Blood 132: 559–564, 2018. doi: 10.1182/blood-2018-02-832519