The etiologic, microbiologic, clinical and outcome characteristics of immunocompetent young children <2 years of age hospitalized with acute neutropenia

Leukopenia, neutropenia, and procalcitonin levels in young febrile infants with invasive bacterial infections

BACKGROUND AND OBJECTIVE

Serum procalcitonin (PCT) is a highly accurate biomarker for stratifying the risk of invasive bacterial infections (IBIs) in febrile infants ≤60 days old. However, PCT is unavailable in some settings. We explored the association of leukopenia and neutropenia with IBIs in non-critically ill febrile infants ≤60 days old, with and without PCT.

METHODS

We conducted a secondary analysis of a prospective observational cohort consisting of 7407 non-critically ill infants ≤60 days old with temperatures ≥38°C. We focused on the risk of IBIs in patients with leukopenia (white blood cell [WBC] count <5000 cells/μL) or neutropenia (absolute neutrophil count [ANC] <1000 cells/μL), categorized to extremes of lower values, and the impact of PCT on these associations. Multiple logistic regression was used to identify independent predictors of IBIs.

RESULTS

Final analysis included 6865 infants with complete data; 45% (3098) had PCT data available. Of the 6865, a total of 111 (1.6%) had bacteremia without bacterial meningitis, 18 (0.3%) had bacterial meningitis without bacteremia, and 19 (0.3%) had both bacteremia and bacterial meningitis. IBI was present in four of 20 (20%) infants with WBC counts ≤2500 cells/μL and four of 311 (1.3%) with ANC <1000 cells/μL. In multivariable logistic regression analysis not including PCT, a WBC count <2500 cells/μL was significantly associated with IBI (OR 13.48, 95% CI 2.92-45.35). However, no patients with leukopenia or neutropenia and PCT ≤0.5 ng/mL had IBIs.

CONCLUSIONS

Leukopenia ≤2500 cells/μL in febrile infants ≤60 days old is associated with IBIs. However, in the presence of normal PCT levels, no patients with leukopenia had IBIs. While this suggests leukopenia ≤2500 cells/μL is a risk factor for IBIs in non-critically ill young febrile infants only when PCT is unavailable or elevated, the overall low frequency of leukopenia in this cohort warrants caution in interpretation, with future validation required.

Brucellosis: A Rare Cause of Febrile Neutropenia in a Child

We report a case of brucellosis-induced severe neutropenia in a 2-year-old girl who presented with a 2-week history of fever. On clinical examination, the patient was febrile with mild aphthous stomatitis. However, her general condition was stable, and systemic examination did not show involvement of any other organ. Laboratory test results revealed severe neutropenia, mild anemia, and an elevated serum C-reactive protein level. Flow cytometry of peripheral blood leukocytes revealed no malignancy, and blood film morphology was unremarkable except for mild microcytosis and hypochromia. Antineutrophil antibody and Coombs test results were negative. We administered intravenous cefuroxime; however, therapy was switched to meropenem plus clarithromycin because fever persisted for 5 days, despite treatment. On the 10th day after admission, Brucella serology tests showed positive results, and trimethoprim-sulfamethoxazole plus rifampicin therapy was prescribed for 8 weeks. The fever defervesced, and the child was discharged in a good state of health. Neutropenia persisted for several months but gradually resolved. Neutropenia, defined as an absolute neutrophil count (ANC) < 1.5 cells × 10 9 /L beyond the first year of life, is a benign transient condition associated with an intercurrent infection (usually viral illnesses or infections) in immunocompetent children. However, severe neutropenia (ANC < 0.5 × 10 9 /L) associated with fever necessitates hospitalization and administration of broad-spectrum antibiotics to avoid the high risk of sepsis, particularly in children. Brucellosis is rarely associated with hematologic abnormalities such as neutropenia. Early diagnosis of hematologic complications of brucellosis is essential for prompt initiation of specific and aggressive treatment.

Diagnosis and therapeutic decision-making for the neutropenic patient

Determining the cause of a low neutrophil count in a pediatric or adult patient is essential for the hematologist's clinical decision-making. Fundamental to this diagnostic process is establishing the presence or lack of a mature neutrophil storage pool, as absence places the patient at higher risk for infection and the need for supportive care measures. Many diagnostic tests, eg, a peripheral blood smear and bone marrow biopsy, remain important tools, but greater understanding of the diversity of neutropenic disorders has added new emphasis on evaluating for immune disorders and genetic testing. In this article, a structure is provided to assess patients based on the mechanism of neutropenia and to prioritize testing based on patient age and hypothesized pathophysiology. Common medical quandaries including fever management, need for growth factor support, risk of malignant transformation, and curative options in congenital neutropenia are reviewed to guide medical decision-making in neutropenic patients.