Can Bartonella infection cause leukocytosis (elevated white blood cell count), neutrophilia (elevated neutrophil count), mild arthralgia (joint pain) and insomnia (poor sleep quality) in a teenager?

Bartonella as a Potential Cause of This Clinical Presentation

Yes, Bartonella infection can explain this teenager's presentation of persistent mild neutrophilia (neutrophils in mid-40s%), mild leukocytosis (WBC in low 50s), unexplained knee joint pain, and poor sleep quality, and should be strongly considered in the differential diagnosis, particularly if there is a history of cat or kitten exposure. 1

Clinical Evidence Supporting Bartonella as the Cause

Hematologic Manifestations Match the Pattern

• Bartonella henselae characteristically causes leukocytosis with neutrophilia rather than lymphocytosis, distinguishing it from typical infectious mononucleosis presentations 1
• A case series documented six children with Bartonella henselae infection presenting with leukocytosis and neutrophilia (similar to your patient's WBC in the 50s with neutrophils in the 40s%), along with elevated inflammatory markers 1
• One documented case of Bartonella henselae infection mimicking adult-onset Still's disease presented with fever, arthralgia, and persistent leukocytosis that remained even after initial treatment 2

Joint Pain is a Recognized Manifestation

• Arthralgias and joint pain are well-documented symptoms of Bartonella infection in immunocompetent patients 3
• Bartonella vinsonii subsp. berkhoffii has been isolated from immunocompetent patients specifically presenting with arthritis and neurological disease 3
• The knee joint pain in your patient fits the pattern of Bartonella-associated musculoskeletal symptoms 2

Sleep Disturbance is a Documented Symptom

• Insomnia and poor sleep quality are specifically reported in Bartonella infections 3
• A case report documented a daughter with Bartonella vinsonii and B. henselae bacteremia who presented with headaches, muscle pain, and insomnia as primary symptoms 3
• Another patient with Bartonella infection presented with trouble sleeping as an early symptom following arthropod exposure 4

Diagnostic Approach

Key Historical Features to Elicit

• Cat or kitten exposure is critical - all six children in the pseudoinfectious mononucleosis series had contact with kittens 1
• History of scratches, bites, or exposure to fleas from cats 5
• Any arthropod bites (ticks, fleas, biting flies) in the preceding weeks to months 3
• Geographic location and outdoor activities 3

Laboratory Testing Strategy

• Standard serologic testing may be falsely negative - the patient should not be ruled out based on negative conventional testing alone 4
• Serology for Bartonella henselae IgM with high IgG titers (≥1/1024) is the initial diagnostic approach 1
• If clinical suspicion remains high despite negative serology, consider enrichment blood culture in Bartonella alpha Proteobacteria growth medium (BAPGM) followed by PCR and DNA sequencing 3
• Novel molecular testing methods may be required for definitive diagnosis when conventional testing is negative 4
• Rule out other causes: Epstein-Barr virus, cytomegalovirus, adenovirus, and Toxoplasma gondii serology should be negative 1

Additional Inflammatory Markers

• Expect elevated erythrocyte sedimentation rate and hypergammaglobulinemia in Bartonella infection 1
• The combination of neutrophilic leukocytosis with elevated inflammatory markers strongly suggests bacterial infection, with Bartonella being a key consideration when routine bacterial cultures are negative 6

Treatment Considerations

When to Treat

• For uncomplicated lymphadenopathy alone, antibiotics do not significantly affect cure rates and the condition is often self-limited 7
• However, with systemic symptoms including arthralgias, neurological symptoms (sleep disturbance), and persistent laboratory abnormalities, treatment is warranted 7, 3

First-Line Treatment Options

• Doxycycline is the first-line treatment for bartonellosis according to CDC guidelines, administered for at least 3 months for standard infections 8
• For teenagers, doxycycline dosage is 2-4 mg/kg body weight (maximum 100-200 mg/day) per day orally once daily or divided into 2 doses 8
• Azithromycin can be used initially, but if treatment fails, switching to doxycycline with or without rifampin is recommended 8
• Erythromycin (30-50 mg/kg body weight, maximum 2 g/day) is an alternative first-line agent 8

Important Treatment Caveats

• Therapeutic elimination can be challenging - follow-up testing is recommended to confirm clearance 3
• Patients on oral doxycycline should take doses with adequate liquid and not immediately before bed to avoid pill-associated ulcerative esophagitis 8
• Penicillins and first-generation cephalosporins have no in vivo activity against Bartonella and should never be used 8
• Treatment duration of at least 3 months is typically required 8, 3

Monitoring Response

• Sequential testing over time may be needed to assess treatment response, including repeat blood cultures and antibody titers 3
• Expect decremental decrease in antibody titers to non-detectable levels with successful treatment 3
• Clinical symptoms (joint pain, sleep quality) should resolve with appropriate therapy 3

Critical Diagnostic Pitfalls

• Do not rely solely on negative conventional serologic testing - Bartonella species are stealth pathogens that are particularly difficult to detect with standard methods 4
• The presentation may mimic other conditions like adult-onset Still's disease or infectious mononucleosis, leading to misdiagnosis 2, 1
• Without specific testing for Bartonella, the diagnosis will be missed, as routine bacterial cultures are typically negative 7
• Consider co-infection with other vector-borne pathogens (such as Borrelia) if symptoms persist despite appropriate treatment 4, 3