Approach to the Critical Patient

Red flags requiring urgent evaluation

Alarm features mandating escalation

Immediate stabilization

Stabilization priorities for severe CSD

Monitoring and escalation triggers

Monitoring targets for admitted patients

Immediate consults

Consultation triggers

History

Exposure and inoculation history

Feline exposure

Symptom timeline

Inoculation site papule

Lymphadenopathy onset

Systemic symptoms

Classic and atypical presentations

Classic presentation

Atypical presentations (5–20% of cases)

Risk factors

Host risk factors

Important negatives and red flags

Features requiring urgent evaluation

Physical Exam

Vital signs

Vital sign assessment

Lymph node exam

Lymphadenopathy characterization

Skin and inoculation site

Inoculation site findings

Ocular exam

Ophthalmologic findings

Abdominal exam

Abdominal findings in disseminated CSD

Neurologic exam

Neurologic assessment in suspected encephalitis

PITFALLS

Examination pitfalls

Differential Diagnosis

Life-threatening mimics

Lymphoma

Bacterial endocarditis

Infectious mimics

Mycobacterial lymphadenitis

Toxoplasmosis

EBV or CMV mononucleosis

Tularemia

Bacterial lymphadenitis (Staph/Strep)

Non-infectious mimics

Sarcoidosis

Kikuchi-Fujimoto disease

Sporotrichosis

Laboratory Tests

Serology

Bartonella henselae serology (IFA)

PCR and molecular testing

PCR for B. henselae

Routine laboratory tests

Complete blood count

Inflammatory markers

Liver function tests

Exclusionary workup

Tests to rule out dangerous mimics

Diagnostic Tests

Scoring Systems

Severity stratification (clinical framework)

MRI

MRI indications in CSD

CT

CT indications in CSD

Ultrasound

Ultrasound applications in CSD

Disposition

Discharge criteria

Safe for outpatient management

Admission criteria

Indications for inpatient management

Observation and monitoring

Indications for observation unit or extended ED stay

Follow-up planning

Outpatient follow-up

Treatment

First-line antibiotic therapy

Azithromycin (IDSA first-line recommendation)

Disseminated and severe disease therapy

Doxycycline-based regimens

Immunocompromised host therapy

Bacillary angiomatosis and peliosis hepatis

Alternative antibiotics

TMP-SMX (trimethoprim-sulfamethoxazole)

Rifampin monotherapy or combination

Contraindicated and ineffective antibiotics

Antibiotics without efficacy against Bartonella

Supportive care

Symptomatic management

Lymph node aspiration

Procedure for suppurative lymph nodes

Encephalitis management

CSD encephalitis

Special Populations

Pregnancy

CSD in pregnancy

Geriatric

CSD in older adults

Pediatrics

CSD in children

Background

Epidemiology

Incidence and prevalence

Pathophysiology

Causative organism

Disease mechanism

Histopathology

Therapeutic Considerations

Treatment rationale

Patient Discharge Instructions

copy discharge instructions

Discharge instructions for Cat Scratch Disease

References

Guidelines and key sources

IDSA skin and soft tissue infection guidelines

Key clinical studies

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.