- Published on
Emergency And Acute Medicine – Immunosuppression
Basics
Description Immunosuppression is a congenital or acquired deficiency in host defense mechanisms, including impaired antibody production (B-cell), cellular immunity (T-cell), phagocytic dysfunction, complement deficiency, or disruption of skin and mucosal barriers.
Etiology
Congenital immune disorders. Immunosuppressive medications. Aging with immunosenescence, poor circulation, and impaired wound healing. Chronic diseases (lung, kidney, heart). HIV infection, with susceptibility related to CD4 count. Diabetes mellitus causing impaired immune response and vascular insufficiency. Malnutrition related to poverty, alcoholism, drug abuse, or eating disorders. Asplenia (functional in sickle cell disease or postsplenectomy) with increased risk from encapsulated organisms. Organ transplantation with immunosuppressive therapy; infections may be donor-derived, recipient-derived, or nosocomial, with timing since transplant guiding likely pathogens. Malignancy and chemotherapy with infection risk proportional to depth and duration of neutropenia. Neutropenia defined as ANC <500 />m³ or <1,000 />m³ with anticipated nadir <500 />m³. Gram-positive organisms are most common in the U.S.; gram-negative organisms are less common but often more virulent. Risk of fungal infection increases with prolonged neutropenia, prior broad-spectrum antibiotics, or intensive chemotherapy.
Diagnosis
Signs And Symptoms Fever may be the only sign of severe infection. Symptoms are often subtle or absent. Review systems carefully for localizing complaints. Assess for recent hospitalization, nursing home exposure, sick contacts, and current or prophylactic antimicrobials that may alter pathogen spectrum.
Physical Exam Perform a thorough head-to-toe exam. Avoid digital rectal exam in febrile neutropenia. Infection may lack classic inflammatory signs (e.g., meningitis without nuchal rigidity, pneumonia without focal findings).
Essential Workup
Diagnostic evaluation must be individualized. Inflammatory responses may be blunted, leading to atypical presentations such as pneumonia without infiltrate, UTI without pyuria, or meningitis without CSF pleocytosis.
Diagnosis Tests And Interpretation
Labs CBC with differential to assess neutropenia or left shift. Blood cultures ×2 (include line cultures if present). Urinalysis and urine culture. Serum lactate for occult hypoperfusion. ABG if respiratory compromise or suspected Pneumocystis jirovecii pneumonia. Pregnancy test when appropriate.
Imaging Chest x-ray for neutropenic, hypoxic, or pulmonary findings; CT or MRI as guided by symptoms.
Procedures Lumbar puncture if meningitis suspected; check platelets and coagulation first. Consider cryptococcal antigen testing even without CSF pleocytosis.
Differential Diagnosis
Infectious sources (oropharynx, sinuses, lungs, GI tract, perineum, urinary tract, skin, bone, indwelling devices). Noninfectious causes of fever include drug fever, malignancy, graft rejection, vasculitis, rheumatologic disease, pulmonary embolism, thyroid disease, and transfusion reactions.
Treatment
Prehospital Establish IV access and begin IV fluids.
Initial Stabilization Aggressive fluid resuscitation for hypovolemia. Goal-directed therapy for sepsis. Use vasopressors for refractory hypotension (dopamine or norepinephrine).
Emergency Department Management Apply infection-control precautions. Obtain cultures promptly and administer empiric broad-spectrum antibiotics without delay. Most febrile neutropenic patients require admission; selected low-risk patients may be treated as outpatients.
Medication
Empiric broad-spectrum therapy should be individualized.
Oral (low-risk): Ciprofloxacin 750 mg PO BID plus amoxicillin–clavulanate 875 mg PO BID.
IV monotherapy options: Cefepime 2 g IV q8h; ceftazidime 2 g IV q8h; meropenem 1 g IV q8h; imipenem–cilastatin 500 mg IV q6h; piperacillin–tazobactam 4.5 g IV q6h.
Add aminoglycoside for high-risk patients if indicated.
Add vancomycin only for suspected line infection, MRSA, or severe skin/soft tissue infection.
Add anaerobic coverage (e.g., clindamycin) if oral, abdominal, or perianal source suspected.
Follow-Up And Disposition
Admission Criteria ANC <100 />m³, high-risk immunocompromised state, unstable vitals, significant comorbidities, or lack of reliable follow-up.
Discharge Criteria Low-risk, well-appearing patients tolerating oral therapy with reliable 24-hour follow-up, after discussion with the treating specialist.
Follow-Up Recommendations Reassessment within 24 hours to review cultures and clinical status.
Pearls And Pitfalls
Isolated fever may be the only sign of life-threatening infection. Do not delay antibiotics in febrile neutropenia. Review prior microbiology and resistance patterns. Involve oncology, transplant, or infectious disease specialists early.
Basics
Description Immunosuppression is a congenital or acquired deficiency in host defense mechanisms, including impaired antibody production (B-cell), cellular immunity (T-cell), phagocytic dysfunction, complement deficiency, or disruption of skin and mucosal barriers.
Etiology
Congenital immune disorders. Immunosuppressive medications. Aging with immunosenescence, poor circulation, and impaired wound healing. Chronic diseases (lung, kidney, heart). HIV infection, with susceptibility related to CD4 count. Diabetes mellitus causing impaired immune response and vascular insufficiency. Malnutrition related to poverty, alcoholism, drug abuse, or eating disorders. Asplenia (functional in sickle cell disease or postsplenectomy) with increased risk from encapsulated organisms. Organ transplantation with immunosuppressive therapy; infections may be donor-derived, recipient-derived, or nosocomial, with timing since transplant guiding likely pathogens. Malignancy and chemotherapy with infection risk proportional to depth and duration of neutropenia. Neutropenia defined as ANC <500 />m³ or <1,000 />m³ with anticipated nadir <500 />m³. Gram-positive organisms are most common in the U.S.; gram-negative organisms are less common but often more virulent. Risk of fungal infection increases with prolonged neutropenia, prior broad-spectrum antibiotics, or intensive chemotherapy.
Diagnosis
Signs And Symptoms Fever may be the only sign of severe infection. Symptoms are often subtle or absent. Review systems carefully for localizing complaints. Assess for recent hospitalization, nursing home exposure, sick contacts, and current or prophylactic antimicrobials that may alter pathogen spectrum.
Physical Exam Perform a thorough head-to-toe exam. Avoid digital rectal exam in febrile neutropenia. Infection may lack classic inflammatory signs (e.g., meningitis without nuchal rigidity, pneumonia without focal findings).
Essential Workup
Diagnostic evaluation must be individualized. Inflammatory responses may be blunted, leading to atypical presentations such as pneumonia without infiltrate, UTI without pyuria, or meningitis without CSF pleocytosis.
Diagnosis Tests And Interpretation
Labs CBC with differential to assess neutropenia or left shift. Blood cultures ×2 (include line cultures if present). Urinalysis and urine culture. Serum lactate for occult hypoperfusion. ABG if respiratory compromise or suspected Pneumocystis jirovecii pneumonia. Pregnancy test when appropriate.
Imaging Chest x-ray for neutropenic, hypoxic, or pulmonary findings; CT or MRI as guided by symptoms.
Procedures Lumbar puncture if meningitis suspected; check platelets and coagulation first. Consider cryptococcal antigen testing even without CSF pleocytosis.
Differential Diagnosis
Infectious sources (oropharynx, sinuses, lungs, GI tract, perineum, urinary tract, skin, bone, indwelling devices). Noninfectious causes of fever include drug fever, malignancy, graft rejection, vasculitis, rheumatologic disease, pulmonary embolism, thyroid disease, and transfusion reactions.
Treatment
Prehospital Establish IV access and begin IV fluids.
Initial Stabilization Aggressive fluid resuscitation for hypovolemia. Goal-directed therapy for sepsis. Use vasopressors for refractory hypotension (dopamine or norepinephrine).
Emergency Department Management Apply infection-control precautions. Obtain cultures promptly and administer empiric broad-spectrum antibiotics without delay. Most febrile neutropenic patients require admission; selected low-risk patients may be treated as outpatients.
Medication
Empiric broad-spectrum therapy should be individualized.
Oral (low-risk): Ciprofloxacin 750 mg PO BID plus amoxicillin–clavulanate 875 mg PO BID.
IV monotherapy options: Cefepime 2 g IV q8h; ceftazidime 2 g IV q8h; meropenem 1 g IV q8h; imipenem–cilastatin 500 mg IV q6h; piperacillin–tazobactam 4.5 g IV q6h.
Add aminoglycoside for high-risk patients if indicated.
Add vancomycin only for suspected line infection, MRSA, or severe skin/soft tissue infection.
Add anaerobic coverage (e.g., clindamycin) if oral, abdominal, or perianal source suspected.
Follow-Up And Disposition
Admission Criteria ANC <100 />m³, high-risk immunocompromised state, unstable vitals, significant comorbidities, or lack of reliable follow-up.
Discharge Criteria Low-risk, well-appearing patients tolerating oral therapy with reliable 24-hour follow-up, after discussion with the treating specialist.
Follow-Up Recommendations Reassessment within 24 hours to review cultures and clinical status.
Pearls And Pitfalls
Isolated fever may be the only sign of life-threatening infection. Do not delay antibiotics in febrile neutropenia. Review prior microbiology and resistance patterns. Involve oncology, transplant, or infectious disease specialists early.
0 Comments
