13–19 minutes
NCCN Guidelines Version 1.2026, March 11, 2026 — Prevention and Treatment of Cancer-Related Infections
BACKGROUND & PATHOPHYSIOLOGY
What is PJP?
Pneumocystis jirovecii pneumonia (PJP), formerly called PCP, is an opportunistic fungal infection caused by Pneumocystis jirovecii. It is NOT a neutropenic complication — it is a T-cell (cellular) immunity defect that allows the organism to cause life-threatening pneumonia. Patients can have a completely normal neutrophil count and still develop PJP.
Key Points
- Organism: Pneumocystis jirovecii (fungus; previously classified as protozoan)
- Reservoir: Human-to-human airborne transmission; latent infection in most healthy adults
- Infection type: Reactivation of latent infection OR new acquisition when cellular immunity is impaired
- Mortality: Untreated PJP in immunocompromised non-HIV can exceed 30–50%; prophylaxis reduces mortality by 83% (RR 0.17)
RISK FACTORS & PATIENT POPULATIONS
HIGH RISK — Prophylaxis Required (NCCN INF-6)
| Patient Population | Category | Duration of Prophylaxis |
| Allogeneic HCT recipients (including cord blood) | Category 1 | ≥6 months AND while receiving IST |
| Cellular immunotherapies (CAR T-cell, TCR, TIL therapy) | Category 1 | ≥6 months AND while receiving IST |
| Acute Lymphoblastic leukemia | Category 1 | Throughout entire anti-leukemic therapy |
| Alemtuzumab recipients | Category 1 | Minimum 2 months AND until CD4 >200 cells/mcL |
| PI3K inhibitors (copanlisib, idelalisib, duvelisib) ± rituximab | Category 2A | At least through active treatment |
| Prolonged corticosteroids (≥prednisone equivalent 20 mg/day for ≥4 weeks) | Category 2A | At least through active treatment |
| Temozolomide ± radiation therapy | Category 2A | At least through active treatment; continue until lymphocytopenia resolves |
CONSIDER Prophylaxis (Category 2B)
- Purine analog therapy (fludarabine, cladribine/2-CdA, clofarabine, nelarabine) and other T-cell depleting agents → until CD4 count >200 cells/mcL
- Autologous HCT recipients → 3–6 months post-transplant
- Certain bispecific antibodies (consult full NCCN guidelines)
- Ibrutinib, bendamustine — reported increased susceptibility
NCCN Note: For the intermediate-risk group (lymphoma, multiple myeloma, CLL, auto-HCT, CAR T-cell), PJP prophylaxis is listed under ‘Consider’ (INF-1). For HIGH risk (allo-HCT, acute leukemia, alemtuzumab, GVHD), PJP prophylaxis is explicitly listed.
SIGNS, SYMPTOMS & CLINICAL PRESENTATION
| Feature | PJP in Non-HIV Oncology Patients | PJP in HIV (for comparison) |
| Onset | Subacute to acute (days to 1–2 weeks) | Subacute (weeks to months) |
| Fever | Present, often low-grade; may be high | Low-grade, common |
| Cough | Dry, non-productive | Dry, non-productive |
| Dyspnea | Progressive; may be rapid onset; can require O2 quickly | Progressive, exertional |
| O2 saturation | Often low; may desaturate with exertion | May be preserved early |
| Chest X-ray | Bilateral diffuse perihilar/ground-glass infiltrates; may be normal early | Bilateral interstitial infiltrates |
| CT findings | Bilateral ground-glass opacities; diffuse pattern | Ground-glass opacities |
| LDH | Elevated (non-specific but useful marker of disease severity) | Elevated |
| Beta-D-glucan | Elevated (>80 pg/mL — supportive, not diagnostic) | Elevated |
CRITICAL PEARL: Non-HIV patients with PJP deteriorate FASTER and more severely than HIV patients. PJP in oncology = medical emergency. Do not wait for BAL before empiric treatment if the patient is hypoxic or in respiratory distress.
DIFFERENTIAL DIAGNOSIS
Diffuse pulmonary infiltrates in immunocompromised oncology patients — broad differential per NCCN:
| Category | Etiology | Key Distinguishing Feature |
| Fungal | Aspergillus spp., Cryptococcus neoformans, dimorphic fungi (Histoplasma, Coccidioides, Blastomyces) | Galactomannan, BAL cultures, nodules/halo sign on CT |
| Opportunistic | PJP (Pneumocystis jirovecii) | Bilateral GGO, no prophylaxis, T-cell depletion |
| Bacterial | Enterobacteriaceae, Pseudomonas, S. aureus, Legionella, Nocardia spp., Mycobacteria (TB/NTM) | Focal consolidation, acute onset, cultures |
| Viral | CMV, respiratory viruses (influenza, RSV, parainfluenza, hMPV, adenovirus) | CMV PCR blood, nasopharyngeal NAAT |
| Non-infectious | Drug-induced pneumonitis (eg, checkpoint inhibitors, MTX, bleomycin), hemorrhage, pulmonary edema, BOOP/COP | Drug history, bronchoscopy/biopsy, response to steroids |
| Other | Malignant infiltration of lungs | Imaging pattern, biopsy |
DIAGNOSTIC WORKUP
Step-by-Step Approach
Step 1 — CT Chest
- Obtain CT chest (NOT plain CXR alone) to characterize infiltrate pattern, extent, and guide BAL
- PJP: bilateral diffuse ground-glass opacities; may be subtle on CXR in early disease
Step 2 — Blood & Urine Studies
| Test | Pathogen Targeted | Comments |
| Aspergillus galactomannan | Aspergillus spp. | Serum; cut-off ≥0.5 OD in 2 consecutive samples |
| Cryptococcal antigen | Cryptococcus neoformans | Serum; highly sensitive |
| Coccidioides antigen/serology | Coccidioidomycosis | Endemic: SW United States |
| Blastomyces / Histoplasma antigen | Dimorphic fungi | Urine AND serum; Histoplasma endemic to Central US |
| Legionella urinary antigen | Legionella pneumophila type 1 | Note: only detects type 1; some non-pneumophila resistant to tetracyclines |
| Pneumococcal urinary antigen | S. pneumoniae | Rapid, highly specific |
| Beta-D-glucan | PJP & invasive fungi | >80 pg/mL: supportive of PJP; not diagnostic alone |
| Blood cultures x2 | Bacteremia, fungemia | Before antibiotics if possible |
| CMV PCR (blood) | CMV pneumonitis | Negative CMV blood PCR makes CMV pneumonia very unlikely |
Step 3 — Respiratory Specimens & BAL
| Test | Target | Comments |
| Pneumocystis jirovecii PCR or DFA | PJP — KEY TEST | From BAL fluid or bronchoscopy specimen; gold standard |
| Aspergillus galactomannan (BAL) | Aspergillus | BAL GM more sensitive than serum |
| Mycobacterial PCR | TB / NTM | BAL or induced sputum |
| Mycoplasma & Chlamydia PCR | Atypical bacteria | BAL or NPS |
| NAAT viral panel | Influenza A/B, RSV, hMPV, parainfluenza, adenovirus | Nasopharyngeal swab or BAL fluid |
| Microbial cell-free DNA (cfDNA) | Broad pathogens | Center-dependent; variable experience per NCCN |
Non-Invasive vs. Invasive Approach
- Sputum induction (hypertonic saline): diagnostic for PJP in ~60% of non-HIV patients per NCCN. If negative → MUST proceed to BAL.
- BAL (bronchoalveolar lavage): GOLD STANDARD for PJP. High diagnostic yield for alveolar infiltrates. Sensitivity for focal lesions >2 cm: 50–80%.
- If BAL/percutaneous biopsy non-diagnostic → consider thoracoscopic lung biopsy (preferred over open) if platelets allow.
CLINICAL RULE: If patient is in respiratory distress (labored breathing, requiring O2) → START EMPIRIC TMP/SMX BEFORE BAL. Do NOT delay treatment to perform diagnostic workup.
PHARMACOTHERAPY —
DOSING, MONITORING & ADJUSTMENTS
First-Line: TMP/SMX (Trimethoprim/Sulfamethoxazole) — PREFERRED, Category 1
NCCN Evidence: Meta-analysis of 12 RCTs, N=1,245. TMP/SMX reduced PJP occurrence by 91% (RR 0.09; 95% CI 0.02–0.32) and PJP-related mortality by 83% (RR 0.17; 95% CI 0.03–0.94).
| Indication | Dose | Notes |
| Prophylaxis | Single Strength (SS: 80mg TMP/400mg SMX) PO daily OR Double Strength (DS: 160mg TMP/800mg SMX) PO 3x/week | Both regimens equivalent for prophylaxis per NCCN. 3x/week may improve GI tolerability. IV form available if oral not feasible. |
| Treatment (Active PJP) | 8–15 mg/kg/DAY of the TMP component, in divided doses every 6–8 hours, PO or IV Typical adult dose (DS tablets): 2 DS tabs q8h PO (or q6h in severe disease) | Weight-based (TMP component). 21-day course standard. IV for moderate-severe disease or if oral not tolerated. Oral bioavailability excellent (~100%) — IV→PO switch early if tolerated. |
TMP/SMX Monitoring Parameters
| Parameter | What to Monitor | Threshold / Action |
| Renal function | SCr, BUN, eGFR at baseline and regularly | TMP can increase SCr by blocking tubular secretion of creatinine (NOT true kidney injury necessarily). TMP also can cause true nephrotoxicity. Dose adjust if CrCl <30 mL/min per institutional guidelines. |
| CBC with differential | ANC, platelets, hemoglobin — weekly during treatment | Myelosuppression: neutropenia, thrombocytopenia, anemia. TMP is a DHFR inhibitor → antifolate effect. More pronounced with concurrent MTX. |
| Liver function | ALT, AST, bilirubin | Hepatotoxicity possible; monitor LFTs |
| Potassium | Serum K+ — weekly | Hyperkalemia: TMP blocks distal nephron K+ excretion (similar to K+-sparing diuretics). Risk ↑ with renal insufficiency, concurrent ACEi/ARB/calcineurin inhibitors. |
| Glucose | Blood glucose | Rare hypoglycemia reported |
TMP/SMX Key Drug Interactions
| Drug | Interaction | Management |
| Methotrexate (MTX) | TMP inhibits dihydrofolate reductase (DHFR) — same mechanism as MTX. Additive antifolate toxicity: severe myelosuppression, mucositis | Use with EXTREME CAUTION. Monitor CBC very closely. Consider dose timing separation or alternative PJP agent if MTX toxicity occurs. |
| Warfarin | TMP/SMX inhibits CYP2C9 → increased warfarin levels → elevated INR | Monitor INR closely; may need warfarin dose reduction |
| ACE inhibitors / ARBs / Calcineurin inhibitors | Additive hyperkalemia risk | Monitor K+ more frequently |
| Dofetilide, sotalol | TMP inhibits renal tubular secretion of dofetilide → increased dofetilide levels → QTc prolongation | Contraindicated combination |
DESENSITIZATION NOTE: Per NCCN, TMP/SMX desensitization should be STRONGLY CONSIDERED before switching to alternatives. Many mild reactions (maculopapular rash, drug fever) can be managed through desensitization. Only switch if desensitization fails or is contraindicated.
Alternatives for TMP/SMX-Intolerant Patients
Per NCCN: alternatives are listed alphabetically and do NOT reflect a preference order. All three are equivalent second-line options.
Option 1: Atovaquone (Mepron)
| Parameter | Details | Clinical Pearls |
| Prophylaxis dose | 1500 mg PO once daily (suspension) | Suspension preferred over tablet for better absorption |
| Route | Oral only | NOT available IV — cannot use if gut failure/mucositis |
| Food requirement | MUST be taken with food (fatty meal preferred) | Bioavailability doubles with high-fat food. Without food, absorption is inadequate. Key counseling point. |
| G6PD check | Not required | Advantage over dapsone |
| Bonus coverage | Potential Toxoplasma gondii activity (per NCCN) | Useful in severely T-cell depleted patients |
| Side effects | GI intolerance, rash, headache, elevated LFTs | Generally well tolerated — safest alternative profile |
| Evidence | Equivalent to dapsone in HIV patients intolerant to TMP/SMX (RCT: El-Sadr et al., NEJM 1998) | Also shown effective in pediatric ALL patients (Madden et al., Cancer 2007) |
Option 2: Dapsone
| Parameter | Details | Clinical Pearls |
| Prophylaxis dose | 100 mg PO once daily | Oral only |
| G6PD check | MANDATORY before starting — measure G6PD levels | G6PD deficient: significantly increased risk of hemolytic anemia. Do NOT use dapsone if G6PD deficient. |
| Toxicity 1: Methemoglobinemia | Occurs regardless of G6PD status | Watch for: cyanosis with normal (falsely reassuring) pulse ox. Co-oximetry (ABG) required for true MetHb measurement. Treatment: methylene blue 1–2 mg/kg IV. |
| Toxicity 2: Hemolytic anemia | Risk increased in G6PD deficiency | Monitor CBC; check reticulocyte count, LDH, bilirubin if suspected |
| Other toxicities | Peripheral neuropathy, agranulocytosis, rash/hypersensitivity, GI | Rare but serious |
| Monitoring | G6PD (baseline), CBC, MetHb if symptomatic, LFTs | Per NCCN: G6PD measurement RECOMMENDED before initiation |
Option 3: Pentamidine (Aerosolized or IV)
| Parameter | Aerosolized (Inhaled) | IV |
| Prophylaxis dose | 300 mg inhaled monthly via Respirgard II nebulizer | 4 mg/kg IV every 2–4 weeks |
| Treatment dose | NOT used for treatment | 4 mg/kg IV daily x 21 days |
| Advantage | Monthly dosing; minimal systemic exposure; no systemic toxicity; safe in G6PD deficiency | Only IV option for patients unable to take oral agents (mucositis, gut failure, critically ill) |
| Disadvantage | Poor upper lobe distribution; NO extrapulmonary or bacterial/Toxo coverage; bronchospasm risk | Significant toxicity profile (see below) |
| IV Toxicities | — | Nephrotoxicity (SCr), hypoglycemia (then hyperglycemia), QTc prolongation, pancreatitis (lipase), hypotension (infusion-related), myelosuppression, ↓Mg, ↓Ca, ↓K+ |
| IV Monitoring | — | SCr, glucose, QTc (ECG), lipase, electrolytes (Mg, Ca, K+), CBC — ALL before and during therapy |
| Evidence (pediatric HCT) | Safe and effective per NCCN citation (Kim et al.; DeMasi et al.) | Safe and effective in pediatric allo-HCT (Diri et al.; DeMasi et al.) per NCCN citation |
PENTAMIDINE IV GLUCOSE WARNING: Can cause SEVERE hypoglycemia (stimulates pancreatic insulin release) followed by hyperglycemia (beta-cell destruction with prolonged use). Monitor glucose before, during, and after each infusion. ICU-level monitoring recommended for IV pentamidine.
AGENT SELECTION — DECISION ALGORITHM
| Step | Question | Action |
| 1 | Is PJP prophylaxis indicated? | Check risk table (Section 2). If YES → proceed to Step 2. |
| 2 | Any TMP/SMX allergy or intolerance? | No → USE TMP/SMX (preferred, Category 1). |
| 3 | TMP/SMX intolerant? | FIRST: Attempt TMP/SMX desensitization (NCCN recommendation). Only proceed to alternatives if desensitization fails or is contraindicated. |
| 4a | Can take oral meds AND G6PD normal? | Use Atovaquone 1500mg daily OR Dapsone 100mg daily. Atovaquone if G6PD deficiency or methemoglobinemia risk. Dapsone if cost is a concern and G6PD confirmed normal. |
| 4b | G6PD deficient or dapsone contraindicated? | Use Atovaquone 1500mg daily (no G6PD concern, potential Toxo coverage). If oral not feasible → pentamidine. |
| 4c | Unable to take oral agents (mucositis, gut failure, critical illness)? | Use IV Pentamidine 4 mg/kg q2–4 weeks (prophylaxis) or 4 mg/kg daily x21 days (treatment). |
| 4d | Can nebulize, no systemic/extrapulmonary PJP concern? | Aerosolized Pentamidine 300mg monthly via Respirgard II nebulizer. CAUTION: no upper lobe or extrapulmonary coverage. |
DURATION OF PROPHYLAXIS — QUICK REFERENCE
| Clinical Scenario | Duration | Stop Criteria |
| Allogeneic HCT | ≥6 months | AND while receiving IST |
| CAR T-cell / TCR / TIL therapy | ≥6 months | AND while receiving IST |
| ALL (acute lymphoblastic leukemia) | Throughout anti-leukemic therapy | Until completion of ALL therapy |
| Alemtuzumab | Minimum 2 months after last dose | AND until CD4 count >200 cells/mcL |
| Purine analogs / T-cell depleting agents (Category 2B) | 6–12 months | AND until CD4 count >200 cells/mcL |
| Autologous HCT (Category 2B) | 3–6 months post-transplant | Until immune reconstitution |
| Corticosteroids ≥20mg/day prednisone eq. ≥4 weeks | At least through active treatment | Taper steroids to below threshold |
| Temozolomide ± radiation | At least through active treatment | Until lymphocytopenia resolves |
MANAGEMENT OF ACTIVE / SUSPECTED PJP
Step-by-Step Treatment Approach
Step 1 — Risk Assessment & Severity Classification
- Mild-moderate: PaO2 >70 mmHg on room air OR A-a gradient <35 mmHg
- Moderate-severe: PaO2 <70 mmHg OR A-a gradient >35 mmHg OR requiring supplemental O2
Step 2 — Empiric Treatment (per NCCN)
- Start TMP/SMX empirically if PJP is in the differential diagnosis for diffuse pulmonary infiltrates
- NCCN empiric regimen PENDING BAL results:
- Respiratory fluoroquinolone (levofloxacin 750mg daily or moxifloxacin 400mg daily) for community-acquired bacterial coverage
- PLUS TMP/SMX at treatment dose for PJP coverage
- Add mold-active antifungal if allo-HCT with GVHD not on prophylaxis (eg, voriconazole)
- Add antiviral (oseltamivir) during influenza season if applicable
Step 3 — Definitive Treatment (Confirmed PJP)
- TMP/SMX: 8–15 mg/kg/day IV or PO in divided doses q6–8h (TMP component) x 21 days
- IV preferred for moderate-severe disease; switch to oral as tolerated (oral bioavailability ~100%)
- Alternative if TMP/SMX intolerant: IV pentamidine 4 mg/kg/day x 21 days, OR atovaquone (for mild-moderate disease)
Step 4 — Adjunctive Corticosteroids
Note: Not explicitly detailed in this NCCN section. Standard of care based on other guidelines (IDSA/evidence-based): prednisone 40mg PO BID x5 days → 40mg daily x5 days → 20mg daily x11 days for moderate-severe PJP (PaO2 <70 or A-a gradient >35). Should be started within 72 hours of anti-PJP therapy. Seek ID consultation.
Step 5 — Monitoring During Treatment
| Parameter | Frequency | Action Threshold |
| SCr / eGFR | Every 2–3 days | Rising SCr → consider dose reduction or switch. True nephrotoxicity vs. TMP-induced tubular secretion blockade (benign SCr rise). |
| CBC with differential | Every 3–5 days | TMP/SMX myelosuppression — may need leucovorin supplementation or dose reduction in severe cytopenias |
| Serum potassium | Every 2–3 days | Hyperkalemia (TMP blocks renal K+ excretion); treat if K+ >5.5 mEq/L |
| LFTs | Weekly | Hepatotoxicity — hold if significant elevation (>5x ULN) |
| Oxygenation | Daily (O2 sat, respiratory rate) | Worsening O2 in first 3–5 days can represent immune reconstitution — may need corticosteroids |
| Clinical response | Re-evaluate at 48–72 hours | No response after 2–3 days of broad-spectrum antibiotics → definitive diagnostic workup (BAL) is critical per NCCN |
KEY CLINICAL TRIALS — BRIEF SUMMARY
| Trial / Study | Population | Intervention | Comparator | Key Results |
| Green et al., Mayo Clin Proc 2007 (Systematic review, 12 RCTs, N=1,245) | Acute leukemia / HCT patients | TMP/SMX prophylaxis | Placebo, no Rx, or non-PJP antibiotics | 91% reduction in PJP occurrence (RR 0.09; 95% CI 0.02–0.32). 83% reduction in PJP-related mortality (RR 0.17; 95% CI 0.03–0.94). Category 1 recommendation basis. |
| El-Sadr et al., NEJM 1998 (CPCRA/ACTG) | HIV patients intolerant to TMP/SMX or sulfonamides | Atovaquone 1500mg daily | Dapsone 100mg daily | Atovaquone equivalent to dapsone for PJP prevention. Similar efficacy; atovaquone had fewer treatment failures from adverse reactions. Supports atovaquone as dapsone alternative. |
| Madden et al., Cancer 2007 | Pediatric ALL patients intolerant to TMP/SMX | Atovaquone prophylaxis | Historical controls / TMP/SMX | Atovaquone effective for PJP prophylaxis in pediatric ALL intolerant to TMP/SMX. Supported NCCN recommendation for pediatric use. |
| DeMasi et al., Pediatr Infect Dis J 2013 | Pediatric HCT patients | IV pentamidine prophylaxis | Historical / observational | IV pentamidine safe and effective as PRIMARY PJP prophylaxis in pediatric HCT. Supports use in patients unable to tolerate oral agents. |
| Diri et al., Transpl Infect Dis 2016 | Allogeneic HCT adults | IV pentamidine | Retrospective review | IV pentamidine effective for PJP prophylaxis in allo-HCT. Toxicity (hypoglycemia, renal) notable and requires monitoring. |
PHARMACIST WATCHOUTS — ROUNDS, TUMOR BOARD, CHEMO REVIEW & COUNSELING
A. Chemotherapy Review Watchouts
- TMP/SMX + MTX combination: Both inhibit DHFR (antifolate). High risk of severe myelosuppression and mucositis. Flag and monitor CBC aggressively. May need to time doses apart or switch PJP agent.
- Temozolomide regimens: PJP prophylaxis is mandatory. Do NOT allow TMZ orders to go through without PJP prophylaxis co-prescribed.
- Idelalisib / copanlisib / duvelisib (PI3K inhibitors): PJP prophylaxis required from treatment start. Do not miss this in chemo order review.
- Alemtuzumab: PJP prophylaxis must continue a MINIMUM of 2 months AFTER the last dose AND until CD4 >200. Alert team if it is stopped too early.
- CAR T-cell therapy: PJP prophylaxis required for ≥6 months AND while on IST (e.g., corticosteroids for CRS/ICANS).
B. Key Lab Cutoffs to Know
| Lab | Significance in PJP | Cutoff / Action |
| CD4 count | Guides duration of prophylaxis (alemtuzumab, purine analogs) | >200 cells/mcL = can consider stopping prophylaxis in those indications |
| G6PD level | Required before dapsone | If deficient → CONTRAINDICATION to dapsone. Switch to atovaquone. |
| Beta-D-glucan | Elevated in PJP | >80 pg/mL supportive of PJP (non-specific; also elevated in other fungal infections) |
| SCr / eGFR | TMP/SMX dosing and monitoring | CrCl <30 mL/min → dose adjustment required. TMP raises SCr by blocking tubular secretion — may not be true AKI. |
| Potassium | TMP/SMX hyperkalemia risk | >5.5 mEq/L → evaluate and treat; especially at-risk with ACEi/ARB/calcineurin inhibitors |
| LDH | PJP severity marker (non-specific) | Elevated LDH in setting of diffuse GGO + T-cell depletion → suspicious for PJP |
C. Patient Counseling Points
- TMP/SMX tablets: Can be taken with or without food. Take at the same time each day. Drink plenty of water.
- TMP/SMX — sun exposure: Avoid prolonged sun exposure; sulfonamide photosensitivity. Use sunscreen.
- Atovaquone suspension: MUST take with a high-fat meal (fatty snack, full meal). Shake the bottle well. If vomiting within 1 hour of dose, repeat dose.
- Dapsone: Report immediately: shortness of breath, blue-gray skin discoloration (methemoglobinemia). Do not stop without telling your doctor.
- Duration: Do not stop PJP prophylaxis early without physician guidance — it protects against a life-threatening infection. Duration depends on your type of cancer treatment.
- Compliance: Missing doses significantly increases risk of PJP. Set a daily alarm if needed.
D. Rounds & Tumor Board Prompts
- Is this patient on a regimen that requires PJP prophylaxis? (Check allo-HCT, CAR T, ALL, alemtuzumab, TMZ, PI3K inhibitors, steroids ≥20mg/day ≥4 weeks)
- Has TMP/SMX been prescribed? If not, is there a documented reason (allergy, intolerance, renal failure)?
- If on dapsone — was G6PD checked before starting?
- If on alemtuzumab — how long since last dose? Has CD4 been checked? Is it >200?
- If patient presents with diffuse bilateral GGO + not on PJP prophylaxis → push for BAL + empiric TMP/SMX NOW
- On MTX + TMP/SMX? → High-risk combination; alert team to monitor CBC closely
- If atovaquone prescribed — is patient actually eating with the medication?
- If IV pentamidine → Is glucose being monitored before, during, and after infusions? Is QTc/Mg/K+ being followed?
E. Clinical Pearls — Takeaways
| # | Clinical Pearl |
| 1 | PJP is a T-cell problem, NOT a neutrophil problem. A normal ANC does NOT rule out PJP risk. |
| 2 | Non-HIV oncology patients with PJP decompensate faster and have higher mortality than HIV patients. Treat aggressively and early. |
| 3 | If patient is hypoxic with bilateral GGO and not on PJP prophylaxis → start empiric TMP/SMX BEFORE waiting for BAL. |
| 4 | TMP/SMX is preferred (Category 1) and also covers Nocardia, Toxoplasma, and Listeria — critical for the heavily immunocompromised. |
| 5 | Before switching from TMP/SMX due to ‘allergy,’ always consider desensitization first (NCCN recommendation). |
| 6 | G6PD must be checked BEFORE starting dapsone — G6PD deficiency is a contraindication. |
| 7 | Dapsone can cause methemoglobinemia even in G6PD-normal patients. Pulse ox is falsely normal — need co-oximetry (ABG). |
| 8 | Atovaquone MUST be taken with a fatty meal — bioavailability is severely reduced without food. |
| 9 | IV pentamidine causes severe hypoglycemia (then hyperglycemia) — glucose monitoring is non-negotiable around each infusion. |
| 10 | Aerosolized pentamidine has poor upper lobe distribution and no extrapulmonary coverage — NOT appropriate as sole prophylaxis in the highest-risk patients. |
| 11 | TMP/SMX + MTX = dangerous antifolate combination. Flag every time in chemo review. |
| 12 | TMP can raise SCr by blocking tubular secretion (not always true AKI). Differentiate before stopping TMP/SMX unnecessarily. |
| 13 | TMP acts like a K+-sparing diuretic — monitor K+ especially in patients on ACEi/ARBs/calcineurin inhibitors. |
| 14 | BAL is the gold standard, but sputum induction diagnoses only ~60% of PJP in non-HIV patients. Always follow negative sputum induction with BAL. |
NCCN Guidelines Version 1.2026 | Prevention and Treatment of Cancer-Related Infections | March 11, 2026
For clinical/educational use. Always verify against current institutional guidelines and full NCCN publication.