The Daily Differential — Thursday, April 30, 2026

2 of 5

Tick-Borne Disease

Tick-borne illnesses can progress rapidly to shock, meningoencephalitis, carditis, respiratory failure, or hemolytic anemia. Empiric doxycycline saves lives...

At the Bedside

History: geography/travel, outdoor exposure, pets, tick bite, timing, fever, rash, headache, myalgias, arthralgias, neurologic symptoms, immunocompromise/asplenia.
Key syndromes:
Rocky Mountain spotted fever: fever, severe headache, myalgias, GI symptoms; rash often starts wrists/ankles then palms/soles, but may be absent early.
Lyme disease: erythema migrans, facial palsy, meningitis, radiculopathy, AV block, migratory arthritis.
Ehrlichiosis/anaplasmosis: fever, headache, myalgias, leukopenia, thrombocytopenia, transaminitis; rash less common, especially anaplasmosis.
Babesiosis: malaria-like illness, hemolytic anemia, thrombocytopenia; severe in asplenia/immunocompromise.
Tularemia: ulceroglandular disease, pneumonia, sepsis; rabbit/tick exposure.
Workup:
CBC, CMP/LFTs, bilirubin, hemolysis labs if babesiosis suspected, UA, pregnancy test.
ECG if Lyme carditis symptoms, syncope, palpitations, chest pain, dyspnea.
Blood cultures if septic; smear/PCR for babesiosis where available.
Serology/PCR may be negative early; do not delay empiric treatment for RMSF/ehrlichiosis/anaplasmosis.
POCUS/ED monitoring: assess volume status in sepsis; cardiac monitoring for suspected Lyme carditis.
Disposition:
Discharge reliable, nontoxic patients after treatment plan.
Admit for sepsis, altered mental status, meningitis/encephalitis, hypoxia, severe lab abnormalities, pregnancy with severe illness, immunocompromise, high-grade AV block, severe babesiosis, or inability to tolerate PO.

A Classic Presentation

A 42-year-old hiker presents in July with fever, severe headache, myalgias, vomiting, thrombocytopenia, hyponatremia, and elevated AST/ALT. He has a faint petechial rash on wrists and ankles. RMSF is suspected. Doxycycline 100 mg PO/IV BID is started immediately before serology returns, and he is admitted due to systemic illness and lab abnormalities.

Study Directive

Make a one-page tick-borne illness chart: organism/vector, region, rash, labs, treatment.
Memorize the “RMSF lab triad”: thrombocytopenia, hyponatremia, elevated transaminases.
Practice three ECG-based Lyme carditis dispositions: normal ECG, PR prolongation, high-grade AV block.
Review when babesiosis needs admission and exchange transfusion consideration.

Key Medications

Doxycycline: 100 mg PO/IV BID.
First-line for RMSF, ehrlichiosis, anaplasmosis, and many Lyme presentations.
Use in children when RMSF suspected; short courses are recommended despite historical tooth-staining concern.
Lyme erythema migrans: doxycycline 100 mg PO BID x 10 days; alternatives include amoxicillin 500 mg PO TID x 14 days or cefuroxime 500 mg PO BID x 14 days.
Lyme facial palsy/meningitis without severe carditis: doxycycline often appropriate; duration commonly 14–21 days, verify with protocol.
Severe Lyme carditis or neuroborreliosis: ceftriaxone 2 g IV daily, usually 14–21 days.
Babesiosis, mild-moderate: atovaquone 750 mg PO BID + azithromycin 500 mg PO day 1, then 250 mg PO daily, typically 7–10 days.
Babesiosis, severe: clindamycin 600 mg IV q6h + quinine 650 mg PO q6–8h; exchange transfusion may be needed. Check institutional protocol.
Tularemia severe: gentamicin 5 mg/kg IV/IM daily; dosing varies by renal function/institution—check reference.

High-Yield Pearls

RMSF rash can be absent early; fever + headache + thrombocytopenia/transaminitis in tick season is enough to treat.
Doxycycline is the empiric “tick fever” drug for RMSF, ehrlichiosis, and anaplasmosis.
Lyme carditis can cause fluctuating AV block; syncope or PR prolongation warrants monitoring/admission.

Board Question

A febrile patient from an endemic area has headache, thrombocytopenia, hyponatremia, elevated transaminases, and a rash involving wrists and ankles. What is the best next step?

AWait for acute and convalescent serology
BStart doxycycline immediately
CGive amoxicillin only
DGive oseltamivir

Reveal answer

Correct: B

RMSF is a clinical diagnosis early, and delayed doxycycline increases mortality. Serology is often negative early and should not delay therapy.

Recent Literature

Review or guideline Emerging Tick-Borne Diseases
Clin Microbiol Rev, 2020 · cited 590×

Full text · open access
Recent clinical A potent Gc neutralizing antibody reveals architecture-dependent bispecific protection against SFTSV
Emerg Microbes Infect, 2026

Full text · open access

3 of 5

Urogenital Infections

Urogenital infections range from uncomplicated cystitis to septic obstructing pyelonephritis, PID, testicular infection, and STI emergencies. The ED...

At the Bedside

History: dysuria, frequency, flank pain, fever, vaginal/urethral discharge, pelvic/testicular pain, pregnancy, instrumentation, stones, immunocompromise, prior resistant organisms, sexual exposures.
Exam:
CVA tenderness, abdominal tenderness, sepsis signs.
Pelvic exam if discharge, pelvic pain, bleeding, PID concern, cervicitis.
Testicular exam for epididymitis vs torsion; torsion is sudden severe pain, high-riding testis, absent cremasteric reflex.
Prostate exam if suspected prostatitis; avoid vigorous massage.
Testing:
UA with microscopy, urine culture for pyelo/complicated UTI/pregnancy/recurrent infection.
Pregnancy test in patients with pregnancy potential.
GC/CT NAAT from urine or swab; wet prep if vaginitis; HIV/syphilis testing when STI risk.
CBC/CMP/lactate/blood cultures if septic or admitted.
CT abdomen/pelvis if stone, obstruction, emphysematous infection, abscess, severe/refractory symptoms, or high-risk patient.
Scrotal ultrasound if torsion cannot be excluded.
Management decision points:
Uncomplicated cystitis: outpatient oral antibiotics.
Pyelonephritis: assess PO tolerance, sepsis, pregnancy, obstruction, comorbidity; give initial IV antibiotics if moderate/severe or local resistance concern.
Obstructed infected stone: urologic emergency—broad-spectrum IV antibiotics + urgent decompression.
PID: treat empirically if pelvic/lower abdominal pain plus cervical motion, uterine, or adnexal tenderness without better diagnosis.
Epididymitis: treat based on age/risk; rule out torsion first.

A Classic Presentation

A 24-year-old woman presents with dysuria, fever, right flank pain, nausea, and CVA tenderness. UA shows pyuria and nitrites; pregnancy test is negative. She is tachycardic but normotensive and tolerating PO after antiemetics. She receives ceftriaxone 1 g IV, urine culture is sent, and she is discharged on an appropriate oral pyelonephritis regimen with strict return precautions.

Study Directive

Build an antibiotic grid for cystitis, pyelo, PID, urethritis, epididymitis, and prostatitis.
Practice disposition decisions for five UTI cases: simple cystitis, pyelo tolerating PO, pregnant pyelo, septic stone, recurrent ESBL UTI.
Review scrotal pain algorithms and rehearse “torsion first” decision-making.
Memorize current ceftriaxone dosing for gonorrhea by weight cutoff.

Key Medications

Uncomplicated cystitis:
Nitrofurantoin 100 mg PO BID x 5 days.
TMP-SMX DS 160/800 mg PO BID x 3 days if local resistance acceptable and no contraindication.
Fosfomycin 3 g PO once.
Pyelonephritis outpatient options:
Ceftriaxone 1 g IV/IM once, then oral therapy based on local resistance.
Ciprofloxacin 500 mg PO BID x 7 days or levofloxacin 750 mg PO daily x 5 days if susceptible/appropriate.
TMP-SMX DS 160/800 mg PO BID x 14 days if susceptible.
Complicated UTI/urosepsis: ceftriaxone 1–2 g IV q24h, cefepime 2 g IV q8–12h, piperacillin-tazobactam 4.5 g IV q6h, or carbapenem for ESBL risk; tailor to renal function/local antibiogram.
Gonorrhea: ceftriaxone 500 mg IM once if <150 kg; 1 g IM once if ≥150 kg. Add doxycycline if chlamydia not excluded.
Chlamydia/NGU: doxycycline 100 mg PO BID x 7 days.
PID outpatient: ceftriaxone 500 mg IM once + doxycycline 100 mg PO BID x 14 days + metronidazole 500 mg PO BID x 14 days.
Epididymitis likely GC/CT: ceftriaxone 500 mg IM once + doxycycline 100 mg PO BID x 10 days.
Epididymitis enteric organisms: levofloxacin 500 mg PO daily x 10 days if gonorrhea ruled out.
Pediatric, pregnancy, renal impairment, and local resistance patterns meaningfully alter choices—check institutional guidance.

High-Yield Pearls

Pyuria + obstructing stone + systemic illness = infected obstruction until proven otherwise.
PID is a clinical diagnosis; do not wait for GC/CT results if exam supports it.
Testicular torsion can mimic epididymitis; sudden severe pain or abnormal lie requires emergent torsion evaluation.

Board Question

A patient with fever, flank pain, pyuria, and CT showing a 7 mm obstructing ureteral stone with hydronephrosis becomes hypotensive. Best management?

ADischarge with oral antibiotics and urology follow-up
BNSAIDs and trial of passage
CIV antibiotics and urgent urologic decompression
DImmediate lithotripsy in the ED

Reveal answer

Correct: C

An infected obstructing stone is a source-control emergency. Treat sepsis with IV antibiotics and fluids, and obtain urgent decompression by ureteral stent or nephrostomy.

Recent Literature

Review or guideline Bacterial Vaginosis: What Do We Currently Know?
Front Cell Infect Microbiol, 2021 · cited 213×

Full text · open access
Recent clinical Monkeypox virus replication and host response in vaginal and ectocervical epithelial cells
Virulence, 2026

Full text · open access

4 of 5

Addiction Medicine

Substance use disorders are chronic, treatable diseases, and the ED visit is a high-impact moment to reduce mortality. ED-initiated buprenorphine, naloxone...

At the Bedside

Core ED approach:
Stabilize ABCs, treat toxidromes/withdrawal, screen for co-ingestions, suicidality, trauma, infection, pregnancy, and social needs.
Use person-first language: “person with opioid use disorder,” not “addict.”
Offer medications for opioid use disorder and harm-reduction tools.
Opioid intoxication:
Respiratory depression, miosis, decreased mental status.
Treat ventilation first; naloxone to restore breathing, not necessarily full arousal.
Observe for recurrent sedation, especially long-acting opioids or polysubstance use.
Opioid withdrawal/OUD:
Symptoms: mydriasis, yawning, rhinorrhea, piloerection, diarrhea, vomiting, myalgias, anxiety.
Use COWS; start buprenorphine when moderate withdrawal is present to avoid precipitated withdrawal.
Provide bridge prescription and rapid follow-up when possible.
Stimulant use disorder/intoxication:
Cocaine/meth: agitation, hyperthermia, chest pain, hypertension, psychosis, rhabdo.
Treat with benzodiazepines, cooling, fluids, cardiac evaluation as indicated.
Sedative-hypnotic use disorder:
Benzodiazepine/barbiturate withdrawal can cause seizures and death; treat with long-acting benzodiazepines or phenobarbital-based protocols.
Injection-related complications:
Look for cellulitis, abscess, endocarditis, septic thrombophlebitis, epidural abscess, HIV/hepatitis.
Offer sterile injection resources where legal/available.
Disposition:
Discharge with naloxone, buprenorphine plan if appropriate, follow-up, and harm-reduction counseling.
Admit for severe withdrawal, overdose requiring repeated naloxone/infusion, serious infection, suicidality, pregnancy complications, unstable housing with medical risk, or severe polysubstance toxicity.

A Classic Presentation

A 31-year-old man presents requesting help after daily fentanyl use. He last used 18 hours ago and has vomiting, diarrhea, mydriasis, yawning, piloerection, and COWS 14. He receives buprenorphine 8 mg SL, improves after repeat dosing to 16 mg total, receives take-home naloxone, harm-reduction counseling, and next-day addiction clinic follow-up with a bridge prescription.

Study Directive

Practice calculating a COWS score from three sample patients and deciding when to give buprenorphine.
Memorize naloxone titration endpoints and infusion calculation.
Create a discharge checklist: naloxone, buprenorphine/bridge plan, follow-up, HIV/hepatitis testing, safer-use counseling.
Review local laws/protocols for buprenorphine prescribing and methadone administration.

Key Medications

Naloxone:
IV: start 0.04 mg IV, repeat/titrate every 2–3 min to adequate respirations; escalate to 0.4 mg, then 2 mg if needed.
IN: commonly 4 mg intranasal spray, repeat every 2–3 min as needed.
Infusion: use about 2/3 of the effective reversal dose per hour, titrate to respirations.
Buprenorphine for opioid withdrawal/OUD:
Standard ED induction: 8 mg SL when COWS generally ≥8–12, reassess in 30–60 min; repeat 8 mg SL as needed. Typical day-1 total 16 mg, sometimes up to 24–32 mg depending on protocol.
Dose ranges vary; check institutional protocol for high-dose or micro-induction strategies.
Clonidine for withdrawal symptoms: 0.1 mg PO q6–8h PRN, hold for hypotension/bradycardia.
Ondansetron: 4–8 mg PO/IV q6–8h PRN.
Loperamide: 4 mg PO once, then 2 mg after each loose stool, max OTC 8 mg/day or prescription 16 mg/day.
Stimulant agitation: lorazepam 1–2 mg IV/IM q5–10 min PRN or diazepam 5–10 mg IV q5–10 min PRN, titrate to calm.
Methadone: ED/hospital initiation rules and dosing are regulated and protocol-dependent; initial doses often 20–30 mg PO with day-1 maximum limits. Check local policy.

High-Yield Pearls

Naloxone endpoint is adequate ventilation, not full wakefulness.
Buprenorphine given too early can precipitate withdrawal, especially after fentanyl exposure; use objective withdrawal signs and local protocols.
Addiction care is emergency care: start treatment, reduce harm, and arrange rapid follow-up.

Board Question

A patient with opioid use disorder presents in moderate withdrawal and wants treatment. Which ED intervention is most likely to improve engagement in care and reduce illicit opioid use?

ADischarge with a list of clinics only
BED-initiated buprenorphine with facilitated follow-up
CHaloperidol for withdrawal symptoms
DNaloxone only, no further treatment

Reveal answer

Correct: B

ED-initiated buprenorphine plus linkage to follow-up improves treatment engagement and reduces ongoing illicit opioid use compared with referral alone.

Recent Literature

Review or guideline ACG Clinical Guideline: Alcohol-Associated Liver Disease
Am J Gastroenterol, 2024 · cited 210×

Full text · open access
Recent clinical A neuroimmune framework for understanding adolescent stress and risk of alcohol misuse
Brain Behav Immun Health, 2026

Full text · open access

5 of 5

Alcohol Dependence and Abuse

Alcohol-related ED visits include intoxication, trauma, withdrawal, seizures, Wernicke encephalopathy, ketoacidosis, pancreatitis, hepatitis, and chronic...

At the Bedside

Initial ED priorities:
ABCs, glucose, temperature, trauma evaluation, co-ingestions, suicidality, capacity, and safe disposition.
Check point-of-care glucose early in altered patients.
Alcohol intoxication:
Diagnosis of exclusion; do not attribute coma solely to ethanol.
Evaluate for head trauma, hypoglycemia, hypothermia, infection, toxic alcohols, hepatic failure.
Observe until clinically sober and safe; consider CT head/labs if atypical course.
Alcohol withdrawal timeline:
6–24 hr: tremor, anxiety, tachycardia, HTN, insomnia, GI symptoms.
12–48 hr: seizures.
48–96 hr: delirium tremens—confusion, autonomic instability, hallucinations.
Workup for withdrawal/severe AUD:
Glucose, CMP/Mg/Phos, CBC, ethanol level when useful, pregnancy test, ECG, CK if prolonged down time/agitation, LFTs/lipase if indicated.
Consider infection/trauma/ICH if altered or febrile.
Treatment principles:
Give thiamine early, especially malnourished or altered patients.
Benzodiazepines are first-line for withdrawal; phenobarbital is effective as monotherapy or adjunct depending on protocol.
Correct Mg/K/Phos; treat dehydration and alcoholic ketoacidosis with dextrose-containing fluids after thiamine when feasible.
Disposition:
Discharge only if mild symptoms, stable vitals, no severe comorbidity, no history of severe withdrawal/seizures/DTs, and reliable support/follow-up.
Admit for severe withdrawal, hallucinosis, seizures, DTs, significant electrolyte derangement, pancreatitis/hepatitis, GI bleed, suicidality, pregnancy, or unsafe social situation.
ICU for refractory withdrawal, high-dose sedative needs, respiratory compromise, severe autonomic instability, or delirium tremens.

A Classic Presentation

A 56-year-old man with daily heavy alcohol use stopped drinking 24 hours ago and presents with tremor, diaphoresis, vomiting, HR 128, BP 176/102, and visual hallucinations. Glucose is normal; Mg is low. He receives IV thiamine, lorazepam 4 mg IV with repeated symptom-triggered dosing, magnesium repletion, fluids, and admission for severe alcohol withdrawal with close monitoring.

Study Directive

Memorize the alcohol withdrawal timeline and match symptoms to hours since last drink.
Practice three treatment pathways: mild withdrawal discharge, severe withdrawal admission, refractory withdrawal ICU.
Review your institution’s benzodiazepine vs phenobarbital protocol and dosing limits.
Write from memory the Wernicke triad and high-dose thiamine regimen.

Mechanism Pearl of the Day: Many of today’s topics hinge on recognizing syndromic patterns before confirmatory tests return: syphilis stages, tick fever labs/rash, STI/UTI anatomy, opioid withdrawal physiology, and alcohol withdrawal neuroadaptation. In the ED, mechanism-driven pattern recognition often determines when to treat empirically.

Key Medications

Thiamine:
Prevention in AUD/malnutrition: 100 mg IV/IM/PO daily.
Suspected Wernicke encephalopathy: commonly 500 mg IV TID x 2–3 days, then 250 mg IV/IM daily; regimens vary—check protocol.
Lorazepam withdrawal dosing: 2–4 mg PO/IV/IM q15–20 min for moderate-severe symptoms until controlled, then symptom-triggered or scheduled taper.
Diazepam: 10–20 mg PO/IV q5–15 min until calm/lightly sedated; avoid/caution in severe liver disease.
Chlordiazepoxide: 25–100 mg PO, repeated based on symptoms; useful outpatient/inpatient mild-moderate withdrawal, avoid/caution in liver failure/elderly.
Phenobarbital: loading commonly 10–15 mg/kg IV/IM total, often divided and titrated; adjunct doses 130–260 mg IV may be used. Respiratory depression risk, especially with benzodiazepines—follow institutional protocol.
Magnesium sulfate: 2 g IV for significant hypomagnesemia, torsades risk, or seizures with low Mg.
Dextrose: D50 25 g IV for severe hypoglycemia; for alcoholic ketoacidosis use dextrose-containing fluids such as D5NS/D5LR after thiamine when feasible.
AUD relapse prevention from ED: naltrexone may be considered in selected patients, commonly 50 mg PO daily, but avoid in acute hepatitis/liver failure or current opioid use/dependence; confirm suitability and follow-up.

High-Yield Pearls

Alcohol withdrawal is a hyperadrenergic state from unopposed excitatory signaling after chronic GABA adaptation.
Withdrawal seizures are usually generalized and occur 12–48 hours after last drink; focal seizures require broader evaluation.
Intoxication is never a complete diagnosis for altered mental status—check glucose and look for trauma/co-ingestions.

Board Question

A chronic alcohol user presents with confusion, ataxia, and ophthalmoplegia. What treatment should be given immediately?

AHaloperidol only
BThiamine IV
CFlumazenil
DNaltrexone

Reveal answer

Correct: B

Confusion, ataxia, and ophthalmoplegia suggest Wernicke encephalopathy. Give high-dose IV thiamine immediately; do not wait for imaging or labs.

Recent Literature

Review or guideline Stigma, social inequality and alcohol and drug use
Drug Alcohol Rev, 2005 · cited 891×
Recent clinical Substance use among incarcerated male population in Freetown, Sierra Leone: Prevalence, predictors, and risk profiles using the WHO ASSIST
Glob Public Health, 2026

Full text · open access

TheDaily Differential

Syphilis

At the Bedside

Study Directive

Recent Literature

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