A 65-year-old man with diabetes presents with a non-healing foot ulcer for 3 months. X-ray shows osteolytic changes in the underlying bone. MRI confirms osteomyelitis. What is the most appropriate treatment duration for antibiotics?

4-6 weeks IV followed by 2-6 weeks oral

A 35-year-old man with HIV infection (CD4 count 80 cells/mm³, viral load 125,000 copies/mL, not on antiretroviral therapy) presents with a 4-week history of headache, fever, and confusion. CT head shows basal meningeal enhancement and multiple small nodules. Lumbar puncture shows: opening pressure 32 cmH2O, CSF white cells 45/mm³ (80% lymphocytes), protein 1.2 g/L, glucose 1.9 mmol/L (serum glucose 5.4 mmol/L). India ink stain is positive. Cryptococcal antigen is positive in both CSF and serum at titres of 1:2048 and 1:1024 respectively. He is started on liposomal amphotericin B and flucytosine. Which one of the following additional interventions has been shown to improve survival in this patient?

Performing daily therapeutic lumbar punctures until opening pressure normalizes

Commencing antiretroviral therapy immediately alongside antifungal treatment

Adding adjunctive dexamethasone 0.4 mg/kg daily for 6 weeks

Adding adjunctive interferon-gamma to enhance immune response

Inserting a ventriculoperitoneal shunt to manage hydrocephalus

A 48-year-old woman from Kazakhstan is diagnosed with pulmonary tuberculosis. Initial molecular testing (GeneXpert MTB/RIF) detects Mycobacterium tuberculosis with rifampicin resistance. Subsequent culture and phenotypic drug susceptibility testing confirms resistance to rifampicin and isoniazid, but the isolate is sensitive to pyrazinamide, ethambutol, fluoroquinolones, bedaquiline, and linezolid. She has a history of seizures controlled with carbamazepine and is otherwise well. Which one of the following represents the most significant drug interaction that needs to be considered when designing her MDR-TB treatment regimen?

Carbamazepine induces cytochrome P450 enzymes which will reduce levels of bedaquiline and fluoroquinolones

Linezolid may reduce seizure threshold and interact with carbamazepine

Bedaquiline requires dose adjustment due to carbamazepine-induced enzyme induction

Moxifloxacin may prolong QT interval which is exacerbated by carbamazepine

Clofazimine absorption is significantly reduced by carbamazepine

A 28-year-old previously healthy man is admitted with suspected bacterial meningitis. He is treated empirically with IV ceftriaxone 2 g twice daily and IV dexamethasone 10 mg four times daily. Lumbar puncture performed before antibiotics shows: CSF white cells 2,100/mm³ (90% neutrophils), protein 2.3 g/L, glucose 1.5 mmol/L (serum glucose 6.0 mmol/L). Blood and CSF cultures taken on admission subsequently grow Streptococcus pneumoniae fully sensitive to penicillin (penicillin MIC 0.06 mg/L). He improves clinically over 48 hours. Which one of the following represents the most appropriate modification to his antimicrobial therapy at this stage?

Switch to benzylpenicillin 2.4 g four-hourly and stop dexamethasone

Continue ceftriaxone 2 g twice daily and stop dexamethasone

Switch to benzylpenicillin 2.4 g four-hourly and continue dexamethasone

Switch to amoxicillin 2 g four-hourly and continue dexamethasone

Continue ceftriaxone 2 g twice daily and continue dexamethasone for the full 10-day course

A 56-year-old man with end-stage renal failure on haemodialysis three times per week is diagnosed with fully drug-sensitive pulmonary tuberculosis. He weighs 70 kg. His renal function shows: creatinine 680 micromol/L, eGFR <10 mL/min/1.73m². Which one of the following represents the most appropriate dosing regimen for the intensive phase of treatment?

Rifampicin 600 mg once daily, isoniazid 300 mg once daily, pyrazinamide 1.5 g three times per week post-dialysis, ethambutol 600 mg three times per week post-dialysis

Rifampicin 450 mg once daily, isoniazid 200 mg once daily, pyrazinamide 1 g once daily, ethambutol 800 mg three times per week post-dialysis

Rifampicin 600 mg three times per week post-dialysis, isoniazid 300 mg three times per week post-dialysis, pyrazinamide 25 mg/kg three times per week post-dialysis, ethambutol 15 mg/kg three times per week post-dialysis

Rifampicin 600 mg once daily, isoniazid 300 mg three times per week post-dialysis, pyrazinamide 25 mg/kg three times per week post-dialysis, ethambutol 15 mg/kg three times per week post-dialysis

Rifampicin 600 mg once daily, isoniazid 300 mg once daily, pyrazinamide 500 mg once daily, ethambutol 400 mg once daily

Meningitis for UKMLA AKT: High-Yield Infectious Diseases Lessons

Quick Overview

Meningitis is inflammation of the meninges requiring emergency recognition and treatment. NICE NG240 emphasizes immediate antibiotic administration before transfer/investigations if suspected. Bacterial meningitis (mortality 10-15%) demands urgent intervention; viral is self-limiting. Key skills: recognizing clinical features, interpreting CSF parameters, administering pre-hospital antibiotics, and providing chemoprophylaxis to contacts.

Core Facts & Concepts

Clinical Features (Classical Triad in 44% only)

Headache (severe, sudden-onset)
Fever (>38°C)
Neck stiffness (meningism)
Additional: photophobia, altered consciousness (GCS <14), seizures, non-blanching rash

Emergency Antibiotic Timing (NICE NG240)

Pre-hospital: IM/IV benzylpenicillin 1.2g (adult) if suspected bacterial meningitis
Hospital <1 hour: IV ceftriaxone 2g (adult) before LP if no contraindication
Do NOT delay antibiotics for LP/imaging if bacterial meningitis suspected

LP Contraindications

GCS ≤12 or deteriorating consciousness
Focal neurological signs
Papilloedema
Signs of raised ICP (bradycardia, hypertension, irregular respirations)
Coagulopathy (platelets <100, INR >1.4)
Infection at LP site

![CSF microscopy showing numerous polymorphonuclear neutrophils in bacterial meningitis](Image: bacterial meningitis CSF microscopy)

CSF Interpretation Thresholds

Parameter	Bacterial	Viral	Normal
Appearance	Turbid/cloudy	Clear	Clear
WCC (cells/mm³)	>1000 (PMN)	10-1000 (lymph)	<5
Protein (g/L)	>1.0	0.4-1.0	<0.45
Glucose (CSF:blood)	<0.4	>0.6	>0.6
Opening pressure	↑↑ (>25 cmH₂O)	Normal/↑	10-20 cmH₂O

Problem-Solving Approach

Emergency Management Sequence

Recognize meningitis signs (headache + fever ± meningism)
Assess severity: GCS, signs of raised ICP, septic shock
Blood cultures + blood glucose (for CSF:blood ratio)
Antibiotics within 1 hour: IV ceftriaxone 2g BD (+ ampicillin if >55 years/immunocompromised for Listeria)
CT head before LP if: GCS ≤12, focal signs, papilloedema, seizures, immunocompromised
LP if safe: opening pressure, cell count/differential, protein, glucose, Gram stain, culture, PCR (meningococcal/pneumococcal)
Dexamethasone: 10mg IV QDS for 4 days if bacterial suspected (before/with first antibiotic dose)

Figure 1: Non-blanching purpuric rash on skin indicating meningococcal septicaemia

🚩 Red Flags

Non-blanching rash = meningococcal septicaemia (antibiotics IMMEDIATELY)
Rapid deterioration in GCS
Signs of raised ICP (Cushing's triad)

Analysis Framework

Bacterial vs Viral Differentiation

Feature	Bacterial	Viral
Onset	Hours (rapid)	Days (gradual)
Severity	Critically unwell	Mild-moderate
Rash	Purpuric (meningococcal)	Absent
CSF WCC	>1000 PMN	10-1000 lymphocytes
CSF protein	>1.0 g/L	0.4-1.0 g/L
CSF glucose	<40% blood	>60% blood
Gram stain	Positive (60-90%)	Negative

Chemoprophylaxis for Contacts (NICE NG240)

Who: Household/kissing contacts within 7 days of illness onset
When: Within 24 hours of index case diagnosis
Regimen:
- Ciprofloxacin 500mg single dose (adult) OR
- Rifampicin 600mg BD for 2 days (adult)
Applies to: Meningococcal and Hib meningitis only

Visual Aid

Common Causative Organisms by Age

Age Group	Most Common Organisms
Neonates (<3 months)	Group B Strep, E. coli, Listeria
Children/Adults	N. meningitidis, S. pneumoniae
>55 years	S. pneumoniae, Listeria, Gram-negatives
Immunocompromised	Listeria, TB, Cryptococcus

Key Points Summary

✓ Antibiotics <1 hour: IV ceftriaxone 2g before LP if bacterial meningitis suspected (NICE NG240)

✓ CSF thresholds: Bacterial = WCC >1000 PMN, protein >1.0, glucose <40% blood; Viral = lymphocytic, protein 0.4-1.0, glucose >60%

✓ LP contraindications: GCS ≤12, focal signs, papilloedema, raised ICP signs, coagulopathy

✓ Dexamethasone 10mg IV QDS for 4 days if bacterial meningitis (give before/with antibiotics)

✓ Chemoprophylaxis: Ciprofloxacin 500mg single dose for household/kissing contacts within 24 hours (meningococcal/Hib only)

✓ Non-blanching rash = meningococcal septicaemia requiring immediate antibiotics (don't wait for LP)

✓ Add ampicillin to ceftriaxone if >55 years/immunocompromised for Listeria coverage

⚠️ Warning: Never delay antibiotics for imaging or LP in suspected bacterial meningitis - mortality increases significantly with treatment delay

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Meningitis