Last updated: April 19, 2026Bookmark
Malignant otitis externa is an invasive bacterial infection of the external ear. It occurs in diabetic patients and other immunocompromised patients, typically following ear trauma.
The mortality rate, even with the best care, is nearly 10%.
- Patient history
- Diabetes mellitus
- Immunocompromise
- History of ear trauma
- Signs and symptoms
- Otalgia
- Unrelenting
- Deep and piercing quality
- Ear swelling
- Scant drainage
- Erythema with or without a small amount of granulation tissue in the external auditory canal
- Symptoms may slowly progress over days to weeks
- Facial nerve palsy
- Otalgia
- Investigations
- CT scan
- Culture
- Grows Pseudomonas aeruginsa
- Treatment
- IV antibiotics for 6 – 8 weeks with double coverage of Pseudomonas
- Aminoglycoside + fourth-generation cephalosporin + anti-pseudomonal penicillin/fluoroquinolone
- IV antibiotics for 6 – 8 weeks with double coverage of Pseudomonas
- Complications
- Osteomyelitis of the temporal bone
- Facial nerve palsy
Reference Intervals
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Biochemistry
| ACTH | P: <80 ng/L |
| ALT | P: 5–35 U/L |
| Albumin | P: 35–50 g/L |
| Aldosterone | P: 100–500 pmol/L |
| Alk. phosphatase | P: 30–130 U/L |
| α-Amylase | P: 0–180 IU/dL |
| α-Fetoprotein | S: <10 kU/L |
| Angiotensin II | P: 5–35 pmol/L |
| ADH | P: 0.9–4.6 pmol/L |
| AST | P: 5–35 U/L |
| Bicarbonate | P: 24–30 mmol/L |
| Bilirubin | P: 3–17 μmol/L |
| BNP | P: <50 ng/L |
| CRP | P: <10 mg/L |
| Calcitonin | P: <0.1 mcg/L |
| Calcium (ionized) | P: 1.0–1.25 mmol/L |
| Calcium (total) | P: 2.12–2.60 mmol/L |
| Chloride | P: 95–105 mmol/L |
| Cholesterol | P: <5.0 mmol/L |
| VLDL | P: 0.128–0.645 mmol/L |
| LDL | P: <2.0 mmol/L |
| HDL | P: 0.9–1.93 mmol/L |
| Cortisol AM | P: 450–700 nmol/L |
| Cortisol Midnight | P: 80–280 nmol/L |
| CK ♂ | P: 25–195 U/L |
| CK ♀ | P: 25–170 U/L |
| Creatinine | P: 70–100 μmol/L |
| Ferritin | P: 12–200 mcg/L |
| Folate | S: 2.1 mcg/L |
| FSH | P: 2–8 U/L ♂; >25 menopause |
| GGT ♂ | P: 11–51 U/L |
| GGT ♀ | P: 7–33 U/L |
| Glucose (fasting) | P: 3.5–5.5 mmol/L |
| Growth hormone | P: <20 mu/L |
| HbA1C (DCCT) | B: 4–6% |
| HbA1C (IFCC) | B: 20–42 mmol/mol |
| Iron ♂ | S: 14–31 μmol/L |
| Iron ♀ | S: 11–30 μmol/L |
| Lactate (venous) | P: 0.6–2.4 mmol/L |
| Lactate (arterial) | P: 0.6–1.8 mmol/L |
| LDH | P: 70–250 U/L |
| LH | P: 3–16 U/L |
| Magnesium | P: 0.75–1.05 mmol/L |
| Osmolality | P: 278–305 mosmol/kg |
| PTH | P: 0.8–8.5 pmol/L |
| Potassium | P: 3.5–5.3 mmol/L |
| Prolactin ♂ | P: <450 U/L |
| Prolactin ♀ | P: <600 U/L |
| PSA | P: 0–4 mcg/mL |
| Protein (total) | P: 60–80 g/L |
| Red cell folate | B: 0.36–1.44 μmol/L |
| Renin (erect) | P: 2.8–4.5 pmol/mL/h |
| Renin (recumbent) | P: 1.1–2.7 pmol/mL/h |
| Sodium | P: 135–145 mmol/L |
| TBG | P: 7–17 mg/L |
| TSH | P: 0.5–4.2 mU/L |
| T4 | P: 70–140 nmol/L |
| Free T4 | P: 9–22 pmol/L |
| TIBC | S: 54–75 μmol/L |
| Triglycerides | P: 0.50–2.3 mmol/L |
| T3 | P: 1.2–3.0 nmol/L |
| Troponin T | P: <0.1 mcg/L |
| Urate ♂ | P: 210–480 μmol/L |
| Urate ♀ | P: 150–390 μmol/L |
| Urea | P: 2.5–6.7 mmol/L |
| Vitamin B12 | S: 0.13–0.68 nmol/L |
| Vitamin D | S: 50 nmol/L |
Arterial Blood Gases
| pH | 7.35–7.45 |
| PaCO₂ | 4.7–6.0 kPa |
| PaO₂ | >10.6 kPa |
| Base excess | ±2 mmol/L |
Urine
| Cortisol (free) | <280 nmol/24h |
| Hydroxyindole acetic acid | 16–73 μmol/24h |
| Hydroxymethylmandelic acid | 16–48 μmol/24h |
| Metanephrines | 0.03–0.69 μmol/mmol cr. |
| Osmolality | 350–1000 mosmol/kg |
| 17-Oxogenic steroids ♂ | 28–30 μmol/24h |
| 17-Oxogenic steroids ♀ | 21–66 μmol/24h |
| 17-Oxosteroids ♂ | 17–76 μmol/24h |
| 17-Oxosteroids ♀ | 14–59 μmol/24h |
| Phosphate (inorganic) | 15–50 mmol/24h |
| Potassium | 14–120 mmol/24h |
| Protein | <150 mg/24h |
| Protein/creatinine ratio | <3 mg/mmol |
| Sodium | 100–250 mmol/24h |
Haematology
| WCC | 4.0–11.0 ×10⁹/L |
| RBC ♂ | 4.5–6.5 ×10¹²/L |
| RBC ♀ | 3.9–5.6 ×10¹²/L |
| Hb ♂ | 130–180 g/L |
| Hb ♀ | 115–160 g/L |
| PCV ♂ | 0.4–0.54 L/L |
| PCV ♀ | 0.37–0.47 L/L |
| MCV | 76–96 fL |
| MCH | 27–32 pg |
| MCHC | 300–360 g/L |
| RDW | 11.6–14.6% |
| Neutrophils | 2.0–7.5 ×10⁹/L (40–75%) |
| Lymphocytes | 1.0–4.5 ×10⁹/L (20–45%) |
| Eosinophils | 0.04–0.44 ×10⁹/L (1–6%) |
| Basophils | 0–0.10 ×10⁹/L (0–1%) |
| Monocytes | 0.2–0.8 ×10⁹/L (2–10%) |
| Platelets | 150–400 ×10⁹/L |
| Reticulocytes | 0.8–2.0% / 25–100 ×10⁹/L |
| Prothrombin time | 10–14 s |
| APTT | 35–45 s |
Paediatric
| Pulse Rate (bpm) | |
|---|---|
| Neonate | 140–160 |
| Infant <1yr | 120–140 |
| 1–5 years | 110–130 |
| 5–12 years | 80–120 |
| >12 years | 70–100 |
| Respiratory Rate (tachypnoea) | |
| 0–2 months | ≥60/min |
| 2–12 months | ≥50/min |
| 1–5 years | ≥40/min |
| >5 years | ≥30/min |
| Blood Pressure (mmHg) | |
| Term | 65/45 |
| 1 year | 75/50 |
| 4 years | 85/60 |
| 8 years | 95/65 |
| 10 years | 100/70 |
| Weight Formulas | |
| 3–12 months | (a + 9)/2 kg |
| 1–6 years | 2a + 8 kg |
| >6 years | (7a − 5)/2 kg |
| Haemoglobin (g/dL) | |
| Term newborn | 13–20 |
| 1 month | 11–18 |
| 2 months | 10–15 |
| 1–2 years | 10–13 |
| >2 years | 11–14 |
| MUAC (6 months–5 years) | |
| Obese | >17.5 cm |
| Normal | 13.5–17.4 cm |
| At risk | 12.5–13.4 cm |
| Moderate malnutrition | 11.5–12.4 cm |
| Severe malnutrition | <11.5 cm |
| Developmental Milestones | |
| Social smile | 1.5 months |
| Head control | 4 months |
| Sits unsupported | 7 months |
| Crawls | 10 months |
| Stands unsupported | 10–12 months |
| Walks | 12–13 months |
| Talks | 18 months |
| CSF WBC (/mm³) | |
| Term newborn | 0–25 |
| >2 weeks | 0–5 |
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