Bacterial Infections in Emergency Care: Recognition, Assessment and Management

1. Learning objectives

• Define bacterial infection, colonisation, contamination, bacteraemia, sepsis and septic shock.
• Recognise common emergency bacterial syndromes and the findings that indicate immediate referral.
• Perform a structured history and ABCDE assessment while protecting the patient, team and community.
• Obtain useful cultures without delaying life-saving treatment; interpret common laboratory and bedside results.
• Describe first aid, pre-hospital care, emergency-department management, nursing care, monitoring and escalation.
• Use antibiotics safely: correct indication, agent, route, timing, dose checks, allergy screening, renal review, de-escalation and documentation.
• Explain source control, infection prevention, antimicrobial stewardship and prevention of recurrent infection.

2. Core definitions

3. How bacterial infection causes emergency deterioration

Bacteria may remain at the original site, spread through lymphatics or invade the bloodstream. Bacterial toxins and host inflammatory mediators increase vascular permeability, cause vasodilation, disturb coagulation and impair cellular oxygen use. The result can be fever or hypothermia, tachycardia, tachypnoea, capillary-leak oedema, hypotension, delirium, oliguria, hypoxaemia and metabolic acidosis. A patient may be septic even when the temperature is normal.

• Local tissue injury: pus, necrosis, abscess formation, cellulitis, consolidation or obstruction.
• Systemic inflammation: vasodilation, capillary leak, relative hypovolaemia and increased oxygen demand.
• Microcirculatory failure: impaired tissue perfusion despite a seemingly acceptable blood pressure.
• Organ dysfunction: altered consciousness, respiratory failure, acute kidney injury, coagulopathy, jaundice or myocardial dysfunction.
• Rapid source progression: meningitis, necrotising fasciitis, obstructed pyelonephritis and intra-abdominal sepsis can worsen before obvious external signs develop.

4. Common bacterial emergency syndromes

5. Triage: identify the patient who cannot wait

• Use an emergency triage category and record the time of arrival, first observations and time of escalation.
• Do not be reassured by one normal vital sign. Compare with the patient's baseline and repeat trends.
• Check blood glucose early in an altered or shocked patient; treat hypoglycaemia according to protocol while investigating infection.
• Separate suspected airborne/droplet disease, cover draining wounds and use standard precautions for every patient.
• Arrange a monitored bed and urgent clinician assessment for possible sepsis rather than placing the patient in an unobserved waiting area.

6. Focused history

1. Presenting illness: onset, progression, fever pattern, rigors, pain site, cough, sputum, dyspnoea, urinary symptoms, diarrhoea, vomiting, rash, wound or discharge.
2. Severity and function: confusion, fainting, reduced activity, inability to drink, urine volume, breathing effort and ability to walk.
3. Exposure: sick contacts, crowded housing, healthcare exposure, animals, food/water, travel, flood water, sexual exposure, wounds, injections or recent procedures.
4. Risk factors: HIV or other immunosuppression, diabetes, malnutrition, pregnancy, extremes of age, sickle cell disease, renal/liver disease, cancer, burns, indwelling devices and recent surgery.
5. Medicines and microbiology: antibiotics in the last three months, adherence, allergies (reaction and timing), resistant organisms, recent admissions and vaccination status.
6. Use SAMPLER: Symptoms, Allergies, Medications, Past history, Last oral intake, Events/environment, Risk factors and relevant pregnancy/menstrual history.

7. ABCDE assessment and immediate actions

8. Investigations and specimen safety

• Bedside: repeat vital signs, SpO₂, glucose, urine output, capillary refill and point-of-care lactate where available.
• Blood: full blood count, renal/electrolytes, liver tests, glucose, lactate and coagulation when indicated. Take blood cultures from separate sites before antibiotics if this causes no clinically important delay.
• Urine: clean-catch or catheter specimen according to protocol; urinalysis and culture when urinary infection is plausible. Do not treat asymptomatic bacteriuria automatically.
• Respiratory: chest radiograph or ultrasound when indicated; sputum culture for severe, recurrent or treatment-failure disease; use respiratory isolation when a transmissible syndrome is suspected.
• CSF: lumbar puncture only after clinical safety assessment. In suspected bacterial meningitis, draw blood cultures and begin empiric treatment promptly; do not wait for imaging or LP if unsafe or delayed.
• Wound/tissue: clean first and obtain deep tissue, aspirate or pus where possible; superficial swabs may reflect colonisation.
• Imaging: ultrasound/CT for abscess, obstruction, perforation, deep infection or necrotising process. A normal early image does not overrule a deteriorating patient.

9. First aid and pre-hospital care

1. Use gloves and other PPE appropriate to blood, body fluids, respiratory droplets and splash risk; perform hand hygiene before and after contact.
2. Move the patient from danger, call for backup and start a structured primary survey.
3. Open and protect the airway, position for breathing, provide oxygen when indicated and assist ventilation if necessary.
4. Control external bleeding, cover wounds with sterile dressings and do not probe a deep wound in the field.
5. Keep a septic or shocked patient warm but do not overheat; avoid oral fluids when consciousness or surgery may be a concern.
6. Check glucose, document vital-sign trends, establish access if trained and arrange early transport to a facility able to provide cultures, antibiotics, surgery and critical care.
7. Pre-alert the receiving team with suspected source, observations, treatments, allergies, antibiotics already given and estimated arrival time.

10. Emergency treatment principles

10.1 Treat time-critical infection early

When sepsis or a rapidly progressive bacterial syndrome is suspected, obtain cultures promptly if feasible, then give locally recommended empiric antibiotics as soon as possible—especially when shock, meningitis, severe pneumonia, necrotising infection or neutropenia is possible. The prescriber must choose the agent, dose, route and duration using the Uganda Clinical Guidelines, local antibiogram, allergy history, renal/hepatic function, pregnancy status and likely source.

• Record exact time of prescription, preparation, administration and any delay.
• Check the five rights plus indication, allergy, interactions, dilution, infusion time and compatibility.
• Use IV therapy for shock, poor absorption, severe infection or altered consciousness; switch to oral therapy when clinically stable and absorption is reliable.
• Review results daily. Narrow, stop or switch treatment when cultures, imaging and clinical progress allow.
• Never share leftover antibiotics or encourage patients to stop when they feel slightly better without review.

10.2 Fluids, perfusion and organ support

• Assess fluid responsiveness rather than giving unlimited fluid. Use isotonic crystalloid according to local protocol, reassessing blood pressure, pulse, capillary refill, mental state, urine output, lung signs and work of breathing after each bolus.
• Use extra caution in heart failure, renal failure, pregnancy, children, severe anaemia and older adults. New crackles, worsening oxygenation or rising work of breathing suggest overload.
• If hypotension persists despite appropriate fluid and the facility has capability, urgent senior/critical-care review is needed for vasopressor support and invasive monitoring.
• Provide oxygen and ventilatory support, analgesia/antipyretic care, glucose control, renal monitoring and prevention of pressure injury and venous thromboembolism as indicated.

11. Source-specific emergency pathways

11.1 Suspected bacterial meningitis

• Isolate appropriately, perform ABCDE and check for rash, seizures, focal deficit, papilloedema, reduced consciousness or shock.
• Take blood cultures promptly and begin empiric antibiotics according to age, pregnancy, immune status and local policy. Add other agents only when indicated by local guidance or specialist advice.
• Manage seizures, hypoglycaemia, fever and raised intracranial pressure; avoid routine fluid restriction and avoid unsafe LP.
• Notify infection-control/public-health teams when a vaccine-preventable or immediately transmissible organism is suspected; assess close contacts for prophylaxis through the appropriate service.

11.2 Pneumonia and lower respiratory infection

• Assess respiratory rate, effort, mental state, oxygenation and ability to speak/drink. Silent hypoxaemia or fatigue is an emergency.
• Give oxygen to the prescribed target, position upright, suction secretions when required and prepare non-invasive or invasive support if deteriorating.
• Look for sepsis, aspiration, tuberculosis, pulmonary oedema and pulmonary embolism; antibiotics should match severity, setting, aspiration risk and local resistance patterns.
• Reassess after treatment: rising respiratory rate, increasing oxygen requirement, hypotension, confusion or reduced urine requires escalation.

11.3 Urinary infection and pyelonephritis

• Check for flank pain, rigors, vomiting, pregnancy, catheter use, stones and reduced urine.
• Take urine culture where indicated and assess for obstruction. An infected obstructed kidney needs urgent urological source control; antibiotics alone may fail.
• Give analgesia, antiemetic and carefully monitored fluids; review renal function before nephrotoxic medicines and dose adjustments.

11.4 Skin, wound, diabetic-foot and necrotising infection

• Mark the edge of erythema and record pain, colour, temperature, sensation, pulses and function. Pain out of proportion, bullae, crepitus, skin anaesthesia or rapid spread suggests necrotising infection.
• Cover wounds, elevate where appropriate, check tetanus status, control glucose and obtain urgent surgical review for abscess, devitalised tissue, deep infection or systemic toxicity.
• Do not delay surgery for repeated superficial swabs or a normal early blood test; source control is often the life-saving intervention.

11.5 Intra-abdominal, pelvic and post-operative infection

• Keep the patient nil by mouth when surgery is possible, provide IV access, analgesia and antiemetic care, and monitor for peritonitis and shock.
• Look for perforation, obstruction, abscess, cholangitis, pelvic infection or an infected wound. Early surgical/obstetric review and source control are essential.
• Use pregnancy testing and safeguarding-sensitive history when relevant; avoid exposing a pregnant patient to unnecessary imaging while not delaying life-saving diagnosis.

12. Source control: antibiotics are not enough

• Identify the probable source during the first assessment, then reassess after investigations.
• Do not repeatedly delay referral while waiting for antibiotic response in a surgical emergency.
• Send deep tissue, pus, blood or fluid for culture at the time of the procedure when safe.
• Document the time of source-control consultation and transfer plan.

13. Nursing and EMT care plan

14. Monitoring and escalation

• Repeat observations at a frequency matched to severity; unstable patients may need continuous ECG, SpO₂ and frequent blood pressure.
• Trend respiratory rate, oxygen requirement, mental status, urine output, capillary refill, lactate and temperature rather than recording isolated values.
• Escalate immediately for increasing oxygen need, new confusion, seizure, systolic hypotension, persistent tachycardia, mottling, anuria/oliguria, rising lactate, severe pain out of proportion or a spreading rash.
• Use a written handover such as SBAR: Situation, Background, Assessment, Recommendation. Include infection source, cultures, antimicrobial times, fluid balance and response.
• After stabilisation, review microbiology, antibiotic spectrum, source control and duration every day; record the review and stop date.

15. Special populations

• Children: compensate with tachycardia before hypotension; assess feeding, wet nappies, interaction, capillary refill and weight-based medicines/fluids.
• Neonates: temperature instability, poor feeding, lethargy, apnoea or grunting may be the only signs. Urgent neonatal referral is required.
• Pregnancy/postpartum: physiological changes can mask shock; consider urinary, uterine, wound and breast sources, and involve obstetric services early.
• Older adults: may have no fever; new confusion, falls, weakness or functional decline can be infection signs.
• Immunocompromised patients: infection may progress rapidly with minimal local inflammation; do not wait for a high white-cell count.
• Renal or hepatic impairment: review dosing, fluid tolerance and nephrotoxic/hepatotoxic combinations with the prescriber or pharmacist.

16. Prevention and antimicrobial stewardship

• Vaccination, safe water and food, hand hygiene, respiratory etiquette, wound care, safe sex, vector control and early treatment of chronic disease reduce bacterial emergencies.
• Use standard precautions for every patient and transmission-based precautions when indicated; clean shared equipment between patients.
• Prescribe antibiotics only for a likely bacterial indication; do not use them for uncomplicated viral respiratory illness.
• Follow the WHO AWaRe/local formulary approach: prefer effective Access agents when appropriate, reserve Watch/Reserve agents for clear indications and specialist oversight.
• Obtain cultures appropriately, review results, narrow spectrum, convert IV to oral when safe and stop when the planned course is complete.
• Teach patients not to share, save or buy antibiotics without assessment, and to return for worsening symptoms or adverse reactions.

17. Clinical scenarios

18. Common errors to avoid

• Waiting for fever, hypotension or a positive culture before acting on a deteriorating patient.
• Delaying antibiotics for imaging or lumbar puncture when meningitis, shock or necrotising infection is likely.
• Giving repeated large fluid boluses without reassessing lungs, perfusion and urine output.
• Using a superficial wound swab as proof of the invasive organism.
• Continuing broad antibiotics without a culture review, stop date or source-control plan.
• Forgetting pregnancy, renal function, allergies, recent antibiotics and local resistance patterns.
• Failing to document exact times, trends, handover and response to treatment.

19. Revision questions

1. Differentiate colonisation, contamination, local infection, bacteraemia, sepsis and septic shock.
2. List at least eight red flags that require immediate senior review in a patient with suspected bacterial infection.
3. Why should cultures be taken before antibiotics when feasible, and why must this never create a dangerous delay?
4. Describe the ABCDE assessment of a shocked patient with pneumonia.
5. Explain why an infected obstructed urinary system requires source control.
6. List the five medication-safety checks that should occur before an IV antibiotic is administered.
7. What findings suggest necrotising soft-tissue infection rather than uncomplicated cellulitis?
8. Give five actions that reduce antimicrobial resistance in an emergency unit.

20. Key take-home points

• Infection plus new organ dysfunction is an emergency even without high fever.
• ABCDE, oxygenation, perfusion, glucose and repeated trends come before a long differential list.
• Give appropriate empiric antibiotics promptly when a time-critical bacterial syndrome is suspected, guided by current local policy.
• Antibiotics cannot replace drainage, debridement, removal of infected devices or relief of obstruction.
• Every dose, specimen, observation, response and escalation should be documented.

References for further study

• World Health Organization: Sepsis and antimicrobial resistance resources
• WHO AWaRe antibiotic book
• CDC Core Elements of Hospital Antibiotic Stewardship
• CDC bacterial meningitis information
• Uganda Ministry of Health: current Uganda Clinical Guidelines and national antimicrobial-resistance/IPC guidance.