Hospital acquired pneumonia Flashcards
what is the definition of HAP?
HAP is an acute lower respiratory tract infection that is by definition acquired after at least 48 hours of admission to hospital and is not incubating at the time of admission
what is the epidemiology of HAP?
Intensive care units and people who have had recent major surgery
High morbidity and mortality
what is the aetiology of HAP?
Early-onset HAP (<5 days after admission to hospital) is often caused by Streptococcus pneumoniae. Late-onset HAP (>5 days after admission to hospital) is usually caused by microorganisms that are acquired in hospital, most commonly MRSA, Pseudomonas aeruginosa, and other non-pseudomonas gram-negative bacteria. Several of the microorganisms causing HAP have increased antibiotic resistance
what are the risk factors for HAP?
Poor injection control
Intubation and mechanical ventilation
Multi drug-resistant bacteria
Aspiration
what is the pathophysiology of HAP?
The most common introduction of bacteria into alveoli is micro-aspiration of oropharyngeal pathogens or leakage of secretions containing bacteria around an endotracheal tube cuff. Other pathways include macro-aspiration (e.g., of vomit), inhalation, haematogenous spread from infected intravenous catheters, direct inoculation (e.g., thoracentesis), and translocation from the gastrointestinal tract. Important factors that predispose patients to the pathways described include the severity of the patient’s underlying disease, prior surgery, exposure to antimicrobials, other medications, and exposure to invasive respiratory devices and equipment. Sources of pathogens for HAP include healthcare devices (infected biofilm in the endotracheal tube), the environment (air, water, equipment, and fomites), and the transfer of microorganisms from patient to patient through healthcare workers (poor hand hygiene). Finally, sinuses may be potential reservoirs of healthcare-associated pathogens that contribute to HAP.
what are the key presentations of HAP?
Cough with increasing sputum production
Dyspnoea
Fever
Risk factors
what are the first line and gold standard investigations for HAP?
Oxygen saturations - decreased
CXR - new and/or persistent consolidation
FBC - may show leukocytosis (WBC >10 x 109/L) or leucopenia (WBC <4 x 109/L)
Blood gas - may show: hypoxia, respiratory alkalosis, metabolic acidosis (due to hypotension, reduced tissue perfusion, or acute kidney injury), raised lactate levels
CRP - elevated
LFTs - may be abnormal, particularly if there is underlying or associated pathology
Culture of sputum, nasopharyngeal or tracheal aspirate samples - growth of causative bacterial pathogen
what are the differential diagnoses for HAP?
COVID 19
Cardiogenic pulmonary oedema
ARDS
how is HAP managed?
Severe:
IV antibiotics (piperacillin/tazobactam: 4.5 g intravenously every 8 hours, may increase to 4.5 g every 6 hours in severe infections), could add MRSA antibiotic cover (vancomycin: 15-20 mg/kg intravenously every 8-12 hours, maximum 2000 mg/dose)
Mild:
Oral antibiotics (amoxicillin/clavulanate: 500/125 mg orally three times daily)
how is HAP monitored?
Measure observations initially at least twice daily, and more frequently (e.g., every hour) in those admitted to a critical care unit (high-dependency unit or ICU).
what are the complications of HAP?
Empyema or lung abscess
SIRS
Pulmonary embolism
what is the prognosis of HAP?
The all-cause mortality for HAP is 30% to 70%, while the attributable mortality is approximately 10%. Many people with HAP die of their underlying cause. Increased mortality has been associated with patients who have HAP due to Pseudomonas aeruginosa or Acinetobacter species, received an antimicrobial that did not cover the offending pathogen, and had medical instead of surgical illness.
