Pneumonia

PneumoniaLecture No.2

Hospital-acquired pneumonia Dr Dhaher Jameel Salih Al-habbo FRCP London UK Professor of medicine Department of Medicine.

Hospital-acquired pneumonia

Hospital-acquired or nosocomial pneumonia refers to a new episode of pneumonia occurring at least 2 days after admission to hospital. It is the second most common hospital-acquired infection (HAI) and the leading cause of HAI-associated death. Older people are particularly at risk, as are patients in intensive care units, especially when mechanically ventilated, in which case the term ventilator-associated pneumonia (VAP) is applied.

Hospital-acquired pneumonia

Health care-associated pneumonia (HCAP) refers to the development of pneumonia in a person who has spent at least 2 days in hospital within the last 90 days, attended a haemodialysis unit, received intravenous antibiotics, or been resident in a nursing home or other long-term care facility.

Aetiology

Factors predisposing to hospital-acquired pneumonia
Reduced host defences against bacteria Reduced immune defences (e.g. corticosteroid treatment, diabetes, malignancy) Reduced cough reflex (e.g. post-operative) Disordered mucociliary clearance (e.g. anaesthetic agents) Bulbar or vocal cord palsy

Factors predisposing to hospital-acquired pneumonia

Aspiration of nasopharyngeal or gastric secretions Immobility or reduced conscious level Vomiting, dysphagia, achalasia or severe reflux Nasogastric intubation

Factors predisposing to hospital-acquired pneumonia

Bacteria introduced into lower respiratory tract Endotracheal intubation/tracheostomy Infected ventilators/nebulisers/bronchoscopes Dental or sinus infection Bacteraemia Abdominal sepsis I.v. cannula infection Infected emboli


Nosocomial Pneumonia (Hospital-Acquired, Ventilator-Associated, and Health Care–Associated)Essentials of Diagnosis Hospital-acquired pneumonia (HAP) occurs > 48 hours after admission to the hospital or other health care facility and excludes any infection present at the time of admission.Health care–associated pneumonia (HCAP) occurs in community members whose extensive contact with healthcare has changed their risk for virulent and drug resistant organisms.At least two of the following: fever, leukocytosis, purulent sputum. New or progressive parenchymal opacity on chest radiograph. Especially common in patients requiring intensive care or mechanical ventilation.

Clinical features and investigations

Clinical features and investigations
Circulating biomarkers may assist with the diagnosis but are currently non-specific. Appropriate investigations are similar to those outlined for CAP, although whenever possible, microbiological confirmation should be sought. In mechanically ventilated patients, bronchoscopy-directed protected brush specimens or bronchoalveolar lavage (BAL) may be performed. Endotracheal aspirates are easy to obtain but less reliable

Management

Adequate Gram-negative cover is usually provided by:A third-generation cephalosporin (e.g. cefotaxime) with an aminoglycoside (e.g. gentamicin)Meropenem or a monocyclic β-lactam (e.g. aztreonam) and flucloxacillinMRSA is treated with intravenous vancomycin, but when appropriate, oral therapy may be considered with doxycycline, rifampicin or linezolid. The nature and severity of most HAPs dictate that these antibiotics are all given intravenously, at least initially. Physiotherapy is important in those who are immobile or old. Adequate oxygen therapy, fluid support and monitoring are essential.

Prevention

The mortality from HAP is high at approximately 30%, emphasising the importance of prevention. Good hygiene is paramount, including both hand washing and equipment. Steps should be taken to minimise the chances of aspiration and limit the use of stress ulcer prophylaxis with proton pump inhibitors. Oral antiseptic (chlorhexidine 2%) may be used to decontaminate the upper airway and some intensive care units use selective decontamination of the digestive tract when the anticipated requirement for ventilation will exceed 48 hours.

Respiratory infection in old age

Respiratory infection in old age

Suppurative pneumonia, aspiration pneumonia and pulmonary abscess

Suppurative pneumonia is characterised by destruction of the lung parenchyma by the inflammatory process and, although microabscess formation is a characteristic histological feature, 'pulmonary abscess' is usually taken to refer to lesions in which there is a large localised collection of pus, or a cavity lined by chronic inflammatory tissue, from which pus has escaped by rupture into a bronchus.

Suppurative pneumonia, aspiration pneumonia and pulmonary abscess

Suppurative pneumonia and pulmonary abscess often develop after the inhalation of septic material during operations on the nose, mouth or throat, under general anaesthesia, or of vomitus during anaesthesia or coma, particularly if oral hygiene is poor. Additional risk factors for aspiration pneumonia include bulbar or vocal cord palsy, stroke, achalasia or oesophageal reflux, and alcoholism. Aspiration tends to localise to dependent areas of the lung such as the apical segment of the lower lobe in a supine patient. Suppurative pneumonia and abscess may also complicate local bronchial obstruction from a neoplasm or foreign body.

Suppurative pneumonia, aspiration pneumonia and pulmonary abscess

Suppurative pneumonia, aspiration pneumonia and pulmonary abscess

Suppurative pneumonia, aspiration pneumonia and pulmonary abscess

The clinical features of a suppurative pneumonia
Cough productive of large amounts of sputum which is sometimes fetid and blood-stained Pleural pain common Sudden expectoration of copious amounts of foul sputum occurs if abscess ruptures into a bronchus. Clinical signs High remittent pyrexia,Profound systemic upset Digital clubbing may develop quickly (10-14 days) Chest examination usually reveals signs of consolidation; signs of cavitation rarely found.Pleural rub common. Rapid deterioration in general health with marked weight loss can occur if disease not adequately treated

Investigations

Radiological features of suppurative pneumonia include homogeneous lobar or segmental opacity consistent with consolidation or collapse. Abscesses are characterised by cavitation and fluid level. Occasionally, a pre-existing emphysematous bulla becomes infected and appears as a cavity containing an air-fluid level. Sputum and blood should be sent for culture.

Management

Oral treatment with amoxicillin 500 mg 6-hourly is effective in many patients. Aspiration pneumonia can be treated with co-amoxiclav 1.2 g 8-hourly. If an anaerobic bacterial infection is suspected (e.g. from fetor of the sputum), oral metronidazole 400 mg 8-hourly should be added. Further modification of antibiotics should be informed by clinical response and the microbiological results.

Management

CA-MRSA is usually susceptible to a variety of oral non-β-lactam antibiotics, such as trimethoprim/sulfamethoxazole, clindamycin, tetracyclines and linezolid. Parenteral therapy with vancomycin or daptomycin can also be considered. Fusobacterium necrophorum is highly susceptible to β-lactam antibiotics and to metronidazole, clindamycin and third-generation cephalosporins. Prolonged treatment for 4-6 weeks may be required in some patients with lung abscess.

Management

Physiotherapy is of great value, especially when suppuration is present in the lower lobes or when a large abscess cavity has formed. In most patients, there is a good response to treatment, and although residual fibrosis and bronchiectasis are common sequelae, these seldom give rise to serious morbidity. Surgery should be contemplated if no improvement occurs despite optimal medical therapy. Removal or treatment of any obstructing endobronchial lesion is essential.

Pneumonia in the immunocompromised patient

Clinical features

Clinical features

Causes of immune suppression-associated lung infection: Infecting organisms Defects in cell-mediated immunity

Clinical features

Diagnosis
The approach to investigation is informed by the clinical context and severity of the illness. Invasive investigations such as bronchoscopy, BAL, transbronchial biopsy or surgical lung biopsy are often impractical, as many patients are too ill to undergo these safely. However, 'induced sputum‘ may offer a relatively safe method of obtaining microbiological samples. HRCT is useful in differentiating the likely cause:Focal unilateral airspace opacification favours bacterial infection, mycobacteria or nocardia.

Diagnosis

Management

Management

Management

Aspergilloma

Antifungal therapy Patient is not a candidate for surgery Concomitant tissue invasion Itraconazole with some help Ampho B for invasive component. Newer Azoles, Voriconazole , Posaconazole , and Ravuconazole.Their role is not clear. Antibiotics for bacterial superinfection.