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9. Prevention of nosocomial lower respiratory tract infection (LRTI) |
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Introduction The cough reflex together with a healthy respiratory mucosa, with its ciliated epithelium, antimicrobial secretions, phagocytosis, and other local immunity mechanisms, effectively prevents microorganisms reaching the lower respiratory tract (LRT). The LRT is thus normally sterile. Post-operative pneumonia is a common surgical complication, often resulting from the patient failing to cough or breath deeply because of pain. In these patients infection is caused by common respiratory pathogens. Ventilator-associated pneumonia is a more serious condition seen in intensive care units in intubated and ventilated patients. It is often caused by antibiotic resistant, opportunistic pathogens. In this group of patients, mechanical or chemical injury to the ciliated epithelium impairs the normal removal of mucous and microorganisms from the lower airways. In addition, reduction of the gastric pH due to H2 blocking agents is associated with colonisation of the upper gastro-intestinal tract and oropharynx by aerobic Gram-negative bacilli derived from the patient's own bowel. These organisms may then pass into the LRT and cause infection. This group of patients has usually had prolonged hospitalisation and received (sometimes several courses of) antibiotics. Because of this, the organisms involved are often multidrug resistant (MDR) opportunistic pathogens. These microbes may be introduced into the respiratory tract via contaminated equipment or staff hands, but often they are organisms that have first colonised the patient's bowel. Definition and diagnosis Nosocomial or hospital acquired pneumonia is a lower respiratory tract infection that appears during or after hospitalisation in a patient who was not incubating the infection on admission. It is diagnosed by the following: clinical signs, pyrexia, usually purulent sputum, relevant X-ray changes and preferably microbiological diagnosis from bronchial lavage, transtracheal aspirate or protected brush culture. Figure 9.1 Mode of acquisition of hospital acquired pneumonia
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Risk factors for nosocomial pneumonia |
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| Condition of patient |
Therapy |
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Etiologic agents of nosocomial pneumonia Streptococcus pneumoniae and Haemophilus influenzae can cause post-operative pneumonia, particularly in patients with existing pulmonary disease. Gram-negative bacilli, e.g., Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Serratia marcesens, Enterobacter species, and Acinetobacter species. Legionella infection may be acquired from the hospital air conditioning system or from water supplies, particularly in immunocompromised patients. Other organisms, e.g., respiratory syncytial and other respiratory viruses, Candida albicans , and, rarely, Aspergillus fumigatus. Pneumocystis carinii causes pneumonia in immunosuppressed patients, particularly if HIV positive, but this is usually a community-acquired infection. Opportunistic pulmonary diseases caused by different mycobacteria, including Mycobacterium tuberculosis, can occur and can be transmitted to other patients. |
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| Basic methods of prevention |
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Risk |
Prevention |
| Surgical operation |
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| Cardiopulmonary illnesses |
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| Respiratory failure and artificial ventilation |
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Other important measures Hand hygiene before and after contact with patients, whether or not gloves are worn. Clean disposable or reprocessed gloves and catheters for tracheal aspiration and tracheostomy care. Disposable or reprocessed gloves when handling respiratory secretions. Education of staff in patient care practices and cleaning and disinfection of respiratory equipment. |
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| Cleaning and Disinfection of Respiratory Equipment |
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Cleaning, drying and filling with sterile distilled or freshly boiled water every 8 to 24 hours. |
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Autoclaving or thermal disinfection preferred after cleaning; sterile nebulizer fluids as aerosols are generated. |
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Autoclaving or thermal disinfection Disposable items are safe but expensive Chemical disinfection may be required |
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Sterile or freshly boiled water for each use |
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Mouthpiece for each patient should be sterile, disinfected or disposable |
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Sterile, disposable, for each procedure except when used for the same patient for 24 hours; flushed for each aspiration with sterile or freshly boiled water |
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Washing in detergent and dried, or disinfected with solution of chlorine-releasing agent, rinsed and dried. Preferably disinfected in washing machine or autoclaved or disinfected in hot water and dried. Disposables available but expensive |
Minimal requirements
Bibliography
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