The upper respiratory tract and oral cavity are abundantly colonized by bacteria

Introduction Multiple lung infections, although clinically quite common, are difficult to diagnose. One is because some pathogens such as viruses do not meet the clinical needs of laboratory diagnostic techniques. Second, due to the difficulty in collecting lower respiratory tract specimens, there is a large number of colonizations in the upper respiratory tract and oral cavity. Bacteria, but in the long-term hospitalization or antibacterial treatment process, its flora often changes, oral cough specimens are susceptible to contamination, culture of a variety of bacterial growth does not mean that there are multiple infections, on the contrary, sterile growth or single bacterial growth can not Eliminate multiple infections.

Cause

(1) Causes of the disease

The pathogen spectrum of multiple lung infections can be simultaneous infection of any different types of pathogens or different species (genus) of pathogens in the same type. The more common pathogen combinations are:

1. Multiple bacterial infections

Two or more aerobic bacteria (including Gram-positive and Gram-negative, two Gram-negative bacilli or two Gram-positive cocci), aerobic and anaerobic bacteria, mycobacteria and common bacteria are co-infected.

2. Bacterial plus fungal infection

Any combination of bacteria and fungi is most common with aerobic bacteria and conditional pathogens such as Candida or Aspergillus.

3. Bacterial plus protozoal infection is common with Pneumocystis carinii and bacterial infection.

4. Bacterial plus viral infection

Common respiratory viral infections are secondary to bacterial infections. Co-infection of bacteria and cytomegalovirus is common in immunosuppressed patients.

(two) pathogenesis

Clinical disease spectrum

Multiple infections are common in aspiration pneumonia and lung abscesses, bronchiectasis, nosocomial pneumonia, especially ventilator-associated pneumonia, immunocompromised host pneumonia, and various other severe pneumonia.

2. Risk factors

Old age, underlying diseases (chronic airway disease, diabetes, renal failure, cardiac insufficiency, etc.), disturbance of consciousness, alcoholism, malnutrition, immunosuppression, mechanical ventilation and other invasive techniques (eg, fiberoptic bronchoscopy), prior Antibiotic treatment, latent infection or some endemic epidemic disease epidemic or special environmental exposure, end-stage disease, long-term hospitalization, special ICU, etc. can be risk factors for multiple lung infections.

an examination

Related inspection

Bacterial identification bacteriological test sputum bacterial smear examination

Anaerobic bacteria combined with other pathogen infections may have clinical features of anaerobic infections such as cough and sputum. Other types of multiple infections lack characteristic symptoms. In general, patients with multiple infections have more severe symptoms.

Multiple lung infections, although clinically quite common, are difficult to diagnose. One is because some pathogens such as viruses do not meet the clinical needs of laboratory diagnostic techniques. Second, due to the difficulty in collecting lower respiratory tract specimens, there is a large number of colonizations in the upper respiratory tract and oral cavity. Bacteria, but in the long-term hospitalization or antibacterial treatment process, its flora often changes, oral cough specimens are susceptible to contamination, culture of a variety of bacterial growth does not mean that there are multiple infections, on the contrary, sterile growth or single bacterial growth can not Eliminate multiple infections.

Clinically, patients with the above-mentioned multiple infections and risk factors or patients with moderate or severe pulmonary infection who are not treated with standardized antibiotics should be alert, considering the possibility of multiple infections. Lung abscess and bronchiectasis are commonly mixed with anaerobic and aerobic bacteria. If the clinical symptoms are typical, multiple infections can be treated. In other types of pneumonia, multiple infections including the diagnosis of a double infection require exact pathogen evidence. The blood and pleural fluid specimens have the most diagnostic value, and the lower respiratory tract anti-pollution or bronchoalveolar lavage specimens need to be combined with quantitative culture. Cough is screened and cultured in qualified samples. If two or more bacteria are dominant growth, they reach 106 CFUml, which has important reference value. Conditional pathogenic fungi also need to be sampled from the lower respiratory tract using anti-pollution techniques, and the results of oral culture specimens are meaningless. Viral detection has reference value due to difficulty in culture, serum immunology and molecular biology techniques. Histopathological examination has important diagnostic value for Pseudomonas aeruginosa pneumonia and certain specific pathogen infections (fungi, Pneumocystis carinii, mycobacteria) combined with special staining.

Cough is screened and cultured in qualified samples. If two or more bacteria are dominant growth, they reach 106 CFUml, which has important reference value. X-ray lesions are more extensive and necrotizing pneumonia is more common.

Differential diagnosis

Upper respiratory tract mucosal irritation: common in hydrogen sulfide poisoning. Hydrogen sulfide is a colorless gas that is irritating and asphyxiating. Low-concentration exposure only has local irritation of the respiratory tract and the eye. At high concentrations, the systemic effect is more obvious, manifesting as central nervous system symptoms and asphyxia symptoms. Hydrogen sulfide has a "smelly egg-like" odor, but very high concentrations quickly cause olfactory fatigue without feeling its taste. Mining, smelting, sugar beet making, carbon disulfide, organophosphorus pesticides, and hydrogen sulfide production in industries such as leather, sulphur dyes, pigments, animal glues, etc.; organic waste sites such as marshes, gutters, septic tanks, and sediments A large amount of hydrogen sulfide can escape during operation in the pool, etc. It is not uncommon for workers to be poisoned.

Fatal upper airway bleeding: A large amount of bleeding in the upper respiratory tract due to trauma or aneurysm rupture, life-threatening. Repeated upper respiratory tract infection: Repeated respiratory infection in children refers to infants under 3 years of age who have repeated respiratory infections for more than 7 times per year or lower respiratory tract infections for more than 3 times. The scope of being a weak child is the object of health care management for child health workers.

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