Classification. Causative agents of respiratory infections. Pharyngitis. S. pyogenes (Group A streptococcus, GAS)

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1 Causative agents of respiratory infections Judit Szabó MD. PhD. Classification Upper respiratory tract infections - common cold (viruses) - tonsillitis, pharyngitis - otitis media - sinusitis - laryngitis, epiglottitis - diphtheria Lower respiratory tract infections - pertussis - acute and chronic bronchitis - bronchiolitis (viruses) - pneumonia - lung abscess (anaerobes) Pyogenic bacteria in respiratory infections Bacteria other than pyogenic in respiratory infections pharyngitis tonsillitis S. pyogenes + sinusitis otitis epiglottitis bronchitis pneumonia pharyngitis tonsillitis sinusitis otitis epiglottitis bronchitis pneumonia L. pneumophila atypical S. pneumoniae S. aureus K.pneumoniae &Eneterobacteriaceae + H. influenzae Pseudomonas spp M. catarrhalis + + M. pneumoniae + + atypical C. pneumoniae + atypical C. burnetii atypical Bacteria with specific symptoms: Corynebacterium diphteriae Bordetella pertussis Mycobacterium tuberculosis Pharyngitis 70 % viruses 30% bacteria: S. aureus, S. pyogenes N. gonorrhoeae, C. diphtheriae Common in winter (outbreaks in crowded living situations) Among children (daycare centers, school) Transmission: by droplets S. pyogenes (Group A streptococcus, GAS) no under age of 3 y 5-15 y: % y: % > 35 y: 5-6 % poststreptococcal diseases can be prevented by penicillin within 9 days healthy carriers: 6 % 1

2 Collection of specimen throat swab culture tilt the head back the patient should open mouth wide rub a sterile cotton swab along the back of throat near the tonsils need to scrape the back of the throat with the swab several times do not use antiseptic mouthwashes before the test put the swab into transport medium keep it at room temperature for hours the presence of the usual mouth and throat bacteria is a normal finding Otitis media common under age 5 y (commonest between 6 mon and 2 y) on otoscopic examination, the tympanic membrane is erythematous, bulging, and has decreased mobility (presence of middle ear fluid) Causative agents: Streptococcus pneumoniae Haemophilus influenzae Moraxella catarrhalis Streptococcus pyogenes In chronic cases: anaerobes Otitis media Symptoms: earache, fever, decreased hearing, tinnitus young infants may present with crying, irritability, lethargy, pulling at the affected ear Complications: mastoiditis, meningitis, conductive hearing loss Treatmment: amox/clav, cefuroxime, TMP- SMX Prevention: conjugated polysaccharide pneumococcal vaccine called Prevenar 13 (Pfizer) Collection of specimen tympanocentesis are not recommended (unless the patient is toxic, or has recurrent infections, or is not responding to empirical treatment) external auditory canal do not accurately reflect the organism nasopharyngeal sample is also not specific Haemophilus influenzae Gram-negative coccobacillus polysaccharide capsule (serologic typing) Pathogenesis, clinical findings: pyogenic infections invasive infections: meningitis, epiglottitis, pneumonia, associated with b type capsular polysaccharide non-invasive infections in upper respiratory tract: no capsule or other than b capsule type Diagnosis: culturing:isolate on chocolate agar (X and V factor) IFA, latex agglutination Treatment: ceftriaxone (meningitis, serious systemic infections) amoxicillin-clavulanate, trimethoprimsulfamethoxazole (TMP-SMX) Prevention: vaccine: capsular polysaccharide of type b conjugated to diphtheria toxoid or other carrier protein rifampin to close contacts of patient with meningitis 2

3 Sinusitis maxillaris the paranasal sinuses are sterile under normal conditions acute sinusitis occurs all ages the causative agents are similar to that of otitis media in chronic cases: anaerobes Symptoms: high fever, facial pain, headache, nasal and postnasal discharge Diagnosis: standard radiography (ethmoid sinuse are poorly seen on plain X-rays), CT, MR Cultures obtained by sinus puncture (yield bacteria in 60 % of cases) Treatment: amox/clav, cefuroxim, TMP-SMX Classification Acute sinusitis, defined as symptoms of less than 4 weeks duration Subacute sinusitis, defined as symptoms of 4 to 8 weeks duration; Chronic sinusitis, defined as symptoms lasting longer than 8 weeks Recurrentacute sinusitis, often defined as three or more episodes per year, with each episode lasting less than 2 weeks. Sinus puncture involves using a needle to withdraw a small amount of fluid from the sinuses it requires a local anesthetic it is not routinely performed, it is recommended, when standard therapy has failed or in an immunocompromised patient who is at high risk for orbital or central nervous system complications culture specimens obtained from nasal swabs correlate poorly with sinus pathogens Laryngitis, epiglottitis Occurs in children between 2-6 y in winter and spring Bacteria: H. influenzae S. pneumoniae S. aureus Symptoms: sore throat, pain on swallowing, shortness of breath, tachypnea, inspiratory stridor Complication: respiratory failure from upper-airway obstruction Treatment: medical emergency, cardiopulmonary life support (eg. intubation), parenteral antibiotics Croup score* Symptom 0 point 1 point 2 point voice of inspirium normal harsh crepitation stridor no inspiratory in-exspiratory Diagnosis arterial blood gas testing for PaO 2 or PaCO 2 blood culture cough no hoarseness wheezing retraction no suprasternal Suprasternal and intercostal cyanosis no decrease in cool air * > 7 point: hospitalisation is recommended do not decrease in 40 % oxigen 3

4 Corynebacterium diphtheriae Gram-positive rod, clubshaped with Babes-Ernst (volutin) granules stained metacromasically by Neisser causes diphtheria Transmission: airborne droplets Pathogenesis, clinical findings: exotoxin (diphteria toxin: inhibits protein synthesis, ADPribosylation of EF-2) local inflammation in the throat grey pseudomembrane over the tonsills and throat fever, sore throat, cervical adenopathy Complications:airway obstruction, myocarditis, arrythmias, circulatory collapse, nerve weakness, paralysis (toxin spreads via circulation!) Laboratory diagnosis: culturing : Löffler s medium, Clauberg agar toxin production: Elek-test, gel precipitation Elek test Clauberg medium Treatment: antitoxin plus antibiotics are recommended (penicillin G, erythromycin) Prevention: diphtheria toxoid (combination with tetanus toxoid and acellular pertussis vaccine) 2, 4, 6 months of age, boosters at 3 and 6 years Pertussis (whooping cough) B. pertussis B. parapertussis B. bronchiseptica Transmitted person-to-person by respiratory route Highly contagious Adolescents and adults are the major reservoirs (mild or atypical infection) 4

5 Gram-negative coccobacillus Bordetella pertussis Stages Pathognesis, clinical findings: attaches to the ciliated epithelium by pili, decreased cilia activity resulting in death of the ciliated epithelial cells pertussis toxin: stimulates adenilate cyclase (ADP-ribosylation of inhibitory subunit of G protein) occurs primarily in infants and young children acute tracheobronchitis, severe paroxysmal cough 1. stage: catarrhal stage (mild cough, rhinorrhea, low-grade fever, lasts 1-2 weeks 2. stage: paroxismal stage (severe, repetitive coughing with the characteristic whoop and frequently followed by vomiting lasts 1-4 weeks 3. stage: convalescent stage (recovery) decreasing intensity and frequency of cough, lasts 2-4 weeks Complications:pneumonia, encephalopathy Laboratory diagnosis: nasopharyngeal swab taken during the paroxysmal stage culturing on Bordet-Gengou medium direct IFA PCR Treatment: erythromycin, supportive care Prevention: acellular vaccine (five purified antigens) Acute bronchitis occurs more often in adults than in children Occurs most frequently in winter most often caused by viruses bacteria: Mycoplasma pneumoniae and Chlamydophila pneumoniae cough, ow-grade fever most patients require only symptomatic treatment Bronchiolitis viruses (mainly RSV ) more common in younger children < 2 years (2-6 months of age) cough, tachypnea, wheezing chest radiographs show diffuse hyperinflation, patchy prihilar infiltrates, peribronchial cuffing supportive care, bronchodilatation and occasioanl ventilatory support required Pneumonia community-acquired (CAP) nosocomial (hospital-acquired) pneumonia (HAP or NAP) affects any age of group productive or nonproductive cough, fever, dyspnea, pleuritic chest pain tachypnea, crepitations, leucocytosis, increased CRP level Chest radiography demonstrates patchy, segmental lobar or multilobar infiltration (S. pneumoniae) or diffuse, bilateral interstitial infiltrates (viruses, atypical pneumonia) 5

6 Collection of specimen Gram- stain examination and culture of sputum bronchoalveolar lavage (BAL) bacteria/ml protected BAL 1000 bacteria/ml blood (hemoculture) serum ( IgM ELISA) urine (Legionella antigen) Gram stained sputum from a patient with Haemophilus influenzaepneumonia demonstrating numerous polymorphonuclear leukocytes and small gram-negative coccobacilli S. pneumoniae H. influenzae K. pneumoniae M. catarrhalis CAP Atypical pneumonia: Mycoplasma pneumoniae Chlamydophila pneumoniae Coxiella burnettii Legionella pneumophila lobar pneumonia Mycoplasma pneumoniae years of ages are most often affected incubation period: 2-3 weeks low-grade fever, headache, dry cough (walking pneumonia) chest radiographic abnormalities: diffuse interstitial infiltrates diagnosis: IgM ELISA treatment: macrolides(azithromycin), respiratory fluoroquinolones (moxifloxacin, levofloxacin) Legionella pneumophila Sources: aerosols from arteficial reservoirs of water (cooling towers, evaporative condensers, air conditioners, humidifiers, fountains, whirlpool spas) 25 Legionella species, 48 serodroups (serogroup 1 causes % of cases) Risk factors: smoking, transplant recipients, elderly patients, corticosteroid treatment Incubation period: 2-10 days Productive cough, low-grade fever, headache, altered mental status Diagnosis: direct IFA from sputum, antigen detection from urine Treatment: macrolides, respiratory fluoroquinolones Nosocomial pneumonia occurs hours after hospitalisation Gram-negative rods, multiresistant(mrsa, ESBL, MACI, MPAE) bacteria ICU: 10 % (among mechanically ventilated patients) Risk factors: advanced age (> 70 years), diabetes, renal or pulmonary disease, malnutrition, mechanical ventilation, nasogastric intubation, surgical procedures Letality: % 6

7 Adolescent Elderly Alcoholism COPD Cystic fibrosis Aspiration Causative agents S. pneumoniae, M. pneumoniae, viruses S. pneumoniae, H.influenzae, C. pneumoniae, anaerobes S. pneumoniae, M. tuberculosis Gram-negative rods (H. influenzae, enterobacteria) P. aeuginosa, S. aureus anaerobes Diabetes mellitus S. pneumoniae Steroid treatment fungi Neutropenia Decreased immunity Gram-negative rods, Gram-positive cocci, fungi Gram-negative rods, fungi viruses (HSV, CMV, VZV) Splenectomy Hospital environment S. pneumoniae, H. influenzae, K. pneumoniae Gram-negative rods, MRSA, legionella 7