Respiratory Infections (Modified Final) PDF

Bana abusaleh Sara Almadani 8 Asma Albtoosh outline  Anatomy  Upper respiratory tract infection  Lower respiratory tract infection Quick review of the anatomy: In upper respiratory tract we need to focus on the sinuses and to be familiar with the pharynx, t...

Bana abusaleh Sara Almadani 8 Asma Albtoosh outline  Anatomy  Upper respiratory tract infection  Lower respiratory tract infection Quick review of the anatomy: In upper respiratory tract we need to focus on the sinuses and to be familiar with the pharynx, trachea, main bronchi. Familiarize yourself with the nasal cavity. Going down to the lower respiratory tract we should be familiar with the alveolar sacs and alveolar capillary membrane because this is very important in explaining symptoms and signs in patients with lower respiratory tract infections. The alveoli are lined by epithelial cells and they are surrounded by network of capillaries, and this is in close contact with the interstitium of the lungs.  Respiratory System Functions 1. supplies the body with oxygen and disposes of carbon dioxide We breathe in oxygen and breathe out carbon dioxide 2. filters inspired air Function of mucosal membrane and celia as well 3. produces sound 4. contains receptors for smell 5. rids the body of some excess water and heat 6. helps regulate blood pH What we see in patients with metabolic acidosis or other acid-base disorders, in these patients the lungs usually compensate quickly. Unlike the kidneys which usually takes 4 to 5 days for the pH to be corrected. Upper Respiratory Tract  Composed of the nose and nasal cavity, paranasal sinuses, pharynx (throat), larynx.  All part of the conducting portion of the respiratory system. They are responsible for conducting air into the alveoli so no gas exchange happens in these areas. So patients with upper respiratory tract infections they are not hypoxic and this is very important to remember. You never diagnose a patient with pharyngitis or bronchitis when they are hypoxic because no gas exchange happens there, so you should think of other causes mainly lower respiratory tract infections. Upper Respiratory Tract Paranasal sinuses About the previous figure: If you take cross-sectional area of any part of the respiratory system then you will be able to visualize the following parts, so starting from the top where we have the celia connected to the columnar epithelium. We have also goblet cells which produce mucous and thats why infection of the respiratory system is usually associated with mucus production and we have here the direction of the mucus as you can see as it moves to the upper airways. Any impairments of any of these functions will cause respiratory tract infections. Lower Respiratory Tract  Conducting airways (trachea, bronchi, up to terminal bronchioles).  Respiratory portion of the respiratory system (respiratory bronchioles, alveolar ducts, and alveoli). In conducting airways we don’t have alveoli so no gas exchange, when patients encounter infections in these areas, they are usually not hypoxic. While in respiratory portion these patients have usually involvement of area of gas exchange and that’s why they become hypoxic and complain of shortness of breath Conducting zone of lower respiratory tract Conducting part: so we have the trachea divides into right and left main bronchus and then it branches into segmental and sub-segmental bronchi, then infectionof the lung or pneumonia can happen in any lobe of the lung and this depends on the division of the bronchial tree Further illustration of the respiratory zonewhere the gas exchange occurs as you can see here the alveolar are usually filled with air, oxygen goes to the capillary network around and co2 diffuses from the blood back into the conducting airways and comes out in the exhaled breath. Respiratory Zone of Lower Respiratory Tract  If you inhaled any microorganisms or any irritants, how does the respiratory system gets rid of them? Respiratory defense mechanism  Cough reflex.  Mucociliary clearance mechanisms.  Mucosal immune system:  Phagocytosis At the cellular level  Alveolar macrophages  Lysozyme  IgA Some inflammatory  Interferons markers like:  Surfactant. When we label someone to have upper respiratory tract infection we need to be specific about what do we mean (we need to be very specific about the diagnosis). Upper respiratory tract infection  Acute tonsillitis  Acute pharyngitis  Acute otitis media  Acute sinusitis  Common cold No specific area (can involve any part of upper airways  Acute laryngitis  Otitis externa  Acute epiglotitis  Most common cause of URI is viral  Upper respiratory tract infection (URI) represents the most common acute illness evaluated in the outpatient setting.  Most common cause of sick leaves.  Short incubation period. Symptoms resolve without specific  Most of the time symptomatic treatment treatment  Secondary bacterial infection may occurred. Pathophysiology  URIs involve direct invasion of the mucosa lining the upper airway.  viruses accounts for most URIs.  bacterial infections may present with a superinfection of a viral URI.  Inoculation by bacteria or viruses begins when secretions are transferred by touching a hand exposed to pathogens to the nose or mouth or by directly inhaling respiratory droplets from an infected person who is coughing or sneezing. Droplets are particles in the air containing microorganisms and it is transferred by coughing or sneezing. (droplet transmission) Direct contact transmission means touching a hand exposed to pathogens to the nose or mouth. This is very important in highly contagious infections to know how to isolate these patients. some terminology : Nasal cavity + sinuses —> we cannot inspect them so we diagnose them clinically  Rhinitis - Inflammation of the nasal mucosa Nasal mucosa + sinuses Only in the sinuses  Rhinosinusitis or sinusitis - Inflammation of the nares and paranasal sinuses, including frontal, ethmoid, maxillary, and sphenoid  Pharyngitis - Inflammation of the pharynx, hypopharynx, uvula, and tonsils We can diagnose them by inspection. ( asking the patients to open their mouth and inspect these areas.)  Above the vocal cords  Epiglottitis (supraglottitis) - Inflammation of the superior portion of the larynx and supraglottic area.  Laryngitis - Inflammation of the larynx At the level of vocal cords  Laryngotracheitis - Inflammation of the larynx, trachea, and subglottic area.  Tracheitis - Inflammation of the trachea and subglottic area. They have different presentation, specific signs and symptoms to help you diagnose at which level is the infection. Some of these infections are dangerous like epiglottitis or laryngitis because they are associated with upper airway obstruction. So it’s important to differentiate these infections from simple rhinitis or rhinosinusitis Common Cold = flu  Adults Rhinovirus  Children Parainfluenzae and RSV / 42 18 Common Cold (influenza): inflammation of upper respiratory tract, it involves everywhere, starting from the nasal cavity and it can spread anywhere in the upper airways. Most common viral cause in the adults is rhinovirus and in children **exam q Parainfluenzae and Respiratory syncytial virus. There are other viral causes and each virus has serotypes and it’s hard to differentiate between them,we need to isolate them by PCR.But clinically they’re the same.  Virology Over 200 viruses Virus type Serotypes Andenoviruses 41 Coronaviruses 2 Influenza viruses 3 Parainfluenza viruses 4 Respiratory syncytial virus 1 Rhinoviruses 100+ Enteroviruses 60+ 10/2/98  Self limiting disease.  Fatigue  Feeling cold.  Nose burning, obstruction, running  Sneezing  Less likely Fever. This is a clue for common cold that patients usually don’t have fever and fever should alert you to think of something else. Tonsilitis-pharyngitis  Bacteria  Viruses  S. Pyogenes  Epstein-Barr virus (group A beta hemolytic  Adenovirus streptoccocus)  Influenza A, B  C. diphteriae  Coxsackie A  N. gonorrhoeae  Parainfluenzae / 42 21 Adult upper respiratory tract infections are mainly caused by viruses but we should also be able to remember the bacterial causes: After viruses, one of the most important bacteria that causes pharyngitis and tonsillitis is Streptococcus Pyogenes and it is important to be treated because if not with AB treated this bacteria gets access to the blood, and then it goes to the heart and damages the valves so the patient will suffer from endocarditis and then rheumatic heart failure and heart diseases, usually this is diagnosed later in the infection. murmer How to know that it’s bacterial? Usually the tonsils will have follicles containing pus. So we should be cautious in prescribing antibiotics. Causative organisms no need to memorize numbers but know what is the most common  < 3 years   100 % viral  5-15 years  15-30 % GABHS= (group A beta hemolytic streptoccocus)  Adult  10 % GABHS / 42 22  if the cause is Due to streptococci:  Spreads by close contact and through air ( droplet )  Spread more in crowded areas (KG, school, army..)  Most common among 5-15 age group  More frequent among lower socio-economic classes  Most common during winter and spring  Incubation period 2-4 days / 42 23 Signs/symptoms Exudates is the whitish discharge that you get to see over the tonsils and this is very characteristic for GABHS. ❖ Sore throat Lymph adenopathy ❖Tonsillar hyperemia / ❖ Anterior cervical LAP exudates ❖ Fever > 38 C Is common, especially if it’s bacterial. ❖Soft palate petechia ❖ Difficulty in swallowing due to tonsillar enlargement ❖Absence of coughing ❖ Headache, fatigue ❖Absence of nose drip From the inflammatory ❖ Muscle pain response or if the cause ❖Absence of hoarseness was viral ❖ Nausea, vomiting Because the infection is at the level of the tonsils and hoarseness happens when we get to the area of the larynx. / 42 24  Viral tonsillitis/pharyngitis  Having additional rhinitis, hoarseness, conjunctivitis and cough  Pharyngitis is accompanied by conjunctivitis in adenovirus infections  Oral vesicles, ulcers point to viruses Clue to viruses Usually if the cause is bacterial it will be localized to the level of the tonsils but if it’s viral it usually affects everywhere in the upper respiratory tract and eyes. / 42 25  Exudates  GABHS If you see white discharge you have to prescribe antibiotics. / 42 26  Lymphadenopathy This is the areas where you should look for the lymph nodes cervical lymph node enlargement  GABHS Other causes of LAP:  Epstein-Barr virus  Adenovirus  Human herpesvirus type 6  Tularemia  HIV infection no need to memorise all of these Usually painful cervical lymph nodes if they are painless we should think of causes / 42 other than infections. 27  Laboratory  Throat swab  Gold standard  Rapid antigen test  If negative need swab  ASO antistreptolysin titer itstreptococcus is an antibody indicates that this person hase been exposed to early on its IgM then IgG  May remain + for 1 year  WBC count high count  Peripheral smear In practice, we don’t do any of these so this is just for teaching purposes and usually if the patient comes with tonsillar enlargement, sore throat and white exudate we prescribe antibiotics and we don’t do any of these because they will not change the management, but this is what we do to prove GABHS / 42 28  Tonsillitis due to Streptococci  Supurative complications  Abscess neck stiffness, and photophobia. because  Sinusitis, otitis, mastoiditis the patient will have neurological deficits. (Infectious the complications may represent as stroke). bacteria has  Cavernous sinus thrombosis reached Hypertensive, fever because the infection spreads the  Toxic shock syndrome through the blood and may cause scaling of the skin. blood so it may  Cervical lymphadenitis destroy anywher  Septic arthritis, osteomyelitis e  Recurrent tonsillitis/pharyngitis  Nonsupurative complications long term , not by the infx. itself Damaging the valves by initiating inflammatory  Acute romatic fever response  Acute glomerulonephritis / 42 29  Antibiotics in Tonsillitis/pharyngitis due to GABHS ORAL Doses for you to read Penicilline V Children:2x250 mg or 3x250mg,10 days Cefuroxime Adults:3x500 mg or 4x500mg,10 days PARENTERAL Benzathine penicilline Adults:27 kg:1.200 000 U single dose, IM ALLERGY TO PENICILLINE Erithromycine estolate 20-40 mg/kg/day, 2x1 or 3x1, 10 days Erithromycine ethyl succinate 40 mg/kg/day, 2x1 or 3x1, 10 days ➡ For patients who don’t need hospitalization We can prescribe Augmentin or Cefuroxime alone and if they are allergic we give azithromycin. 30/ 42  Infection of middle ear Acute Otitis Mediacauses Most common bacteria affecting respiratory tract except the tonsils is streptococcus pneumonia. (After viruses of course).  S. pneumoniae 30% Most common bacterial cause  H. İnfluenzae 20%  M. Catarrhalis 15%  S. pyogenes 3%  S. aureus 2% we do empirical treatment  No growth 10-30% The treatment is difficult  Chronic otitis media: P. aeruginosa, S. aureus, anaerobic bacteria Be careful if you’re dealing with chronic otitis media because you need to identify what microorganisms you are dealing with and you need to obtain culture. / 42 31 Acute Otitis Media  85% of children up to 3 years experience at least one,  50% of children up to 3 years experience at least two attacks  AOM is usually self-limited. Rarely benefits from antibiotics. Because most commonly the cause is viral.  81 % undergo spontaneus resolution. / 42 32 Signs and Symptoms  Symptoms  Otoscopic findings Autalgia Ear pain  Otalgia  Tympanic membrane  Ear draining erythema  Hearing loss  Inflammation  Fever  Bulging  Fatigue last stage Effusion   Irritability  Hearing loss  Tinnitus, vertigo So it’s very important to be identified and treated / 42 33 Acute Rhinitis / Sinusitis Acute sinusitis Chronic sinusitis  Str. pneumoniae %41  Anaerobe bacteria:  H. influenzae %35 Bactroides, Fusobacterium  M. catarrhalis %8  S. aureus  Others %16  Strep. pyogenes Strep. pyogenes S. aureus  Str. pneumoniae Rhinovirus  Gram (-) bacteria Parainfluenzae  Fungal. Symptoms more than 3 months. / 42 34 In acute sinusitis, the most common bacteria is streptococcus pneumonia just like acute otitis. In chronic infections the microorganisms change their behavior so in chronic sinusitis we get to isolate different kinds of bacteria that are not common (unlikely to be causing acute sinusitis. The difference between acute and chronic sinusitis is duration of symptoms: More than two or three months = chronic Less than 1 month = acute Between 1-3 months = subacute  Predisposition to Sinusitis  Anatomical: septal deviation, chronic cough of sputum Genetic disorders (abnormal cilia) and chronic sinusitis  Mucociliary functions: cystic fibrosis, immotile cilia synd.  Systemic dis., immune deficiency.: DM, AIDS, CRF Chronic renal failure  Allergy: Nasal polyps, asthma  Neoplasia Usually hidden diagnosis  Environmental: smoking, air pollution, trauma... Clue of immune deficiency= infections in other systems + family history DM is cause of recurrent infections one of them is sinusitis / 42 35 Empirical means that we give antibiotic regardless of knowing the microorganism or not, because we don’t know when secondary bacterial infection can happen. Management  Empirical antimicrobial therapy.  Acute sinusitis usually no need for Abs. But we usually give Abs because of secondary bacterial infections.  Symptomatic treatment.  Chronic sinusitis requires prolonged abs treatment 2-3 wks. +steroids in the nose This is a sinus x-ray you can see the maxillary sinus and we have fluid level this sinus is blocked by inflammation. We usually see this in acute sinusitis, but in chronic we don’t. Acute bronchitis  Only lasts for a few days to weeks.  Generally viral in origin.  Rhinovirus, parainfluenzae, RSV, influenzae viruses.  expectorating cough, shortness of breath (dyspnea), and wheezing. chest pains, fever, and fatigue.  In addition, bronchitis caused by Adenovirus may cause systemic and gastrointestinal symptoms.  the coughs due to bronchitis can continue for up to three weeks or more even after all other symptoms have subsided It is called post viral cough and it can get better by inhaled medication. It is normal because basically the airways are still irritated and they need time to recover. expectorating cough= cough with a lot of sputum ( clue that the source is the bronchi) because the bronchi have more goblet cells so when they get inflamed they produce more sputum. Shortness of breath caused by narrowing of the conducting airway, not hypoxia and the narrowing also causes the wheezing. Chest pain is caused by repeated cough. Acute Bronchitis  Only about 5-10% of bronchitis cases are caused by a bacterial infection.  Secondary bacterial infection can occur.  H. influenzae  S. pneumoniae  S.aureus. Secondary bacterial infections are very common in adults so we give empirical antibiotics.  Diagnosis is mostly clinical(signs and symptoms).  No radiologic changes on chest X-Ray.We don’t see bronchitis on the x-ray the only way to see airways is by bronchoscopy  Usually no need for antibiotics Tx.  Antibiotics only for secondary bacterial infections proved by microbiology, or in patient with chronic lung disease(COPD exacerbations, bronchiactesis). Case from the doctor: Patient have fever, cough productive of sputum, retrosternal chest pain, wheezing, dyspnea and chestx-ray is normal, the most likely cause is? Acute bronchitis Patients with acute bronchitis can have hemoptysis so if the patient have the same symptoms and also hemoptysis wait until the infection subsides if the hemoptysis persists then you need to take further actions. But the most common cause of hemoptysis is acute bronchitis. Pneumonia is infection of the lungs and x-ray is always abnormal. Normal lung is black on the x-ray cause it’s filled with air so if something fills it, it will appear white because we will lose the area of the air. So pneumonia on the x-ray is increased attenuation of the lung or increased radio opacity of the lungs.  Pneumonia S.pneumo Legionella TB Plague Tularemia RICIN toxin SARS Staphylococcal Enterotoxin B Pneumonia  Inflammation of the alveoli of the parenchyma of the lung with consolidation and exudation Symptoms:  Cough. At first it’s dry and later with sputum  Pleuritic chest pain  Production of purulent sputum.  Fever. Lung tissue itself it’s not painful so pneumonia becomes painful when it’s close to the plural surface where we have the nerves and this is what we usually see in pneumonia because we are talking about infection of the lung parenchyma that is distal from the central airways. Pleuritic chest pain = always pneumonia and pleuritic chest pain means when you take a deep breath you can’t continue the breath. Purulent sputum = rusty or green unlike bronchitis not white Case from the doctor about the next slide: 45 years old patient drinks alcohol 3 times a day for the last 10 years and he complained of cough, fever, dyspnea and chest x-ray showed patchy opacity, the most likely cause of his pneumonia is? aspiration pneumonia. And the most important microorganism that needs to be covered by antibiotics is? Anaerobes  mild pneumonia - don't require hospitalization- can happen for anyone ( immunocompetent)  Risk factors:  COPD or structural lung disease.  Diabetes Mellitus DM  Cardiac / Renal failure  Immunosuppression  Reduced levels consciousness, neurological disease.  Anything that inhibits the gag / cough reflex Reduced levels of consciousness—> like people drinking alcohol or taking seizure medications. We call it aspiration pneumonia because of the contents of saliva or stomach in patients with reflux gets into the lungs and most of the times the cause is anaerobes. Pneumonia is a clinical diagnosis —> X-ray findings and symptoms. We try to find the cause what’s in 50% of the cases we can’t find it But I do not need the microorganism to confirm my diagnosis, x-ray and symptoms are enough.  About 40-60% of persons with pneumonia do not have a defined etiology… We give empirical antibiotics. even after extensive testing for known respiratory pathogens.  Classified to: Typical or Atypical pneumonia(microorganisim) Community acquired, nosocomial. Typical pneumonia is caused by the typical microorganisms like: Streptococcus pneumonia and Haemophilus influenza (most common bacteria that causes pneumonia). Patient comes with acute symptoms: cough, shortness of breath and sputum but the duration is short. for example, the patient comes to the ER after two or three days from the symptoms has started. Atypical pneumonia is pneumonia that is caused by atypical microorganism Which means less common microorganisms like: chlamydia, mycoplasma and legionella. The duration is more insidious. For example the patient comes to the ER after seven days from the symptoms has started. The treatment of atypical pneumonia differs from the treatment of typical pneumonia. In both typical and atypical pneumonia the symptoms are acute in less than two weeks so they usually present in less than 2 weeks, but the patient who comes earlier has typical pneumonia and the patient who comes later has atypical pneumonia. In typical pneumonia, patient looks very sick, very unwell and his x-ray is bad and in blood test the inflammatory markers are very high. Unlike atypical pneumonia, patient looks fine, he doesn’t look that ill but his x-ray is bad and in blood test the inflammatory markers are not that high. The definitive definition of typical and atypical pneumonia is the microorganisms, so if I isolated the microorganisms I can say with confidence if it’s typical or atypical pneumonia. But in practice we don’t always isolate microorganisms, we depend on x-rays, clinical scenario and blood test.  From the environment Community Acquired Pneumonia  Infection of the lung parenchyma in a person who is not hospitalized or living in a long-term care facility for ≥ 2 weeks  5.6 million cases annually in the U.S.  Estimated total annual cost of health care = $8.4 billion  Most common pathogen = Streptoccocus. pneumonia (60-70% of CAP cases) The choice of antibiotic for community acquired pneumonia is different from hospital acquired pneumonia. In pneumonia we have to start the antibiotic within 4 hours of diagnosis, we shouldn’t delay it!! Community acquired pneumonia  S. pneumoniae  H. influenzae  Moraxella  K. pneumoniae (Friedlander’s bacillus)  Chlamydia.pneumonia  Staphylococcus. Aureus. “Nosocomial” Pneumonia  Hospital-acquired pneumonia (HAP)  Occurs 48 hours or more after admission, which was not incubating at the time of admission  Ventilator-associated pneumonia (VAP)  Arises more than 48-72 hours after endotracheal intubation The patient is unconscious —> I can’t ask him if he has cough so I depend on x-ray and other clues like fever, CRP is high and wbc count also.( after 48 hours of intubation) Hospital acquired pneumonia  Risk factors include mechanical ventilation  Anerobes: Enterobactericiae.  Gram negative: Acinetobacter Pseudomonas species  S.aureus (MRSA) Streptococcus pneumonia  Most common cause of CAP  Gram positive diplococci  “Typical” symptoms (e.g. malaise, shaking chills, fever, rusty sputum, pleuritic hest pain, cough)  Lobar infiltrate on CXR  Suppressed host  25% bacteremic Patchy opacity affecting one lobe so usually it is caused by streptococcus pneumonia. Atypical Pneumonia  #2 cause (especially in younger population)  Commonly associated with milder Sx’s: subacute onset, non-productive cough, no focal infiltrate on CXR, usually diffuse infiltration.  Mycoplasma: younger Pts, extra-pulm Sx’s (anemia, rashes), headache, sore throat  Chlamydia: year round, URI Sx, sore throat  Legionella: higher mortality rate, water-borne outbreaks, hyponatremia, diarrhea  ‫مش مطلوب‬ Atypical pneumonia  Mycoplasma pneumoniae (Eaton agent)  Obligate human pathogen  Epidemics occur at 4-6 year intervals  Spread requires close contact  Common in children