Respiratory Infections Flashcards
What is rhinitis
nasal turbinate swelling and congestion, nasal drainage which can be clear, yellow, green
What is sinusitis
inflammation of the sinus cavity with filling of the sinuses with mucous
What is pharyngitis
inflammation of the pharynx, with or without exudate
What is laryngitis
inflammation of the larynx/vocal cords, usually with changes in the voice or a characteristic barking cough.
Clinical features of upper respiratory infections
Clinical features of acute rhinosinusitis
Nasal congestion, purulent nasal discharge, facial pain or pressure are all seen. Fever only lasts a few days in viral disease, but the other symptoms cough, nasal drainage, sputum production, etc can last for almost 2 weeks in viral disease
Criteria for bacterial rhinosinusitis
Persistent > 10 days without improvement
Severe symptoms for 3-4 days
“Double-sickening” indicating bacterial superinfection after viral illness
Non-antibiotic treatment for rhinosinusitis
Saline irrigation “neti pot”
Intranasal glucocorticoids—decreases inflammation
Intranasal sympathomimetic decongestants (pseudoephedrine spray—use for max of 3 days only! Or will get “rhinitis medicamentosa”)
Oral sympathomimetic decongestants—relieve pressure in sinuses and nasal turbinate swelling through sympathomimetic effect
Antihistamines—help with itching and pain of nose, helps dry secretions
Mucolytics—thin mucus so it drains more easily from sinuses
NNT for rhinosinusitis
13 for adults
5 for children
Most common cause of pharyngitis in children
Group A beta-hemolytic Streptococcus (GAS)
Serious cause of pharyngitis that presents with intense pharyngitis, cervical lymphadenopathy and white/gray membranes that can occlude airways and cause death
Diphtheria due to Corynebacterium diphtheriae
Vaccine preventable
Clinical features of pharyngitis
Diagnostic testing performed for pharyngitis
Rapid streptococcal tests- sensitivity and specificity of up to 95%! Throat culture is done reflexively if negative. If suspect STI’s, need to test specifically for those with additional tests
Treatment for Group A Strep
1st generation Penicillin (IM or oral) as recommended primary treatment! Clinically, because it can be dosed less often, amoxicillin is used unless the patient refuses oral medications.
The main reason why GAS pharyngitis is always treated is that treatment lessens the risk of Rheumatic Fever happening as a complication to GAS infection
Presentation of Peritonsillar or parapharyngeal abscess
Infection and pus collection in the deep tissues of the pharynx around the tonsillar pillar. Presents with fever, very sore throat, and deviation of the uvula on examination as well as swelling behind or around the tonsil unilaterally. People may sound like they are speaking with a mouthful of hot food aka “hot-potato” voice, and may have pain with opening the jaw or refusal to open the mouth.
These are less dangerous compared to retropharyngeal abscesses, because they rarely cause concern for airway safety, and may nor may not require drainage in addition to IV antibiotics.
Presentation of retropharyngeal abscess
Infection and pus collection in the prevertebral spaces of the posterior pharynx. These also present with throat pain are intrisically dangerous and considered an airway emergency as they can rapidly enlarge, obstruct breathing, and make intubation impossible. They may be symmetric or asymmetric, and imaging is required to diagnose.
The retropharyngeal soft tissues should usually be minimally seen on a lateral film, any widening that is greater than the adjacent vertebral bodies is significant retropharyngeal edema indicating possible abscess.
Epiglottitis def and presentation
Inflammation of the epiglottis and adjacent supraglottic structures. This starts out as what looks like a routine cold or croup, but can progress to life-threatening airway obstruction as shown above when the usually thin, flexible epiglottis becomes edematous and woody, swelling to close off the airway completely. Pediatric patients may present in the “tripod” position, shown below, to try to open their airway and get more air, and will usually be drooling and very sick appearing, with breathing their sole focus.
Causes of epiglottitis
Haemophilus influenzae type b (Hib) is the most common infectious cause of epiglottitis in children and prevented with vaccine. Also, Staph Aureus can be seen as a cause, usually in kids with underlying varicella. In adults, epiglottitis has been associated with a broad range of bacteria, viruses, combined viral-bacterial infections, fungi, and noninfectious causes, and is a rare diagnosis.
Treatment for epiglottitis
Securing the airway with expert airway help from an anesthesiologist or critical care physician is the first priority and all other care is delayed until that occurs to prevent the child crying and occluding their airway irreversibly with IV placement orr other stimulation. Epiglottitis is always treated with broad spectrum antibiotics empirically due to its immediately life-threatening nature.
Laryngitis def and presentation
Commonly known as “I lost my voice.” Extremely common and self-limited, lasts less than 3 weeks. Clinical findings are hoarseness-to-total voice loss, associated with rhinorrhea, cough, and mild sore throat. Causes are mostly viral, but can also be caused by common pharyngeal flora: Moraxella catarrhalis, Hemophilus influenzae, and Streptococcus pneumoniae. Antibiotics not used empirically; if persistent voice changes, get ENT to see and scope to evaluate for tumor, GERD, functional problem, or unusual infection as cause.
What is laryngotracheitis
Croup
inflammation and infection of the upper airway, typically just below the vocal cords, also referred to as subglottic edema.
Presentation of croup
Children less than two are most symptomatic due to the small diameter of their airways. They will also have other typical cold symptoms, like runny nose and low grade fever.
Croup causes a characteristic “seal’s bark” cough and stridor
Imaging of croup
Croup is a clinical diagnosis most of the time, if there is doubt about the diagnosis, or respiratory distress due to another cause is in the differential diagnosis, a neck x-ray can be done to look for the characteristic subglottic narrowing associated with croup. There are a few neck x-rays findings to be familiar with after this lesson–this “steeple sign” of croup is one of them!
Croup treatment
Croup that causes stridor at rest should be treated with a one-time dose of oral steroids, to decrease the airway edema and prevent worsening respiratory distress. The illness usually lasts 3 or so days, and peaks on the evening of the second day, so using dexamethasone as a steroid that has a long half-life of about 24 hours is the usual choice. When patients are observed to have significant respiratory distress with tachypnea and retractions due to croup, they can temporarily benefit from a racemic epinephrine nebulized treatment. This gives epinephrine, which acts as a vasoconstrictor, topically to the subglottic edema, and will temporarily decrease edema for a few hours until the treatment wears off.
Causes of acute bronchitis
Usually caused by a virus, yet 60% to 90% of patients who seek care receive antibiotics due to their concern about the length of time until the illness self-resolves.
Acute bronchitis presentation
Cough, +/- sputum. Initially cannot be distinguished from other upper respiratory tract infections, and tends to persist for 2-3 weeks. Prolonged fever more than a day or two is unusual, and pneumonia should be considered for any systemic ill symptoms in addition to cough. This diagnosis commonly causes wheezing that looks like asthma and responds to bronchodilators! However, it’s not asthma if wheezing only happens in the setting of infection, and would not need controller meds that are always prescribed in the care of asthma. On exam, wheezing may or may not be present, but signs of parenchymal disease should not be, meaning there should be no crackles or areas of dullness or decreased air entry as can be seen in pneumonia.
Diagnostic testing for bronchitis
There are no specific tests that need to be done to make a diagnosis of acute bronchitis. In sicker patients that may have bronchopneumonia rather than just bronchitis due to the presence of systemic symptoms (fever, crackles on exam, high respiratory rate, dyspnea, altered mental status) a chest xray should be performed to evaluate for pneumonia, looking for infiltrates in lung parenchyma.
When should bronchitis be treated with antibiotics
The only true indication for acute bronchitis to be treated with antibiotics is in treating or preventing Bordetella pertussis, “whooping cough”, as a specific cause
The other infectious cause that is treated with antimicrobials is influenza, and oseltamivir is treatment of choice.
How to treat symptoms of acute bronchitis
Ipatropium bromide, a short-acting anticholinergic medication, can be used to decrease symptomatic mucous production and albuterol used to alleviate wheezing.
What is bronchiolitis
Bronchiolitis is inflammation and infection of the lower respiratory tract, below the level of the bronchi. It is extremely common, is seen mostly in children < 2 years of age, and is also most severe in this age group.It is exclusively a viral illness, and the most common cause is respiratory syncytial virus (RSV), but it can also be seen with rhinovirus, influenza, human metapneumovirus, parainfluenza virus, etc. It is the most common reason for hospitalization in children! Bronchiolitis is seasonal and is most prevalent Sept-April.
Pathophysiology of bronchiolitis
Bronchiolitis causes problems by causing spasm of the bronchiolar smooth muscle, thick secretions, and swelling of the small airways due to intense inflammation.
Presentation and diagnosis of bronchioloitis
Young children and infants start with typical cold symptoms and cough, and may progress to wheezing, bronchospastic cough, hypoxia, and respiratory failure. The majority of bronchiolitis is mild, but it can be severe enough to cause total respiratory failure and require ECMO, heart-lung bypass. On examination, crackles are commonly heard throughout all lung fields and wheezing, squeaks, and retractions showing respiratory distress are also common.
Clinical diagnosis
What is pneumonia
Infection of the actual parenchyma of the lung, rather than the surrounding structures like bronchi or epithelium only.
The alveoli are filled with congestion and debris, and the septae are thickened, both preventing effective oxygen exchange. This makes hypoxia a cardinal clinical finding in pneumonia.
Stages of pneumonia
Interstitial pneumonia presentation
Interstitial patterns of pneumonia present with insidious onset, dry cough, low to moderate fever, less shortness of breath/hypoxia, and less respiratory distress than other forms of pneumonia, at least initially. The clinical exam usually shows crackles over the entire lung field bilaterally, as the whole lung is involved. This form of pneumonia is more likely to be associated with viral, fungal, and atypical bacterial pathogens than the other forms on examinations.
Lobar pneumonia presentation
Lobar pneumonia indicates that the entire lobe of the lung, or most of it, has been overtaken with infection. Any lobe can be involved, and multiple lobes can also be involved if it is severe. The clinical findings of decreased air movement, dullness to percussion, egophony, rhonchi, and crackles are commonly seen as well as described on exam questions, and will be limited to the affected area. Patients with lobar pneumonia usually look sicker than patients with interstitial pneumonia, with hypoxia and respiratory distress, and the causes are more “typical” pneumonia pathogens, usually bacterial: Strep pneumoniae, Haemophilus influenzae, group A streptococci, Moraxella catarrhalis, anaerobes, and aerobic gram-negative bacteria
Bronchopneumonia presentation
Bronchopneumonia pathogens and presentation are very similar to lobar pneumonia, but with more diffusely abnormal lung findings rather than being limited to a single lobe. Similar to lobar pneumonia, these patients will also be sicker at presentation than interstitial pneumonia patients, with respiratory distress and hypoxia.
Diagnosis of lung abscess
Chest X-ray shows a lung cavity with air-fluid level, usually in a location that gravity would draw secretions towards when aspiration occurs. Chest CT to get better visualization and evaluate for possible associated obstruction/tumor as a cause is indicated, and if a specific cause is suspected like TB, additional tests may be run
Pleural effusion on imaging
We might suspect it by percussing the lung and finding dullness, but to diagnose it, we get a CXR! If the effusion is >200 mL, you will be able to see it on a plain film. The diaphragms will look like flat fluid levels rather than dome-shaped on an upright film, and the effusion can be bilateral or unilateral.
Transudate vs exudate
Transudate = Starling forces are pushing or pulling fluid out of capillaries, with cells and large proteins staying behind inside the intact capillary wall.
Exudate = the capillary wall is more permeable than usual due to inflammation, and cells, proteins, fluid are all exiting the capillary.
Light’s def of exudate:
Pleural fluid protein/serum protein ratio greater than 0.5, or
Pleural fluid LDH/serum LDH ratio greater than 0.6, or
Pleural fluid LDH greater than two-thirds the upper limits of the laboratory’s normal serum LDH
TB Granuloma
Histoplasma on histology
Histoplasma loves to live inside macrophages, which will be seen on representative images, and are described verbally as round or oval, small yeast forms 2-5 micrometers in diameter. They are a lot smaller than either blasto or coccidio and fit inside of cells as a result, in infected tissue macrophages are typically stuffed with them. You can remember the word “plasma” in Histoplasma and they they are much smaller than plasma cells (lymphocytes) and also love to live inside macrophages, also found in plasma. The majority of histoplasmosis in immune competent people does not require treatment and is a self-limited infection.
Coccidioides immitis location and histo
Endemic in the southwestern and far western US, particularly the San Joaquin valley in California, where the infection is known as “valley fever.” These appear in pathologic images as thick-walled, nonbudding, always round spherules 20-50 micrometers in diameter (much bigger than histo), and can be filled with small endospores.
Blastomyces dermatiditis location and histo
This is endemic in areas where Histoplasmosis is also found and is in the same differential for those patients. The fungal forms in tissue are larger than histoplasma, spherical, and are usually described and shown with broad-based budding. Remember Blasto = Broad Based Buds! You can also see the thick wall, but ther are no endospores like with coccidio.
Pneumocystis jiroveci pneumonia cause and presentation
Caused by Pneumocystis jirovecii, a fungus. The clues are that the patient will usually have oral thrush or other opportunistic infection, AIDS, or another cause for a CD4 cell count less than 200 cells/microL. Serum lactate dehydrogenase (LDH) will also usually be high as an additional clue. The pneumonia looks clinically like an atypical pneumonia usually, with diffuse crackles and diffuse interstitial infiltrate on CXR but cross-sectional imaging in a patient with prolonged infection will show the formation of empty cystic lung spaces
Not in macrophages like histo
Candida albicans appearance
This agent can also be a pathogen in the imunosuppressed, causing an interstitial pneumonia with nodular infiltrates that mimics Pneumocystis jiroveci pneumonia
pseudohyphae and budding yeasts.
Cryptococcus neoformans histo
thick gelatinous capsule of the fungus resisting staining and standing out as a clear halo when various stains are used, most famously the india ink stain. If the capsule is not seen, then look at the base of the budding yeast. Crypto has a narrow-based bud, unlike blasto with its broad-based buds.
Chronic pulmonary aspergillosis presentation
look clinically very much like TB, and is usually found either in people who have been treated for TB, or who have COPD or emphysema as an underlying predisposing condition, or chronic steroid use. Basically, anything that creates increased dead space in the airways and impairs mucociliary clearance will increase the risk for this diagnosis
Allergic bronchopulmonary aspergillosis (ABPA) presentation
cause for severe asthma or worsening formerly stable asthma, and reflects interplay between the immune system and the pathogen as the sensiziation of the immune system to the fungal spores worsen the inflammation of the underlying asthma
Clinically, this manifests as asthma that does not respond as expected to usual stepwise management, and hemoptysis, fever, eosinophilia, and coughing up brown mucus plugs may also be seen. Apergillus-specific IgE are used to help make the diagnosis, with a cutoff of >1000 as likely ABPA
ACUTE angle hyphal branching, tassle like head
Cytomegalovirus pneumonia presentation
causes pneumonia in immunosuppressed patients
The classic presentation of CMV post-organ transplant is the start of high fever and malaise 40 days post transplant: 40 degrees celsius, 40 days post-transplant. Multiple organs can be affected, in the lung CMV causes an interstitial pneumonia that is severe and progresses to necrosis and sometimes to ARDS.
gigantism of infected cells as well as the nuclei, with an enlarged basophilic nuclear inclusion surrounded by a halo, and called “owl’s eyes.”
