chapter 19 (module 7) Flashcards
(82 cards)
1
Q
19.1 The Respiratory Tract and Its Defenses
A
-resp tract is the most common place for infectious agents to gain access to the body
2
Q
components of upper resp tract
A
mouth, nose, nasal cavity and sinuses above it, throat/pharynx, epiglottis, and larynx
3
Q
components of lower resp tract
A
trachea, bronchi, bronchioles, lungs
4
Q
________ are attached to the bronchioles and are small balloon like structures; sites of oxygen exchange in lungs
A
alveoli
5
Q
anatomical features of resp system that protect from infection
A
- nasal hairs serve to trap particles
- cilia on the epithelium of trachea and bronchi propel particles up and out of resp tract (ciliary escalator)
- mucus on the surface of mucous membranes lining the resp tract is a natural trap for invading microorganisms
- ->once trapped, involuntary responses like coughing, sneezing, and swallowing can move them out of sensitive areas
(FIRST LINE DEFENSES)
6
Q
small piece of cartilage that partially covers the larynx; its job is to help prevent inhalation of food and fluids into your lungs
A
Epiglottis
7
Q
_______ occurs when infection or injury causes the epiglottis to swell, which may result in the inability to draw air into the lungs
sx: fever, extremely sore throat, muffled or hoarse voice, stridor (high pitched breathing sound on inhalation), and difficulty breathing and swallowing
A
8
Q
name some serious infections besides epiglottitis, that have been decreased in incidence since the intro of Hib vaccine (Haemophilus influenzae b.)
A
Meningitis, otitis media, and pneumonia
9
Q
second and third lines of defense that also protect the resp tract
A
complement action, antimicrobial peptides, and increased levels of cytokines all help battle pathogens in the lungs
- macrophages inhabit the alveoli of the lungs and the cluster of the lymphoid tissues (tonsils) in the throat (pharynx)
- secretory IgA against specific pathogens can be found in the mucus secretions as well
10
Q
19.2 Normal Biota of Resp. Tract
A
latest research shows that a healthy upper resp. system harbors thousands of commensal microorganisms and that even the LUNGS have a normal, if limited, biota
- –> part of this normal biota can cause serious disease especially in immunocompromised people, including:
- S. pyogenes
- S. aureus
- Streptococcus pneumoniae
- Neisseria meningitidis
- Haemophilus influenzae
Yeasts, especially Candida albicans, also colonize the mucosal surfaces of the mouth
-other fungi can be found
- biota in lung differs in patients suffering from lung disorders such as COPD, asthma, and cystic fibrosis
- smokers vs nonsmokers appear to have different biota
11
Q
reduces the chances of pathogens establishing themselves in the same area by competing with them for resources and space (in resp system)
A
microbial antagonism
12
Q
19.3
Upper Resp Tract Diseases Caused by Microorganisms
A
13
Q
Pharyngitis
A
inflammation of the throat, pain and swelling experienced by host (ranging from mod to severe for pain depending on causative agent
14
Q
Pharyngitis
Viral sore throats are generally ______ and sometimes lead to __________
A
mild
hoarseness
15
Q
Pharyngitis
Bacterial sore throats are generally more ________ than those caused by viruses, and are more likely to be accompanied by _____, ______, and _____
A
painful
nausea
headache
fever
16
Q
Clinical signs of pharyngitis (sore throat)
A
reddened mucosa, swollen tonsils, sometimes white packets of inflammatory products visible on the walls of the throat, especially in streptococcal disease
- the mucous membranes may be swollen, affecting swallowing and speech
- often pharyngitis results in foul smelling breath
17
Q
incubation period for most sore throats
A
generally 2-5 days
18
Q
Streptococcus pyogenes
A
gram + coccus that grows in chains, does not form endospores, nonmotile, forms capsules and slime layers
- facultative anaerobe that ferments a variety of sugars
- does not produce catalase but does have a peroxidase system for inactivating hydrogen peroxide, which allows its survival in the presence of oxygen
19
Q
causative agents for most serious cases of pharyngitis
A
S. pyogenes
group A streptococcus
Fusobacterium necrophorum
20
Q
Scarlet Fever
as a result of complication with pharyngitis - extra toxin
A
result of S. pyogenes strain that is itself infected with a bacteriophage
-this lysogenic virus gives streptococcus the ability to produce ERYTHROGENIC TOXIN,
characterized by sandpaper-like rash, most often on the neck, chest, elbows, and inner surfaces of the thighs, HIGH FEVER
21
Q
the deposition of antibody-antigen complexes in the body that occurs with untreated throat infections can result in
A
glomerulonephritis
22
Q
Rheumatic Fever (as a result of a pharyngitis complication)
A
thought to be due to an immunologic cross-reaction between the streptococcal M protein and heart muscle.
–> means that the lymphocyte clones activated by the M protein also react with an epitope on the heart muscle
- tends to occur approx. 3 weeks after pharyngitis has subsided
- can result in PERM heart valve damage
-other sx include nodules over bony surfaces just under the skin, arthritis in multiple joints
23
Q
Pharyngitis
Virulence Factors of S. pyogenes
A
virulence is a result of two main factors:
- ability of its surface antigens to mimic host proteins
- –> display numerous surface antigens
-possession of superantigens
- –> specialized polysaccharide on the surface of the cell wall help to protect the bacterium from being dissolved by lysozymes
- –> Lipoteichoic acid (LTA) contributes to the adherence of S. pyogenes to epithelial cells in the pharynx
- –> spiky surface projection called M. protein contributes to virulence by resisting phagocytosis
- –> capsule made of Hyaluronic Acid is formed by most S. pyogenes strains (adhesiveness)
24
Q
Pharyngitis:
Extracellular Toxins
A
Group A streptococci owe some of their virulence to the effects of hemolysins called streptolysins (rapidly injure many cells/tissues, inc. leukocytes and liver and heart muscle)
- Streptolysin O (SLO)
- Streptolysin S (SLS)
- Key toxin in development of SCARLET FEVER is ERYTHROGENIC TOXIN
- responsible for bright red rash and fever
- -> only lysogenic strains of S. pyogenes that contain genes for temperate bacteriophage can synthesize this toxin
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Transmission of pharyngitis S. pyogenes
resp. droplets or direct contact with mucus secretions
| - humans are only significant reservoir
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Group A streptococcal infection Culture/Dx of pharyngitis
rapid diagnostic tests (swab samples)
if culture is needed, it is usually done on sheep blood agar
-->is pharyngitis is caused by a virus: blood agar will show a variety of colony types
POC testing
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Prevention of Group A streptococci of pharyngitis
no vaccine exists
| good handwashing
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Treatment of S. pyogenes in pharyngitis
penicillin is antibiotic of choice
-if allergy than first-generation cephalosporin, such as cephalexin is used
--SHould be treated with antibiotics when S. pyogenes infection b/c of potential sequelae
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Pharyngitis: S. pyogenes
Causative Org: Streptococcus pyogenes (G+)
Trans: droplet or direct contact
Virulent Factors: LTA, M protein, HA capsule, SLS/SLO (streptolysins), superantigens, induction of autoimmunity
Culture/Dx: Beta-hemolytic on blood agar, sensitive to Bacitracin, rapid antigen tests
Prevention: hygiene practices
Tx: Penicillin, cephalexin in penicillin-allergic
D Feats: generally more severe than viral pharyngitis
Epi Feats: US: 20-30% of all cases of pharyngitis
S/S: swollen and painful pharynx/throat, potentially rheumatic fever, scarlet fever, difficulty swallowing
30
Pharyngitis: Fusobacterium necrophorum
Causative Org: Fusobacterium necrophorum (G-)
Trans: usually endogenous
Virulent Factors: invasiveness, endotoxin
Culture/Dx: culture anaerobically , CT scan for abscess(es)
Prevention: ?
Tx: Penicillin
D Feats: can lead to Lemierre's syndrome
Epi Feats: causes up to 15% of acute pharyngitis in teens/young adults (can lead to septic thrombophlebitis)
S/S:
31
Pharyngitis: Viruses
Causative Org: viral
Trans: all forms of contact
Virulent Factors: ---
Culture/Dx: goal is to rule out S. pyogenes, further diagnosis usually not performed
Prevention: hygiene
Tx: symptom relief only
D Feats: hoarseness frequently accompanies viral cases
Epi Feats: ubiquitous; responsible for 40-60% of all pharyngitis
S/S:
32
The Common Cold
| S/S
sneezing. scratchy throat, runny nose, which usually begin 2-3 days post-infection
---> an uncomplicated cold is often not accompanied by fever, but children may experience low grade fevers
INC. PERIOD: 2-5 days
33
the common cold is caused by one of over _______ different kinds of viruses.
Most common type of virus leading to rhinitis is a group called ________, of which there are more than 150 serotypes
Coronaviruses and adenoviruses are also common causes, and respiratory syncytial virus (RSV) causes colds in more people is it infects but children and infants may experience more resp. distress with RSV
200
| rhinoviruses
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The Common Cold
Causative Org: approx. 200 viruses
Trans: indirect contact, droplet contact
Virulent Factors: attachment proteins; most symptoms induced by host response
Culture/Dx: not necessary
Prevention: hygiene practices
Tx: for symptoms only
D Feats: ---
Epi Feats: highest incidence among preschool and elementary schoolchildren with average of 3-8 colds per year; adults and adolescents on average experience 2-4 colds per year
S/S:
35
Sinusitis
(commonly called a sinus infection, and can be in any four pairs of sinuses in the skull - can be caused by allergy, infections, or structural problems such as narrow passageways or deviated nasal septum)
Causative Org: Viruses
Trans: droplet contact, indirect contact
Virulent Factors: ---
Culture/Dx: culture not usually performed; diagnosis based on clinical presentation
Prevention: hygiene
Tx: none
D Feats: viral and bacterial much more common than fungal
Epi Feats: commonly follows the common cold
S/S:
36
Sinusitis: Various bacteria, often mixed infection
Causative Org: various bacteria, often mixed infection
Trans: endogenous (opportunistic)
Virulent Factors: ---
Culture/Dx: culture not usually performed; dx based on clinical presentation; occasionally X rays or other imaging tech used
Prevention: ---
Tx: recommendation is for no antibiotics unless it remains unresolved for some weeks
D Feats: viral and bacterial much more common than fungal
Epi Feats:
S/S: US: affects 1 in 7 adults, between 12 and 30 million dx's a year
37
Sinusitis: Various fungi
Causative Org: various fungi
Trans: introduction by trauma or opportunistic overgrowth
Virulent Factors: ---
Culture/Dx: same as bacterial and viral
Prevention: ---
Tx: physical removal of fungus; in severe cases antifungals used
D Feats: suspect in immunocompromised patients
Epi Feats:
S/S:
38
Acute Otitis Media (Ear Infection)
viral infections of the upper resp. tract can lead to inflammation of the EUSTACHIAN TUBES and build up of fluid in the middle ear, which can lead to bacterial multiplication in those fluids
--> although the middle ear normally has no biota, bacteria can migrate along the eustachian tube from the upper resp tract, and when the bacteria encounter mucus and fluid build up in the middle ear, they multiply rapidly
the presence of the bacteria increases the inflammatory response, leading to pus production and continued fluid secretion, the fluid is called EFFUSION
39
new data suggest that chronic otitis media is caused by a mixed _____ or bacteria that is attach to the mucosa of the middle ear.
________ are generally les susceptible to antibiotics
and scientists now suggest that the majority of acute and chronic otitis media cases are mixed infection with _________ and ___________ acting together
biofilm
biofilms
viruses and bacteria
40
Otitis Media: Streptococcus pneumoniae
Causative Org: S. pneumoniae
Trans: endogenous (may follow upper resp. tract infection by S. pneumoniae or other microorganisms)
Virulent Factors: Capsule, hemolysin
Culture/Dx: usually relies on clinical sx and failure to resolve within 72 hours
Prevention: Pneumococcal conjugate vaccine
Tx: wait for resolution, if needed, amoxicillin or amoxicillin + clavulanate or cefuroxime; in serious threat category in CDC antibiotic resistance
D Feats: ---
Epi Feats:
S/S:
41
Otitis Media: Candida auris
Causative Org: Candida auris (F)
Trans: not known
Virulence Factors: adherence, biofilm formation, enzymes
Culture/Dx: MALDI-TOF or PCR; CDC will identify if requested
Prevention: ---
Tx: consult with CDC; in urgent threat in CDC antibiotic resistance
D Feats: ---
Epi Feats:
S/S:
42
Otitis Media: Other bacteria/viruses
Causative Org: other bacteria or viruses
Trans: endogenous
Virulent Factors: ---
Culture/Dx: usually relies in clinical sx and failure to resolve within 72 hours
Prevention: none
Tx: wait for resolution; if needed, a broad spectrum antibiotic (azithromycin) may be used in absence of etiologic diagnosis
D Feats:
Epi Feats:
S/S:
43
19.4 Lower Resp Tract Diseases Caused by Microorganisms
44
Highlight Disease: Pneumonia
characterized by ANATOMICAL DIAGNOSIS
-defined as an inflammatory condition of the lung in which fluid fills the alveoli
-
45
Pneumonia
Microorganisms of infectious relation to pneumonia must avoid being phagocytosed by alveolar _________, or at least avoid being killed once inside them.
macrophages
46
Pneumonia
Microorganisms of infectious relation to pneumonia must avoid being phagocytosed by alveolar _________, or at least avoid being killed once inside them.
macrophages
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Bacteria, fungi, and a wide variety of _____ can cause pneumonias; and there is a lot of variation in the virulence of different pathogenic agents
viruses
48
what are the two types of pneumonia?
| they are characterized by different modes of transmission and pathogenic agents
Community-acquired pneumonia (CAP) - experienced by persons in the general population
Healthcare-associated pneumonia (CAP - develops in individuals receiving treatment at healthcare facilities, including in hospitals
49
SARS-CoV-2 was first recognized as causing a deadly ________.
pneumonia
50
In non-pandemic times, S. pneumoniae accounts for up to 40% of __________-acquired bacterial pneumonia cases
-> causes more lethal pneumonia cases than any other micro
community
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The _______virus, which emerged in 1993, also causes a very serious pneumonia
hantavirus
52
What bacteria causes a pneumonia form of anthrax
Bacillus anthracis
53
a number of bacteria cause a milder form of pneumonia that is often referred to as "_______ _______", two of these bacteria are Mycoplasma pneumoniae and Chlamydophila pneumoniae.
walking pneumonia
54
most deaths stemming from influenza are caused by ___________, either from the original virus or from secondary infection
pneumonia
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SARS-CoV-2 and pneumonia
in December 2019, a cluster of pneumonia cases of unknown etiology was reported in China; it was identified as a novel coronavirus and named SARS-CoV-2
56
COVID-19 S/S
can cause no sx at all, or may lead to death
- although first recognized for its pneumonia manifestations, it can damage blood vessels all over the body, leading to damage to the heart, kidneys, brain, and other organs
- -> blood clots
- -> ventilation may be needed
- -> potentially post-infection symptoms, lasting weeks to months
Children and young adults are at risk for MIS-C (multisystem inflammatory syndrome in children), an inflammatory disease that follows COVID-19 in some young patients
57
COVID-19 causative agent
coronaviruses are mild, generally speaking, and four different coronaviruses circulate constantly among humans causing the common cold
---> prob originated in bats but may have circulated in a mammal such as the pangolin
it is an RNA virus with spikes (glycoproteins) which allow it to attach to host cells, these spikes are visible under the electron microscope and give it its name corona, for crown
58
COVID-19 pathogenesis and V factors
although it is a pneumonia-causing virus, it also has systemic effects
- triggers widespread activation of bradykinins, which cause damage to the lungs and other tissues
- early studies suggest the virus has proteins that block production of interferon, crippling an important part of the innate immune response
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COVID-19 trans and epi
droplet and airborne contact
-transmissible even in the absence of sx, so "well" people circulating between public spaces and home are reservoirs and carriers
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COVID-19 Culture and dx
scientists learned to grow the virus in a cell culture
- Real-time PCR of nasopharyngeal swab material (low accuracy)
- blood tests developed to detect IgG to the virus (low accuracy)
61
COVID-19 tx and prevention
CAP
masking, social distancing
drug called Remdesivir
vaccine + boosters
62
Streptococcus pneumoniae: Pneumonia
CAP
Causative Org: S. pneumoniae
Trans: droplet contact or endogenous transfer
Virulent Factors: Capsule
Culture/Dx: gram stain often diagnostic, alpha-hemolytic on blood agar; nucleic acid amplification test
Prevention: Pneumococcal polysaccharide vaccine (PPSV23) or the conjugate vaccine PCR13
Tx: Cefotaxime, ceftriaxone, with or without vancomycin; in serious threat category of antibiotic resistance
D Feats: patients usually severely ill
Epi Feats: 5% of CAP cases (community)
S/S:
63
Pneumonia: Legionella species
CAP
Causative Org: Legionella species (G-) ie. L. pneumophila
-found in aqueous habitats, resistant to chlorine, can live in association with free-living amoebas
Trans: vehicle (water droplets)
Virulent Factors: ---
Culture/Dx: requires selective charcoal yeast extract agar; PCR available
Prevention: ---
Tx: Levofloxacin, azithromycin, moxifloxacin
D Feats: mild pneumonias in healthy people; can be severe in elderly or immuno-compromised
Epi Feats:
S/S:
64
pharyngitis: Hantavirus
CAP
Causative Org: hantavirus
Trans: vehicle--- airborne virus emitted from rodents (contam. with infected feces, saliva, urine)
Virulent Factors: ability to induce inflammatory response, enveloped virus
Culture/Dx: serology (IgM)m PCR identification of antigen in tissue
Prevention: avoid mouse habitats and droppings
Tx: supportive
D Feats: rapid onset; high mortality rate, "lung edema"
Epi Feats:
S/S:
65
Atypical Pneumonias
CAP
caused by Mycoplasma and Chlamydophila
they are "atypical" b/c: symptoms do not resemble that of pneumococcal or other severe pneumonias
transmitted by aerosol droplets (so close quarters like in houses or in military or students)
"walking pneumonia"
66
```
Histoplasma capsulatum (F)
PNEUMONIA
```
CAP
grows most abundantly in moist soils high in nitrogen content especially those supplemented in bird and bat droppings
testing is similar to TB skin test: inject a fungal extract into the skin, and monitor for allergic reaction
survives in phagocytes
67
Pneumocystis (carinii) jirovecii (F)
PNEUMONIA
CAP
Pneumocystis pneumonia
-opportunistic infection (especially in AIDS, but cancer patients and other immunosuppressed at risk)
trans: inhalation of spores, and may be endogenous in healthy people's lungs
antifungals not effective due to difference in cell wall make up compared to usual fungi
68
together with surgical site infections, __________ is the most common healthcare-associated infection and is most commonly associated with ________ _________.
```
pneumonia
mechanical ventilation (VAP- ventilator associated pneumonia)
```
69
Healthcare-associated Pneumonia
Cause Org: G- and G+ bacteria from upper resp tract or stomach; environmental contamination or ventilator
Trans: endogenous (aspiration)
V Factors: ---
Culture/Dx: culture of lung fluids
Prevention: elevating head of bed, preoperative education, care of resp equipment
Tx: broad spectrum antibiotics
Epi. Feats: 300,000 cases per year
D. Feats:
S/S:
70
Influenza S/S
begins in upper resp tract but in serious cases may affect the lower resp tract
1-4 day inc. period, then sx occur quickly: headache, fever, chills, sore throat, stuffy nose, body aches, dry cough; you feel lousy
71
Influenza
Cause Org: Influenza A, B, or C viruses (Orthomyxoviridae family)
Trans: droplet contact, direct contact, indirect contact
V Factors: glycoprotein spikes (hemagglutinin (H) and neuraminidase (N)), overall ability to change genetically (antigenic drift), ability to slow down immune system, can cause overreaction of immune system: "cytokine storm"
Culture/Dx: gold standard is RT-PCR
Prevention: annual vaccination with one of several types of vaccine; some are killed and some are live attenuated
Tx: Zofluza, Tamiflu, Relenza; Antiviral drugs: Zanmivir for A and B, Oseltamivir (Tamiflu) for A and B, Baloxavir (Xofluza)
Epi. Feats: deaths vary from year to year
D. Feats: primarily binds to ciliated cells of resp tract, and eventually causes stripping of resp epithelium eliminating ciliary clearance
S/S:
72
antigenic _______ is more serious than antigenic _____
shift (major changes in flu A virus due to recombination of viral strains from two different host species - swapping out of 10 genes)
---> when a duck flu virus and human flu virus infect the same animal and then morph spikes and create flu that is unfamiliar to body
drift (antigens GRADUALLY change their amino acid composition resulting in decreased ability of memory cells)
73
Whooping Cough (Pertussis)
Cause Org: Bordetella pertussis (G-)
Trans: droplet contact
V Factors: Fimbrial hemagglutinin (adhesion), pertussis toxin and tracheal cytotoxin, endotoxin
Culture/Dx: PCR or grown on B-G, charcoal, or potato-glycerol agar; dx can be made on sx
Prevention: Acellular vaccine (DTaP), azithromycin, sulfamethoxazole for contacts
Tx: Azithromycin or erythromycin; in watch list for CDC antibiotic resistance report
Epi. Feats:
D. Feats:
S/S: two distinct symptom phases:
1. Catarrhal: after inc. period for 3-21 days begins; bacteria present in resp tract cause sx like runny nose; lasts 1-2 weeks
2. Paroxysmal: severe and uncontrollable coughing with whooping noise from trying to breath between coughing
-followed by long recovery phase (convalescent)
74
Respiratory Syncytial Virus Infection
Cause Org: resp. syncytial virus (RSV)
Trans: droplet and indirect contact
V Factors: syncytia formation (clumping together to make cell that has multiple nuclei)
Culture/Dx: RT-PCR preferred
Prevention: passive antibody (humanized monoclonal) in high risk children (Palivizumab)
Tx: Ribavirin in severe cases; no vaccine
Epi. Feats: infection in older children and adults usually manifests as a cold, older adults and those with chronic illness are more susceptible
S/S: highly contagious, conspicuously ill, with signs typical of pneumonia and bronchitis
75
Tuberculosis caused by Mycobacterium tuberculosis
Cause Org: mycobacterium tuberculosis (acid fast, anaerobe, slow generation time of 15-20 hours and period of 6 weeks for colonies to appear in culture)
Trans: vehicle (airborne) (can survive 8 months in fine aerosol particles)
V Factors: lipids in wall (cord factor - serpentine cords), ability to stimulate strong cell mediated immunity (CMI)
Culture/Dx: rapid methods; initial tests are skin testing, chest x ray
Prevention: avoiding airborne TB; BCG vaccine in other countries
Tx: Isoniazid, rifampin, and pyrazinamide + ethambutol or streptomycin for varying lengths of time (always lengthy)
D Feats: remains airborne for long periods; extremely slow-growing, which has implications for dx and tx
Epi Feats:
S/S:
76
Tuberculosis caused by MDR-TB and XDR-TB bacteria
Cause Org: MDR-TB and XDR-TB bacteria
Trans: ---
V Factors: lipids in wall, ability to stimulate strong cell mediated immunity (CMI)
Culture/Dx: rapid methods; initial tests are skin testing and chest x ray
Prevention: avoiding airborne M. tuberculosis; BCG vaccine in other countries
Tx: multiple drug regimen, which may include bedaquiline; in serious threat category in CDC antibiotic resistance report
D Feats:
Epi Feats:
S/S:
77
Primary TB
infectious dose is 10 cells, and alveolar macros ingest these cells but do not kill them, and the bacteria cells multiply; infection is hidden and symptomatic or accompanied by mild fever
--> some bacteria escape from the lungs into the blood and lymphatics
after 3-4 weeks: large influx of mononuclear cells into lungs plays a part in formation of infection sites called TUBERCLES (granulomas that consist of a central core containing TB bacteria in enlarged macrophages and an outer wall made of fibroblasts, lymphocytes, and macrophages)
neutrophils will release enzymes that break down Tubercles into necrotic caseous lesions that gradually heal by calcification -- normal lung tissue is replaced by calcium deposits; resembles cheese
TB infection outside of the lung is more common in immunosuppressed patients and young children (extrapulmonary TB - regional lymph nodes, kidneys, long bones, genital tract, brain, meninges)
Mantoux test/TB test
78
Secondary (Reactivation) TB
most recover completely, but live bacteria can remain dormant and become reactivated weeks, months, or years later, especially in those with weakened immunity
chronic TB: tubercles expand and cause cavities in the lungs and drain into bronchial tubes and upper resp tract
- -> sx include: violent coughing greenish or bloody sputum, low grade fever, anorexia, weight loss, extreme fatigue, night sweats, chest pain
* untreated secondary disease has nearly 60% mortality
79
TB is an infection of _________.
poverty
80
TB culture/dx
1. Tuberculin testing (Mantoux test - PPD)
2. Interferon-gamma release assays (IGRAs) performed on blood samples
3. Gene amplification and antimicrobial susceptibility testing
-acid fast staining is used as a supplement to these techniques, of sputum or other specimens
Ziehl-Neelsen stain produced bright red acid-fast bacilli (AFB) against a blue background
81
TB tx
Three drugs for latent:
Isoniazid (continued for 9 months)
Rifampin (4 months)
Rifapentine (3 months)
four drugs for active TB, in two phases:
1.
rifampin, isoniazid, ethambutol, and pyrazinamide are used for 2 months
2.
rifampin and isoniazid for 4-7 months
82
TB patient noncompliance etc. has lead to antibiotic resistant strains of bacteria
---> MDR-TB (multidrug-resistant TB) to at least rifampin and isoniazid
requires 18-24 months of tx with 4-6 drugs
patients with MDR-TB are generally sicker and higher mort
---> XDR-TB (extensively drug-resistant TB) these are MDR-TB strains with resistance to at least two additional drugs
few tx options and mort rate is estimated to be about 70% within months of dx
