RTI Flashcards
What are some examples of RTI specimens
Sputum Bronchial washing Nasopharyngeal swabs Exceetions from ventilators Sinus aspirates Tympanicentesis Throat swabs
What would be considered a poor quality specimen?
Oropharingeal contamination
Many squamous cells and no neutrophils
What are atypical pathogens
Mycoplasma pneunoniae
Chlamydia pneumoniae
Legionella pneumoniae
What is the correct name for whooping cough
B. Pertussis
What pathogen is commonly associated with a high pneumonia infuced mortality
Streptococcus pneumoniae
Define pneumonia
An inflammatory condition of the lungs primarily affecting the alveoli (air sacs)
What are typical signs of pneumonia
Fever, cough, chest pain, shortness of breath
Why are throat swabs a bad idea when testing for pneumonia
S. Pneumoniae colonizes in the throats of 5-10% of adults and 20-40% of children, can lead to pneumonia infection if swabbed
Describe S.pneumoniae
Most common bacterial cause of RTIs, small gram positibe diplococci
Alpha hemolytic
True or false: s. Pneumoniae is bile soluble
True
What is the most important virulance factor of S. Pneumoniae
The capsule; aids in escape from phagocytic cells
Aids in adherance which is essential for colonization
What is pneumolysin
Type of hemolysin
Destroys epithelial cells
Activate classical complement pathway
Suppress oxidative burst by phagocytic cells
Describe pneumovax
A carbohydrate vaccine
Protexrs against 23 serotypes
Infants and elderly do not respond well to carbohydrate vaccines
What is prevnar
Conjugate vaccine
Indicated for use in infants and adults
What are indications of pneumonia vaccine use?
Advanced age HIV/AIDS Alcoholism Diabetes Lymphoma
What are potential treatments for S.pneumoniae?
Penecilins, cephalosporins, macrolides, fluroquinolones, vancomycin
Define COPD
Chronic obstructive pulmonary disease
An unbrella twem for progressive lung diseases
Characterized by increasing breathlessness
Describe H.influenzae
Most common cause of AE COPD
small gram NEGATIVE BACILLI
Require x&v factors for growth
Will only grow on chocolate agar
If RBC is liced what does that mean?
More nutritious, x&v available
H. Influenzae will culture here
What are effective treatments for H.influenzae
2nd/3rd generation cephalosporins
Newer macrolides
Fluroquinolones (not for kids!)
Amoxicillin-clavulanate very effective
Describe moraxella cartarrhalis
Small gram negative cocco-bacilli
90% of strains resistant to ampicillin and amoxicillin with the exception of tmp/smx
Describe legionella pneumophilla
1st described in legionare convention in philly Gram NEGATIVE BACILLI Widespread environment Wide spectrum of illness Intracellular organism
Desceibe legionella pneumophilia staining
Faintly staining and easy to miss on gram stain
Required BCYE agar to be seen
How is legionella lab diagnosed
Cultures and urinary AG most effective in lab diagnosing
How is legionella treated?
Predictably susceptible to fluroquinolones
Macrolides are an excellent alternative
Describe bordetella pertussis
Causative agent of pertussis
Small gram NEGATIVE cocci-bacilli
Strictly aerobic and fastidious
Requires growth on media containing blood, charcoal or startch
What are the 3 stages of pertussis
Catarrhal stage
Paroxysmal stage
Convalescent stage
Describe catarrhal stage
Very contagious
Sneezing runny nose mild cough low grade fever
Describe paroxysmal stage
Cough, whoop present, posttussive vomiting
Describe convalescent stage
Symptoms gradually resolve
Risk of secondary infection
How is pertussis diagnosed
PCR
How is pertussis treated
Macrolides
Describe bacterial pharyngitis
Caused by S. Pyrogenes
Gram postibe, catalase negative beta haemolytic
Group A
How is bacterial pharyngitis treated?
Penicillin/amoxicillin
Because it is beta haemolytic it is ALWAYS susceptible to penicillin
Why do we treat bacterial pharyngitis
Eradication
Prevention of complications
10 days to treat so wait for the lab results, no need to treat empirically
Describe aracnobacterium
Pharyngitis in teens and young adults
Invasive disease can occur but it is rare
May respond poorly to penecillin but the disease is self limiting
What makes Mycoplasma pneumoniae atypical
No cell wall
Betalactams do not work here
What makes chlamydia pneumoniae atypical
Cell wall but no peptidoglycan
What makes legionella pneumophilia atypical?
Intracellular
Describe mycoplasma
Smallest free living bacteria
Requires sterol for growth as there js cholesterol in the membrane
Lacks a cell wall
Facultative anaerobes
Describe chlamydia pneumoniae
Unique cell wall structure is considered a virulence factor
Inhibits phagysosome fusion in phagocytes
Resembles gram negative bacteria
Lacks peptidoglycan in its cell wall, not a true bacterial cell wall
Why wont betalactams work on chlamydia pneumoniae cells
Lacks peptidoglycan
Describe chlamydia pneumoniae life cycle
Biphasic
EB (elementary bodies) ineffective form, attach to susceptible host
RB (reticulate bodies) divide by binary fission, reorganize to EB
Describe mycobacteria
Aerobic, non spore forming bacilli
Cell walls contain long chain fatty acids (mycolic acid) which make them acid fast
Grow exceedingly slow
Whag makes mycobacteria acid fast
Long chain fatty acids known as mycolic acid
Desceibe ziehl neelsen stain
Used to identify acid fast organisms
Slide is flooded with CARBOL FUCHIN which is the heated to dry
Flooded with alcohol and counterstained blue
Acid fast organism retain carbol fuchin due to mycolic acids in the cell wall
What are the mycobacterial classifications
Tuberculosis complex
And
Non tuberculosis (atypical) mycobacteria
How does mutation occur in M.tuberculosis
Resistance can only occur through chromosomal mutation
Mutation rate for individual genes varies between and within genes
Describe TB transmission
Spread by airborne droplets
Nuclei droplets generated when a person with tb speaks, coughs or sneezes
Infective dose <10 bacilli
Very small infectibe dose
What are clinical clues for TB
Fever
Night sweats
Weight loss
Focal symptoms
What are some clues for diagnosis of tb
History of tb
Immuno compromised
Exposure history (travel, close contact)
Describe lab identification for pulmonary tb
First morning sputum for 3 days Bronchial washing Bronchoalveolar lavage Gastric washings Pleural fluid
Desceibe lab identification specimens for extra pulmonary tb
First morning whole urine for 3 days
Pus or tissue
Liver/bone marrow biopsy
CSF in meningitis
Describe lab identification of tb
Must be done in level three lab
Fluorescent stain, mark where lit up then restain with acid fast and compare
Pcr also used and molecular probes
What is the treatmenr for TB
Must use drug combinations to delay emergence of drug resistance
Patients become non infective after 2-3 weeks of chemotherapy
Why is the treatment period for tb long?
Long doubling time of tubercle bacilli
Metabolically inactive bacilli are not killed by drugs
Caseous material interferes with drug action
