L12 MHD: Chlamydia/Mycoplasma/Legionella Flashcards
1
Q
Chlamydia General Features
- ________ _______ Bacteria (needs to use host’s ATP)
- Nucleic acid content?
- Cell membrane lacks what structure?
- Gram stain?
- Giemsa stain- what color do elementary bodies stain? What color to reticular bodies stain?
- Penicillin sensitive or resistant?
A
- Obligate Intracellular Bacteria
- Host cell dependent for energy
- Produces no ATP (unlike Rickettsia which can eventually start making its own ATP)
- Derives energy in the endosome (ADP exchanged for ATP) - Contains DNA & RNA
- Lacks peptidoglycan layer
- Gram stain- negative or variable- not used
- Giemsa Stain:
- EB: purple
- RB: blue - Penicillin resistant
- Although cell wall contains PBP, penicillin is not clinically effective
2
Q
Describe the 5 steps of the Chlamydia lifecycle.
What two forms can Chlamydia exist?
A
- Elementary body (EB) attaches and enters cells (usually columnar epithelial) via endocytosis
- Fusion with lysosome is prevented and EB reorganize into Reticular bodies (RB)
- Multiplication of RBs via binary fission
- Reorganization of RBs into EBs
- Release of EBs, which go on to infect more cells
- EBs are the infectious form*
- Small & dense
- RBs are the form seen on tissues*
3
Q
Chlamydiaceae - what are the 3 species?
A
- Chlamydiae Trachomatis
- Chlamydiae Psittaci
- Chlamydiae Pneumoniae
4
Q
How does Chlamydia get into the cell and what does it induce?
A
Gains access through minor abrasions, produces significant cell damage and a severe inflammatory response
5
Q
C. trachomatis - Serotypes A,B,C
- What does Trachoma of the A, B, C serotype group cause?
- Where is this commonly seen?
- How is it treated?
- How is it prevented?
A
- Chronic Follicular Conjunctivitis, eyelid curling and scarring- major cause of preventable blindness worldwide due to increased vascularization/scarring
- Seen in underdeveloped countries (Africa, Asia, Mediterranean)
- Treated with surgery, tetracycline 1% ointment, or azithromycin
- Prevented by improved hygiene standards
C. Trachomatis A/B/C–>Africa/ Blindness/Chronic infection
6
Q
C. Trachomatis- Genital Infection
- Caused by what serotypes?
- Who is most likely to get this disease? What is the incubation period?
- What is the most common sign seen in men? Men under 35 may have what clinical symptoms?
- What is the most common sign in women? What are the consequences of infection?
- How can infants be affected?
A
- Serotypes D-K
- Sexually active teenagers
- High rate of transmission
- 2-6 wk incubation - Males: may be relatively asymptomatic
- Urethritis
- Under 35: epidymitis, prostatitis - Females: usually asymptomatic
- Cervicitis
- May lead to: salpingitis, PID
- If untreated, high association with infertility - Infants can get pneumonia (acquired from passage through infected birth canal)
7
Q
Inclusion Conjunctivitis
- Affects what age group the most?
- How is it acquired?
- What C. Trachomatis serotypes cause it?
- Clinical sign after birth?
- Dx?
- Treatment?
A
- Mostly affects neonates
- Most common cause of neonatal conjunctivitis in the US
- Can also occur in adults - Acquired through vaginal secretions
- Serotypes D-K
- Mucopurulent eye discharge
- 2-25% after birth - Dx: inclusions demonstrated or by culture
- Treatment: Tetracycline
8
Q
Chlamydia trachomatis - Neonatal Pneumonia
- Serotypes?
- How long after birth does it take for pneumonia to develop?
- What other symptom is it seen with?
- What are two clinical symptoms?
A
- D-K
- 2-12 weeks after birth
- Inclusion Conjunctivitis
- Tachypnea (rapid breathing), paroxysmal cough (staccato cough- comes as a series of outbursts with time for at least one breath in between each cough)
9
Q
- Serotypes L1, L2, L3 of Chlamydia Trachomatis cause what disease?
- Where is this commonly seen?
- Clinical presentation?
- What diagnostic test is helpful?
- How is disease treated?
A
- Lymphogranuloma Venereum
- South America & Africa
- Suppurative multilocular inguinal lymph nodes (bubos)
- Fistula drainage
- Structures (urethra, rectal)
- Perirectal abscess - Serology helpful in LGV (1:64)
- Tetracycline/Erythromycin
- 3 week course
- may not influence ulcerations- drainage may be necessary
10
Q
Chlamydia Trachomatis Dx
1. Where do you get cell culture from?
- What are 3 non-culture tests you can do to diagnose?
a)
b)
c) - Serology is useful for what serotype?
A
- Epithelial scrapings
- Used to isolate organism - Non-Culture
a) Direct Fluorescent Ab (DFA)- Ab against elementary bodies’ major outer membrane protein- 80-90% sensitive, 99% specific
b) Lipopolysaccharide Enzyme Assays
c) DNA Probe of RIBOSOMAL RNA Sensitivity- 85%, Specificity- 99% - Serology helpful in LGV (1:64)
11
Q
Chlamydia trachomatis Treatment
- What 4 classes of antibiotics can be used?
- Examples? - Which one only requires 1 dose?
- Which should be given to a pregnant patient?
A
1.
- Tetracyclines*
- Tetracycline 2g/d x 7days
- Doxycycline 200g/d x 7 days
- Quinolones*
- Ofloxacin/Levaquin x 7 days
- Azithromycin* 1g/d x 1 day
- Erythromycin* 2g/d x 7 days
- Azithromycin only requires one dose and has a 95% cure rate
- Erythromycin is given to pregnant patients
12
Q
C. pneumoniae
- Serotype?
- Causes what % of pneumonia/bronchitis?
- Clinical symptoms?
- Diagnosis?
- Treatment?
A
- Single serotype- TWAR
- 10% of pneumonia/bronchitis via respiratory spread
- Clinically pt may have:
- pharyngitis
- laryngitis
- pneumonia (walking)
- atherosclerosis (??) - Serology would be the way to dx, rarely performed
- Treate with Tetracycline, erythromycin or fluoroquinolone for 10-14 days
13
Q
C. psittaci
- What is the typical animal reservoir?
- Causes what type of infection?
- How is it diagnosed?
- Treatment?
A
- BIRDS (parrots, parakeets)
- Inhalation of respiratory secretions or droppings of infected birds- enters lung and spreads via RE system - Lower respiratory tract infection
- Dx- complement fixation (four fold increase in IgM > 1:16)
- Tetracycline or erythromycin can be used to treat
14
Q
Mycoplasma pneumoniae
- Smallest organism to ___________ on complex cell free medium
- What is unique about its structure? What does it require to grow?
- Divides via?
- Appearance on culture?
A
- Smallest organism to replicate on complex cell free medium
- No cell wall, single triple layered membrane- requires cholesterol for growth
- Divides by binary fission
- Fried egg appearance, stained with fluorescent Abs
15
Q
Epidemiology of Mycoplasma Pneumoniae
- How often do epidemics occur?
- Causes 5-15% of what type of pneumonia?
- Peak incidence in what age group?
- How is it spread? What is the incubation period?
A
- Every 4-7 years
- Community acquired pneumonia
- Peak incidence in teenagers (more common in patients
16
Q
Mycoplasma Pneumoniae
- What are the clinical symptoms?
- What occurs in 25-50% of patients?
- What is unique about chest x-ray (CXR) finding
- Describe the cough associated with mycoplasma pneumoniae
A
- Headache, fever, chills
- 20-50% of patients will have chest pain, sore throat, myalgias and rhinorrhea
- X-ray looks worse than the patient- CXR findings out of proportion to clinical presentation/findings
- Non-productive cough, later, white/clear sputum
17
Q
What other diseases can Mycoplasma cause?
A
-Dermatologic Macular, morbilliform, E. nodosum rash -Cardiac Underestimated: arrhythmia, CHF, EKG Mycocarditis, pericarditis -Arthritis -Neurologic Guillain-Barre, transverse myelitis, meningoencephalitis (1:1000)
18
Q
What are 4 ways to diagnose Mycoplasma?
A
- CXR
-may appear severe, interstitial pattern
-not diagnostic - Culture (10-14 days)
- Serology (high titer > 1:32)
PCR - Cold hemagglutinins- bind I Ag or erythrocytes @ 40C
>1:128
**High titer of cold agglutinins (IgM) which can agglutinate or lyse RBCs
19
Q
What three antibiotics are used to treat mycoplasma diseases?
A
- Macrolides
- Erythromycin, Azithromycin, Clarithromycin - Tetracyclines
- Fluoroquinolones
Penicillin is ineffective because Mycoplasma have no cell wall
20
Q
Mycoplasma hominus
- Common isolate in what disease?
- Cause of fever following what two procedures?
- What type of infection does it cause?
- How is it diagnosed?
- What can you give to treat it? What can’t be used?
A
- Bacterial vaginosis
- Cause of fever following abortion or post partum endometritis
- Opportunistic infection- joint, wound, CNS (neonates)
- Diagnos via mycoplasma broth
- Tx with tetracycline, clindamycin or chloramphenicol
* *Do not use macrolides**
21
Q
Legionella
- Gram positive or negative?
- What stain do you use to see bacterium?
- 85% of all infections are caused by what species? What serotypes of this species?
A
- Slender gram-negative rods
- Seen in tissue with Dieterle’s Silver Stain
- 85% of infections caused by Legionella pneumophila - Serotypes 1-6
22
Q
Legionella: Cultural Characteristics
- Aerobe/anaerobe?
- Fermentation?
- Growth requirements?
- Motility?
- Catalase test?
- Oxidase test?
- Beta-lactamase (+)/(-)?
A
- Obligate aerobe
- Non-fermentative
- Derive energy from amino acids - Fastidious growth requirements
- Motile
- Catalase positive
- Weakly oxidase positive
- Beta-lactamase positive
23
Q
- Where does Legionella live?
- Where is community acquired typically found?
- How do outbreaks occur?
- What are host risk factors for the disease?
A
-
The Water
- aquatic lakes
- amplified man made reservoirs
- potable water (hot water systems) - CA-Legionella- cooling towers, showers, grocery store mist, fountains, high pressure chambers, air conditioners, whirlpools, hotels (travel associated);
- Outbreaks occur as sporadic disease or as epidemics
- Healthcare associated - 25% - Risk factors: transplant recipients, cigarette smokers, chronic lung disease
24
Q
Pathogenesis of Legionella
- Route of entry?
- What happens after pathogen enters body?
- What type of immunity is required to kill the infection?
A
- Inhaled infectious aerosols
-Shower, sink tap, cooling tower, humidifier - OMP (porin) binds C3b complement receptor on mononuclear phagocytes- endocytosis–>inhibit phagolysosome fusion–>intracellular multiplication
Kill cell with lysis of vacuole - Immunity is cell mediate- requires sensitized T-cells to activate macrophages
25
Q
Clinical Manifestations of Legionella
- What is Pontiac Fever?
- What is Legionellosis?
- Are asymptomatic infections common?
A
- Pontiac Fever- self limited febrile influenza like illness without respiratory component
- Short incubation 1-2 days - Legionellosis (severe pneumonia)
- Longer incubation 2-10 days
- Multilobular pneumonia
- Multisystem disease: GI, liver, kidney, CNS
- 10-20% mortality - Asymptomatic infection common
26
Q
Legionella: Laboratory Diagnosis
- What type of stain is used?
- What’s a low sensitivity test?
- Where is culture gathered from?
- What is the special media used for Legionella?
- Describe urinary antigen test
- What are two other tests that can be used?
A
- Tissue Dieterle Silver Stain
- Direct fluorescent antibody test
- Sputum- low yield; BAL, lung biopsy, pleural fluid, other body fluid/tissue
- Buffered charcoal yeast extract agar (BYCE) TEST
- Urinary antigen tests- utilizes ELISA to detect L. pneumophila serogroup 1 (60-90% sensitive- sensitivity increases with severity of disease)
- PCR & Serology tests (requires 4 fold rise in titer- 1:128)
27
Q
How is Legionella Treated?`
A
Antibiotics with intracellular activity required!
- Macrolides: Erythromycin, Clarythromycin, Azithromycin (all work by inhibiting the bacterial ribosomal function at the 50S subunit)
- Fluoroquinolones: ciprofloxacin and moxifloxacin can be used
28
Q
List three ways to prevent Legionella
A
- Eliminate or reduce numbers in water supply
- Clean reservoirs (air conditioning cooling towers)
- Remove from potable water systems
- Superheating, hyperchlorination, copper/silver ionization
29
Q
Cold hemaglutinins are used to diagnose which bacteria?
A
Mycoplasma
30
Q
Legionella produces ____ which renders penicillins inactive
A
B - lactamases
