Legionella Flashcards
Ubiquitous gram-negative bacilli
and acquired through inhalation.
Legionella
Laboratory diagnosis for Legionella except:
A. Isolation using special media
B. Urine antigen detection
C. Direct fluorescent antibody
D. PCR
E. Serology
D
The most common pathogen of Legionella.
Legionella pneumophila
They have the ability to enter, survive, and multiply within host’s
cells,
Legionella / L. pneumophila
Most Legionella invades what macrophage?
bronchoalveolar macrophages
Legionella has the ability to produce ___.
proteolytic enzymes
T or F
Legionella spp. cause intracellular infections in humans but also survive in an extracellular environment.
True
Legionella can cause all the infections except:
A. BPF
B. Legionnaire’s Disease
C. Pontiac Fever
D. Asymptomatic Infection
A
Febrile disease with pneumonia brought by Legionella.
Legionnaire’s Disease
Febrile disease without pulmonary caused by Legionella
Pontiac Fever
Three major patterns of Legionnaire’s Disease.
- Sporadic
- Epidemic
- Nosocomial
Most common patterns of Legionnaire’s Disease and spread in comunity.
Sporadic
Short duration pattern of Legionnaire’s disease and has low attack rates
Epidemic
patterns of Legionnaire’s Disease in immunocompromised
Nosocomial
Caused by L. pneumophila that can be pneumonia (atypical).
Legionnaire’s Disease
A nonpneumonic form, short incubation period (2 days), Flulike symptoms caused by L. pneumophila
Pontiac fever
It occurs naturally in aquatic sources (lakes, rivers,
hot springs, mud)
Legionella
T or F
Legionella can tolerate chlorine (resists water treatment)
True
Major reservoir of Legionella.
- Hot water systems
- cooling towers
- evaporative condensers
Laboratory Diagnosis for Legionnaire’s disease.
Urine antigen detection + culture
Lab. diagnosis for pontiac fever.
Serology
Specimens for Legionella
– Sputum
– Bronchoalveolar lavage
– Bronchial washings
Why saline or buffer should not be used in isolation of Legionella? (inhibitory effect
of sodium)
It has an inhibitory effect of sodium
How many hours req. To refrigerate the specimens of Legionella for transportation
2 hours
Characteristics of Legionella under microscope.
Pleomorphic, weakly staining, gram-negative bacilli.
Since the Legionella is weakly stained in safranin, how many mins. Need to stain the organisms properly?
10 mins. For better absorption.
weakly acid-fast; stains best with
modified Kinyoun procedure.
L. micdadei
Confirmation test for Legionella.
DFA TEST (Direct Fluorescent Antibody Test)
Common dye for DFA Test.
FITC (Fluorescein isothiocyanate) yellow green color
Most important test for Legionnaire’s disease is __.
Culture
_____ of specimens contaminated with other bacteria, such as sputum, before inoculation enhances isolation of Legionella spp.
Acid treatment
Medium for Legionella spp. Requires ____ for growth.
L-cysteine
Best medium for Legionella spp.
BCYE agar with L-cysteine
True or false
Legionella is aerobic, fastidous, and does not grow in SBA.
True
Appearance of Legionella spp. in BCYE.
- Grayish-white or blue-green,
- convex
- glistening
The central portion of young Legionella colonies has a _____ appearance, and the color is ___.
groundglass appearance”, light gray and granular
Color of periphery of Legionella colonies.
- pink
- light blue
- bottle green
(bands with a furrowed appearance)
All are common Phenotypic Characteristics of Legionella Species except:
A. Slow growth (3 to 5 days)
B. Catalase or oxidase: weakly (-)
C. ground-glass” colony morphology
D. Asaccharolytic
B.Catalase or oxidase: weakly (+)
Urine Antigen test for Legionella.
- RIA
- EIA,
- Immunochromographic assay
___ test: LRT specimen; FITC-labeled (bright yellow to green)
DFA test
3 rapid methods for identifying Legionella.
- Urine Antigen test:
- DFA test
- DNA detection
