Transcript Corybacteruim,Listeria, Legionella,Actinomycetes

Corybacteruim,Listeria,
Legionella
By:
Maria Rosario L.Lacandula,MD,MPH
Department of Microbiology and Parasitology
College of Medicine
Our Lady of Fatima University
Corynebacteruim
• C. diptheriae
– Irregularly staining ,pleomorphic, bacillus
– Arranged in V or Y configuration-chinese
characters
– Normal colonizer of the skin, upper respiratory
tract,GIT & GUT in humans
– Metachromatic granules
Virulence
• Exotoxin- tox gene by a lysogenic
bacteriophage
– A-B exotoxin
• B-subunit- receptor-binding region and
translocation region
• A- subunit- catalytic region
– Receptor for the toxin- heparin binding
epithelial growth factor
Epidemiology
• Worldwide distribution-asymptomatic
carriers and unvaccinated hosts
• Humans-reservoirs, carriage in oropharnyx
or on skin hosts
• Spread- person to person by respiratory
droplets or skin contact
• Seen among unvaccinated people living in
crowded urban areas and in children and
adults with waning immunity
Diseases
• Clinical presentation of diptheria
– Site of infection
– Immune status of the patient
– Virulence of the organism
• Asymptomatic-fully immune
• Mild respiratory disease-partially immune
• Fulminant fatal disease-non immune patients
Diseases
• Respiratory Diptheria
– I.P- 2-6 days
– Sudden onset, with malaise, sore throat,
exudative pharyngitis and low grade fever
– Cervical lymphadenopathy
– Pseudomembrane
– Complications: breathing obstruction, cardiac
arrythmias, coma and death
• Paralysis of soft palate
• polyneuritis
Diseases
• Cutaneous Diptheria
– Papule- chronic non healing ulcer, covered by
a grayish membrane
Laboratory Diagnosis
• Microscopy – non specific
• Culture- should be performed on
nonselective and selective media
– Cysteine-tellurite agar, serum tellurite agar,
loeffler’s meduim)
• Biochemical tests
• Toxigenicity testing
– ELEK test/ PCR
Treatment, prevention & Control
• Diptheria- diptheria antitoxin
• Penicillin or erythromycin
• Vaccination- booster every 10 years
– DPT
• Schick test
Listeria
• Listeria monocytogenes- only human
pathogen
• Short, gram positive, facultatively
anaerobic bacillus, singly, pairs, or in short
chains
• Motile- tumbling motion-room temperature
but not at 37 C
• Immunocompromised
Virulence
• Intracellular pathogen-macrophages,
epithelial cells and cultured fibroblast
• Entry- nonphagocytic cell-internalins
• Exotoxin-listeriolysin O and two different
phospholipase C enzymes
• Movement- Act A to cell membrane
• Filopod- push bacteria to adjacent cell
• Favor Growth- inside refrigerator
Epidemiology
• Isolated in soil, water, and vegetation and fro
wide variety of animals, including humans
• Disease- consumption of contaminated food
products ( soft cheese, milk, turkey, raw
vegetable esp cabbage); transplacental spread
from mother to offspring
• Sporadic cases and epidemics occur throughout
the year but peak in warmer months
• Young and the elderly as well as patient with
defects in cellular immunity are at risk
Diseases
• Neonatal infections- bacteremia,
meningitis, meningoencephalitis
– Early onset- acquired in utero- granulomatosis
infantica- formation of disseminated
abscesses and granuloma in multiple organs
– Late onset- acquired at or soon after birthmeningitis or meningoencephalitis
• Adult- mild influenza-like illness, primary
bacteremia, and meningitis
Laboratory Diagnosis
• Microscopy
– CSF gram stain show no organism
• Culture
– Grows on most conventional mediasmall round colonies on agar after 1 to 2
days
• Use selective media and cold enrichment
Treatment, Prevention and Control
• Penicillin or ampicillin with gentamicin
• High risk- avoid eating raw or partially
cooked foods
• Avoid storage of raw vegetable inside the
refrigerator for long periods of time
Legionella
• Gram negative bacilli
• 1976- outbreak of severe pneumonia
• Short coccobacilli in tissue and
pleomorphic on artificial media
• Do not stain with common reagents
• Requires L-cysteine and enhanced growth
with iron salts
• Dieterle’s stain
Virulence
• Facultative intracellular parasite- alveolar
macrophages and monocytes
• Prevents phagosome lysosomal fusion
Epidemiology
• Commonly found in natural bodies of
water, cooling towers, condensers and
water systems
• Patient at high risk- patient with
compromised pulmonary function and
decreased cellular immunity
Diseases
• Pontiac fever
– Self limiting illness characterized by fever, chills,
myalgia, malaise, headache with no evidence of
pneumonia
– Symptoms develop over 12 hour period persisted for
2-5 days then resolved spontaneously
• Legionnaires’ disease
–
–
–
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More severe
I.P 2-10 days
Primary manifestation- pneumonia
Involvement of GIT, CNS, liver and kidneys
Laboratory Diagnosis
• Microscopy
– Most sensitive- Direct Flourescent antibody
• Culture
– Medium of choice- BYCE- buffered charcoalyeast extract agar
– Grow in air or 3-5% CO2 at 35 C after 3-5
days
– Colonies- ground glass appearance
Laboratory Diagnosis
• Antigen detection- ELISA, RIA Latex
agglutination test
• Serology- IFA
• Treatment
– DOC- erythromycin or tetracycline