Class Notes on Bacteriology – Actinomycetes, Yersinia, Francisella, & Pasteurella
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Course
Bacteriology
Institution
Far Eastern University
This document includes information on clinically significant bacterial genera: Actinomycetes, Yersinia, Francisella, and Pasteurella. General information include history, origins, discovery, general description, pathogenicity, epidemiology, diagnosis, disease caused, and treatment and prevention.
Actinomycetes, Yersinia, Francisella & Pasteurella
Bacteriology
ACTINOMYCETES • Chronic infection
o Form burrowing sinus tracts to skin
or mucus membranes
▪ Discharge purulent material
PULMONARY ACTINOMYCOSIS
ACTINOMYCOSIS
● Most are cervicofacial type
● Development of chronic granulomatous
lesions that become suppurative and • Aspiration of organism from the
form abscesses oropaharynx
o Connected to sinus tracts • Slowly progressive process involving lung
● Thoracic – non-specific symptoms and pleura
● Abdominal – involving potentially every • May be mistaken for malignancy
organ • Symptoms
● Pelvic – relatively benign form of vaginitis o Chest pain
● CNS – solitary brain abscess o Fever
EPIDEMIOLOGY o Weight loss
• Part of normal mouth and gut flora o Hemoptysis
• Cervicofacial infection DIAGNOSIS
o Tooth extraction • Specimen
o Poor oral hygiene o Pus
• Thoracic infection – aspiration o Sputum
• Abdominal infection o Tissue biopsy
o Perforated gut • Microscopic examination – sulphur
o Ruptured appendix granules
• Foot infection – bacteria in soil • Culture
• Infection mainly in immunocompromised o Thioglycolate medium
patients o BHI
• Not a communicable disease • Incubation – anaerobic for 2 weeks
• Gas liquid chromtography (GLC) of
metabolic by-products
Sulfur granule
• Form indurated masses with fibrous walls
and central loculations with pus
o Pus contains "Sulfur Granules"
▪ Gritty, yellow white
▪ Average diameter – 2mm
▪ Composed of “mycelial”
mass Anaerobic jar
BS BIOLOGY (MICROBIOLOGY TRACK) | 1
, Actinomycetes, Yersinia, Francisella & Pasteurella
Bacteriology
TREATMENT, PREVENTION, AND CONTROL o Plasminogen activator (pla)
• Drainage of localized abscess / surgical EPIDEMIOLOGY
debridement • Zoonotic
• Prolonged administration of antibiotics • Humans are accidental host
o Penicillin – Antibiotic of choice • 2 forms of Y. pestis infection
o Carbapanems, macrolides, o Urban plague – rats
clindamycin o Sylvatic plague – infection in
• Preventio & Control ▪ Squirrels
o Good oral hygiene ▪ Rabbits
o Use of appropriate antibiotic ▪ Field rats
prophylaxis when mouth ▪ Domestic cats
or GI is penetrated • Infected fleas (Xenopsylla cheopis) –
YERSINIA major Mechanism of transmission
• Gram – negative, facultative anaerobic • Y. enterocolotica – pigs, rodents, livestock,
rods and rabbits
• Fermenter • Y. pseudotuberculosis – rodents, wild
• Oxidase negative animals, and gamebirds
• Lipopolysaccharide consist of CLINICAL DISEASE
o Somatic O polysaccharide • 2 clinical manifestations of Y. pestis
o Core polysaccharide – common infection
antigen o Bubonic plague
o Lipid A – endotoxin o Pneumonic plague
• Best known human pathogens within the BUBONIC PLAGUE
genus • Incubation period of no more than 7 days
o Y. pestis • High fever
• Painful bubo in the groin or axilla
• If untreated
o Bacteremia develops rapidly
o 75% die
PNEUMONIC PLAGUE
• Incubation period – 2 to 3 days shorter
than bubonic plague
Y. pestis on sheep blood agar (72 hours) • Fever and body malaise
o Yersinia enterocolitica • Pulmonary signs develop within 1 day
o Yersinia pseudotuberculosis • Patients are highly infectious
• Y. pestis – covered with a protein capsule • Person to person spread by aerosols
• Some species can grow on cold • If untreated – mortality rate exceeds 90%
temperatures Yersinia enterocolitica
PATHOGENESIS AND IMMUNITY • Enterocolitis
• Common characteristic – resist phagocytic • Incubation period
killing o 1 to 10 days
o Type III secretion system mediates o Average of 4 to 6 days
this property • Diarrhea, fever, and abdominal pain
• Y. pestis – 2 plasmids that encode virulence o Duration up to 1 to 2 weeks
genes • Involves the terminal ileum
o Fraction 1 (f1) gene – protein • Can mimic acute appendicitis if
capsule mesenteric lymph nodes are involved
BS BIOLOGY (MICROBIOLOGY TRACK) | 2
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