Upload
indian-dental-academy
View
218
Download
0
Embed Size (px)
Citation preview
Haemophilus and Other Fastidious Gram-Negative Rods
INDIAN DENTAL ACADEMY
Leader in continuing dental education www.indiandentalacademy.com
www.indiandentalacademy.com
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Case Study
A 2-year-old unvaccinated child was seen in the emergency room because of complaints of headache and fever
A cerebrospinal fluid(CSF) sample was obtained and sent to the laboratory for culture
The Gram stain showed many white blood cells and many gram-negative, small bacilli
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Points to Consider What clinical findings led the physician to request a
CSF culture? Based on the patient’s age, which organism would be
suspected? What growth requirements must be met to recover
the suspected agent? Which other fastidious organisms would be
considered? Other points to consider
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus and Other Fastidious Gram-negative Rods
The fastidious group of gram-negative bacilli include: Haemophilus HACEK Legionella Bordetella Pasteurella Brucella Francisella
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Influenzae: Clinical Infections Infections caused by typable (encapsulated) strains
Acute epiglottis or laryngotracheal infection in small children Cellulitis/arthritis Meningitis Pneumonia/septicemia (in children) Conjunctivitis
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Influenzae: Clinical Infections Infections caused by Nontypable strains
Otitis media Sinusitis Pneumonia, bronchitis (in adults)
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species
Haemophilus species require hemoglobin for growth:X-factor ( hemin): Heat-stable substanceV-factor (NAD): Heat- labile, coenzyme I, nicotinamide adenine dinucleotide, found in blood or secreted by certain organisms
H. influenzae satellitism around and between the large, white, hemolytic staphylococci
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species
Direct smear of H. influenzae in CSF in a case of meningitis. Note the intracellular and extracellular pleomorphic gram-negative bacilli.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus speciesH.influenzae growing on chocolate agar. Notice the semi-opaque, gray-white, mucoid colonies characteristic of encapsulated strains.
Gram stain of H. influenzae from colony
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species: Identification
This organism would be identified as H. influenzae because it is using both X and V factors.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species: Identification
This organism would be identified as H. parainfluenzae because it is using V factor only.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species: Identification
This organism would be identified as H. aphrophilus because it is using X factor only.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Haemophilus Species: Identification
Under ultraviolet light, the organism on the bottom is showing a positive porphyrin reaction, whereas the organism on the top is demonstrating a negative porphyrin reaction.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK Group and Capnocytophaga HACEK is an acronym of the first initial of each genus
that belong in the group: Haemophilus aphrophilus Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella species
Capnocytophaga sp. Has similar requirements as the HACEK group
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK Group and Capnocytophaga: General Characteristics
Gram-negative bacilli Require an increased CO2 (5%-10%) environment Significant cause of endocarditis Usual flora of the oral cavity Opportunists in immunocompromised hosts
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK Group
H. aphrophilus growing on blood agar
Gram stain morphology of H. aphrophilus
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK GroupA. actinomycetemcomitans on blood agar. Note the star-shaped centers of the colonies.
Microscopic morphology of A. actinomycetemcomitans (Gram stain).
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK GroupThe 48-hour growth of colonies of C. hominis
Gram stain of C. hominis showing typical “rosettes”
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK Group
E. corrodens on chocolate agar
Gram stain morphology of E. corrodens
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK Group and CapnocytophagaGrowth of Capnocytophaga colonies on chocolate agar. Compare this growth with Eikenella
Gram stain of Capnocytophaga species
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
HACEK group
Gram stain of Kingella kingae showing plump rods in chains. Compare this morphology with other members of the HACEK group.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Pasteurella species
General characteristics Colonizes mucous membranes of the upper respiratory tract
and gastrointestinal tracts of mammals and birds Human infections occur from bites and scratches inflicted by
animals Most common isolated species is Pasteurella multocida
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Pasteurella species
P. multocida: Clinical manifestations Localized infection after a bite or scratch Respiratory tract infection Life-threatening systemic diseases (e.g., meningitis,
bacteremia)
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Pasteurella Multocida
Culture characteristics Growth on 5% blood or chocolate shows small, smooth, convex
colonies “Musty” odor No growth on MacConkey agar; oxidase positive
Microscopic examination Very small gram-negative rods Bipolar staining with Giemsa or methylene blue “Safety-pin” appearance
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Pasteurella Multocida
P. multocida growing on blood agar and chocolate agar. No growth on MacConkey agar plate.
Gram stain morphology of P. multocida showing bipolar staining
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Case Study Ten members of a group of 2 dozen retirees from the
tobacco industry became acutely ill with pneumonia during a 2-week cruise
The group was staying in a block of rooms together and spent time socializing over drinks and cigarettes in the cabins and saunas and at the poolside
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Case Study On the fifth day of the cruise, several members went
to see the ship’s doctor because of a worsening cough
Chest x-rays revealed patchy lobar pneumonia in all affected individuals
The condition improved with erythromycin therapy
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Legionella Species
General characteristics Ubiquitous gram-negative rods Acquired by humans primarily through inhalation of aerosols
Clinical infections Febrile disease with pneumonia (Legionnaire’s disease) and
extrapulmonary involvement Pontiac fever (without pulmonary involvement) Asymptomatic infection
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Legionella pneumophilaGram stain of specimen showing intracellular and extracellular Legionella pneumophila
L. pneumophila in specimen stained by direct fluorescent antibody technique.
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Legionella pneumophila
(A) Nonselective buffered charcoal yeast extract (BCYE) plate inoculated with sputum specimen.
(B) Selective BCYE inoculated with the same specimen but treated before inoculation. Legionella colonies are the smallest visible colonies.
A B
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Legionella pneumophila
L. pneumophila colony on BCYE agar after 3, 4, 5, and 7 days of incubation
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Legionella pneumophila: Identification
Schema for identification of L. species
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Points to Remember
Clinical manifestations presented by the patient The types of infections these organisms produce The risk factors that predispose susceptible
individuals
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Points to Remember
What special growth supplements are required for isolation
Where these groups of organisms are usually found Characteristic features of the organisms for
identification and differentiation among closely-related species
W.B. Saunders Company items and derived items copyright © 2001 by W.B. Saunders Company.
Thank you
For more details please visit www.indiandentalacademy.com