HAEMOPHILUS, BORDETELLAE, BRUCELLAE, FRANCISELLA, YERSINIA AND PASTEURELLA, NEISSERIA Flashcards
• Small, Gram-negative, pleomorphic bacteria (do not have definite shape e.g. cocci, bacilli, or coccobacilli)
• Require special media (usually containing BLOOD or its derivatives) for isolation
- FAMILY PASTEURELLACEAE
HAEMOPHILUS spp.
the major human pathogen under Haemophilus
HAEMOPHILUS INFLUENZAE
etiologic agent of chancroid (a sexually transmitted disease)
HAEMOPHILUS DUCREYI
Aggregatibacter aphrophilus
(H. aphrophilus , H. paraphrophilus)
REQUIRES
X
V
NON HEMOLYTIC
Haemophilus influenzae
REQUIRES
X
V
HEMOLYTIC
Haemophilus haemolyticus
REQUIRES X
DO NOT REQUIRE V
NON HEMOLYTIC
Haemophilus ducreyi
• Found on the mucous membranes of the URT in humans
• Important cause of meningitis in unvaccinated children, upper & lower respiratory tract infections in children and adults
HAEMOPHILUS INFLUENZAE
COCCOBACILLARY
COCCOID BACILLI
IN PAIRS OR SHORT CHAINS
EXPRESS A CAPSULE (ANTIGEN FOR TYPING)
HAEMOPHILUS INFLUENZAE
HAEMOPHILUS MEDIUM
flat, grayish,
translucent colonies
1-2 mm diameter
after 24 hours of incubation
CHOCOLATE AGAR
H.INFLUENZAE
GROW ON sheep blood agar if with
STAPHYLOCOCCI COLONIES
—SATELLITE PHENOMENON
—— RELEASE NICOTINAMIDE ADENINE DINUCLEOTIDE (NAD)
H. INFLUENZAE
MEDIA ENHANCES GROWTH
IsoVitaleX
—-contains X and V
TEST FOR THE IDENTIFICATION OF Haemophilus INFLUENZAE
SATELLITISM TEST
acts physiologically as HEMIN
(derived from blood)
FACTOR X
invasive infections
H. influenzae biotypes I and II
polyribitol ribosephosphate (PRP)
(a sugar alcohol phosphate)
Type b- capsular antigen
test with specific antiserum immunofluorescence
CAPSULE SWELLING TEST
Most H. influenzae organisms in the normal flora of
the URT are
NOT encapsulated NTHi-
Non-typeable H. influenzae
most commonly encountered
in serious infections in humans
Type b H. influenzae
NO EXOTOXIN
H.INFLUENZAE
antiphagocytic (helps them to evade
the human’s immune system) in the absence of
specific anticapsular antibodies
CAPSULE
capsule of type b H. influenzae is the major
virulence factor
PRP CAPSULE
POLYRIBITOL RIBOSE PHOSPHATE
MORE SEVERE TYPE OF H. INFLUENZAE
Type b H. influenzae
Two most common etiologic agents of bacterial OM & acute sinusitis:
• H. influenzae (mostly NTHi)
• Pneumococci
• Encapsulated organisms may reach the bloodstream, carried to the meninges, or establish in the joints
(septic arthritis)
• Fulminating obstructive laryngotracheitis with swollen,
cherry-red epiglottis in young children (prompt
tracheostomy, intubation)
• Pneumonitis, epiglottitis may follow URTI in small
children, old & debilitated people
• Bronchitis, pneumonia in adults
H. INFLUENZAE
- Immunologic detection of antigens in spinal fluid using commercial kits
- Gram stain
- Nucleic acid amplification methods. Such as the PCR.
H. INFLUENZAE IDENTIFICATION
STANDARD MEDIUMFOR H. Influenzae
IsoVitaleX
enriched chocolate agar
• Test for X factor requirement :
o Inoculum incubated with _______________ Haemophilus organisms that do not require X factor synthesize porphobilinogen, porphyrins, protoporphyrin IX and heme.
gama- aminolevulinic acid
This indicates the presence of porphyrins so if we get a red fluorescence it is not a Haemophilus influenzae.
Red fluorescence under UV light.
INFANTS may have serum antibodies transmitted from their mothers
AT WHAT AGE
INFANTS UNDER 3 MONTHS
BY AGE ____
unimmunized children have naturally acquired anti- PRP antibodies that promote complement- dependent bactericidal killing and phagocytosis.
By age 3-5 years
H.INFLUENZAE TREATMENT
- AMPICILLIN
— but 25% produce beta lactamases - CEPHALOSPORINS ( CEFOTAXIMINE IV)
- CARBAPENEMS
LATE COMPLICATIONS OF INFLUENZA MENINGITIS:
Localized subdural accumulation of fluid w/c requires
surgical drainage.
Encapsulated H. influenzae type b is transmitted
from
person – to- person spread
by contaminated respiratory droplets
3 combination vaccines that contain
Haemophilus b conjugate vaccine:
- PRP -OMP – Hep B ( Merck & Co.,Inc)
- Dtap – IPV / PRP -T ( Sanofi Pasteur ,Inc)
- MenCY / PRP-T ( GlaxoSmithKline)
IN H. INFLUENZAE
IMMUNIZATION STARTS
age of 2 months
(3 doses at 2,4,6 months)
2 doses at 2,4 months ; booster dose between 12- 18 months.:
Koch- Weeks bacillus
HAEMOPHILUS AEGYPTUS
PINK-EYE CONJUNCTIVITIS
MILD TYPE
Brazilian purpuric fever-fever,purpura, shock ,&
death
HAEMOPHILUS AEGYPTIUS
• Causes CHANCROID ( soft chancre)
o A sexually – transmitted disease
o Ragged ulcer on the genitalia,with Marked swelling
and tenderness
o (+) Painful enlarged regional lymph nodes
HAEMOPHILUS DUCREYI
Small G(-) rods occur in strands in the lesions
HAEMOPHILUS DUCREYI
Requires X-factor but not V factor
grow best from scrapings of the ulcer base on chocolate agar containing
1% IsoVitaleX
vancomycin
incubated at 10% CO2 at 33°C.
HAEMOPHILUS DUCREYI
treatment for HAEMOPHILUS DUCREYI
- 1g Azithromycin oral
- Ceftriaxone IM
- Oral Ciprofloxacin —- 3 days
- Oral Erythromycin—- 7 days
HEALING - 2 WEEKS
- whooping cough (pertussis)
- Highly communicable and
- important pathogen of human
Bordetella pertussis
- Bordetella bronchicanis causes diseases in animals - (kennel cough for dogs, snuffles for rabbits),
respiratory disease & rarely bacteremia in human
Bordetella bronchiseptica
• minute gram-negative coccobacilli resembling H. influenza
• capsule is present
• small faintly-staining G (-) rods identified by immunofluorescence staining;
• non motile
—- ATTACHED TO CILIATED CELLS
BORDETELLA PERTUSSIS
Bordet-Gengou medium
Regan Lowe
BORDETELLA PERTUSSIS
CULTURE BORDETELLA PERTUSSIS
Bordet-Gengou medium
[potato-blood-glycerol agar] with Penicillin G
0.5mg/mL
CULTURE BORDETELLA PERTUSSIS
REGAN LOWE
[charcoal-containing medium
with
horse blood,
cefalexin
amphotericin B
• Strict aerobe; Oxidase & catalase (+)
• Nitrate, citrate & urea (-)
• Forms acid but not gas from lactose and glucose
• Does not require X and V factors on subculture
BORDETELLA PERTUSSIS
B. PERTUSIS
Bordetella operons
bvgA:
bvgA: is a transcriptional activator of the
virulence genes
B. PERTUSIS
Bordetella operons
bvgS:
responds to environmental signals
mediate adhesion to ciliated epithelial cells -
essential for tracheal colonization
Filamentous hemagglutinin and fimbriae
- similar to cholera toxin
- promotes lymphocytosis, sensitization to
histamine and enhanced insulin secretion - structure that reaches the bloodstream, thus, responsible for the systemic manifestations of pertussis disease
Pertussis toxin
inhibits phagocyte function
Adenylate cyclase toxin (ACT)
regulated by the bvg system
Dermonecrotic toxin (DNT)
Hemolysin
- inhibits DNA synthesis in ciliated cells
- responsible for the damage of ciliated cells
- not regulated by bvg
Tracheal cytotoxin
ANTIGENIC STRUCTURES PATHOGENESIS, PATHOLOGY:
B. pertusis
- in the cell wall important in causing damage to the
epithelial cells of the URT
Lipooligosaccharide
SURVIVES FOR ONLY BRIEF PERIODS
NO vectors
RESPIRATORY ROUTE
blood is NOT invaded
BORDETELLAPERTUSSIS
B. PERTUSIS
liberate TOXINS and substances that irritate surface cells
coughing and marked lymphocytosis as defense
IN B. PERTUSIS
necrosis of parts of the
epithelium
PMN infiltration
peribronchial inflammation
interstitial pneumonia
obstruction of the smaller bronchioles by mucous plugs results in atelectasis and diminished oxygenation of the
blood
——convulsions in whooping cough
Seizures and convulsions with accompanying cough
(whooping) are manifestations of B. pertussis infection.
B. PERTUSIS
INCUBATION PERIOD
2 WEEKS
B. PERTUSIS
STAGES
- mild coughing and sneezing
- large number of organisms are sprayed
- in droplets
- patient is higly infectious but not very ill
- resembles common colds
“CATARRHAL” STAGE:
B. PERTUSIS
STAGES
- cough develops in explosive character
- characteristic “whoop” upon inhalation
- this often results to broken ribs in children
“PAROXYSMAL” STAGE:
B pertussis is a common cause of
—-PROLONGED COUGH (4-6 WEEKS)
—-WBC count high 16,000 – 30,000/mL, with absolute lymphocytosis (than PMN)
—-Convalescence is slow; may take months
o 50% sensitivity
o Most useful in identifying B. pertussis after culture
on solid media
DIRECT FLUORESCENT ANTIBODY (FA) TEST
Most sensitive method to diagnose pertussis
POLYMERASE CHAIN REACTION
SEROLOGY
AFTER EXPOSURE TO B. PERTUSIS
IgA
IgG
IgM
B.PERTUSIS TREATMENT
during catarrhal stage promotes
elimination of the organism
ERYTHROMYCIN
PREVENTION OF B. PERTUSIS
PERTUSSIS VACCINE
DTaP 2,4,6, 15-18 mos, booster at 4-6 y/o
Prophylactic use of erythromycin for 5 days
• Obligate parasites of animals and humans
• Located INTRACELLULARLY
• Inactive metabolically
BRUCELLAE
Causes BRUCELLOSIS (Undulant fever, Malta fever)
BRUCELLAE
Characterized by acute bacteremic phase followed by a chronic stage
BRUCELLOSIS
o Cocci to rods 1.2 um in length in young cultures, short coccobacillary forms predominating
o Gram-negative, often stain irregularly o Aerobic, nonmotile, non-spore forming
BRUCELLA MELITENSIS
Small convex smooth colonies on enriched media
o Use carbohydrates but produce neither acid nor gas o Catalase and oxidase (+)
o H2S produced by many strains (black color)
o Reduce nitrates to nitrites
Brucella melitensis
Routes of infection OF B. MELITENSIS
○ Intestinal tract (ingestion of infected milk)
○ Mucous membranes (droplets)
○ Skin (contact with infected tissues of animals)
Portal of entry OF B. MELITENSIS
lymphatic channels
regional LN
thoracic duct
bloodstream
parenchymatous organs
present with granulomatous nodules- these
develop into abscesses form in lymphatic tissue, liver,
spleen, bone marrow, other parts of the RES
BRUCELLOSIS
growth factor for brucella
THAT CONTAINED IN
Placentas and fetal membranes of cattle, swine, sheep and goats
ERYTHRITOL
should be inoculated and
observed frequently for positive results for Brucella
Christensen’s urea slant
B.MELITENSIS
SEROLOGY
IgM —during first week
IgG —rise about 3 weks
IgA levels parallel to IgG levels
BRUCELLA MELITENSIS
IgG agglutinin titers above 1:80 is indicative of active infection
Agglutination test
BRUCELLA MELITENSIS
● Rapid immunocapture agglutination method based on the Coombs test (detects non-agglutinating IgG & IgA Abs)
Brucellacapt
(Vircell, Granada, Spain)
BRUCELLA MELITENSIS
● IgA, IgG, IgM may be detected
● Uses cytoplasmic proteins as antigens.
ELISA assays
TREATMENT
BRUCELLA MELITENSIS
- TETRACYCLINE
- RIFAMPIN
- TMP-SMX
- AMINOGLYCOSIDES
- QUINOLONES
TREATMENT
BRUCELLA MELITENSIS
—-COMBINED TREATMENT
tetracycline + streptomycin or gentamicin for 2-3 weeks or rifampin for 6-8 weeks
—NOT READILY ELIMINATED FROM THE HOST
most virurlent/ pathogenic
• Transmitted to humans by biting anthropods and flies, direct contact with infected animal tissue, inhalation of aerosols, ingestion of contaminated food or water
FRANCISELLA TULARENSIS
Culture: requires enriched media containing
- cysteine chocolate agar
- modified Thayer-martin agar
- buffered charcoal yeast extract (BCYE) agar
- incubated in CO2 at 35-37 degrees C for 2-5 days
o need for a biosafety level 3 when there is a need to process specimens
FRANCISELLA TULARENSIS
Serology:
- Polysaccharide antigen and > 1 protein antigen/s
that cross-react with brucellae
FRANCISELLA TULARENSIS
FRANCISELLA TULARENSIS
major bio groups of strains
- produces severe illness in
humans, ferments glycerol anf contains
citulline ureidase
Jellison type A
FRANCISELLA TULARENSIS
major bio groups of strains
- produces milder disease in
humans usual anti-body response consists of agglutinins developing 7-10 days after the onset of illness
Jellison type B
-ULCERS
- LYMPHADENOPATHIES
TULAREMIA
o Inflammatory, ulcerating papule
o regional lymph nodes enlarge and become
necrotic, sometimes draining for weeks
Ulceroglandular tularemia
o Peribronchial inflammation is due to the inhalation of an infective aerosols
o Localized pneumonitis
Pneumonic tularemia
o Yellowish granulomatous lesions on the eyelids
o Preauricular adenopathy
Oculoglandular tularemia
o Lymphadenopathy but no ulcers
Glandular tularemia
Involves the mouth and pharynx
Oropharyngeal tularemia
SEPTICEMIA
o Spread of the Francisella Tularensis in the
circulation
Typhoidal tularemia
Serologic studies
o Rise in agglutination titer in paired serum samples
collected 2 weeks apart
o Single serum titer of 1: 160 or a microagglutination
titer of > 1:128 highly suggestive of history and
physical findings are compatible with the diagnosis
FRANCISELLA TULARENSIS
TREATMENT OF
FRANCISELLA TULARENSIS
• Streptomycin
• Gentamycin for 10 days- rapid improvement
• Tetracycline
• Chloramphenicol
• Ciprofloxacin
• Resistant to all beta-lactam antibiotics
BIPOLAR STAINING
SAFETY PIN APPEARANCE
• Short, pleomorphic Gram-negative rods that often exhibit bipolar staining
YERSINIA
• High mortality (40 – 100%)
• “Black Death”
• Potential use as an agent of Biowarfare
PLAGUE
• Gram negative rod
• Exhibits striking bipolar staining with special stains such as
Wright, Giemsa, Wayson, or methylene blue • Nonmotile
• Grows as a facultative anaerobe on many bacteriologic media
• Growth is more rapid when agar are incubated at 28°C.
• Cefsulodin-irgasan-novobiocin (CIN) agar incubated at 25–
28°C
YERSINIA PESTIS
•Colonies are typically gray to white, sometimes opaque, and are 1–1.5 mm in diameter with irregular edges; the organism does not produce hemolysis
YERSINIA PESTIS
YERSINIA PESTIS
ANTIGENIC STRUCTURE
- V and W antigens
- Ppcp1
- pFra/pMT plasmid
encoded by genes on a plasmid of approximately 70 kb (virulence) – V and W antigens yield the requirement for calcium for growth at 37 °C
V and W antigens
9.5-kb plasmid that contains genes that yield plasminogen-activating protease that has temperature-dependent coagulase activity (20- 28°C, the temperature of the flea) and fibrinolytic activity (35-37 °C, the temperature of the host).
This factor is involved in the dissemination of the organism from the flea bite injection site.
Ppcp1
encodes the capsular protein (fraction F1)
that is produced mainly at 37 °C and
confers antiphagocytic properties;
contains genes that encode phospholipase D
(required for organism survival in the flea midgut)
pFra/pMT plasmid
have a pathogenicity island (PAI) that encodes for an iron-scavenging siderophore, yersiniabactin
- Y. pestis
- Y. enterolitica
Flea feeds on a rodent infected with Y. pestis à ingested organisms multiply in the gut of the flea (+ coagulase) à block its ______
proventriculus
Bacteria multiply at ______, produce the antiphagocytic proteinàresist phagocytosis
37°C
often reach the bloodstream and become widely disseminated cause sepsis
YERSINIA PESTIS
YERSINIA PESTIS
TYPE OF PLAGUE
MOST common clinical manifestation of Yersinia infection.
It is manifested by high fever and painful lymphadenopathy, commonly with greatly enlarged, tender nodes (buboes) in the neck, groin, or axillae.
Bubonic Plague
YERSINIA PESTIS
TYPE OF PLAGUE
• This is a result of the direct inhalation of the organism into the lungs
—CLOSE AND DIRECT CONTACT, DROPLET INFECTION
Pneumonic Plague
YERSINIA PESTIS
TYPE OF PLAGUE
• May be a complication of untreated Bubonic plague.
• Y. pestis multiplies intravascularly and can be seen in blood smears; sudden onset of high fever, chills, and weakness, progressing rapidly to septic shock
Septicemic Plague
SMEARS
Ø Small gram-negative bacilli that appear as single cells,
as pairs or short chains in clinical material
Ø Striking bipolar appearance (safety pin shape)
YERSINIA PESTIS
CULTURE
• Blood agar, chocolate, and MacConkey agar plates,
brain–heart infusion
YERSINIA PESTIS
produces non-lactose-fermenting colonies
on MacConkey agar,
grows better at 25°C than at 37°C;
catalase (+);
indole, oxidase, and urease (-);
nonmotile
YERSINIA PESTIS
Definite identification of cultures is best done by immunofluorescence or by lysis
YERSINIA PESTIS
YERSINIA PESTIS
MORTALITY RATE:
50%
100% (PNEUMONIC PLAGUE)
TREATMENT FOR YERSINIA PESTIS
- STREPTOMYCIN
- GENTAMICIN
ALTERNATIVES
—-DOXYCYCLINE
—-CIPROFLOXACIN
—-OTHER QUINOLONES (combination with streptomycin or gentamicin)
does not form spores and is extremely susceptible to UV radiation (sunlight) and dessication
YERSINIA PESTIS
CAPSULE +
FLAGELLA -
ALL NEGATIVE:
GAS
GRAM STAIN
H2S
HEMOLYSIS
YERSINIA PESTIS
YERSINIA PESTIS
FERMENTATION OF:
GLUCOSE
MALTOSE
MANNITOL
LACTOSE
SUCROSE
GLUCOSE. +
MALTOSE. +
MANNITOL. +
LACTOSE. -
SUCROSE. -
Gram-negative, nonmotile coccobacilli.
bipolar appearance on stained smears
• Aerobes or facultative anaerobes that grow readily on ordinary bacteriologic media at 37 °C
• Oxidase (+), catalase (+)
PASTEURELLA MULTOCIDA
History of bites from cats and dogs.
PASTEURELLA MULTOCIDA
• History of animal bite followed within hours by an acute onset of redness, swelling and pain
• Regional lymphadenopathy is variable
• Low grade fever
PASTEURELLA MULTOCIDA
TREATMENT OF:
PASTEURELLA MULTOCIDA
DOC: PENICILLIN G
—Susceptible to most antibiotics
ALTERNATIVE:
—- TETRACYCLINE
—- FLUOROQUINOLONES
• Gram (-) diplococci, kidney bean-shaped
• Aerobic, non-motile, non-hemolytic
NEISSERIA SPECIES
TYPE OF NEISSERIA THAT
are exclusively pathogenic for humans and are typically found with or inside PMNs
NEISSERIA GONORRHOEAE (GONOCOCCI)
NEISSERIA MENINGITIDIS (MENINGOCOCCI)
NO CAPSULE
+ PLASMID
GENITAL INFECTIONS
ENRICHED CHOCOLATE AGAR
+GREENISH COLOR
GLUCOS ONLY
NO VAX
NEISSERIA GONORRHOEAE (GONOCOCCI)
+ POLYSACCHARIDE CAPSULE
-/RARE PLASMID
URT INFECTIONS, MENINGITIS
CHEP BLOOD AGAR
GLUCOSE AND MALTOSE
WITH VAX
NEISSERIA MENINGITIDIS (MENINGOCOCCI)
SAME FOR:
NEISSERIA GONORRHOEAE (GONOCOCCI)
NEISSERIA MENINGITIDIS (MENINGOCOCCI)
+ PILI
+ PORINS
OKAY WITH ML AGAR
NEISSERIA
OXIDASE + OR -
NEISSERIA IS
OXIDASE +
Convex, glistening, elevated, mucoid colonies 1-5 mm in diameter.
N. meningitidis on BAP
• Antigenically heterogenous and capable of changing its surface structure in vitro and in vivo to avoid host defenses
Neisseria gonorrhoeae (Gonococci)
MEDIUM FOR
NEISSERIA gonorrhoeae (Gonococci)
MODIFIED THAYER MARTIN AGAR
Hairlike appendages
IN NESSERIA GONORRHOEAE (GONOCOCCI)
PILI (FIMBRIAE)
PILI (FIMBRIAE) M/O OF
PILIN PROTEINS
Facilitates adhesion of the gonococci to host cell receptors
USEFUL METHOD OF STRAIN TYPING
OPA PROTEINS
FORM PORES
POR PROTEINS
ASSCOCIATED WITH POR IN THE FORMATION OF PORES IN THE CELL SURFACE
RMP (PROTEIN III)
—ATTRIBUTE TO ENDOTOXIC EFECTS OF GONOCOCCAL INFECTIONS
—CAN CAUSE CILIARY LOSS AND MUCOSAL DEATH IN THE FALOPIAN TUBE
—MIMICS HUMAN CELL MEMBRANE GLYCOSPHINGOLIPIDS TO EVADE IMUNE RECOGNITION
LIPOOLIGOSACCHARIDE
(NO LONG O-ANTIGEN)
Expressed when available iron supply is limited
FBP
FERRIC BINDING PROTEIN
Splits and inactivates IgA1 in mucosal immunity.
IgA1 PROTEASE
PATHOGENESIS OF NEISSERIA
ATTACKS MUCOSAL EPITHELIUM
Single exposure: 20-30% risk for men
GREATER RISK FOR WOMEN (NEISSERIA)
PROTECT AGAINST PHAGOCYTOSIS
GONOCOCCAL OMPS
N.GONORRHOEAE IN MEN
MORE SYMPTOMATIC
Urethritis (yellow, creamy pus and dysuria) or referred to as “Tulo” in Filipino, it can ascend and extend to epididymitis, and long-term cause urethral strictures due to fibrosis.
N. GONORRHOEAE IN MEN
mucopurulent discharge in urethra and vagina, salpingitis, fibrosis, obliteration of the fallopian tubes→infertility in 20% of all infected patients.
IN WOMEN
N. GONORRHOEAE
Hemorrhagic papules
and pustules on hands, forearms, feet and legs, tenosynovitis and suppurative arthritis of knees, ankles and wrists.
GONOCOCCAL BACTEREMIA
• Eye infection in newborns acquired during passage through an infected birth canal wherein there is mucopurulent discharge in the eyes of the neonate.
• Rapidly progressive conjunctivitis that may result to blindness if untreated.
GONOCOCCAL OPTHALMIA NEONATORUM
GONOCOCCAL OPHTHALMIA NEONATORUM
PREVENTION:
0.5% erythromycin ointment
or
1% tetracycline ointment
into the conjunctival sac of newborns.
GONOCOCCAL OPHTHALMIA NEONATORUM
TREATMENT:
Ceftriaxone 250 mg IM single dose
+ Azithromycin 1g orally single dose,
both administered on the same day
GONOCOCCAL OPHTHALMIA NEONATORUM
RESISTANT TO:
PENICILLIN G
N. meningitidis (meningococci)
SEROGROUPS
- ABCXY
- W-135
______ are the only natural hosts where
meningococci are pathogenic.
HUMANS
BLOODSTREAM INFECTION CAUSED BY N.MENINGITIDIS
MENINGOCOCCAL BACTEREMIA
Thrombosis of many small blood vessels with perivascular infiltration and petechial hemorrhages.
Fulminant meningococcemia
FULMINANT MENINGOCOCCEMIA
High fever, hemorrhagic rash disseminated intravascular coagulation, circulatory collapse with hemorrhagic necrosis of the adrenal glands and subsequent adrenal failure
WATERHOUSE- FRIEDERICHSEN SYNDROME).
the most common complication OF N.MENINGITIDIS
MENINGITIS
IN GROS EXAMINATION OF N.MENINGITIDIS:
In gross examination, meninges are inflamed, thrombosis of blood vessels, exudation of PMN so that the brain surface is covered with thick “cheese-like” purulent exudate.
TREATMENT OF N.MENINGITIDIS
- PENICILLIN
- CHLORAMPHENICOL
- CEFOTAXIME
- CEFTRIAXONE
FLU LIKE INFECTION
INVASIVE MENINGOCOCCAL DISEASE (IMD)
N. MENINGITIDIS TREATMENT:
PENICILLIN G
if with allergy
—-CHLORAMPHENICOL
—-3RD GENCEPHALOSPORINS
- This is the transport medium used when collecting fecal
specimen suspected of Vibrio cholerae. *
a) Aimes
b) Cary-Blair
c) Buffered glycerol
d) Any of the above may be used
Answer: b. Cary-Blair
Stool specimens suspected of containing Vibrio spp. should be collected and transported in Cary-Blair medium.
Buffered glycerol saline is not acceptable, because glycerol is toxic
to vibrios. Feces is preferable, but rectal swabs are acceptable
during the acute phase of diarrheal illness.
- This is the characteristic appearance of Vibrios on dark-field
microscopy. *
a) shooting-star motility
b) “fried-egg” appearance
c) swarm of fish motility
d) none is correct
Answer: b. shooting-star motility
The characteristic appearance of Vibrios using stool specimen on
dark-field microscopy – exhibit characteristic rapid
darting or shooting-star motility.
- This test differentiates Aeromonas from Yersinia enterolitica. *
a) Catalase test
b) Oxidase test
c) Beta-hemolysis
d) Triple sugar iron
Answer: b. Oxidase test
Oxidase test must be performed to differentiate Aeromonas from
Yersinia Enterolitica
- This test differentiates Vibrios from Aeromonas spp. *
a) Catalase test
b) Beta-hemolysis
c) String test
d) Oxidase test
Answer: c. String test
String test is used to differentiate Vibrio from Aeromonas spp
Both organisms are emulsified in 0.5% sodium deoxycholate,
which lyses Vibrio cells, but not those of Aeromonas spp
Vibrio cell lysis releases DNA, which can be pulled up into a string
with an inoculating loop.
- When testing for Vibrios, this substance is added to TCBS agar
which inhibits the growth of other intestinal microbiota. *
a) Thymol blue
b) Safranin
c) Acridine orange
d) Carbol fuchsin
Answer: a. Thymol blue
Bromothymol blue and thymol blue - pH indicators that are added
to TCBS; their high pH (8.6) inhibits the growth of other intestinal
microbiota.
- This non-invasive is test is commercially available and is used
for presumptive identification of Helicobacter. *
a) ELISA antigen
b) PCR immunoassay
c) Urease test
d) DNA amplification
Answer: c. Urease test
For presumptive identification of Helicobacter, UREASE test used
– a non-invasive test. Place a portion of crushed tissue biopsy
material directly into urease broth, onto commercially available
urease agar kits, or on a paper strip containing a pH indicator
A positive test is considered indicative of the organism’s presence
- The incubation period of Helicobacter spp before colonies are
observed.
a) 1-4 days
b) 4-7 days
c) 1-7 days
d) 7-10 days
Answer: b. 4-7 days
Colonies of Helicobacter spp. may require 4 to 7 days of incubation before small, translucent, circular colonies are observed. Culture plates should be reviewed daily for a minimum of 10 days before a negative culture is reported.
- This particular species require microaerobic environment for
incubation in order to produce gray to pink or yellow gray colonies.
a) Aeromonas
b) Vibrios
c) Campylobacter
d) Helicobacter
Answer: d. Campylobacter
Campylobacter have different optimum temperatures, hence two sets of selective plates should be incubated
Filtration method can also be used in conjunction with a nonselective medium to enhance recovery of Campylobacter spp A filter (0.65-mm pore-size cellulose acetate) is placed on the agar surface, and a drop of stool is placed on the filter. The plate is incubated upright. After 60 minutes at 37°C, the filter is removed
and the plates are reincubated in a microaerobic atmosphere. Take Note: Campylobacter require a microaerobic environment as previously indicated; however, not all species will grow in this environment.
- Recovery of Campylobacter from stool specimens is best
enhanced by the following media: *
a) Modified Skirrow
b) Campy-brucella agar base
c) charcoal-based selective medium
d) all may be used
Answer: d. All may be used
All may be used as selective media for Campylobacter spp.
- This method of recovery of campylobacter from stool makes us
of a non-selective medium PLUS a cellulose acetate filter that is
placed on the agar surface. *
a) Filtration method
b) Centrifugation method
c) Broth enrichment method
d) none is correct
Answer: a. Filtration method
Filtration method can also be used in conjunction with a
nonselective medium to enhance recovery of Campylobacter
species.
A filter (0.65-mm pore-size cellulose acetate) is placed on the agar
surface, and a drop of stool is placed on the filter.
The plate is incubated upright. After 60 minutes at 37°C, the filter
is removed and the plates are re-incubated in a microaerobic
atmosphere.
The organisms are motile and capable of migrating through the
filter,
producing isolated colonies on the agar surface and effectively
removing contaminating stool microbiota.
- In Gram staining Haemophilus spp, this dye is used to detect
smaller number of organisms that may be undetectable. *
a) carbol fuchsin
b) Kinyoun
c) acridine orange
d) thymol blue
Answer: c. acridine orange
ACRIDINE orange is used to detect smaller numbers of
Haemophilus that may be undetectable by Gram staining. It stains
a pale pink and may be difficult to detect in the pink background of
proteinaceous material often found in clinical specimens.
- Which of the following statement/s correctly describe the
collection of specimens for Haemophilus spp? *
a) When obtaining samples from genital ulcers, the area
should be moistened with cotton swab dipped in
povidone iodine.
b) Blood cultures should be obtained if infection is highly
suspected.
c) Specimens may be placed at room temperature up to 4
hours.
d) all statements are correct
Answer: d. all statements are correct
In Laboratory identification of Haemophilus blood cultures should
be obtained for infections (pneumonia) and suspected infections of
other sterile body fluids (CSF). Recovery of H. ducreyi from genital
ulcer ulcer should be cleaned with sterile gauze moistened with
sterile saline (e.g., Povidone Iodine). A cotton swab moistened
with phosphate-buffered saline is then used to collect material from
the base of the ulcer, then the swab must be plated to special
selective media within 10 minutes of collection.
- The optimal temperature required by H. ducreyi to achieve
growth of colonies. *
a) 30 deg C
b) -30 deg C
c) 30 deg F
d) -30 deg F
Answer: a. 30 deg C
H. ducreyi grows optimally at a temperature of 33 °C.
- This is a selective medium which is also used to isolate H.
influenzae from respiratory secretions of patients with cystic
fibrosis.
a) horse blood agar
b) fresh rabbit blood agar
c) horse blood-bacitracin agar
d) none is correct
Answer: c) horse blood-bacitracin agar
Horse blood–bacitracin agar- a selective medium which may be
used for isolation of H. influenzae from the respiratory secretions
of patients with cystic fibrosis
-also designed to prevent overgrowth of H. influenzae by mucoid
Pseudomonas aeruginosa.
- The purpose of adding vancomycin in the selective media in
isolating H. ducreyi is to ~ *
a) inhibit gram-negative colonizers in the GIT
b) inhibit gram-positive colonizers in the GIT
c) promote aerobic growth
d) promote anaerobic growth
Answer: b. inhibits gram-positive colonizers in the GIT
The vancomycin inhibits gram-positive colonizing organisms of the
in the selective media in isolating H. ducreyi.
- This test is used to identify Haemophilus influenzae type B
strains. *
a) serotyping
b) slide agglutination test
c) both are correct
Answer: c. both are correct
In identification of H. influenzae both serotyping and slide
agglutination test.
- The differentiation of Pasteurella multocida from the other
Pasteurella spp is: *
a) positive ornithine decarboxylase and negative urease tests
b) negative ornithine decarboxylase and negative urease tests
c) positive ornithine decarboxylase and positive urease
tests
d) negative ornithine decarboxylase and positive urease tests
Answer: a. positive ornithine decarboxylase and negative
urease tests
P. multocida can be differentiated from other Pasteurella spp. on
the basis of positive reactions for ornithine decarboxylase and
indole, with a negative reaction for urease.
- Mode of transmission of Pasteurella infections *
a) dog scratch
b) cat bite
c) animal dander
d) animal droplet
e) options 1 and 2 are correct
Answer: e. options 1 and 2 are correct
Species of Pasteurella mode of transmission to are the following:
humans by contact with infected animals, usually following bites or
scratches from cats or dogs. Respiratory tract infections may occur
through airborne transmission. Refer to the table below.
- The best time to obtain cultures for Francisella is ~ *
a) first 2 weeks of symptoms.
b) first 4 weeks.
c) no special requirement for collection.
d) none is correct.
Answer: a. first 2 weeks of symptoms
Francisella spp are most sensitive early in the illness and
organisms may become undetectable by culture 2 weeks after the
start of paroxysms.
- Indications of a possible tularemia infection are the following,
EXCEPT: *
a) on Gram stain, poorly staining gram-negative rods as
single cells without distinct cell forms
b) subcultures yielding pinpoint colonies on chocolate agar
c) positive satellite on X and V tests
d) prolonged incubation on chocolate agar
Answer: c. positive satellite on X and V tests
Indications of a possible Francisella spp.
-on gram stain, poorly staining gram-negative rods as single cells
without distinct cell forms
-subcultures yielding pinpoint colonies on chocolate agar
-requires prolonged incubation on chocolate agar
- When collecting specimen for a possible Legionella infection,
the following is used for antigen testing? *
a) respiratory secretions
b) urine
c) body fluids
d) all are correct
Answer: d. all are correct
Legionella specimen that can be used for testing:
-Respiratory secretions: expectorated sputum and lower
respiratory tract secretions
-Pleural fluid: has not yielded has not yielded many positive c
- Blood
- Transbronchial biopsy/aspirates
-Urine: for antigen testing
- The purpose of adding charcoal into the agar plate for
Legionella is to ~ *
a) detoxify the medium
b) remove carbon dioxide
c) modify the surface tension of the medium to allow the
organisms to proliferate easily
d) all are correct
Answer: d. all are correct
- The characteristic appearance of Legionella colonies. *
a) cut-glass internal granular speckling
b) swarming motility
c) shooting star appearance
d) mosaic appearance
Answer: a. cut-glass internal granular speckling
After incubating Legionella incubated at 35°C to 37°C in a humid
using either BCYE and buffered charcoal yeast extract agar, at 5
days, colonies are 3 to 4 mm in diameter, gray-white to -,
glistening, convex, and circular and may exhibit a cut-glass type of
internal granular speckling
- Legionella species stain poorly in Gram stain if safranin or
neutral red is used as counterstain. The substitute stain is ~ *
a) phenol red
b) methylene blue
c) 0.1% fuchsin
d) carbol fuchsin
Answer: c. 0.1% fuchsin
Legionella species stain poorly in the gram procedure if neutral red
or safranin is used as the counterstain.
This characteristic is related to the composition of the cell walls,
which have large amounts of branched-chain cellular fatty acids
The use of 0.1% fuchsin substituted for safranin may enhance the
organism’s visibility.
- What is the best course of action when Legionella specimens
from non-sterile sites are submitted for culture? *
a) process just like other specimen
b) use non selective media
c) pre-treat the specimen to reduce the number of
contaminating organisms
d) all are correct
Answer: c. pre-treat the specimen to reduce the number of
contaminating organisms
When Legionella specimens collected are from nonsterile body
sites are submitted for culture, treatment of the specimen should
be done first to reduce the numbers of contaminating organisms.
- Presumptive identification of Brucella species *
a) catalase positive
b) catalase negative
c) oxidase positive
d) oxidase negative
e) translucent gamma-hemolytic colonies after 48H
f) opaque beta-hemolytic colonies after 24H
Answer: a.catalase positive
b.oxidase positive
c.translucent gamma-hemolytic colonies after 48H
Brucella spp. are catalase and urease positive, and most strains
are oxidase positive, its colonies appear small, convex, smooth,
translucent, gamma-hemolytic, and slightly yellow and opalescent
after at least 48 hours of incubation.
- These organisms are closely related to Brucella abortus and
grow best on cell coculture systems. *
a) Bartonella
b) Pasteurella
c) Legionella
d) Francisella
Answer: a. Bartonella
Other non-fermentative gram-negative coccobacilli that may be
confused with Brucellae are Bordetella, Moraxella, Kingella, and
Acinetobacter spp.
- Common cultivation methods for Bartonella. *
a) direct inoculation on agar plates
b) shell-vial centrifugation
c) cocultivation in cell culture
Both shell-vial centrifugation and cocultivation in cell culture are widely used methods for isolating and culturing Bartonella species. These methods are employed because Bartonella bacteria are fastidious and may require specific conditions or host cells to grow successfully in laboratory culture.
