Non-spore-forming Gram-positive Bacilli Flashcards
an acute disease caused by toxigenic (toxin-producing) strains of C. diphtheriae.
Diphtheria
The incubation period for diphtheria is [?], with a range of 1 to 10 days.
2 to 5 days
The most common sites of diphtheria infection are the pharynx and the tonsils.
Respiratory diphtheria (pharyngeal, tonsillar, laryngeal, nasal)
Characterized by gradual onset of pharyngitis; early symptoms include sore throat with low-grade fever and dyspnea.
Respiratory diphtheria (pharyngeal, tonsillar, laryngeal, nasal)
Localized manifestations:
[?] forms in the throat (i.e., gray-white patches composed of fibrin, necrotic host cells and bacteria) over the pharynx, tonsils, uvula, and palate.
The membrane is firmly adherent to the tissue, and forcible attempts to remove it cause [?]
Pseudomembrane
bleeding
In severe disease, marked edema of the submandibular areas and the anterior neck along with lymphadenopathy giving a characteristic [?] appearance is usually present.
“bull neck”
Systemic manifestations:
Major complications include
myocarditis
polyneuritis
nephritis
thrombocytopenia
Paralysis of [?] can occur after the fifth week.
eye muscles, limbs, and the diaphragm
Secondary pneumonia and respiratory
failure may result from [?].
diaphragmatic paralysis
Damage to the heart causes [?], which is the most common cause of mortality in diphtheria.
heart failure
Death occurs in [?].
5-10%
Cutaneous diphtheria (wound diphtheria)
• Presents as [?] which lack a characteristic appearance; a membrane forms on the infected wound that fails to heal.
infected skin lesions
Cutaneous diphtheria (wound diphtheria)
May be associated with [?] strains of C. diphtheriae
non-toxigenic
Appears to result less frequently in [?] complications
systemic
[?] and [?] are closely related to C. diphtheriae and may carry the diphtheria tox gene.
Both are zoonotic organisms. Whereas the toxigenic C. ulcerans can cause disease similar to clinical diphtheria, C. pseudotuberculosis rarely causes disease in humans.
Corynebacterium ulcerans and Corynebacterium pseudotuberculosis
Produced by lysogenized strains of C. diphtheriae infected by [?] that carry the tox gene; all strains produce the same antigenic type of toxin.
β-prophages (corynebacteriophages)
Absorption of toxins through the mucous membranes and into the blood circulation causes local tissue destruction damage to the peripheral nervous system, heart, and other organs of the body.
Diphtheria exotoxin (Diphtherotoxin)
Diphtheria toxin consists of two polypeptide fragments:
Fragment A
Fragment B
interacts metabolically with factors in the cytoplasm and stops protein synthesis by inhibiting polypeptide chain elongation. It is assumed that the abrupt arrest of protein synthesis is responsible for the necrotizing and neurotoxic effects of diphtheria toxin
Fragment A
binds to and facilitates the entry of the toxin into the cytoplasm of the cells of the heart and nervous system through receptor-mediated endocytosis.
Fragment B
a modified diphtheria toxin that induces protective antitoxin antibodies
diphtheria toxoid
is grown in liquid media and the toxin is converted to the inactive toxoid by treatment with formalin
Toxin-producing C. diphtheriae
It is usually given as part of a vaccine
against tetanus and pertussis called the
DPT (diphtheria, pertussis, tetanus) vaccine.
Three vaccinations are recommended, starting at
- 6-8 weeks of age
- 15 months
- school age
(with Hep B, Hib, or IPV — respectively, Hepatitis B vaccine, Haemophilus influenzae type B vaccine, or inactivated poliovirus vaccine) are increasingly being used.
DPT-containing multi-antigen vaccines
Persons with suspected respiratory diphtheria should be promptly given [?], produced in horses, in adequate dosage, without waiting for laboratory confirmation.
diphtheria antitoxin
will neutralize circulating toxin and prevent progression of disease, but does not neutralize toxin that is already fixed to tissues,
Diphtheria antitoxin
Diphtheria infections are also managed by [?], i.e., patients are treated with antibiotics.
chemotherapy
The disease is usually no longer contagious [?] after antibiotics have been given.
48 hours
[?] should not be relied alone. This must be done in addition to antitoxin therapy,
Antibiotic therapy
Schick test is performed to determine the following:
• [?] (due to lack of antitoxins), or [?] (due to presence of circulating antitoxins) of an individual against diphtheria.
• [?] to diphtheria toxin or other proteins of the diphtheria cell.
susceptibility
immunity
hypersensitivity
This serves as a basis whether a person may receive vaccination against diphtheria or not. Individuals who are [?] to diphtheria are to be vaccinated, and if they are [?], they should be vaccinated with caution — the doses of the vaccine shall be reduced with increased number of [?]. It should also be performed first before[?] since antitoxin is normally of horse origin, which may cause hypersensitivity.
susceptible
hypersensitive
injections
antitoxin therapy
The procedure involves injection of [?] on the test arm (TA) and [?] (vaccine preparation or heat-inactivated toxin — whose toxicity is destroyed but retains capacity to elicit allergic reactions) on the control arm (CA)
- 1 mL of diphtheria toxin
0. 1 mL of diphtheria toxoid
• The injection site (TA and CA) is inspected daily up to the 6th day for [?] which consists of a positive reaction.
erythema, induration or necrosis
Results interpretation are as follows:
(1) POSITIVE REACTION:
TA –
CA –
reaction persists until the 6th day
no reaction
Results interpretation are as follows: (2) NEGATIVE REACTION: TA – CA – *Immuned; Not hypersensitive
no reaction
no reaction
Results interpretation are as follows: (3) COMBINED REACTION: TA – CA – *Susceptible and hypersensitive
reaction persists until the 6th day
reaction peaks at about 48 hours and subsides by day 5
Results interpretation are as follows: PSEUDOREACTION: TA – CA – *Immuned and hypersensitive
reaction subsides by day 5
reaction subsides by day 5
Disease for Listeria monocytogenes is known as
listeriosis
Are [?] intracellular pathogens, within phagocytes and non-phagocytic cells
facultative
the organisms can penetrate the epithelial cells of the gastrointestinal (GI) tract and grow within [?]
hepatic and splenic macrophages
from there, the organism can spread to the [?] or the [?].
CNS
pregnant uterus
it is often a mild or subclinical infection with non specific symptoms of fever, diarrhea, and sore throat
In normal adults
listeriosis usually presents as meningitis and septicemia
In children and immunocompromised adults, esp. renal transplant patients and cancer patients, and the elderly
most common in the third trimester, listeriosis presents as mild flu-like illness without meningitis
Bacteremia occurs concomitantly, during which time the uterine contents are infected
Progression to amnionitis may lead to abortion, stillbirth, or delivery of an acutely ill infant
In pregnant women
listeriosis may have an early or late onset
In neonates
is the result of infection in utero and is a disseminated form of the disease characterized by neonatal sepsis, pustular lesions, and granulomas containing L monocytogenes in multiple organs. Death may occur before or after delivery.
Early-onset syndrome (granulomatosis infantiseptica)
causes the development of meningitis between birth and the third week of life; it is often caused by serotype 4b and has a significant mortality rate
The late-onset syndrome
which facilitate bacterial binding to the host cells.
Adhesin proteins (Ami, Fbp A, and flagellin)
are cell wall surface proteins that interact with E-cadherin, a receptor on epithelial cells, promoting phagocytosis of L. monocytogenes cells into the epithelial cells.
Internalins (A and B)
is an enzyme produced by the bacterium at low pH. It lyses the phagolysosome membrane allowing the listeriae to escape into the cytoplasm of the epithelial cell.
Listeriolysin O
another listerial surface protein, induces host cell actin polymerization, which propels the listeriae to the cell membrane of the host’s epithelial cells and permits it to move from cell to cell without being exposed to antibodies, complement, or polymorphonuclear cells.
Act A
Prevention of L. monocytogenes can be improved by:
- avoidance of
- adequate pasteurization temperatures and thorough cooking foods that are suspected of being contaminated with [?]
- unpasteurized dairy products
- animal manure or sewage
Unlike [?], there is no vaccine available to prevent listeriosis.
diphtheria
Cold storage is not an effective control \ measure because the microbe can grow at most
refrigeration temperature
is most commonly isolated from acutely ill or immunocompromised patients.
Corynebacterium jeikeium
It produces infections, including bacteremia that have a high mortality rate and is resistant to many commonly used antimicrobial drugs.
Corynebacterium jeikeium
is a normal inhabitant of the human nasopharynx, can colonize natural and artificial heart valves.
Corynebacterium pseudodiphtheriticum
It has been associated with respiratory tract infections.
Corynebacterium pseudodiphtheriticum
normally lives in the eye, skin, and mucous membranes and is an occasional opportunist in eye and postoperative infections.
Corynebacterium xerosis
is the causative agent of erythrasma, a superficial skin infection characterized by small, brown-red macular areas, commonly of the axillary and inguinal skin, and also between the toes and finger, axilla.
Corynebacterium minutissimum
gives a coral (brick red) fluorescence when exposed to Wood’s light (long-wave UV radiation, also called black light) due to porphyrin
Corynebacterium minutissimum
has been associated with hospital-acquired respiratory tract and other infections.
Corynebacterium striatum
is a slowly growing species that is multiply resistant to antibiotics. It has been associated with acute or chronic encrusted urinary tract infections manifested by alkaline urine pH and crystal formation.
Corynebacterium urealyticum
is most commonly isolated species in the clinical laboratory and may represent a skin contaminant or a significant agent of infection
Corynebacterium amycolatum
• Gram-positive, nonmotile bacilli that are arranged singly, in short chains, or in long non-branching filaments. It sometimes look gram-negative since it decolorizes easily.
Erysipelothrix rhusiopathiae
Forms small, transparent, and glistening colonies that may be alpha-hemolytic or
gamma-hemolytic on blood agar medium.
Erysipelothrix rhusiopathiae
Catalase(-), oxidase (-)
Erysipelothrix rhusiopathiae
Erysipelothrix rhusiopathiae exhibits a [?] growth in gelatin stab culture
“test tube brush-like” or “pipe cleaner”
is distributed in land and sea animals worldwide, including a variety of vertebrates and invertebrates. It causes disease in domestic swine, turkeys, ducks, and sheep.
Erysipelothrix rhusiopathiae
The most important impact is in swine, in which it causes [?].
erysipelas
Humans, acquire E. rhusiopathiae infection by [?] from animals or animal products.
direct inoculation
Persons at greatest risk are fishermen, fish handlers, abattoir workers, butchers, and others who have [?] with animal products.
contact
most common E. rhusiopathiae infection in humans
erysipeloid
a nodular type of cellulitis
erysipeloid
erysipeloid usually occurs on the fingers by direct inoculation at the site of a cut or abrasion, and has been called
“seal finger” and “whale finger”
Additional clinical forms of infection (both rare) are a [?] form and [?] with or without endocarditis. [?] has also been reported.
diffuse cutaneous
bacteremia
Septic arthritis
Swine erysipelas can be prevented by [?], but the vaccine is not
protective for humans.
vaccinating pigs
Animal handlers can lower their risk by
wearing protective gloves
gram-positive bacilli within square ends; arranged in pairs and in chains. They are anaerobes that can be aerotolerant and α-hemolytic; nonmotile, catalase (-); and majority are vancomycin resistant.
lactobacilli
are major members of the normal microbiota of the human vagina, gastrointestinal tract, and oropharynx.
Lactobacillus species
Glycogen deposited in vaginal epithelial cells under the influence of [?] is metabolized by lactobacilli to lactic acid.
estrogenic hormones
The [?] product of their metabolism helps maintain the low pH (pH 4 to 5) of the normal adult female genital tract which is optimal for growth and survival of the lactobacilli, but inhibits many other organisms.
lactic acid
They rarely cause disease, and if present, they may be found occasionally in
deep-seated infections
