Gram Positive Bacili 1,2 Flashcards by NURAN A ALJIHANI

Characteristics of Corynebacterium diphtheriae

Gram positive bacilli
Chinese letter arrangement
Club shaped
Appear in clusters joined at the end

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Corynebacterium diphtheriae stains ?

Simple stain :Methylene blue
Deferential stain : gram stain

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Diphtheria is comment at which site ?

Oropharynx
Tonsils

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Source of infections in Diphtheria

Carrier
Direct contact

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Corynebacterium diphtheriae do not penetrate deep tissue, they multiply at site of entry leading to ?

No bacteriemia, produce exotoxin in blood, toxicemia

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What strain of Corynebacterium diphtheriae that can produce exotoxin ?

Only strains lysogenized by phage

Strains, that are not lysogenized by phage, do not
produce exotoxin and are non-pathogenic.

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Mechanism of action of diphtheria toxin:

Inhibition of protein synthesis

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Corynebacterium diphtheriae Gene for exotoxin is carried on

prophage in the bacterial chromosome

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The commonest type of diphtheria, transmitted by droplet

Tonsillar diphtheria

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Conjunctival and skin diphtheria are transmitted by ?

Direct contact

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Manifestation of nasopharyngeal infection with diphtheria ?

Pseudomembranous on tonsils causes difficulty in swallowing

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Manifestation of larynx infection with diphtheria ?

Respiratory obstruction and suffocation

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Patients with Corynebacterium diphtheria infection present with

Malaise, sore throat, fever

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Manifestation of cutaneous diphtheria ?

Ulcer covered with necrotic pseudomembranes

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Myocarditis - Periph. Neuritis - Difficult swallowing - Paralysis of arms and legs - Paraysis of eye muscles
Are indication of ?

Intoxication with corynebacterium diphtheria

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initial diagnosis of diphtheria?

Clinical
Antitoxin serum must never be delayed

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Laboratory diagnosis of diphtheria, specimen?

Throat, nasopharyngeal or skin swabs.

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Laboratory diagnosis of diphtheria, result of specimen on gram smear stained

Gram +ve bacilli, Have Chinese letters
like arrangement , Club shaped

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Cultural characteristics of Corynebacterium diphtheria of environment

Aerobic

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Cultural characteristics of Corynebacterium diphtheria on lofflers serum

At 37 degree
Opaque white Colonies

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Cultural characteristics of Corynebacterium diphtheria on blood tellurite

selective, enriched and differential medium

C.diphtheriae produced grey black colonies

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detection of diphtheria toxin is done by ?
Identification of toxogenic corynebacterium diphtheria strains

-animal inoculation
-elks test (gel diffusion perciptin test )
-pcr
-Enzyme linked immunosorbant assay (ELISA)

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In treatments of diphtheria what is the most critical, must be administered early
because it only neutralizes circulating unbound
toxin and has no effect on toxin already fixed to
cells.

Diphtheria antitoxic serum

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Antibiotics for diphtheria?

Penicillin or erythromycin

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Alum precipitated toxoid combination

Diphtheria toxiod + tetanus toxiod + pertussis vaccine

Close contacts of a case of diphtheria should receive ?

Booster dose of diphtheria toxiod , cource or erythromycin or a injection of long acting penicillin

Non spore forming Gram positive bacilli that are spread widely in GIT of animals, plant, water and soil all are characteristic of ?

Listeria

medically important member of listeria ?

Listeria monocytogenesis

Listeria monocytogenesis cause?

Listriosis

Organisim with tumbling motile?

Listeria monocytogenes

Listeria monocytogenes culture on blood agar result

Narrow zone of beta hemolysis

The pathogenesis of listeria is dependent upon its ability to invade mononuclear phagocytic cells and lysis the wall With

listeriolysin O

acquired transplacentally ,causes: **abscesses and granulomas in multiple organs and very frequently results in abortion ,intrauterine fetal death or death after delivery

Neonatal lisreosis early onset

It is acquired at birth or soon after birth ➢Exposure on vaginal delivery may result in meningitis or meningo- encephalitis with sepsis

Late onset lisreosis

Usually **asymptomatic or results in **self-resolving flu-like symptoms and/or **mild gastrointestinal disturbance. Chills and fever are due to bacteremia

Adult listreosis

can produce serious illness leading to meningitis, endocarditis and sepsis.

Immunosuppressed and elderly listreosis case

Specimen of listreosis?

CSF BLOOD ~bactremia and sepsisemia case

Lisreosis culturived on ?

Blood agar giving beta hemolysis

Treatment in neonatal and adult listreosis?

Ampicillin

Treatment in cases of meningitis accompanied with listreosis

Trimethoprim-sulfamethoxazole or an aminoglycoside is given in addition to ampicillin

Listeosis primarily caused by ?

unpasteurized cheese ** contaminated vegetables ❑The organism can also be transmitted by contact with animals or their feces

What organism contain a polypeptide(D-glutamic acid) capsule?

Bacillus anthracis

Gram positive spore forming aerobic bacilli arranged in chains non motile

Bacillus anthracis

principle pathogen of bacillus group ?

Bacillus anthracis which causes anthrax

pathogenic member of bacillus group causing food poisoning.

B.cereus

Humans are infected by spores on animal products such as wool or by contact with sick animals.

Anthrax

In cases like Cutaneous anthrax, bacillus anthrax are transmitted by?

Portals of entry are skin

In cases like inhlation anthrax, bacillus anthrax are transmitted by?

Respiratory tract

In cases like intestinal anthrax, bacillus anthrax are transmitted by?

Ingestion

Zoonosis diseases

-Anthrax -Listerosis

protects the organism from phagocytosis

Capsule

Anthrax toxin is considered?

Exotoxin

Anthrax toxin contains three separate proteins?

Edema factor (EF) Protective antigen (PA) Lethal factor (LF)

Infection occurs through handling infected material through skin abrasions

Cutaneous Anthrax: (Malignant pustule)

Occurs in wool sorter’s due to inhalation of spores sticking to wool.

Inhalation anthrax (wool sorter’s disease)

occurs due to eating infected meat of infected animals containing spores. The spores germinate and the organism multiplies in the intestine producing bloody diarrhea. Spread by blood and lymphatics produces septicemia.

Intestinal anthrax

What bacillus anthrax form in vivo ?

In vivo, they form capsule. When stained with polychrome methylene blue, the capsule appears as pink rim around the blue bacillus (McFadyean reaction).

What bacillus anthrax form in vitro

❑In vitro, they form spores. The spores are central, ovoid, not stained with Gram. However, the spores could be stained with acid fast spore stain.

Culture of bacillus anthrax?

Nutrition agar Blood agar non hemolytic

McFadyean reaction result in ?

capsule appears as pink rim around the blue bacillus

Spores stained with

acid fast spore stain

Spores are not stained with?

Gram stain

Bacillus cerus cause Opportunistic infections in immunocompromised patients like?

endocarditis, meningitis and post- traumatic endophthalmitis

Bacillus cereus produces two enterotoxins are ?

Cholera like enterotoxin, watery diarrhea Staphylococci like enterotoxin, superantigen

short incubation period (4 hours) and consists primarily of nausea and vomiting, similar to staphylococcal food poisoning.

Syndrome of bacillus cereus

long incubation period (18 hours) and features watery, nonbloody diarrhea.

Syndrome of bacillus cereus

Treatment of bacillus cereus

Only symptomatic treatment is given.

A 7-year-old girl who recently immigrated to the United States from Africa is brought to her primary care physician because of a sore throat and fever of 38.3°C Physical examination reveals a grayish membrane covering her pharynx as well as cervical lymphadenopathy. What is the most likely diagnosis? A. Diphtheria. B. Mycobacterium tuberculosis. C. Botulism. D. Tetanus

Diphtheria.

The mother of a 1-week-old girl calls her pediatrician because the infant has been fussy all morning. The infant’s temperature is 39°C and the mother is asked to bring the infant to the hospital for further workup and treatment. The workup includes cerebrospinal fluid (CSF) analysis, hematology studies, and cultures. Empiric antibiotic therapy is initiated. Later, upon microscopic examination of the CSF, microorganisms with tumbling motility are visualized. What is the most likely diagnosis?

Listerosis meningitis

Gram positive bacilli

A local craftsman who makes garments from the hides of goats visits his physician because over the past few days he has developed several black lesions on his hands and arms .The lesions are not painful, but he is alarmed by their appearance. He is afebrile and his physical examination is unremarkable. What is the most likely diagnosis? A. Tinea corporis B. Cutaneus plague C. Cutaneus anthrax. D. Staphylococcal carbuncle

Cutaneus anthrax.

Disease caused by which one of the following bacteria is prevented by a toxoid vaccine? (A) Bacteroides fragilis (B) Corynebacterium diphtheriae (C) Neisseria meningitidis (D) Salmonella typhi (E) Vibrio cholerae

Corynebacterium diphtheriae

causes meningitis and sepsis in newborns, pregnant women, and immunosuppressed adults. It also causes outbreaks of febrile gastroenteritis. It is a major cause of concern for the food industry.

LISTERIA MONOCYTOGENES

Which one of the following is a club-shaped, gram-positive rod that causes disease by producing an exotoxin that kills cells by inhibiting elongation factor-2, resulting in the inhibition of protein synthesis? (A) Bacillus anthracis (B) Bacillus cereus (C) Clostridium perfringens (D) Corynebacterium diphtheriae (E) Listeria monocytogenes

D) Corynebacterium diphtheriae

Which one of the following is a large gram-positive rod that causes necrosis of tissue by producing an exotoxin that degrades lecithin, resulting in the lysis of cell membranes? (A) Bacillus anthracis (B) Bacillus cereus u (C) Clostridium perfringens (D) Corynebacterium diphtheriae (E) Listeria monocytogenes

Clostridium perfringens

Which one of the following sets of bacteria causes disease characterized by a pseudomembrane? (A) Bacillus anthracis and Listeria monocytogenes (B) Bacillus cereus and Clostridium perfringens (C) Bacillus cereus and Clostridium tetani (D) Corynebacterium diphtheriae and Clostridium difficile (E) Corynebacterium diphtheriae and Listeria monocytogenes

Corynebacterium diphtheriae and Clostridium difficile

Disease caused by which one of the following sets of bacteria can be prevented by a toxoid vaccine? A Bacillus anthracis and Clostridium botulinum (B) Bacillus anthracis and Clostridium perfringens Bacillus cereus and Clostridtum tetant (D) Corynebacterium diphtheriae and Clostridium tetani (E) Corynebacterium diphtheriae and Listeria monocytogenes

Corynebacterium diphtheriae and Clostridium tetani

Your patient in the pediatric intensive care unit is a 2-week-old boy with a high fever and the signs of meningitis. Gram stain of the spinal fluid reveals small gram-positive rods. Colonies on blood agar show a narrow zone of B-hemolysis. Which one of the following is the most likely cause of his neonatal meningitis? (A) Bacillus anthracis [k) Bacillus cereus (C) Clostridium perfringens (D) Corynebacterium diphtheriae (E) Listeria monocytogenes

Listeria monocytogenes

Best treatment for Listeria monocytogenes

'Trimethoprim-sulfamethoxazole

Your patient is a 30-vear-old man with a 2-cm lesion on his arm. It began as a painless papule that enlarged and, within a few days. ulcerated and formed a black crust (eschar). He works in an abattoir where his job is removing the hide from the cattle. A Gram stain of fluid from the lesion reveals large gram-positive rods. Which one of the following bacteria is likely to be the cause? (A) Bacillus anthracis (k) Clostridium botulinum (C) Clostridium perfringens (D) Clostridium tetani (E) Listeria monocytogenes

Bacillus anthracis

Your patient is a 30-vear-old man who was brought to the emergency room following a motorcycle accident in which he sustained a compound fracture of his leg. He now has a high fever and a rapidly spreading cellulitis with crepitus in the area of the fracture. Large gram-positive rods are seen on the exudate. Necrotic tissue was debrided. Which one of the following is the best antibiotic to treat the infection? (A) Azithromycin (B) Ciprofloxacin (C) Gentamicin (D) Penicillin G (E) Vancomycin

Penicillin G