Gram positive

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Questions and Answers

Which of the following culture samples is collected for diagnosing gastroenteritis?

Amniotic fluid culture

Stool culture (correct)

Blood culture

Cerebrospinal fluid (CSF) culture

What is the characteristic of Clostridium bacteria?

Gram-positive, motile and obligate anaerobes (correct)

Gram-negative, straight or curved rods

Non-motile, facultative anaerobes with catalase activity

Motile, obligate aerobes with catalase activity

What is the appropriate treatment for disseminated Listeriosis?

Supportive care with hydration and rest

Intravenous ampicillin combined with gentamicin (correct)

Meropenem only for those with contraindications to ampicillin

Ultrasound or CT scan to identify liver abscesses

What is the characteristic of Clostridium spores?

Endospores can survive in the presence of oxygen Signup and view all the answers

What is the characteristic of Clostridium perfringens?

It is oxygen-tolerant and can grow in the presence of oxygen Signup and view all the answers

What is the function of exotoxins produced by Clostridium bacteria?

Killing of host cells Signup and view all the answers

What is a common symptom of Clostridium perfringens foodborne illness?

Abdominal cramping Signup and view all the answers

How does Clostridium perfringens enterotoxin (CPE) affect intestinal epithelial cells?

Targets and destroys tight junctions Signup and view all the answers

What is the minimum temperature required to inactivate Clostridium perfringens enterotoxin (CPE)?

72°C Signup and view all the answers

What is a common source of Clostridium perfringens infection in wounds?

Dirty, sharp objects in contact with soil Signup and view all the answers

What is a characteristic symptom of clostridial myonecrosis (gas gangrene)?

Thin watery pus Signup and view all the answers

What is the primary treatment for Clostridium perfringens foodborne illness?

Hydration Signup and view all the answers

What is the purpose of anaerobic tissue culture in diagnosing Clostridium perfringens infection?

To confirm diagnosis Signup and view all the answers

What is the primary treatment for clostridial myonecrosis?

Surgical intervention Signup and view all the answers

What is the primary mode of transmission of Clostridium difficile?

Fecal-oral route through ingestion of bacteria from fecal matter Signup and view all the answers

What is the role of Toxin A in the pathogenesis of C.difficile?

It is a potent enterotoxin that destroys the cytoskeleton of intestinal cells Signup and view all the answers

What is a common symptom of C.difficile infection?

Diarrhea with or without mucus and blood Signup and view all the answers

What is a complication of C.difficile infection?

Toxic megacolon Signup and view all the answers

What is the typical Gram stain appearance of C.difficile?

Gram-positive, rod-shaped Signup and view all the answers

What is a risk factor for C.difficile infection?

Antibiotic use, chemotherapy, and prolonged elemental diets Signup and view all the answers

What is the primary treatment for C.difficile infection?

High-dose penicillin B Signup and view all the answers

What is the characteristic of C.difficile infection that distinguishes it from cholera?

Slow progression to death over months Signup and view all the answers

Study Notes

Diagnosis of Listeriosis

Culture samples are used to diagnose Listeriosis, depending on symptoms:
- Stool culture for gastroenteritis
- Blood culture for bacteremia
- Cerebrospinal fluid (CSF) culture for meningitis
- Amniotic fluid culture for trans-placental infection
Imaging studies like ultrasound or CT scan can identify liver abscesses

Treatment of Listeriosis

Gastrointestinal Listeriosis: Supportive care (hydration, rest) is used
Disseminated Listeriosis: Intravenous ampicillin combined with gentamicin is used
Alternatives: Meropenem is used for those with contraindications to ampicillin (e.g., pregnant individuals, those allergic to ampicillin)

Clostridium Bacteria

General characteristics:
- Gram-positive, may appear Gram-negative in older cultures
- Straight or curved rods, may appear singly, in pairs, or in chains
- Spore former, with endospores
- Motile, with peritrichous flagella (except C. ramosum and C. innocuum)
- Non-encapsulated (except C. perfringens)
- Obligate anaerobes, strict anaerobes
- Catalase-negative
Virulence factors:
- Exotoxins, varied among species
- C. perfringens has type A, B, C, D, E toxins

Clostridium difficile

Growth and laboratory identification:
- Gram-positive, appearing purple and rod-shaped under the microscope
Colonization and infection:
- Fecal-oral route, typically acquired through ingestion of bacteria from fecal matter
- Asymptomatic carriers, about 5% of the population
- Disturbance of gut flora, allowing C. difficile overgrowth
Pathogenic mechanism:
- Toxin production, main pathogenic mechanism
- Toxin A (TCDA), a potent enterotoxin
- Toxin B (TCDB), a cytotoxin
Symptoms and complications:
- Diarrhea, abdominal pain, and high fever
- Severe complications, such as toxic megacolon, intestinal rupture, septic shock, and death if untreated

Foodborne Illness

Common cause, often called the "cafeteria germ"
Contamination, spores can contaminate food left out for a while
Toxin production, produces Clostridium perfringens enterotoxin (CPE) within 24 hours of colonization
Heat sensitivity, CPE is heat-labile and can be inactivated by cooking at 72°C or above
Symptoms, abdominal cramping, watery diarrhea, and vomiting
Symptoms typically improve within a day without the need for antibiotics, hydration is the primary treatment

Wound Infections

Introduction to wounds, can infect wounds made by dirty, sharp objects in contact with soil
Myonecrosis, causes clostridial myonecrosis (gas gangrene) via Clostridium perfringens alpha-toxin (CPAT)
Symptoms, extreme pain, swelling, thin watery pus, blood-filled bullae, and crepitus (crackling sound of gas in tissue)
Pathogenesis and symptoms of myonecrosis:
- Cell death, causes necrosis (uncontrolled cell death)
- Progression, rapidly progresses to fever, tachycardia, hypotension, shock, and potentially death within hours if untreated

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Description

This quiz covers the diagnosis and treatment of Listeriosis, including culture samples and imaging studies, as well as treatment options for gastrointestinal and disseminated Listeriosis.