Microbiology of Hematopoietic and Lymphoid System (HLS) Quiz

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Questions and Answers

What is the primary causative organism of Salmonellosis?

Salmonella paratyphi

Escherichia coli

Salmonella typhi (Salmonella enterica Serovar Typhi) (correct)

Brucella

Which of the following characteristics is NOT true about Salmonella?

Non-sporing

Facultative anaerobe

Motile with peritrichous flagella

Gram-positive enteric bacillus (correct)

What is the optimal temperature for the growth of Salmonella?

25°C

50°C

41°C

37°C (correct)

What is the characteristic of Salmonella colonies on MacConkey medium?

Colorless Signup and view all the answers

What is the family to which Salmonella belongs?

Enterobacteriaceae Signup and view all the answers

Which of the following is NOT a characteristic of Salmonellosis?

Caused by a gram-positive bacterium Signup and view all the answers

What is the size range of Salmonella?

2-4 micron Signup and view all the answers

What is the pH range for optimal growth of Salmonella?

pH 6-8 Signup and view all the answers

What is the primary cause of typhoid fever?

Salmonella Typhi Signup and view all the answers

What is the function of the Vi-surface antigen in some Salmonella species?

It protects the bacilli against phagocytosis Signup and view all the answers

What is the outcome of boiling the Vi-surface antigen at 60°C for 1 hour?

It is destroyed Signup and view all the answers

Which of the following is NOT a mode of transmission of typhoid fever?

Exposure to sunlight Signup and view all the answers

What is the function of O-antigens in Salmonella?

They form an integral part of the cell wall Signup and view all the answers

What is the purpose of using Wilson Blair Bismuth Sulphide medium?

To isolate Salmonella from contaminated specimens Signup and view all the answers

What is the outcome of H2S production by Salmonella Typhi in Wilson Blair Bismuth Sulphide medium?

Jet black colonies are produced Signup and view all the answers

Which of the following is a characteristic of Flagellar or H-antigens?

They are strongly immunogenic and induce antibody formation rapidly Signup and view all the answers

What is a possible complication of the typhoid ulcer?

Hemorrhage and perforation Signup and view all the answers

What is the typical pattern of fever in typhoid fever?

Fever that starts low and increases daily Signup and view all the answers

Which of the following is a characteristic feature of Paratyphoid A?

Abrupt onset with mild symptoms Signup and view all the answers

What is the preferred specimen for isolation of Salmonella spp.?

Freshly passed stool Signup and view all the answers

On MacConkey and EMB agar, Salmonella forms:

Non-lactose-fermenting colonies Signup and view all the answers

What is the duration of blood culture positivity in enteric fevers?

First 2 weeks of illness Signup and view all the answers

What is the Gram stain characteristic of S. typhi or S. paratyphi?

Gram negative rod Signup and view all the answers

Which of the following can be isolated from urine?

Both S. typhi and S. paratyphi Signup and view all the answers

What biochemical test is positive for Salmonella Paratyphi A?

Methyl Red Signup and view all the answers

What is the primary method of diagnosis for Brucellosis?

Serology Signup and view all the answers

Which of the following is a characteristic of Brucella?

Non-motile Signup and view all the answers

What is the purpose of Widal test?

To detect antibodies in serum against the O&H antigens of Salmonella species Signup and view all the answers

What is the minimum titer required for a diagnosis of Salmonella infection using Widal test?

1:160 Signup and view all the answers

What is the mode of administration of one of the vaccines against Salmonella typhi?

Intramuscular Signup and view all the answers

What is the primary host of Brucellosis?

Domestic animals Signup and view all the answers

What is the purpose of pasteurization of milk in preventing Salmonella infection?

To kill bacteria Signup and view all the answers

What is the primary mode of transmission of Brucella?

Ingestion of contaminated animal products Signup and view all the answers

Which of the following Brucella species has the highest concentration of M antigen?

Brucella melitensis Signup and view all the answers

What is the incubation period of Brucella?

2-6 weeks Signup and view all the answers

What is the primary effect of pasteurization on Brucella?

It kills Brucella Signup and view all the answers

What is the primary site of infection of Brucella in the body?

Gastrointestinal tract (GIT) Signup and view all the answers

What is the characteristic of Brucella in terms of heat sensitivity?

Moderately sensitive to heat Signup and view all the answers

What is the common route of infection of Brucella?

Ingestion of contaminated milk Signup and view all the answers

What is the characteristic of Brucella in terms of its growth in culture media?

It can be grown on defined media containing amino acids, vitamins, salts, and glucose Signup and view all the answers

Study Notes

Salmonellosis and Brucellosis

Objectives of the Lecture

Define Salmonellosis and Brucellosis
Describe the causative organisms
Describe pathogenesis and clinical features of the disease
Mention diagnostic methods of Salmonellosis and Brucellosis
State treatment of Salmonellosis and Brucellosis
Describe prevention and control of the disease

Salmonellosis

Definition: An infectious disease caused by the bacterium Salmonella typhi (Salmonella enterica Serovar Typhi) and less commonly by Salmonella paratyphi
Characteristics of Salmonella:
- Gram-negative enteric bacillus
- Belongs to the family Enterobacteriaceae
- Motile with peritrichous flagella
- Non-sporing, non-capsulated (except S. typhi/paratyphi)
- Size varies from 2-4 x 0.6 micron
Cultural Characteristics:
- Aerobics, facultative anaerobes
- Grow optimally in temperature of 37°C and pH 6-8
- Grow on simple media - Nutrient agar, MacConkey medium, and Wilson Blair Bismuth sulphide medium
- Produce H2S
Typhoid fever:
- A systemic bacterial disease caused primarily by Salmonella Typhi
- Causes:
  - Ingestion of contaminated food or water
  - Contact with an acute case of typhoid fever
  - Water contaminated with inadequate sewerage systems and poor sanitation
  - Contact with a chronic asymptomatic carrier
  - Eating food or drinking beverages handled by a person carrying the bacteria
- Signs and symptoms:
  - Fever that starts low and increases daily
  - Headache
  - Weakness and fatigue
  - Muscle aches
  - Sweating
  - Dry cough
  - Loss of appetite and weight
  - Abdominal pain
  - Diarrhea or constipation
  - Rash

Paratyphoid Fever

Caused by Salmonella paratyphi A, B, and C
Presents with more abrupt onset and mild symptoms compared to typhoid fever
Features:
- Fever
- Headache
- Abdominal pain
- Malaise
- Anorexia
- Cough
- Hepatomegaly and splenomegaly
Paratyphoid A:
- Causes paratyphoid fever with mild symptoms
Paratyphoid B:
- May occur as typhoid-like illness or severe gastroenteritis
- Cold sores or fever blisters are frequently seen in this infection
Paratyphoid C:
- A rare type of infection

Laboratory Diagnosis

Hematological investigations
Bacteriological investigations:
- Blood culture
- Stool culture
- Urine culture
- Duodenal juice or bile culture
Identifying Enteric Organisms:
- Non-lactose fermenting
- Motile
- Indole positive
- Urease negative
- Oxidase negative
- Ferment Glucose, Mannitol, Maltose
- Do not ferment Lactose, Sucrose
- Some Paratyphoid forms acid and gas
- H2S produced by Salmonella typhi
Serology:
- Widal test: detects antibodies in serum against the O&H antigens of Salmonella species

Prevention and Control

Apply public health and personal hygiene measures
Proper sewage disposal and proper chlorinated water supply
Cultures of stool for food handlers to detect carriers
Pasteurization of milk, proper cooking of poultry, eggs, and meat
Vaccination:
- Two vaccines are available, giving 50-80% protection against S. typhi
- One vaccine consists of acetone-killed S typhi organisms, administered I.M.
- The other vaccine is a live, attenuated S typhi and is taken orally

Brucellosis

Definition: A zoonosis primarily of domestic animals, causing a chronic debilitating septicemic disease leading to abortion
Morphology of Brucella:
- Small (0.4～0.8 ×0.5～1.5μm)
- Non-motile
- Non-capsulate
- Gram-negative coccobacilli
- Aerobic
Growth Characteristics:
- Nutritional requirements are complex
- Some strains have been cultivated on defined media containing amino acids, vitamins, salts, and glucose
- Inoculated on trypticase-soy agar or blood culture media
Antigenic Structure and Classification:
- A and M antigens are common to 3 main Brucella spp.
- B. melitensis has the highest concentration of M antigen and causes the most serious infections
- The difference between species is related to the amount of the two main antigens
Spread of Brucella in the body:
- Mode of transmission:
  - Oral entry - most common route
  - Ingestion of contaminated animal products (often raw milk or its derivatives)
  - Contact with contaminated fingers
  - Aerosols
  - Contamination of the conjunctivae
  - Percutaneous infection through skin abrasions or by accidental inoculation
Pathogenesis:
- Incubation period: between 2 and 6 weeks
- Common route of infection: ingestion of contaminated milk, mucous membrane droplets

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Description

This quiz covers microbiology of hematopoietic and lymphoid system, including Salmonella typhi, enteric fever, and Brucella. It is based on the course contents of Medical Microbiology and Prescott's Microbiology.