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Microbiology A > Salmonella > Flashcards

Salmonella Flashcards

1
Q

Who discovered the genus Salmonella and in what year?

A

Salmon and Smith in 1885

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2
Q

What family do Salmonella belong to?

A

Enterobacteriaceae

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3
Q

What are the main diseases caused by Salmonella in humans?

A
  • Enteric fever
  • Gastroenteritis
  • Septicemia
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4
Q

How many serotypes of Salmonella are currently recognized?

A

Above 2463 serotypes

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5
Q

What is the nickname of Mary Mallon and why?

A

Typhoid Mary; she was a healthy carrier of Salmonella typhi

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6
Q

What are the morphological characteristics of Salmonella?

A
  • Gram-negative bacilli
  • Size: 2-4 × 0.6 μm
  • Motile with peritrichous flagella (except S. gallinarum and S. pullorum)
  • Non-capsulate
  • Non-sporing
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7
Q

What temperature range can Salmonella grow in?

A

15°C to 45°C (optimum 37°C)

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8
Q

What is the appearance of Salmonella colonies on MacConkey Agar?

A

1-3mm in diameter, pale yellow or nearly colorless

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9
Q

What are the two clinical classifications of Salmonella?

A
  • Typhoidal Salmonella
  • Non-typhoidal Salmonella (NTS)
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10
Q

What are the two species of Salmonella classified by DNA hybridization studies?

A
  • Salmonella enterica
  • Salmonella bongori
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11
Q

Name the three important antigens present in Salmonella.

A
  • Flagellar H antigen
  • Somatic O antigen
  • Surface antigen Vi
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12
Q

What is the Vi antigen, and which serotypes express it?

A

A surface polysaccharide envelope; expressed in S. typhi, S. paratyphi C, S. dublin

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13
Q

True or False: The O antigen is more immunogenic than the H antigen.

A

False

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14
Q

What are the four types of selective media for isolating Salmonella?

A
  • MacConkey Agar
  • Brilliant Green MacConkey Agar
  • Deoxycholate-Citrate Agar (DCA)
  • Xylose Lysine Deoxycholate (XLD) Agar
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15
Q

What are the risk factors that promote transmission of Salmonella?

A
  • Stomach acidity
  • Intestinal integrity
  • Poor sanitation
  • Improper cleaning of drinking water, food and drinks
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16
Q

What are common clinical signs of typhoidal salmonella infection?

A
  • Fever
  • Headache
  • Chills
  • Cough
  • Sweating
  • Myalgia
  • Rashes/rose spots
17
Q

What specimens are used for diagnosing enteric fever?

A
  • Blood
  • Feces
  • Urine
  • Bone marrow
  • Duodenal drainage
18
Q

What biochemical reactions are characteristic of Salmonella?

A
  • Catalase positive
  • Oxidase negative
  • Nitrate reduction positive
  • Ferment glucose and mannitol but not lactose or sucrose
19
Q

What is the treatment for enteric fever?

A

Safe drinking water, proper food hygiene, sanitary sewage disposal, treatment of carriers

20
Q

What are the two major non-typhoidal Salmonella serotypes causing infections?

A
  • S. typhimurium
  • S. enteritidis
21
Q

What is the primary source of non-typhoidal Salmonella infections?

A

Animal food products, especially eggs and poultry

22
Q

Fill in the blank: Salmonella can be transmitted through _______.

A

[contaminated food or water]

23
Q

Name a method used to detect carriers of Salmonella.

A
  • Stool and bile culture
  • Urine culture
24
Q

What is the incubation period for Salmonella infections?

A

7 to 14 days

25
What is the effect of mercuric chloride on Salmonella?
Kills within 5 minutes
26
True or False: Non-typhoidal Salmonella are strictly human pathogens.
False
27
What is the clinical manifestation of gastroenteritis caused by non-typhoidal Salmonella?
Massive neutrophil infiltration into intestinal mucosa
28
What are the most common sources of Non Typhoidal Salmonellae (NTS)?
Animal food products, especially eggs, poultry, undercooked ground meat, and dairy products ## Footnote NTS are acquired from multiple animal reservoirs, making them zoonotic.
29
What characterizes Typhoidal Salmonellae?
Strictly human pathogens and mainly waterborne ## Footnote Typhoidal Salmonellae do not typically originate from animal sources.
30
What are the risk factors for bacteremia associated with Non Typhoidal Salmonellae?
NTS serotype, age, and low immunity conditions ## Footnote Common NTS serotypes include S. Choleraesuis (from pigs) and S. Dublin (from cattle).
31
Which age groups are at higher risk for NTS bacteremia?
Infants and elderly people ## Footnote These groups often have weaker immune responses.
32
What are the clinical manifestations of Non Typhoidal Salmonellae infection?
Gastroenteritis characterized by nausea, vomiting, watery diarrhea, fever ## Footnote Abdominal cramps typically onset 6-48 hours after ingestion of contaminated food.
33
What percentage of patients with NTS gastroenteritis may develop bacteremia?
Up to 8% ## Footnote Bacteremia can lead to endovascular infection or metastasis to various organs.
34
List some types of metastatic localized infections caused by NTS.
* Intra-abdominal infections (e.g., hepatic or splenic abscesses) * NTS meningitis (commonly in infants) * Pulmonary infections (e.g., lobar pneumonia) * UTI (e.g., pyelonephritis and cystitis) * Genital tract infections (e.g., ovarian, testicular abscesses) * Salmonella osteomyelitis ## Footnote Sickle cell disease is commonly associated with Salmonella osteomyelitis.
35
What is the standard treatment for uncomplicated NTS gastroenteritis?
Conservative treatment with fluid replacement ## Footnote Antibiotic use can increase rates of carriers and relapse.
36
What antibiotic is given for presumptive treatment of severe NTS gastroenteritis?
Ciprofloxacin ## Footnote Ceftriaxone is indicated for bacteremia and invasive infections.
37
How do drug resistance patterns of NTS compare to typhoidal salmonellae?
NTS are more drug resistant than typhoidal salmonellae ## Footnote MDR strains of NTS are resistant to more than 5 drugs (ACSSuT).
38
What causes the emergence of resistance to ceftriaxone in NTS?
Production of AmpC B-lactamases ## Footnote This resistance is linked to increased use of ceftriaxone for treatment.
39
What genetic change leads to resistance to ciprofloxacin in NTS?
Point mutation in DNA gyrase ## Footnote This mutation is a mechanism that allows NTS to survive despite treatment.

Microbiology A (2 decks)

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