Deck 20: Streptococci, Pneumococci, and Enterococci

Question 1

How can transmission of respiratory infections be prevented?

Answer 1

Respiratory disease is a medical term that encompasses pathological conditions affecting the organs and tissues that make gas exchange.
The transmission of respiratory diseases from one person to other can be prevented by following the below listed measures:
• Patients should not come into contact with others.
• Active vaccination.
• Washing the hands regularly.
• Should touch the contaminated articles.
• Should cover the mouth and nose while others are coughing or sneezing.
• The patients should cough or sneeze into a tissue and throw it away.
• The household surfaces should be kept clean.

Question 2

A School-Associated Pertussis Outbreak
A 13-year-old eighth grader attended school while experiencing a prolonged cough illness. Bordetella pertussis was isolated in culture from the child. Another student in the same classroom had a clinical illness consistent with pertussis 2 weeks earlier, and subsequently, five additional people (two students in the same classroom, two eighth-grade teachers, and one parent of an ill student) developed the coughing illness. In patients with one or more days of illness, the diagnosis was made by culturing the organism from a nasopharyngeal swab. In patients with more than 14 days of illness, the diagnosis was made by either a positive PCR test for B. pertussis DNA from a nasopharyngeal specimen or by finding a link to a person with a laboratory-confirmed case. Antimicrobial therapy was given to students and staff members with coughing, and they were excluded from school through the fifth day of treatment.
Other cases began appearing throughout six communities in the county. As a result, the pertussis vaccination schedule for infants was accelerated. A total of 483 pertussis cases were reported throughout the outbreak, which lasted 6 months. Genetic testing revealed four DNA profiles of B. pertussis, most of which matched the profile of patients attending the middle school. No patients were hospitalized or died during this outbreak. Early recognition, treatment, and chemoprophylaxis were important in preventing pertussis transmission to others.
Would you guess that diagnosis would have been improved if throat swabs rather than nasopharyngeal swabs were cultured or examined for B. pertussis DNA?

Answer 2

Bordetella pertussis causes a severe upper respiratory tract disease called whooping cough. When whooping cough is suspected, nasopharyngeal swab is the best specimen for laboratory diagnosis. Throat swab can also be used. Nasopharyngeal swab will give positive results but throat swab may give negative results in a diseased condition.
For whooping cough, the throat swab will contain very few organisms. So, B.pertussis DNA can be diagnosed in throat swab by using polymerase chain reaction (PCR). PCR is more sensitive than culture. There will be chances for getting negative results when a throat swab is used in diagnosing pertussis.

Question 3

What is the satellite phenomenon?

Answer 3

The V-factor (nicotinamide adenine dinucleotide, NAD) is a heat labile coenzyme. It is required for the growth of Haemophillus species. In some cases, NAD is directly added to the medium. In other cases, NAD will be made available in the medium by growing other organisms like Staphylococci that release it.
When Staphylococci are grown on agar medium, NAD will be secreted into the surrounding medium. The secreted NAD will be utilised by Haemophillus species. So, Haemophillus will grow immediately around the Staphylococcal colony. Such phenomenon of growth of the dependent organism is called satellite phenomenon.

Question 4

A School-Associated Pertussis Outbreak
A 13-year-old eighth grader attended school while experiencing a prolonged cough illness. Bordetella pertussis was isolated in culture from the child. Another student in the same classroom had a clinical illness consistent with pertussis 2 weeks earlier, and subsequently, five additional people (two students in the same classroom, two eighth-grade teachers, and one parent of an ill student) developed the coughing illness. In patients with one or more days of illness, the diagnosis was made by culturing the organism from a nasopharyngeal swab. In patients with more than 14 days of illness, the diagnosis was made by either a positive PCR test for B. pertussis DNA from a nasopharyngeal specimen or by finding a link to a person with a laboratory-confirmed case. Antimicrobial therapy was given to students and staff members with coughing, and they were excluded from school through the fifth day of treatment.
Other cases began appearing throughout six communities in the county. As a result, the pertussis vaccination schedule for infants was accelerated. A total of 483 pertussis cases were reported throughout the outbreak, which lasted 6 months. Genetic testing revealed four DNA profiles of B. pertussis, most of which matched the profile of patients attending the middle school. No patients were hospitalized or died during this outbreak. Early recognition, treatment, and chemoprophylaxis were important in preventing pertussis transmission to others.
What are two laboratory methods that can be used to diagnose pertussis?

Question 5

What is the incidence of Haemophilus influenzae as an agent of meningitis in infants and children under 3 years of age? In adults?

Question 6

A School-Associated Pertussis Outbreak
A 13-year-old eighth grader attended school while experiencing a prolonged cough illness. Bordetella pertussis was isolated in culture from the child. Another student in the same classroom had a clinical illness consistent with pertussis 2 weeks earlier, and subsequently, five additional people (two students in the same classroom, two eighth-grade teachers, and one parent of an ill student) developed the coughing illness. In patients with one or more days of illness, the diagnosis was made by culturing the organism from a nasopharyngeal swab. In patients with more than 14 days of illness, the diagnosis was made by either a positive PCR test for B. pertussis DNA from a nasopharyngeal specimen or by finding a link to a person with a laboratory-confirmed case. Antimicrobial therapy was given to students and staff members with coughing, and they were excluded from school through the fifth day of treatment.
Other cases began appearing throughout six communities in the county. As a result, the pertussis vaccination schedule for infants was accelerated. A total of 483 pertussis cases were reported throughout the outbreak, which lasted 6 months. Genetic testing revealed four DNA profiles of B. pertussis, most of which matched the profile of patients attending the middle school. No patients were hospitalized or died during this outbreak. Early recognition, treatment, and chemoprophylaxis were important in preventing pertussis transmission to others.
What is the recommended age range for receiving the pertussis vaccine?

Question 7

Why is a direct smear of spinal fluid essential when bacterial meningitis is suspected?

Question 8

A School-Associated Pertussis Outbreak
A 13-year-old eighth grader attended school while experiencing a prolonged cough illness. Bordetella pertussis was isolated in culture from the child. Another student in the same classroom had a clinical illness consistent with pertussis 2 weeks earlier, and subsequently, five additional people (two students in the same classroom, two eighth-grade teachers, and one parent of an ill student) developed the coughing illness. In patients with one or more days of illness, the diagnosis was made by culturing the organism from a nasopharyngeal swab. In patients with more than 14 days of illness, the diagnosis was made by either a positive PCR test for B. pertussis DNA from a nasopharyngeal specimen or by finding a link to a person with a laboratory-confirmed case. Antimicrobial therapy was given to students and staff members with coughing, and they were excluded from school through the fifth day of treatment.
Other cases began appearing throughout six communities in the county. As a result, the pertussis vaccination schedule for infants was accelerated. A total of 483 pertussis cases were reported throughout the outbreak, which lasted 6 months. Genetic testing revealed four DNA profiles of B. pertussis, most of which matched the profile of patients attending the middle school. No patients were hospitalized or died during this outbreak. Early recognition, treatment, and chemoprophylaxis were important in preventing pertussis transmission to others.
Do determining genetic profiles help in studying disease transmission? How?

Question 9

How can a diphtheroid be distinguished from the agent of diphtheria?

Question 10

What is a diphtheria toxin test and how is it performed?

Question 11

Can diphtheria be transmitted directly via the respiratory route? If so, how?

Question 12

How is diphtheria prevented?

Question 13

Why is early laboratory diagnosis of diphtheria important?

Question 14

What is the preferred specimen for diagnosing whooping cough?