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15.1.2.2: The Streptococci - Biology

15.1.2.2: The Streptococci - Biology


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Although the Streptococci are Staphylococci are both Gram-positive cocci, Streptococci are quite distinct from Staphylococci. Streptococci do not tolerate exposure to oxygen as well as the other Gram-positive cocci, perhaps due in part to the fact that they are catalase-negative. The different groups of Streptococci are often characterized by their hemolysis (ability to degrade red blood cells) on media that contain blood (Figure (PageIndex{1})). Some of the most pathogenic Streptococci, such as S. pyogenes, are beta-hemolytic, meaning they completely destroy the red blood cells. Some pathogenic Streptococci, such as S. pneumoniae and those in the viridans group, are alpha-hemolytic, only partially degrading the red blood cells which leaves a green tint to the media. Finally, the Enterococci are gamma-hemolytic, not degrading the blood at all. The Enterococci are also more tolerant of salt than most Streptococci, being able to grow in 6.5% salt.


Strep·to·coc·cus

Q. What Is Streptococcal Pneumonia? I have heard that I might have streptococcal pneumonia. What exactly does that mean?

Q. My friend think she has strep in her throat. What should she do. She doesn't want to take antibiotics. Her glands are swollen and she feels kinda out of it. Any more information or links would be greatly appreciated.

Q. 5 year old son diagnosed with streptococcus must I give him antibiotics? He is 5 years old and never received antibiotics before. He feels good and does not complain of any problem. The doctor said he should take antibiotics for 10 days. Is it mandatory?


Streptococcus

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Streptococcus, (genus Streptococcus), group of spheroidal bacteria belonging to the family Streptococcaceae. The term streptococcus (“twisted berry”) refers to the bacteria’s characteristic grouping in chains that resemble a string of beads. Streptococci are microbiologically characterized as gram-positive and nonmotile.

Streptococcus contains a variety of species, some of which cause disease in humans and animals, while others are important in the manufacture of certain fermented products. Streptococcus pyogenes, often referred to as group A streptococcus bacteria, can cause rheumatic fever, impetigo, scarlet fever, puerperal fever, streptococcal toxic shock syndrome, strep throat, tonsillitis, and other upper respiratory infections. Necrotizing fasciitis, a rapidly spreading infection of the skin and underlying tissue caused by S. pyogenes, has been popularly referred to as the “flesh-eating disease.” Streptococcus agalactiae, or group B streptococcus bacteria, can cause infections of the bladder and uterus in pregnant women in newborn infants infection with the bacterium may result in sepsis (blood poisoning), meningitis (inflammation of the membranes covering the brain and spinal cord), or pneumonia. Streptococcus pneumoniae, also called pneumococcus, is an important human pathogen that causes pneumonia, sinusitis, otitis media, and meningitis. Fecal (enterococcal) species occur in great numbers in the bowel and can cause urinary tract infections and endocarditis. S. mutans, belonging to the viridans species, inhabits the mouth and contributes to tooth decay. Among the lactic species, S. lactis and S. cremoris are used in commercial starters for the production of butter, cultured buttermilk, and certain cheeses.

Streptococci generally are classified by the type of carbohydrate contained in the cell wall, a system called the Lancefield classification.

This article was most recently revised and updated by Amy Tikkanen, Corrections Manager.


Streptococcal Diseases

Classification of Streptococci

Streptococci are spherical organisms that grow in chains because of incomplete separation after division of the cells ( Figure 1 ). They were first described in 1874 by Billroth, who used the term ‘ Streptococcus ’ (from two Greek words: streptos = chain, kokhos = berry). In the beginning, streptococci were classified according to the disease they caused however, thanks to advances in diagnostics, and with the availability of modern molecular techniques, many changes have been made in the taxonomy of the Streptococcus genus in the last decade. Historically, a useful identifying characteristic of streptococci has been the reaction they show on blood agar, caused by the lysis of erythrocytes by enzymes released by the Streptococcus – a phenomenon known as hemolysis. Based on this characteristic, streptococci were classified into β-hemolytic and non-β-hemolytic groups. In 1934, streptococci were further classified based on the presence of group-specific polysaccharides on the bacterial surface. In this serogrouping, mostly β-hemolytic streptococci were considered. Thirteen different serological groups have so far been identified, out of which groups A, B, C, and G, Streptococcus pneumoniae, and viridans group streptococci are most important with regards to human health. Molecular methods such as multilocus sequence analysis, 16S rRNA gene sequencing, and whole genome analysis can also be used to determine taxonomic relationships between streptococcal species, particularly among the viridans group. The main focus of this article is on the diseases caused by different streptococci. The classification of streptococci capable of causing disease in humans and animals is depicted in Table 1 .


Health experts estimate that more than 10 million mild infections (throat and skin) occur every year.

NIAID supports research to develop a group A streptococcus vaccine, and several candidate vaccines are in various phases of development. While some scientists are conducting animal model studies to obtain data to pursue clinical trials in humans, other scientists are close to evaluating group A streptococcus vaccine candidates in Phase I clinical trials.

As a result of NIAID-supported research, the first group A streptococcus vaccine clinical trial in 30 years was started. The vaccine was well tolerated by patients and has led to further clinical evaluation of a similar vaccine candidate.

To learn about risk factors for GAS and current prevention and treatment strategies visit the MedlinePlus streptococcal infections site.


Lab Test Tips

Always keep a copy of your results. This can be useful in case you switch doctors, need to show them to a specialist, or just want to look at them again later.

Remind your doctor if you take medications or have a health condition that can affect your results. That should be in your record, but it’s still a good idea to mention it.

Be honest if you didn’t follow the instructions. With some lab tests, you’re supposed to fast (not eat), or not do certain activities, eat certain foods, or take certain drugs. If you forget and mess up, don’t worry -- just tell your doctor before you do the test. It’s not a big deal to reschedule, and it’s a waste of time to get the test if the results won’t be right.

Make sure your doctor always uses the same lab to do your tests if possible. It can be hard to compare results from different labs because they may approach the test differently. For example, one lab might have different ranges for “normal” and “abnormal” than another.

Ask your doctor questions about your results like:

  • Why did I need this test?
  • What exactly does this test result mean?
  • How accurate is this test?
  • When will I need to do this test again?
  • Based on my results, do I need treatment or other tests?

Sources

National Center for Policy Analysis: “Patients Get Direct Access to Lab Tests.”

FDA: “Tests Used In Clinical Care.”

HealthResearchFunding.org: “Kaiser Permanente Blood Test Results Explained.”

Healthy Women: “You Have a Right to Your Lab Results: New Rules Provide Direct Access.”

American Association for Clinical Chemistry’s Lab Tests Online: “Reference Ranges and What They Mean,” “Strep Throat Test,” “Deciphering Your Lab Report,” “Test Preparation: Your Role,” “Making Informed Decisions for Better Health.”

U.S. Department of Veterans Affairs: “HIV/AIDS: Frequently Asked Questions.”

National Cancer Institute: “Understanding Laboratory Tests.”

Dana-Farber Cancer Institute: “What Are False-Positive Test Results, and What Causes Them?”


CDC Streptococcus Laboratory

CDC&rsquos Streptococcus Laboratory provides support for active population-based surveillance for invasive streptococcal disease, primarily caused by groups A and B streptococci and Streptococcus pneumoniae. It supports state and local health departments in the United States to characterize streptococcal isolates and is active in many international collaborations. The laboratory is a reference center for the identification and characterization of streptococci and other Gram-positive catalase-negative cocci.

M protein gene (emm) typing, databases, resources, and protocols.

MICs predicted by penicillin binding protein gene types, resources, protocols, and the global pneumococcal strain bank.

PCR serotyping methods and resources.

Methods for identifying other species and types of streptococci, including PCR assays.

Frequently asked questions about the Streptococcus Laboratory&rsquos reference services and request forms.

Papers published by the Streptococcus Laboratory.

Opportunities concerning molecular epidemiology and biology at the Streptococcus Laboratory.

Group A streptococci: Submit emm gene sequence to determine emm subtype of your strain.

There are many species and subspecies within the Streptococcus genus. CDC provides protocols for how to identify and differentiate species of streptococci.


Substantial Differences in SARS-CoV-2 Antibody Responses Elicited by Natural Infection and mRNA Vaccination

We analyzed data from two ongoing serologic surveys, a longitudinal cohort of health care workers (HCW) from the University of California Irvine Medical Center (Orange County, CA, USA), collected from May and December 2020 through March 2021, and a cross sectional county-wide study in July 2020 (actOC Orange County, CA) and a more focused community study in the city of Santa Ana (Santa Ana Cares Orange County, CA, USA), collected in December 2020 - in order to compare the antibody responses to SARS-CoV-2 natural infection and vaccination. In addition, we serially tested 9 volunteers at multiple time points to analyze the time course of vaccine-induced antibody response in more detail. In May 2020, 1060 HCW were enrolled and had finger stick samples collected. Finger stick samples were again collected in December 2020, before vaccination, as well as January, February and March 2021 during vaccination campaign. A total of 8,729 finger stick blood specimens were probed and analyzed for IgG and IgM antibodies using a coronavirus antigen microarray (COVAM).The microarray contained 10 SARS-CoV-2 antigens including nucleocapid protein (NP) and several varying fragments of the spike protein, as well as 4 SARS, 3 MERS, 12 Common CoV, and 8 Influenza antigens.Based on a random forest based prediction algorithm, between May and December, prior to vaccine rollout, we observed that seropositivity in the HCW cohort increased from 4.5% to 13%. An intensive vaccination campaign with mRNA vaccines was initiated on December 16, 2020 and 6,724 healthcare workers were vaccinated within 3 weeks. The observed seropositivity of the HCW specimens taken in the last week of January 2021 jumped to 78%, and by the last week in February it reached 93%, and peaked at 98% seropositive in March. The antibody profile induced by natural exposure differed from the profile induced after mRNA vaccination. Messenger RNA vaccines induced elevated antibody (Ab) reactivity levels against the Receptor Binding Domain (RBD) domain of SARS-CoV-2 spike, and cross-reactive responses against SARS and MERS RBD domains. Nucleocapsid protein (NP), which is an immunodominant antigen induced after natural exposure, is not present in the vaccine and can be used as a biomarker of past exposure. The results show that naturally-exposed individuals mount a stronger anti-spike response upon vaccination than individuals that were not previously exposed. Longitudinal specimens taken at approximately weekly intervals from 9 individuals show variation in the response to the mRNA vaccine, with some showing a vigorous response to the first dose (prime) and others requiring a subsequent dose (boost) to reach high anti-SARS-CoV-2 levels. Antibody titers determined by serial dilution of the specimens were used to accurately compare antibody levels in these samples. mRNA vaccinees after the boost have higher Ab titers (up to 10 times higher) than convalescent plasmas from donors who recovered from natural infection. The results of this study exemplify the time course and outcomes expected from similar mRNA mass vaccination campaigns conducted in other institutions.

Competing Interest Statement

The coronavirus antigen microarray is intellectual property of the Regents of the University of California that is licensed for commercialization to Nanommune Inc. (Irvine, CA), a private company for which Philip L. Felgner is the largest shareholder and several co-authors (Assis, Jain, Nakajima, Jasinskas, Davies, and Khan) also own shares. Nanommune Inc. has a business partnership with Sino Biological Inc. (Beijing, China) which expressed and purified the antigens used in this study, The other authors have no competing interests


Ex 15.1 Class 8 Maths Question 1.
The following graph shows the temperature of a patient in a hospital, recorded every hour.
(a) What was the patient’s temperature at 1 p.m.?
(b) When was the patient’s temperature 38.5°C?

(c)
The patient’s temperature was the same two times during the period given. What were these two times?
(d) What was the temperature at 1.30 p.m.? How did you arrive at your answer?
(e) During which periods did the patient’s temperature showed an upward trend.
Solution:
In the graph, we find that the time (in hours) are represented on the x-axis and the temperature (in °C) are represented on the y-axis. The temperature at any time can be read from the graph exactly in the same way as we read the coordinates of a point. From the graph, we observe that :
(a) The temperature of the patient at 1 p.m. was 36.5°C.
(b) The temperature of the patient was 38.5°C at 12 noon.
(c) The temperature of the patient was same at 1 p.m. and 2 p.m.
(d) The temperature of the patient at 1.30 p.m. was 36.5°C. The point between 1 p.m. and 2 p.m. on the x-axis is equidistant from the two points showing 1 p.m. and 2 p.m., so it will represent 1.30 p.m. Similarly, the point on the y-axis, between 36°C and 37°C will represent 36.5°C.
(e) During the periods 9 a.m. to 10 a.m., 10 a.m. to 11 a.m. and 2 p.m. to.3 p.m. the patient’s temperature showed an upward trend.

Ex 15.1 Class 8 Maths Question 2.
The following line graph shows the yearly sales figures for a manufacturing company.
(a) What were the sales in
(i) 2002
(ii) 2006?
(b) What were the sales in
(i) 2003
(ii) 2005?
(c) Compute the difference between the sales in 2002 and 2006.

(d)
In which year was there the greatest difference between the sales as compared to its previous year?
Solution:
In the graph, we find that the years are represented on the x-axis and the sales (in ? crores) on the y-axis. The sales at any time (year) can be read from the graph exactly in the same way as we read the coordinates of a point. From the graph, we observe that :
(a)
(i) The sales in the year 2002 is ₹ 4 crore.
(ii) The sales in the year 2006 is ₹ 8 crore.
(b)
(i) The sales in the year 2003 is ₹ 7 crore.
(ii) The sales in the year 2005 is ₹ 10 crore.
(c) The difference between the sales in 2002 and 2006 = ₹ 8 crore – ₹4 crore = ₹ 4 crore.
(d) The year in which there was the greatest difference between the sales as compared to its previous year is the year 2005.

Ex 15.1 Class 8 Maths Question 3.
For an experiment in Botany, two different plants, plant A and plant B were grown under similar laboratory conditions. Their heights were measured at the end of each week for 3 weeks. The results are shown by the following graph :

(a)
How high was Plant A after (i) 2 weeks (ii) 3 weeks?
(b) How high was Plant B after (i) 2 weeks (ii) 3 weeks?
(c) How much did Plant A grow during the 3rd week?
(d) How much did Plant B grow from the end of the 2nd week to the end of the 3rd week?
(e) During which week did Plant A grow most?
(f) During which week did Plant B grow least? *
(g) Were the two plants of the same height during any week shown here? Specify.
Solution:
In the graph, we find that the weeks are represented on the x-axis and the heights (in cm) of two plants A and B on the y-axis. The heights on any week of plants A and B can be read from the graph exactly in the same way as we read the coordinates of a point. From the graph, we observe that :
(a) The height of the plant A after
(i) 2 weeks was 7 cm
(ii) 3 weeks was 9 cm.
(b) The height of the plant B after
(i) 2 weeks was 7 cm
(ii) 3 weeks was 10 cm.
(c) The plant A grows 2 cm during the 3rd week.
(d) The plant B grows 3 cm from the end of the 2nd week to the end of the 3rd week.
(e) The plant A grows most during second week.
(f) The plant B grows most during first week.
(g) At the end of the 2nd week the heights of the two plants were the same.

Ex 15.1 Class 8 Maths Question 4.
The following graph shows the temperature forecast and the actual temperature for each day of a week.
(a) On which days was the forecast temperature the same as the actual temperature?
(b) What was the maximum forecast temperature during the week?
(c) What was the minimum actual temperature during the week?
(d) On which day did the actual temperature differ the most from the forecast temperature?

Solution:

In the graph, we find that the days are represented on the x-axis and the temperature forecast/actual (°C) on the y-axis. The temperature on any day can be read from the graph exactly in the same way as we read the coordinates of a point. From the graph, we observe that :
(a) The days on which the forecast temperature was the same as the actual temperature are Tuesday, Friday and Sunday.
(b) The maximum forecast temperature during the week was 35°C.
(c) The minimum actual temperature during the week was 15°C,
(d) The actual temperature differed the most from the forecast temperature on Thursday.

Ex 15.1 Class 8 Maths Question 5.
Use the tables below to draw linear graphs.
(a) The number of days a bill side city received snow in different years.

(b) Population (in thousands) of men and women in a village in different years.

Solution:
(a) In order to draw the required graph, we represent years on the x-axis and the days on the y-axis. We first plot the ordered pairs (2003, 8), (2004,10), (2005, 5) and (2006, 12) as points and then join them byline segments as shown below :

(b)
In order to draw the required graph, we represent years on the x-axis and the population (in thousands) on the y-axis. The dotted line shows the population (in thousands) of men and the solid line shows the population (in thousands) of women.

We first plot the ordered pairs (2003 12), (2004, 12.5), (2005, 13), (2006, 13.2) and (2007, 13.5) and then join them by the dotted line as shown to get the graph representing the number of men. Further, we plot (2003, 11.3), (2004, 11.9), (2005, 13), (2006, 13.6) and (2007, 12.8) and then join them by line segments as shown to get the graph representing the graph of number of women.
Thus, the required graph is obtained.

Ex 15.1 Class 8 Maths Question 6.
A courier-person cycles from a town to a neighbouring suburban area to deliver a parcel to a merchant. His distance from the town at different times is shown by the following graph :
(a) What is the scale taken for the time axis?
(b) How much time did the person take for the travel?
(c) How far is the place of the merchant from the town?
(d) Did the person stop on his way? Explain.
(e) During which period did he ride fastest?

Solution:
In the graph, we find that the time (in hours) is represented on the x-axis and the distance (in km) is represented on the y-axis. The distance at any time can be read from the graph exactly in the same way as we read the coordinates of a point. From the graph, we observe that :
(a) The scale taken for the time axis is : 4 units = 1 hour.
(b) The person took 3 hours for the travel.
(c) The merchant’s place from the town is 22 km.
(d) Yes this is indicated by the horizontal part of the graph (10 a.m. -10.30 a.m.)
(e) Between 8 a.m. and 9 a.m. he ride faster.

Ex 15.1 Class 8 Maths Question 7.
Can there be a time-temperature graph as follows? Justify your answer.



Solution:
(i) This represents a time-temperature graph because it represents a smooth rise in temperature and is represented by a line graph.
(ii) This represents a time-temperature graph because it represent a smooth fall in temperature and is represented by a line graph.
(iii) This does not represent a time-temperature because it shows different temperatures at the same time.
(iv) This represents a time-temperature graph because it shows a constant temperature at different times and is a line graph.

We hope the NCERT Solutions for Class 8 Maths Chapter 15 Introduction to Graphs Ex 15.1 help you. If you have any query regarding NCERT Solutions for Class 8 Maths Chapter 15 Introduction to Graphs Ex 15.1, drop a comment below and we will get back to you at the earliest.


Watch the video: Streptococci Blood Hemolysis Classification: Beta-Hemolytic, Alpha-Haemolytic u0026 Gamma Haemolytic (February 2023).