Medically Important Gram Positive Bacteria And Mycobacteria

Question 1

Name three examples of gram positive cocci and gram positive bacilli

Answer 1

Staphylococcus
Streptococcus
Enterococci

Clostridium species
Listeria
Corynebacterium

Question 2

Staph appears in what form and strep appears in what form

Answer 2

Staph- clusters

Strep- chains

Question 3

What test is used to differentiate between staph and strep

Answer 3

Catalase test

Question 4

What test is used to differentiate between streptococci

Answer 4

Blood agar haemolysis

Question 5

How is the catalase test done

Answer 5

It uses 3percent hydrogen peroxide
Staph are catalase positive and strep is catalase negative
If it is staph, bubbles are formed

Question 6

A major virulence factor is staph is toxins. Name three toxins produced by staph aureus and their clinical relevance

Answer 6

Enterotoxin- induces git distress
Hemolysins- lyse red blood cells
Toxic shock syndrome toxin- induces fever, vomiting, shock,system organ damage
Exfoliating toxin- separates the epidermis from the dermis

Question 7

Name four diseases caused by staph aureus

Answer 7

Boils
Sepsis, osteomyelitis
Food intoxication - by ingestion of enterotoxins
Staphylococcal scalded skin syndrome-toxin induces blisters then desquammation of epidermis
Toxic shock syndrome toxin(TSST)-toxemia leading to shock

Question 8

Methicillin resistant staph aureus is not resistant to most antibiotics true or false

Answer 8

False. It is

Question 9

Where is MSRA usually spread

Answer 9

In the hospital and it easily spreads

Question 10

Importance of Coagulase test

Answer 10

It singles out staph aureus

If it is staph aureus, in the slide method, there is clumping

Question 11

Samples taken to check for staph aureus

Answer 11

Blood in sepsis

Pus or fluid from boils

Question 12

How to get check for staph aureus

Answer 12

Example
Blood sample is taken and cultured
The culture when it grows, a lab test (gram staining is done). And it’ll be Gram positive. To confirm it is a staph you do a catalase test and if it is staph, you’ll see a Gram positive cocci in clusters . If strept it’ll be Gram positive cocci in clusters . and to check what kind of staph it is you do a coagulase test to see if it is staph aureus

Question 13

Name two types of coagulase test

Answer 13

Slide coagulase test and tube coagulase test
Slide- detects bound coagulase
Tube- detects free coagulase

Question 14

Name some beta hemolytic organisms

Answer 14

Staph aureus and strept pyogenes
Strept agalactiae
And E coli

Question 15

What test is used to differentiate streptococcus

Answer 15

Hemolytic pattern on blood agar

Question 16

Strept pneumoniae is what kind of hemolytic

Answer 16

Alpha hemolytic (partial hemolysis)

Question 17

Apart from blood agar, which other way can strept be grouped

Answer 17

Lancefield serological classification

Question 18

According to lancefield serological grouping and blood agar, strept pyogenes is ?

Answer 18

Group A Beta Hemolytic

Question 19

What are supparative diseases and name four supparative diseases associated with strept pyogenes

Answer 19

Supparative diseases are not complicated diseases

Examples
Sore throat (pharyngitis)
Impetigo-rashes( as opposed to boils for staph aureus)
Cellulitis
Necrotizing fasciitis
Scarlet fever is based on a toxin produced by streptococcus

Question 20

How to check for strept pyogenes

Answer 20

Do Gram staining to see if org is Positive or negative
Itll be positive
Do catalase test to check for the strept
It’ll catalase negative
Then to check for what type of strept it is, use hemolytic pattern on blood agar
To check the type of strept. If it is Beta hemolytic it is strept pyogenes
Then according to the lancefield serological classification, it is Group A

Question 21

What are Non supparative diseases with regards to strept and give two examples

Answer 21

They are complicated diseases that occur due to strept

Acute rheumatic fever- a complication related to heart diseases (carditis) . It occurs in some people who don’t take antibiotics after getting pharyngitis
Acute glomerulonephritis- a complication related to kidney diseases ( hematuria, proteinuria,high bp)

Question 22

Strept pneumoniae although isa strept and so should be in chains. That is not so, it is Rather in what form?

Answer 22

Gram positive diplococci and is capsulated.

It’s cocci are in pairs in short chains not long chains like the other strept

Question 23

Where is strept pneumoniae usually (normally )found

Answer 23

In the upper respiratory tract and when it goes down to the lungs or anywhere else apart from the upper resp tract and that’s where it causes diseases

Question 24

Name two diseases that occur when strept goes to other places apart from the upper respiratory tract and four complications that can can result

Answer 24

Runny nose
Pneumonia causing bloody sputum 
Cold
CN cause upper resp congestion
Complications- 
Meningitis 
Bacteremia 
Sinusitis 
Otitis media

Question 25

Listeria which is a bacilli has flagella therefore it is motile true or false

Answer 25

True

Question 26

Which kind of people are usually affected by Listeria monocytogenes and name three problems caused by it

Answer 26

It causes problems in pregnant women and it is the baby that is affected ``` Problems- intra-uterine death( baby dies in the womb) Early onset neonatal infection( when baby comes out and after two days has a fever) Intermediate onset(3-5) days and gets an infection Late onset(7-5 days and septicemia or meningitis occurs) ```

Question 27

How does it occur in pregnant women?

Answer 27

The women present with cold like symptoms or influenza like symptoms . When this happens, give the person antibiotics in case the woman has been infect with listeria monocytogenes so that the baby will not be affected

Question 28

How to check for listeria

Answer 28

Inoculate the test organism into the central glass tube ● Incubate at room temperature for 18-24h ● Subculture from the outer section of the medium •Positive result: Organism can be recovered from the outer section of the medium •Negative result: Organism remains in the inner tube

Question 29

Corynebacterium diphtheriae causes which diseases.

Answer 29

Diphtheria Sore throat ( lymph nodes get swollen(bull neck ) ) this shows the difference between sore throat caused by this organism and sore throat caused by streptococcus pneumoniae How to show if the organism has progressed is that the tissues in the throat will be white or black (if black it shows tissue is dead. If white the tissue is dying.A toxin is produced to destroy the cells in the throat) Non toxin doesn’t destroy the cells but just causes the sore throat(pharyngitis) Complications- if organism progresses into the heart it causes myocarditis and into the nerves it causes neuritis

Question 30

C diphtheriae is a vaccine preventable condition. True or false

Answer 30

True

Question 31

Which bacilli bacteria is anaerobic and spore forming(spore forms terminally )

Answer 31

Clostridium

Question 32

Clostridium tetani causes what and is found where

Answer 32

Tetanus and Is found as spores in the environment and is vaccine preventable It is characterized as a locked jaw or difficulty in moving the jaw. If you get knife wounds or metal wounds or car accident wounds patient on your hands clean the wound very well having tetanus in mind and if it is possible not to suture then don’t Even if you suture , make sure you give proper antibiotics

Question 33

Diff between anti tetanus serum and tetanus vaccine

Answer 33

Anti-tetanus immunoglobulin, also known as tetanus immune globulin (TIG) and tetanus antitoxin, is a medication made up of antibodies against the tetanus toxin. (Provides passive immunity as the body doesn’t produce the antibodies) But the tetanus vaccine will make your body immune against the tetanus so whenever it tries to enter your body it can’t enter

Question 34

Clostridium perfringens causes ?

Answer 34

Necrotizing enteritis

Question 35

How is clostridium classified as?

Answer 35

A Gram positive bacilli that is anaerobic and it’s spores are formed terminally

Question 36

Clostridium difficile causes what disease?

Answer 36

Abuse of antibiotics or antibiotics associated diarrhea

Question 37

How are bacillus species classified

Answer 37

They are Gram positive bacilli and their spores are oval shaped and centrally located)

Question 38

Which bacillus species is used for bioterrorism

Answer 38

Bacillus anthracis

Question 39

Apart from staph aureus, which other Gram positive bacteria causes food poisoning

Answer 39

Bacillus cereus

Question 40

What infections are caused by bacillus anthracis

Answer 40

Pulmonary anthrax- by inhalation of spores | Intestinal anthrax

Question 41

Name three mycobacterium diseases

Answer 41

Tuberculosis Leprosy Buruli ulcer

Question 42

Why doesn’t Gram staining work well on mycobacterium

Answer 42

It has modified peptidoglycan layer and has lots of layer steroids in the cell wall

Question 43

TB is not caused by only M tuberculosis but caused by each organism in the mycobacterium tuberculosis complex true or false

Answer 43

True but TB is mainly caused by M tuberculosis

Question 44

TB Is divided into two. Name them and explain

Answer 44

Pulmonary tuberculosis : bloody sputum from the lungs | Extra pulmonary tuberculosis : when it affects anywhere else apart from the lungs example spine or brain

Question 45

How is pulmonary TB diagnosed

Answer 45

1. Molecular techniques Using Gene Xpert . Sputum is the sample used Advantages of Gene Xpert- High sensitivity It takes 2 hours. It shows if the Sputum sample is drug resistant or not Does not put health worker at risk It requires one sputum sample Limitation- it works only on sputum sample so you cannot test for TB if you suspect Extra Pulmonary TB cuz the sample for EPTB is not sputum If the person has a lot of blood in the sputum , Gene Xpert will read the sample as invalid Gene Xpert cartridge does not last for so long It detects only M tuberculosis and not the other pathogens in the M tuberculosis complex 2. Microscopy Acid fastness: Ziehl -Nielsen , Auramine staining (fluorescent microscope which has a dark background ) Auramine is better cuz it is easier to identify the pathogens if present due to the dark background while the pathogens are illuminated Disadvantages- A lot of training is needed to process it so it puts the health worker at risk There is low sensitivity - cuz the microscope may not be good enough to see the pathogens , your eyes may not be good enough to see the pathogens so you can easily get a negative result even when the pathogens are present It takes longer 3. Culture: not everyone needs the culture . It is needed when Gene Xpert is not able to detect the pathogen causing the TB because the pathogen causing the TB is not M tuberculosis . So when the result comes out as negative but the person has all the symptoms of TB then you do culture to be extra sure Culture allows the organism to grow so whichever species of TB is there grows in numbers and is identified. It has high sensitivity. Also if the TB is drug resistant a culture is used to different TB medications to check which the sample is resistant to or sensitive to It takes a very long time It puts the healthworker at risk Immunological test: example mantoux test or Heaf test Mantoux test: everyone that has taken TB vaccine , the result will come out as positive So I’m a setting like this, immunological test cannot be used But if getting samples is problematic then Mantoux test is used to support your diagnosis or suspicions. Example- cervical TB you can’t take sputum sample Procedure: inject purified protein derivatives into the skin and check for the appearance of induration. Everyone vaccinated w TB there will be an induration formed but the size won’t be big as that if someone with TB The size of the induration will show if it is TB or not

Question 46

M ulcerans causes buruli ulcer. How are the wounds managed?

Answer 46

It is managed surgically In a very short time the wound becomes very big like three days The infected place must be scraped off if the infection has not crossed joints Wound can be covered after surgical debridement by grafting from the thigh