Bacteriology: Staphylococci and Streptococci

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Questions and Answers

What is the cell shape of Staphylococcus?

Short and oval

Rod-shaped

Spherical or rounded (correct)

Cylindrical

What type of arrangement do Streptococcus bacteria have?

Clusters

Singles

Pairs

Chains (correct)

What is the size range of Corynebacterium cells?

1.0 to 2.0 micrometers

0.5 to 6.0 micrometers (correct)

0.5 to 1.0 micrometers

0.5 to 1.5 micrometers

What is the Gram reaction of Enterococcus?

Gram-positive cocci Signup and view all the answers

Which of the following describes the Gram staining result of Listeria?

Purple in Gram stain Signup and view all the answers

Which shape is typically associated with Enterococcus bacteria?

Spherical or oval Signup and view all the answers

What is the typical size range of Staphylococcus bacteria?

0.5 to 1.5 micrometers Signup and view all the answers

How are Corynebacterium bacteria generally described in terms of morphology?

Rod-shaped or cylindrical Signup and view all the answers

What type of infection is associated with severe cough and production of sputum?

Respiratory infection Signup and view all the answers

Which bacteria is known as a cause of skin infections?

Staphylococcus aureus Signup and view all the answers

What characteristic is associated with general skin infections mentioned?

Generalized skin peeling Signup and view all the answers

What symptom is NOT commonly associated with deep skin infections?

Skin peeling Signup and view all the answers

Which of the following is a mucoid bacterium involved in causing infections?

Streptococcus pneumoniae Signup and view all the answers

What is a potential complication of bacterial endocarditis?

Acute heart failure Signup and view all the answers

Which species is associated with generalized skin peeling without inflammation?

Staphylococcus epidermidis Signup and view all the answers

What condition is characterized by colonization of bacteria leading to heart valve damage?

Bacterial endocarditis Signup and view all the answers

Which organism is unlikely to cause skin infections?

Listeria innocua Signup and view all the answers

What is a possible result of cardiac-related infections involving bacteria?

Hypocomplementemia Signup and view all the answers

What is the staining result for most strains of pneumonia bacteria?

They stain pink. Signup and view all the answers

How are bacteria causing pneumonia primarily transmitted?

Through respiratory droplets. Signup and view all the answers

What kind of motility do most pneumonia bacteria exhibit?

Limited motility. Signup and view all the answers

Which antibiotic do pneumonia bacteria develop resistance to very quickly?

Ampicillin Signup and view all the answers

On which type of culture medium do pneumonia bacteria grow best?

Blood agar. Signup and view all the answers

What type of growth do pneumonia bacteria typically exhibit on blood agar?

Beta hemolytic. Signup and view all the answers

What is the characteristic of the colonies formed by pneumonia bacteria on nutrient agar?

Spherical and smooth. Signup and view all the answers

Which type of oxygen requirement do most pneumonia bacteria have?

Facultative anaerobic. Signup and view all the answers

What are the conditions for the spread of pneumonia bacteria through food?

Using raw or unpasteurized products. Signup and view all the answers

Which symptom is associated with untreated infections from pneumonia bacteria?

Severe abdominal pain. Signup and view all the answers

What is the result of non-hemolytic strains of pneumonia bacteria on blood agar?

Opaque and creamy colonies. Signup and view all the answers

What can develop quickly in response to the use of penicillin for pneumonia bacteria?

Resistance. Signup and view all the answers

What kind of infections can pneumonia bacteria cause other than pneumonia?

Skin infections and sepsis. Signup and view all the answers

Study Notes

Staphylococci

Staphylococcus aureus is a gram-positive bacterium that stains purple
Typically spherical in shape, it is organized in clusters
Stained purple in Gram stain
It can cause skin infections, severe coughs, and production of sputum and pus
S. aureus are found in wounds, clinical infections of respiratory or urinary tracts, and can be spread through direct and indirect contact
Its size ranges from 0.5 to 1.5 micrometers in diameter
Non-motile
It is sensitive to penicillin and develops resistance very quickly
It grows well on selective media (mannitol-salt agar) or non-selective media
Forms yellow and smooth colonies
It is oxygen-rich as it needs oxygen for survival

Streptococci

Streptococcus pneumoniae is a gram-positive cocci that appears in chains
It is sensitive to penicillin, erythromycin, and ampicillin
It stains purple but older colonies stain purple
They are non-motile and do not have flagella
They are hemolytic and grow on blood agar forming grey-white colonies
The bacteria can cause a variety of illnesses, such as pneumonia, bacterial meningitis, otitis media, bacteremia, and endocarditis
It is transmitted through direct person-to-person contact.
Alpha-hemolytic Streptococcus pneumonia strains are sensitive to optochin
Beta-hemolytic streptococci can cause serious infections, such as necrotizing fasciitis and streptococcal toxic shock syndrome

Corynebacterium

Corynebacterium diphtheriae is a gram-positive bacterium that are typically rod or cylindrical shaped
They are sensitive to penicillin
It shows very limited motility
Grows well on blood agar (tellurite blood agar)
It produces small, smooth, opaque, creamy colonies
Causes diphtheria disease, a respiratory illness that is characterized by a thick, gray membrane that forms in the throat
The bacteria is commonly found in the respiratory tract and on the skin
It also causes wound infection
Transmission occurs through the respiratory droplets

Enterococci

Enterococcus faecalis and Enterococcus faecium are gram-positive cocci in spherical shapes
These bacteria are gram-positive and stain purple in a Gram stain
Non-motile
Sensitive to ampicillin, vancomycin, and gentamicin
Commonly found in faeces
They are also sensitive to antibiotics, such as ampicillin, vancomycin, and gentamicin
Can be transmitted through fecal-oral route
Found on nutrient agar

Listeria

Listeria innocua and Listeria ivanovii are gram-positive rods that are short and appear small
They are sensitive to ampicillin and penicillin
Gram-positive bacteria form purple colonies during Gram staining
Most species are non-motile
Usually found in raw milk, contaminated vegetables, and other foodstuffs
Causes listeriosis
Transmission is through eating food contaminated with bacteria
It grows in Müller-Hinton agar.
It is a facultative anaerobe, meaning it can grow in the presence or absence of oxygen
Most commonly known for causing food poisoning

Clinical Manifestations Caused by Staphylococcus aureus and Other Bacteria Mentioned

Staphylococcus aureus:
- Inflammation of a hair follicle
- Non-bullous impetigo
- Severe soft tissue infection
- Endocarditis
- Bacteremia
- Septicemia
- Urinary tract infections
- Neonatal sepsis
- Loss of balance
- Stiff neck
- Muscle aches
- Fever
Streptococcus pneumoniae:
- Pneumonia
- Meningitis
- Otitis media
- Bacteremia
- Endocarditis
Corynebacterium diphtheriae:
- Diphtheria
- Wound infection
Enterococci:
- Endocarditis
- Urinary tract infection
- Bacteremia
- Sepsis
Listeria:
- Listeriosis
- Food Poisoning
- Weight loss
- Diarrhea
- Abdominal pain
- Joint pain
- Lymphadenitis
- Skin hyperpigmentation

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Description

This quiz covers the essential characteristics of Staphylococcus aureus and Streptococcus pneumoniae, exploring their gram-positive nature, shapes, growth conditions, and clinical significance. Understand their roles in infections and their susceptibility to antibiotics.