2. Learning objectives
By the end of the lecture, we should be able to:
• Explain the process of gram staining
• Classify bacteria into gram positive and
negatives
• List the diseases caused by gram positive
microbes
• Pathogenesis of these microbes
• Antibiotic treatment of these microbes
3. Gram staining
• Gram staining is a lab procedure
used to differentiate two large groups
of bacteria based on their different
cell wall constituents.
• The Gram stain procedure
distinguishes between Gram positive
and Gram negative groups by
colouring these cells red or violet.
10. Gram positive bacteria cocci
1. staphylococcus
• Its is responsible for a number of common
infections.
• Staphylococcus is a genus of bacteria that is
characterized by a round shape (coccus).
• it is Gram-stain positive, and found as either single
cells, in pairs, or more frequently, in clusters that
resemble a bunch of grapes.
• The genus name Staphylococcus is derived from
Greek terms (staphyle and kokkos) that mean "a
bunch of grapes,.
13. Gram positive bacteria cocci
1. staphylococcus
• Staphylococcal infections are usually
caused by Staphylococcus aureus.
• However, the incidence of infections
due to Staphylococcus
epidermidis has also been steadily
rising.
14. Gram positive bacteria cocci
1. Staphylococcus cause the following diseases
• Skin infections (e.g. folliculitis, wound infections)
• Soft-tissue infections (eg,pyomyositis, septic
arthritis)
• Toxic shock syndrome
• Endocarditis
• Osteomyelitis
• Pneumonia
• Food poisoning
• Infections related to
prosthetic devices
(eg, prosthetic joints
and heart valves,
catheters):
• Urinary tract
15. Gram positive bacteria cocci
1. staphylococcus
Mode of transmision
Infections occurs when the skin is cut or scratched,
or have contact with a person or surface that has
staph bacteria.
17. Gram positive bacteria cocci
1. staphylococcus
• S. aureus
• It is the leading cause of skin and soft
tissue infections such as abscesses,
folliculitis and cellulitis.
• S. aureus can cause serious infections
such as bloodstream infections,
pneumonia, or bone and joint
infections.
18. Gram positive bacteria cocci
1. staphylococcus
• Staphylococcus epidermidis is a Gram-
positive bacterium, and one of over 40
species belonging to the
genus Staphylococcus.
• Its normal human flora of the skin less
commonly the mucosal flora.
• Although it is not usually pathogenic,
patients with compromised immune
systems are at risk of developing infection.
19. Gram positive bacteria cocci
1. staphylococcus
Staphylococcus epidermidis
it can lead to infection among people
with catheters or other surgical implants.
It is one of the leading cause of nosocomial
infections, particularly associated with
foreign body infections.
Being part of the normal skin flora, S.
epidermidis is a frequent contaminant of
specimens sent to the diagnostic laboratory.
20. Gram positive bacteria cocci
1. staphylococcus
Staphylococcus epiderminiS
Treatment
it has developed resistance to many
common antibiotics such as
methicillin, novobiocin, clindamycin,
and benzyl penicillin.
As a result, vancomycin or rifampicin
is used to treat an infection.
22. Gram positive bacteria cocci
1. staphylococcus
Pathogenesis of staphylococcus
They cause disease by
1. Binding (colonization) to blood cells
causing haemolysis
2. They also bind to body tissues
3. They release toxin that damages the
body tissues.
4. Has a protein inhibit phagocytosis
24. Gram positive bacteria cocci
2. Streptococcus
introduction
The genus Streptococcus is a group
of Gram-positive bacteria.
Various streptococci are important
ecologically as part of the normal
microbial flora of humans.
Some can also cause diseases that
range from acute or even chronic.
27. Gram positive bacteria cocci
2. Streptococcus
Streptococcus pneumoniae,
or pneumococcus, is a Gram-positive.
S. pneumoniae is a normal flora of the
human throat.
May cause disease among elderly
and immunocompromised people and
children.
The bacteria may become pathogenic,
spread to other locations and cause
disease.
28. Gram positive bacteria cocci
2. Streptococcus
Streptococcus
pneumoniae causes
Community acquired pneumonia
Meningitis in children and the
elderly.
Septicemia in HIV-infected persons.
Otitis media
Sinusitis
Endocarditis
29. Gram positive bacteria cocci
2. Streptococcus
Streptococcus pneumoniae,
or pneumococcus,
The methods of transmission include
sneezing, and coughing.
Access to blood stream due to tissue
damage
30. Gram positive bacteria cocci
2. Streptococcus
• Diagnosis of S.pneumonaea and other
microbes
• Gram stain and culture of appropriate specimens
should be obtained,. Potential specimens may include
• Blood
• Cerebrospinal fluid
• Sputum
• Pleural fluid or lung aspirate
• Joint fluid
• Bone
• Other abscess or tissue specimens
31. Gram positive bacteria cocci
2. Streptococcus
• Streptococcus pyogenes is a Gram-positive,
non-motile, microbe that occurs in chains or in
pairs of 2.
• Streptococcus pyogenes is one of the most
frequent pathogens of humans.
• It is estimated that between 5-15% of normal
individuals harbor the bacterium, usually in the
upper respiratory tract, without signs of disease.
• As normal flora, S. pyogenes can infect when
defenses are compromised or when the organisms
are able to penetrate.
32. Gram positive bacteria cocci
2. Streptococcus
• Streptococcus pyogenes causes the
following diseases.
• Puerperal sepsis
• Streptococcal pharyngitis
• Cellulitis
• Acute rheumatic fever and
• Acute glomerulonephritis,
33. Gram positive bacteria cocci
2. Streptococcus
• Streptococcus agalactiae,
• It is a diplococcal (a pair of cocci, gram-
positive Bacteria
• is best known as a cause of postpartum
infection and as the most common cause
of neonatal sepsis.
• It rarely causes infection in healthy adults.
• It can also cause sepsis, pneumonia and
meningitis.
35. Gram positive bacteria cocci
2. Streptococcus
• Viridans Group Streptococci,
• Group of organisms that can be
human commensals, colonizing the
gastrointestinal and genitourinary
tracts in addition to the oral mucosa.
• VGS are generally considered to be of
low pathogenic potential in immuno
competent individuals
36. Gram positive bacteria cocci
2. Streptococcus
• Viridans Group Streptococci.
• VGS can cause invasive disease,
such as
• Endocarditis
• intra-abdominal infection
• Shock
37. Gram positive bacteria cocci
2. Streptococcus
• Pathogenesis
• Have surface protein for attachment to the
host tissue and then multiply.
• Has a substance that inhibits phagocytosis
• Toxin, which cause the rash of scarlet or/ and
damage the host tissue
• Polysaccharide capsule, which protects the
bacterium against phagocytosis.
39. Gram positive bacteria cocci
3. Enterococci
• Enterococcus
• Enterococci are Gram-positive cocci that often
occur in pairs (diplococci) or short chains, and
are difficult to distinguish
from streptococci on physical characteristics
alone.
• Two species are common commensal
organisms in the intestines of humans:
• E. faecalis (90–95%) and E. faecium (5–10%)
43. Pathogenis of enterococci
• Enterococci form of a biofilm on heart
valves at sites of damage that become
integrated into masses called vegetations.
• Proteins helps them to adhere to tissues
and directly affect body tissues.
44.
45. References
• Bhakdi S, Tranum-Jensen J. Alpha-toxin of Staphylococcus
aureus. Microbiol Rev. 1991;55:733. [PMC free article] [PubMed]
• Easmon CSF, Adlam C: Staphylococci and staphylococcal
infections. Vols 1 and 2. Academic Press, London, 1983 .
• Foster TJ. Potential for vaccination against infections caused by
Staphylococcus aureus. Vaccine. 1991;9:221. [PubMed]
• Foster TJ, McDevitt D: Molecular basis of adherence of
staphylococci to biomaterials. p. 31, In Bisno AL, Waldvogel FA
(eds): Infections Associated with Indwelling Medical Devices,
2nd Edition. American Society for Microbiology, Washington,
D.C., 1994.
• Lyon BR, Skurray R. Antimicrobial resistance in Staphylococcus
aureus: genetic basis. Microbiol Reviews. 1987;51:88. [PMC free
article] [PubMed]
46. References
• Prevost G, Couppie P, Prevost P. et al. Epidemiological data on
Staphylococcus aureus strains producing synergohymenotropic toxins. J
Med Microbiol. 1995;42:237. [PubMed]
• Rupp ME, Archer GL. Coagulase-negative staphylococci: pathogens
associated with medical progress. Clin Infect Dis. 1994;19:231.
[PubMed]
• Schlievert PM. Role of superantigens in human disease. J Infect Dis.
1993;167:997. [PubMed]
• Skinner GRB, Ahmad, A: Staphylococcal vaccines - present status and
future prospects. p. 537. In Mollby R, Flock JI, Nord CE, Christensson B
(eds): Staphylococci and Staphylococcal Infections. Zbl. Bakt. Suppl.
26, Fischer Verlag, Stuttgart, 1994 .
• Tenover F, Arbeit R, Archer G. et al. Comparison of traditional and
molecular methods of typing isolates of Staphylococcus aureus. J Clin
Microbiol. 1994;32:407. [PMC free article] [PubMed]
Editor's Notes
Mordant is the substance used to fix dye
Pyomyositis, also known as tropical pyomyositis or myositis tropicans, is a bacterial infection of the skeletal muscles which results in a pus-filled abscess
Rheumatic heart disease is cardiac inflammation and scarring triggered by an autoimmune reaction to infection with group A streptococc
Scarlet fever is caused by an infection with group A streptococcus bacteria (usually strep throat). ... Usually, if a child has this scarlet rash and other symptoms of strep throat, it can be treated with antibioticscarlet fever can occur as a result of a group A Streptococcus (group A strep) infection. The signs and symptoms include a sore throat, fever, headaches, swollen ..
Rheumatic fever is an inflammatory disease that can develop as a complication of inadequately treated strep throat or scarlet fever. Rheumatic fever can cause permanent damage to the heart, including damaged heart valves and heart failure
2)a hyaluronic acid capsule that inhibits phagocytosis
Diverticulosis happens when pouches (diverticula ) form in the wall of the colon get inflamed or infected, it is called diverticulitis. Diverticulitis can be very painful.
Diverticulosis happens when pouches (diverticula ) form in the wall of the colon get inflamed or infected, it is called diverticulitis. Diverticulitis can be very painful.
Diverticulosis happens when pouches (diverticula ) form in the wall of the colon get inflamed or infected, it is called diverticulitis. Diverticulitis can be very painful.