. .... ... .. . ...

1. Lecture Three: Microbiology
Bacteriology

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.

4. Gram staining

5. After staining
• Bacteria can be grouped into
• Gram positive
• Gram negative.

7. GRAM POSITIVES
• GRAM POSITIVE COCCI
• GRAM POSITIVE RODS

8. Gram positive bacteria
1) Gram positive
cocci
A)Staphylococcus
Staph. Aureus
Staph.
Epidermidis
Staph.
saprophyticus
B) Streptococcus
Strep. Pyogenes
Strep. Agalactiae
• Strep.pneumonia
• Strep Viridans
C) Enterococci

9. Gram positive bacteria
2. Bacilli (rod shaped)
• a) Aerobic
• Corynebacterium
• Listeria
• b) Anaerobic
• Clostridium
• Actinomyces

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,.

11. Grapes; FRUITS

12. STAP

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.

16. Antibiotics used in the management of
staphylococcal infections
• Cefazolin
• Ceftaroline
• Cefuroxime
• Clindamycin
• Dalbavancin
• Daptomycin
• Dicloxacillin
• Doxycycline
• Linezolid
• Minocycline
• Nafcillin
• Oritavancin
• Quinupristin/dalfopri
stin
• Tedizolid
• Telavancin
• Tigecycline

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.

21. Gram positive bacteria cocci
1. staphylococcus
S saprophiticus causes urinary tract
infections.

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

23. Gram positive bacteria cocci
1. staphylococcus
S. saprophiticus causes urinary tract
infections.

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.

25. Image of streptococcus

26. Gram positive bacteria cocci
2. Streptococcus
introduction
Diseases attributable to streptococci
Scarlet fever
Rheumatic heart disease
Glomerulonephritis
Pneumonia

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.

34. Streptococcus agalactiae,

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.

38. Gram positive bacteria cocci
2. Streptococcus
• Treatment of
streptococcus
• Amoxicillin
• Azithromycin
• Cephalosporins
• Vancomycin
• Penicillin
• Ginfection
• Ampicillin
• Vancomycin
• Clindamycin:
• Cefazolin
• Telavancin:

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%)

40. Gram positive bacteria cocci
3. Enterococci
• infections caused
includueby Enterococcus include
• urinary tract infections
• Bacteremia
• Endocarditis
• Diverticulitis
• meningitis

41. Gram positive bacteria cocci
3. Enterococci
• Antibiotics
• Ceftaroline
• Ertapenem
• Ampicillin
• Cefepime
• Ceftriaxone

42. Gram positive bacteria cocci
3. Enterococci
• Treatment of enterococci
• Ampicillin,
• Penicillin
• Vancomycin.
• nitrofurantoin

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.

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]