The document discusses four types of microorganisms that are medically important: bacteria, protozoa, fungi, and viruses. It provides details on the structure, size, classification, and some diseases caused by each type. For bacteria, the document describes bacterial cell structure, reproduction, resistance to antibiotics, and classification. It also discusses some pathogenic organisms that resemble bacteria, including Chlamydia, Mycoplasma, and Acid-fast bacilli.

1. ‫الرحيم‬ ‫الرحمن‬ ‫ال‬ ‫بسم‬

2.  The study of living organisms which are very small and
simple in structure (microorganisms)
 There are 4 kinds of microorganisms of medical
importance :
Bacteria , Protozoa , Fungi, and viruses.

3.  Unicellular microorganism.
 1/100 to 1/1000 mm in diameter ,
 Has a very primitive cell with primitive
nuclear material
 Cytoplasm containing ribosomes and cell
wall.

4.  Unicellular,
 1/10 to 1/100 mm in diameter(larger than bacteria)
 More complicated than bacteria , with well defined
nucleus ,
 Cytoplasm containing ribosomes and mitochondria.
 Some protozoa can cause diseases such as
toxoplasmosis , malaria, and amoebic dysentery.

5. Resemble primitive plants ,
They have a structure which is
basically similar to protozoa
Some fungi can cause diseases
such as candidasis

6.  The smallest and simplest of all microorganisms
1/100,000 of mm in diameter only can be seen by
electron microscopy.
 Viruses are not proper cells ,they consists of strands of
nucleic acid surrounded by a a protective protein coating.
 Viruses cannot multiply by themselves , they reproduce
by invading a living cell and facing it to manufacture new
virus particles.
 Some viruses can cause diseases such as influenza
,common cold , herps ,and poliomyelitis.

7. Bacteria Protozoa Fungi viruses
Structure Unicellular Unicellular Resemble
primitive
plants
are not
proper
cells
Size 1/100to 1/1000
mm
1/10to 1/100
mm
1/100000
mm
classificati
on
Primitive cell
(prokaryotic(
Eukarytic eukaryotik
Nucleus Primitive
nuclear
material
Well defined Well defined No
cytoplasm Containing
ribosomes and
cell wall
Containing
ribosomes and
mitochondria
Ribosomes
and
mitochondria
no

8. Bacterial cell

9. Structure of bacterial cell
 Cell wall :
It is the outermost layer of the bacterial cell.
it is rigid to protect the bacterial cell from the environment , the
rigidity is due to the presence of chemical substance called
Peptidoglycan and this substance determine whether the
bacteria will be stain or not by Gram stain
 Cell membrane (cytoplasmic membrane ):
It is located directly under the cell wall
It is permeable to allow nutrients to enter and wastes to leave
the bacterial cell , and to maintain water balance of the cell

10.  Cytoplasm :
it is the soft gel that contain the different organs of the bacterial cell
 Nuclear material :
it is formed of DNA which is responsible for carrying the genetic
information of the bacterial cell
 Ribosome:
They contain RNA
They are responsible for manufacturing proteins and enzymes which
are essential for cell growth and reproduction
 Plasmid :
They are formed of DNA and play an imporant role in transferring the
resistance ability from one bacterium to another
Structure of bacterial cell

11. Other structure
 Pili:
Delicate projection help the bacterial cell to attach to another living
cell and transfer of genetic material from one cell to the other
 Flagella
long thread help the bacterial cell to propel with whipping
movement
 Fimbriae
Shorter thinner and more numerous than flagella , they help the
cell to attach to surface
 Capsules :
Protective coating around the cell wall
 Spores :
Version of cell which are highly resistant to atmospheric

12. Bacterial Reproduction:
 There are 2 method of bacterial reproduction :
1- Asexual reproduction (simple binnary fission)
more common
2- Seuxal reproduction (conjugation ) via plasmid
transfer less common

13. Bacterial resistance:
 There are 2 types of bacterial resistance to
antibacterial agents :
A-A- natural resistance :natural resistance :
some bacteria are naturally resistant to particular
antibiotics irrespective of previous contact with that
antibiotic .
This is a result of specific biochemistry or anatomy
of the cell which renders it insensitive to that
antibiotic
(e.g most of gram –ve bacteria are resistant to
penicillin –G)

14. Bacterial resistance:
 Acquired resistance :
This arises when bacteria were susceptible to an antibiotic
and after exposure to that antibiotic become unsusceptible
may develop by one of the following ways :
1- general mutation :
Occasionally during bacterial reproduction ,DNA
May by imperfectly replaced “mutation “ . Mutant daughter
cell become more resistant to some types of antibiotics
2- Transfer of resistance by plasmid :
plasmid is a fragment of DNA which float in the cytoplasm
Plasmid can carry various kind of genetic information
including information of antibiotic resistance (R-plasmid )

15.  R-plasmid can be transmitted from one
cell to another by one of 2 methods:
A- Conjugation:
Transfer of R-plasmid
During conjugation
between cells
B-Bacteriophage
It is a virus which parasites on
bacteria and during its reproduction it
makes use of bacterial cell
components including R-plasmid .
When the offspring bacteriphages
attack other bacterial cell , they
transfer R-plasmid to their new host
which they become resistance

16. Mechanism of resistant to Antibiotics:
1- production of inhibiting enzymes
2- changing metabolic pathways:
Some bacteria develop resistance to sulphonamides by
increasing their production
of PABA so much that the antibiotic by
fail to compete for the enzyme which
utilize this substance
3- Altering cell membrane permeability :
antibiotic will be unable to introduce into the cell to
exert its function (e.g. pseudomonas )

17. Bacterial classificationBacterial classification
I-According to habitat:
1- Saprophytes: they are harmless , they live in water
2-Parasites :they live only in living bodies (host), they may be
harmless (commensals) or harmful (pathogens )
II-According to shape:
1- Cocci: rounded in shape , they are arranged in pairs
(diplococci), chains (streptococci) or clusters (staphylococci)
2-Bacilli: Rod in shape , they are arranged in pairs or chain
3-spirochaetes : Spiral in shape
4- Vibrio: Comma- shaped .

18. III-According to Gram stain:
Gram stain is to used stain bacteria and according to their
ability to retain the stain , bacteria are classified into
gram +ve and gram –ve .
The thickness of the peptidoglycan layer is determining
whether bacteria are gm +ve or gm –ve (gm +ve
bacteria have a thicker layer than gm –ve ones )
IV- According to oxygen requirement:
-Aerobic: survive only in presence of oxygen
-Anaerobic: survive only in absence of oxygen
-Facultative: can survive in presence or absence of
oxygen
Bacterial classificationBacterial classification

19. Some pathogenic 0rganisms which
resemble bacteria
 Chlamydia : organisms which have similarities to both bacteria and
viruses.
► like bacteria :
they contain both DNA and RNA and can be seen through an
optical microscope .
► like viruses :
They do not have well defined cell walls
Chlamydia can only mulitiply inside living cells (obligatory intracellular
parasites)
Traditional methods for culturing bacteria are not successful with
chlamydia but like viruses ,they can be cultured on special disk.
Species : chlamydia ( trachomatis – genitalis – pneumonia )
Diseases : non specific urethritis – eye infections – pneumonia

20. Some pathogenic 0rganisms which
resemble bacteria
 Mycoplasmas :
Very small microorganisms , smaller than
bacteria , they don’t have a rigid cell wall and
can therefore exhibit a variety of shapes and
sizes .unlike chlamydia , mycoplasmas can
be cultured on artificial media enriched with
serum.
Species : M.( pneumoniae – hominis )
Diseases : mycoplasmal pneumonia – UTI –
peritonities – infections following abortion.

21. Some pathogenic 0rganisms which
resemble bacteria
 Acid fast bacilli :
Mycobacteria
Are slender rods which may be slightly curved .
They have waxy capsule which makes them
very resistant to physical and chemical attack
and prevents them taking up the gram stain.
Species : Mycobacterium tuberculosis
Diseases : Tuberculosis

22. Some pathogens of medical importance
 The classification of the following pathogens of
medical importance is based on their morphology,
staining characters, and oxygen tolerance
1-COCCi
Gram +ve cocci
Streptococcus spp(facultative)
Staphylococcus spp (Aerobic)
Gram –ve cocci
Nesseria spp (Aerobic)
Branhmella (Moraxella)spp
(Aerobic)

23. Gram + ve CocciGram + ve Cocci
SpeciesSpecies HabitatHabitat DiseasesDiseases
Streptococcus pyogens
)Beta –hemolytic streptococci(
Mucous membrane of nose
and throat of infected person
•URT
•Scarlet fever
•Skin and wound infection
Streptococcus pneumoniae
)Pneumococci(
Common in URT •Pneumonia-Otitis media
•Meningitis -Endocarditis
Streptococcus viridans
)Alfa-hamaemolytic streptococci(
Commensal in mouth •Dental abscess
•Subacute bacterial
endocarditis
Streptococcus faecalis
)Enterococci(
Common in large intestine •Urinary tract infection
•Cholecystitis –Peritioitis
Staphococcous aureus Common skin and URT •Skin &wound infection
•Pneumonia-otitia media
•Osteomyelitis
Staphococcous albus
)S.epidermidis(
Common in skin )grows in
sweet gland(
•Skin &wound infection
•Catheter infection

24. Gram – ve cocci
•
•Neissria
Gonorrhoea
)Gonococci(
Mucous membrane
of genito –urinary
tract
•Gonorrhoea –
PIDs
•Eye infection
•Neissria
meningitides
)meningococci(
Common in nose &
throatURTI & LRT
Meningitis &
septicemia
Branhamella
catarrhalis
Upper respiratory
tract
URTI
LRTI

25. Gram +veBacilli Gram -veBacilli
Bacilli
Aerobic and
Facultative
Anaerobic Aerobic and
facultative
Anaerobic
-Bacillus spp
Corynebacterium spp
-Listeria spp
clostridium spp -haemophillus spp
-Bordtella spp
-Brucella spp
Enterobacteriacae
-E coli
-shigella spp
-Proteus spp
_Serratia spp
-Klebsiella spp
-Salmonella spp
-Others:
-Pseudomonas spp
Pseudomonas spp
-bacteroides spp

26. Gram –ve bacilliGram –ve bacilli
Species Habitat Diseases
Hemophilus influenza Common in respiratory tract URT & LRT
Conjunctivitis meningitis
Haemophilus ducreyi Genitalia Chancroid
Haemophilus aegypticus URT of infected person Muco-purulent conjunctivitis
Brodetella pertussis URT of infected person Pertussis )whooping cough(
Echerichia coli Commensal in large intestine Urinary tract infection
Gastro-enteritis
Peritonitis &Septicemia
Kbsiella pneumonia
)friedlander,s bacillus(
Respiratory tract friedlander,s pneumonia
)hospital acquired pneumonia(
Proteus mirabilis Commensal in large intestine Urinary tract infection
Serratia marcescens GIT of man and animals UTI & RTI
Spticaemia & Osteomylitis
Shigella dysenteriae Faceas of infected person Bacillary dysentery
Pseudomonas aeruginosa Commensal in large bowel Wound &burn infect
Urinary tract infection
Spticaemia diabetic foot
ca[pylobacter jejuni
Helicobacter jejuni
Campylobacter pyloridis
Small intestine of infected person
Gastric mucosa
Gastro-enteritis
Gastritis & peptic ulcer
Salmonella
Thypi
Pratypri

Small bowel of infected person
Small bowel o infected person
Typhoid fever
Paratyphoid fever

27. Legionella pneumophila Stagnant water&AC Legionnaire,s diseases
Bacteroides fragilis Commensal in large
intestine , mouth, vagina
Wound infection
Peritonitis
Septicaemia
M coacterium tuberculosis Human lungs T.B
Vibrio cholerae Faeces of infected person Cholera
Spirochaetes)treponema
pallidum(
Gential tract of infected
person
syphilis
Toxiplasma gondii Cats toxolasmosis
Rickettsia prowazekii Blood ofinfected person Thypus fever
Clamydia
Trachomatis
Pneumonia
vaginalis
Gential tract ofinfected
person
Resp.tratct of infected person
Eye infection -- urethritis
Pneumonia )LRTI(- URTI
Mucoplasm
Pneumonia
Hominis
Commensal in resp. tract
Commensal in G.U tract
Pneumonial )LRTI(-URTI
Gentio-urinary tract
infection

28. Gram +ve BacilliGram +ve Bacilli
 Bacillus spp )bacillus antracis anthrax(:gram +ve
spore forming bacilli
 Corynebacterium spp )corynebacterium
diphtheriae;Diptheria(: gram +ve non spore forming
bacilli
 Listeria spp )listeria monocytogenes ;menio-
encephalitis
 Clostriduim spp :anaerobic spore forming bacteria
produce fetal toxins
 Clostridium tetani :tetanus
 Clostridium welchii :gas gangrene

29. Common pathogens responsible for urinaryCommon pathogens responsible for urinary
tract infectiontract infection
 Cocci
 Gram +ve cocci :
Strept.faecalis: commensal in large intestine
Staph Epidermidis: commensal in skin –)catheter infection (
 Gram –ve cocci
Nesseria gonorrhoea )gonorhroea & PID(
 Bacilli
Gram –ve bacilli
Escherichia coli : commensal in large intestine
Proteus mirabilis : commensal in large intestine
Psedomonas aeruginosa : commensal in large bowel
Serratia marcescenc: GIT of man & animals
 Atypical pathogens :
Clamydia
Mycoplasm hominis: gento urinary tract infection
Ureaplasm urealyticum: pelvic inflammatory diseases

30. Common pathogens responsible for respiratoryCommon pathogens responsible for respiratory
tract infectiontract infection
 Cocci
 Gram +ve cocci
*streptococcus pyogenes
*streptococcus pneumoniae )pneumococci(
*streptococcus aureus
*streptococcus Viridans
 Gram –ve cocci
*Branhamella catarhalis )moraxella catarrhalis (
 Atypical pathogens :
*Mycoplasm pneumoniae

31. Some pathogenic organisms which resemble bacteriaSome pathogenic organisms which resemble bacteria::
 Chlamydia:
They are organisms which have similarities to both bacteria
&viruses
Like bacteria they contain both DNA &RNA
However, like viruses they don’t have well –defined cell wall .
Chlamydia can only multiply inside living cell and therfore
sometimes described as obligatory intracellular parasites
Chlamydia , like viruses can be cultured on special disk
SpeciesSpecies NotableNotable
featuresfeatures
HabitatHabitat DiseasesDiseases
Caused in manCaused in man
Chlamydia
)Trachomatis(
Genitalis(
Pneumonia(
Can only
Multiply
Inside living cells
Gential tract
of infected
person
Non-specific urethritis
Lymphogranuloma
venereum , eye
infections, pneumonia
especially in neonates

32. MycoplasmasMycoplasmas
 Are very small Microorganism than bacteria ,they pass through
filters which retain bacteria they do not have a rigid cell wall and can
therefore , exhibit a variety of shapes and sizes
 Mycoplasm can be cultured on artificial media enriched with serum
speciesspecies Notable featuresNotable features habitathabitat Disease caused inDisease caused in
manman
Mycoplasm
pneumoniae
Able to survive and
multiply inside human
cell
Commensal in the
genitourinary tract
Mycoplasmal
pneumonia tonsllitis
Ureaplasm
urealyticum
Able to survive and
multiply inside human
cell
COMMENSAL IN
THE
GENITOURINARY
tract
Pelvic inflammatory
diseases
MYCOPLASMA
HOMINIS
Able to survive and
multiply inside human
cell
GENITOURINARY
tract
Urinary tract
infection,bartholinitis,
salpingitis ,
peritonitis< infection

33. Acid fast bacilliAcid fast bacilli::
Mycobacterium are slender rods which may be slightly curved , they
have waxy capsule which makes them very resistant to physical and
chemical attack and prevent them taking up gram stain
SpeciesSpecies Notable featuresNotable features HabitatHabitat Diseases caused inDiseases caused in
manman
Mycobacteriu
m tubercluosis
Also know as the
tubercle bacillus
Human
lungs
tuberculosis
Mycobacteriu
m avium
Mycobacteriu
m
Intracellulare
These two species
are so similar that
they are often
referred to as the
mycobacterium
avium –intracelluare
complex
Widely
distributed
in soil
water ,
dust, etc
Produce
diseases in
birds and
animals
Infection of the lung,
lymph nodes , skin,
bones , soft tissue
and geiti-urinary tract
Seer and widespread
infection may occur in
immunocompromised
patient as AIDS

34.  Upper respiratory tract infections
(URTI) :
Pharyngitis
Tonsillitis
Sinusitis
Otitis media
Diphtheria
Infectious diseases

35. Infectious diseases
 Lower respiratory tract
infection (LRTI) :
 Acute bronchitis
 Pneumonia ( a typical)
 Pneumonia ( typical)
 Pertussis ( Whooping
cough)

36. Summary of URTI & LRTI
Disease Causative organism Clinical
features
Treatment
Pharingitis
/tonsilitis
Strep.pyrogens
Chlamydia trachomatis
Mycoplasma pneumoniae
Inflamed throat,
swollen tonsils, fever
Macrolids , penicillins ,
cephalosporins
sinusitis Streptococcus pneumoniae,
Haemophilus influenzae
anaerobes
Facial pain
Nasal discharge
Penicillins , tetracyclines ,
macrolides
Otitis media
Diphtheria
Acute bronchitis
Pnumonia
pertussis

37. Urinary tract infectionsUrinary tract infections
 Definitions
 Bacteruria : bacteria in voided urine
 Dysuria : discomfort / pain during urination
 Pyuria : pus in urine
 Hematuria : blood in urine
 Urithritis : infection of the urethra
 Cystitis : infection of the bladder
 Pyelonephritis : infection of the kidney.

38. Urinary system

39. Urinary tract infectionsUrinary tract infections
 Definition :
It’s a common infection that usually occures when
bacteria enter the opening of the urethra and multiply
in the urinary tract.
 Classification of UTI anatomical :
Lower Upper
Cystitis acute or chronic pyelonephritis
Urithritis renal or perirenal abscess
prostatitis

40. Etiologic agents of UTIsEtiologic agents of UTIs
 Uncomplicated : usually gm -ve bacteria that
are part of the intestinal flora .
80 – 90 % due to E.coli
10 – 20 % due to Proteus , Klebsiella , Enterococcus
, staph.saprophyticus.
 Complicated :mostly gm –ve but gm +ve and
fungi also.
10 – 20 % Due to E.coli
80 – 90 % due to Proteus , Klebsiella , Enterococcus
, Serratia , Pseudomonas , enterobacter ,
Staph.aureeus , and candidia

41. Signs and symptoms of UTIsSigns and symptoms of UTIs
 Dysuria ( burning pain upon urination)
 Frequency
 Urgency
 Voiding in small amounts
 Inability to void
 Incomplete emptying of bladder
 Low back suprapubic pain

42. Treatment of UTIs
 Antibiotics
 Analgesics
 Increase fluids
 Repeat urine culture and sensitivity after
antibiotics are finished.

43. Chemotherapy of UT infections
 Sulfonamides :
In combinations with trimethoprim often used in
UTIs , Otitis , Bronchitis , Sinusitis
Several drug resistance cases have restricted
their use
 The Quinolone antibiotics :
Wide spectrum antimicrobial agents
Successfully used in the treatment of UTI ,
prostatitis , STDs , bacterial diarrhea .
Not recommended in children or pregnancy.

44. Thank you and good luckThank you and good luck