The document discusses various types of bacteria and their classification. It describes important pathogenic bacteria such as Staphylococcus, Streptococcus, Pneumococcus, Clostridium, Mycobacterium, Neisseria, Haemophilus, Salmonella, Vibrio, Rickettsia, Chlamydia, Treponema, Klebsiella, Escherichia coli, Shigella, Pseudomonas, Enterobacteriaceae, Bacillus, and Actinomycetes. For each bacterium, it outlines the diseases they cause, virulence factors, and modes of transmission.

1. BACTERIOLOGY
DR. RINSA VAHEED
GLOBAL INSTITUTE OF PUBLIC HEALTH
16th March2022

2. CLASSIFICATION OF BACTERIA

5. BACTERIAL TOXINS
 Alter normal metabolism of host cells
 Often responsible for significant symptoms of
bacterial infections
 Very few toxins have been identified
 Exotoxins (secreted by the bacterium)
 Type III cytotoxins modulate intracellular target
 Other toxins work on the surface of host cells
 Pattern recognition system/ pore forming toxins /
cytotoxins( binds T cell receptor)

6. STAPHYLOCOCCUS
 Gram positive, Grape-like clusters
 Medically important species
 Staphylococcus aureus…causes pyogenic infection
 Staphylococcus epidermidis…..skin commensal
 Staphylococcus saprophyticus…..opportunistic pathogen
 Epidemiological importance
 Hospital cross infection
 More than 50% of hospital nursing staff
 Spread: direct contact, fomites, other vehicles
 Antibiotic resistant strains

7. STAPHYLOCOCCUS
 Colonize in nose, other mucus membrane and
skin of 30-40% of humans/ Carriers
 Causes focal abscess: Skin(boils), lungs, bones,
Kidney and heart
 General Feature: Secrete potent exotoxins
 Toxic Shock Syndrome ...TSST1
 Tampon Use
 Staphylococcal scalded skin syndrome
 Looks like skin has scalded or burned
 Food poisoning
 Develop in 30minutes to 8 hrs after consuming;

8.  Entering the body
 Do not penetrate deep tissue, Unless there
is cut or wound, Laceration, insect bite,
surgery, skin disease
 Area of infection remain localized. (Boil)
 Most local infection : collection of pus
(abscess), furuncle, carbuncle
 Spread to subcutaneous or sub mucosal tissue:
Cellulitis
 Cell for controlling infection: Nutrophils
 Host defense mechanism against
staphylococcus

9. VIRULENCE
FACTORS
1. Adherence factors / Adhesins- (MSCRAMMS)
1. The microbial surface component recognises
adhesive matrix molecules
2. Release of exotoxins
1. TSST
2. Alpha hemolysin

10. STREPTOCOCCUS
 Gram positive, arranged in
chains
 2Groups
 Group A
 Wide range of clinical
manifestations
 Group B
 Leading cause of neonatal
sepsis and meningitis

11. STREPTOCOCCUS
Distributed worldwide, found in skin and mucous membrane..20%of school aged children;
Community-acquired pneumonia
Asymptomatic
Spread: direct contact, respiratory droplets, person to person contact
Common infection in school children.. Pharyngitis or Strep throat....acute rheumatic fever (serious infection)
• Acute rheumatic fever(serious infection)… carditis...inflammation of heart (scarring of valves)
• Autoimmune disease: between strep A and antigen
Affect skin and soft tissue: Pyoderma
• Requires break in skin for bacteria to enter
Infection mostly remain localized, some can invade deeper tissue, causing life-threatening infections

12. VIRULENCE FACTOR
• Adhesin: Protein F
(fibronectin-binding protein)
• Protein G
• Exotoxins: Erythrogenic toxins,
Exotoxin A, Haemolysin

13. CORYNEBACTERIUM
 The most important member of the genus is
Corynebacterium diphtheriae
 A triple vaccine (DPT) is used for active immunization: The
vaccine contains diphtheria toxoid, tetanus toxoid and
pertussis vaccine.
 Pathogenicity: due to the production of a very powerful
exotoxin.
 Immunocompromised individuals.
 Commensal corynebacteria are normally present in the
throat, skin, conjunctiva and other areas.

16. PNEUMOCOCCUS
 Also called Streptococcus pneumoniae
 Gram positive,
 Its cocci in pair
 Most common cause of bacterial pneumonia acquired in
community
 Million death every year, throughout globe
 Infections
 Pneumonia, Bacteremia, Meningitis (in severe case)
 Spread: Person to person by respiratory droplets
 Initial colonization in nasopharynx and spread to lungs

18. VIRULENCE FACTOR
 Undergo classic struggle with phagocytes
 Thick capsule: enables resistance
 Host produce : C reactive protein binds and
activate complement
TREATMENT
 Revolutionized by Penicillin
 Resistance developed... harder to treat
 Vaccines

19. CLOSTRIDIUM
 Large gram positive anaerobic bacilli
 Causes
 Tetanus... Cl tetani
 Botulism.... Cl botulinum
 Antibiotic associated diarrhea... Cl difficile
 Gas gangrene (myonecrosis involving muscle) …..Cl
perfringens; Cl sporogenes ; Cl histolyticum
 Depending on exotoxins they secret A-G variety of
serotype
 Only A, B, E affects humans

20. CLOSTRIDIUM
 Cl tetani
 Pathogenesis: Tetanus toxin.... Spasticity of muscles
 Cl botulinum
 Pathogenesis: Botulinum toxin (Neurotoxin).... Flaccid paralysis
 Food born; Wound botulism, Infant botulism, Iatrogenic
 Cl perfringens
 Pathogenesis: Alpha toxins which destroys phospholipids...gas production
 Compromised blood supply....Myonecrosis

21. VIRULENCE FACTOR OF CL
BOTULINUM
All Neurotoxins (except C2) enters blood stream
Neuromuscular junction
Binds on neuron terminates
Prevent the release of acetyl choline
Inhibition of muscular contraction
Flaccid paralysis

22. MYCOBACTERIUM
 Acid fast bacilli
 Stained using Ziehl-Neelsen
 Three main groups
 Mycobacterium tuberculosis
 Tuberculosis
 Mycobacterium leprae
 Leprosy
 Non tuberculosis mycobacteria (NTM)
 Pulmonary disease

23. MYCOBACTERIUM TUBERCULOSIS
 Obligate aerobic bacilli....prefer oxygen
 Tuberculosis: World's most infectious killer
 Every year 10 million people fell ill
 Founder of bacteriology: Robert Koch
 Tubercle Bacillus, 24th March 1882
 Primary infection...lower lobes of lungs
 Reactivated infection.... upper lobes of lungs
 Spread: droplet spread
 Infects macrophages

24. MYCOBACTERIUM LEPRAE
 Discovered by Hansen, 1873
 Causes Leprosy or Hansen disease
 Affects : Superficial tissue of skin and peripheral nerve
 Incubation period 3-5 years
 Spread : direct contact, air droplets
 Symptoms:
 Numbness of feet (due to nerve damage)
 Thickness and discolouration of skin
 Loss of sensation of skin....( injury or loss of finger and
toes)

26.  Phagocytosis of mycobacterium,
 Bacteria grows and multiplies inside the cell
 Kills macrophage
 Fill bacteria in the lungs
 CD 4 T cells gets activated …(few weeks later)
 Releases interferon gamma
 Interferon gamma+ CD4 T cells + Macrophages …. Type 4 Hypersensitive
reaction
 Granuloma formation... Caseating necrosis... Ghon focus in the lungs...Ranke
complex(multiple complex with calcification)'
VIRULENCE FACTORS

27. NEISSERIA
 Gram negative, aerobic, non-motile,
non-sporing diplococci (arranged in
pairs)
 Pathogenic species if Neisseria
 N. meningitidis
 N. gonorrhoeae
 Commensal of nasopharynx
 Spread: direct contact, droplet spread,

28. TYPES OF NEISSERIA
Neisseria Meningitis
Meningitis common in early childhood (3mnths- 5 years)
• Hemorrhagic skin rash
• Sever condition: Waterhouse-Friedrichson syndrome..(purpuric rash, shock,
Neisseria gonorrhoeae
Characterized by :
• Acute urethritis or dysuria.. In male
• Mucopurulent cervicitis, Vulvovaginitis... in female

29. VIRULENCE
FACTORS
 Capsular polysaccharide...protects phagocytosis
 Serogroups A,B,C,Y....accounts invasion of disease
 Lipopolysaccharide and endotoxins
 Endotoxin bind to CD4 cells of host molecule...
release of inflammatory mediators
 Produce endothelial injury... causes shock and
myocardial dysfunction
 IgA proteases... cleaves mucosal igA

30. HAEMOPHILUS
 Gram negative, oxidase positive, pleomorphic bacilli,
requires special growth factors X and V
 H. influenza: most pathogenic... pneumonia and
meningitis in children
 Spread: person to person, direct contact, droplet
spread

31. CENTRAL NERVOUS SYSTEM INFECTION
 Pyogenic meningitis...in children less then 2 years
 Subdural effusion...common complication; characterized
by seizures
 Epiglottitis...older children 2-7years
 Pneumonia in infants......pleural involvement
VIRULENCE FACTOR
 Capsule polysaccharide
 Endotoxin... induce host inflammatory response
 Outer member proteins
 IgA 1 proteases... inactivate IgA1 in mucosal surface
 Pili and other adhesion proteins.... helps in colonization on
epithelial surface

32. LEPTOSPIRA
 Comes under the classification of spirochaetes
 Delicate, Helical rot like structure, motile with endo flagella
 Important species: Leptospira interrogans and Leptospira biflexa
 Spread : Zoonotic disease (from animal to human)
 Leptospirosis... sever form called Weil's disease
 Contaminated water containing urine of animals...(through cut or abrasions/ mucosa)

34. SALMONELLA
 Rod-shaped Gram-negative bacteria of the family Enterobacteriaceae.
 Salmonella Typhi
 Causes: Typhoid fever / Enteric fever
 Constipation... following indigestion; Rose spot rashes all over the body; Diarrhea
 Salmonella paratyphi
 Parathyphoid fever...(milder infection)
 Spread : Feco-oral route
 Salmonella Enteriditis
 Watery diarrhea
 Spread : Human to animal

36. VIRULENCE
FACTORS
 Vi Capsule... survive phogocytosis
 Endotoxins... systematic manifestation of
salmonellosis
 Fimbriae....mediates binding of bacteria to terminal
part of small intestine
 Acid tolerance response (ATR) gene... produced
from stomach acid and acid PH of phagosome
 Catalase and Superoxide dismutase... protect from
intercellular killing in macrophage

37. VIBRIO
 Short, Curved, Cylindrical
gram-negative bacteria
 Important species: Vibrio
Cholerae
 John Snow: Father of
epidemiology
 Conducted study on cholera
outbreak in mid 1800's
 V. cholerae
 Spread : Contaminated
food and water; Poor
hygiene
 Watery stool,

38. RICKETTSIA
 Nonmotile, gram-negative, non-spore-forming,
highly pleomorphic bacteria
 Caused by Obligate intracellular parasite
 Fleas, lice, ticks and mites
 Rickettsial pox
 Maculopapular rash
 No human to human transmission

39. VIRULANCE
FACTOR

40. CHLAMYDIA
 Small oligate intrecellular parasite
 Gram negative
 Cell wall not not well charcterized
 Inner and outer membrane
 Important species
 C . Trachomatis
 Conjuctivities
 Pneumonia in infants
 Urogenital infections

41. VIRULENCE
FACTOR
 Infects epithelial cells/ Macrophages
 Down regulation of class IMHC
 Lymphoid follicle formation
 Fibrosis
 Disease result from destruction of cells and host
immune response

42. TREPONEMA
PALLADIUM

43. TREPONEMA

44. VIRULENECE
FACTOR

45. KLEBSIELLA
 Gram positive
 Non Motile
 Lactose Fermenting
 Rod shaped Bacteria
 Facultative Anaerobes
 Act as opportunistic human
pathogen

46. VIRULENCE
FACTOR

47. ESCHERIS COLI
 E.coli bacteria discovered by Escherichia .
 Detection of E.coli in water indicates
pollution and contamination and these are main
source of infection
 Produce infection in Humans and Animals
 Morphology : Gram -ve , straight rods appear
in pairs,
 Clasiification of E.coli
 Enteropathogenic
 Enterotoxigenic
 Enteroinvasive
 Enterohemorrhagic
 Enteroaggressive
 It produces Exotoxins : Haemolysin , Enterotoxin
 These exotoxins are the main reason for
diarrheas

48. MAIN INFECTION CAUSED
BY E.COLI
Pyogenic Infection
Intraabdominal Infection
Peritonitis Abcess
Speticimia
Produce Drug resistance infection
Neonatal meningitis
Gastroenteritis

49. VIRULENECE
FACTOR
 Surface Antigen Toxin
 O Endotoxic Activity
 K protects against phagocytosis
 Fimbria which promote virulence

50. SHIGELLA
INFECTION

52. SHIGELLA
 An Enterobacteriaceae
 Gram negative bacilli
 Mostly non-motile and Non-
sporing
 They are aerobic sometimes
facultative anaerobic
 Incubation period is about 12-
48 hours may vary between 1-
7 days

53. VIRULENCE
FACTORS

54. PSEUDOMONAS
 A large group of aerobic
,non sporing gram negative
bacteria
 Found natural water soil
moist environment
 Opportunistic Pathogen

55. VIRULENCE
FACTOR

56. ENTEROBACTERIA
 Aerobic and facultative anaerobic Gram negative enteric
bacilli.
 The most common members are Escherichia, Salmonella,
Shigella, Klebsiella,
 Escherichia coli forms a part of normal intestinal flora of man
and animal.
 There are four major types of clinical syndromes which are
caused by Escherichia coli:
1. Urinary tract infection
2. Diarrhoea
3. Pyogenic infections
4. Septicaemia

57. BACILLUS
 Members of the genus Bacillus are ubiquitous, present in soil,
dust, air and water and are frequently isolated as
contaminants in bacteriological culture media.
 They are sporogenous, rod shaped, aerobic, Gram positive
bacteria.
 Bacillus anthracis, the causative agent of anthrax, is the most
important pathogen of the group.
 Bacillus cereus can cause food poisoning usually associated
with fried rice from Chinese restaurants. It produces
enterotoxin. The diseases is mild and self-limiting, requiring
no specific treatment.

58. ACTINOMYCETES
 Actinomycetes are Gram positive,
filamentous bacteria intermediate in
properties between true bacteria and
fungi.
 The family Actinomycetes contains
three major medically important
genera, Actinomyces, Nocardia and
Actinomadura.
 The Actinomyces causes a disease
known as actinomycosis. The disease
occurs in four clinical forms:
cervicofacial, thoracic, abdominal and
pelvic actinomyces.

59. YERSINIA
 Yersiniae are Gram negative, short bacilli showing
bipolar staining (safety pin appearance) with
methylene blue.
 They are primary pathogens of rodents and men
are accidentally infected.
 The genus yersinia contains three medically
important species
1. Yersenia pestis - the caustive agent of
plague
2. Yersinia pseudotuberculosis - a primary
pathogen of rodents
3. Yersinia entercolitica - causes human
diarrhoeal diseases
 In human, plague occurs in three forms: bubonic,
pneumonic and septicaemic.

60. MYCOPLASMA
 Mycoplasmas differ from other bacteria in that they lack a rigid cell
wall. Due to lack of rigid cell wall, they are extremely plemorphic.
 They are resistant to cell wall antibiotics such as penicillins and
cephalosporins. This again due to absence of cell wall.
 Mycoplasma causes two types of diseases in man – pneumonia and
genital infections.
 Mycoplasma pneumoniae causes primary atypical pneumonia.
 Mycoplasma hominis causes non-gonococcal urethritis (NGU).

61. LEGIONELLA
 Legionella pneumophila is the most important
species of the genus Legionella.
 The natural habitat of L. pneumophila is water.
 The organisms have been isolated from cooling
towers, air conditioning systems, showers and
respiratory ventilators.
 These sources facilitate transmission of the organism
to the human respiratory tract by generating
infectious aerosols.
 Legionella infection may occur in two main forms-
Legionnaire's disease and Pontaic fever, together
known as legionellosis.

62. BORDETELLA
 Three important species of Bordetella include Bordetella
pertussis, Bordetella parapertussis and Bordetella
bronchiseptica.
 Bordetella pertussis is the main causative agent of whooping
cough.
 Pertussis toxin is exotoxin produced by B. pertussis.
 Pertussis vaccine is generally administered in combination
with diphtheria toxoid and tetanus toxoid (DPT). B. pertussis
acts as an adjuvant for the toxoids producing better antibody
response. Vaccine is very effective for prophylaxis.

63. THANK YOU