1- Spore-Forming Gram-Positive Bacilli: A- Strict aerobic

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1- Spore-Forming Gram-Positive Bacilli A-
Strict aerobic Genus Bacillus.B- Strict
anaerobic Genus Clostridium.
Gram Positive Bacteria
Bacillus species
Spore- forming gram positive strict aerobic
capsulated bacilli, 1x3-4 u size, arranged in
long chains spores may central, subterminal or
terminal, depending on the species. Most members
are saprophytic prevelent in soil, water, air and
vegetation such B. cereus, and B. subtilius.
Some are insect pathogens.
B. anthracis
Cause the disease Anthrax in animals in which the
organism is transmitted through eating
vegetations containing the spores. Human is
infected through contact with animals or their
products.
Disease in Human
A- Cutaneous Anthrax(malignant pustule)
Generally occurs on exposed surfaces of the arms,
face and neck through wound contamination by the
spores of the organism. About 95 of the cases
with amortality rate 20 . B- Inhalation
Anthrax(wool sorter disease) About 5 of the
cases with 85-90 mortality.
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Robert Koch's original micrographs of the anthrax
bacillus
The anthrax bacillus, Bacillus anthracis, was the
first bacterium shown to be the cause of a
disease. In 1877, Robert Koch grew the organism
in pure culture, demonstrated its ability to form
endospores, and produced experimental anthrax by
injecting it into animals.
Robert Koch's original micrographs of the anthrax
bacillus
Robert Koch's original micrographs of the anthrax
bacillus
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Bacillus anthracis. Gram stain. The cells have
characteristic squared ends. The endospores are
ellipsoidal shaped and located centrally in the
sporangium. The spores are highly refractile to
light and resistant to staining.
Bacillus cereus
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C- Gastrointestinal Anthrax Is very
rare.Laboratory DiagnosesSpecimen Fluid, pus,
blood, sputum.Gram stain.Culture on blood
agar.Treatment Penicillin.
B. cereus
Cause food poisoning Two types 1- Emitic type
associated with fried rice. 2- Diarrheal type
associated with meat dishes and sauces
Clostridium Species
Large anaerobic gram positive spore forming
motile rods. Many decompose protein or form
toxins and some do both. Their natural habitat
is the soil or the intestinal tract of human and
animals, where they live as saprophytes. Among
the pathogens are the organisms causing botulism,
tetanus, gas gangrene, and pseudomembranous
colitis.
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Morphology and Identification of Clostridium
Species
Spores of clostridia are usually wider than the
diameter of the rods in which they are formed. In
most species, the spores are located centrally,
subterminally or terminally. Most species of
Clostridia are motile with peritrichous
flagella. Culture Clostridia are anaerobes and
grow under anaerobic conditions. Few are
aerotolerant. Anaerobic conditions can be
established by 1- Agar plates or culture tubes
incubated in anaerobic jar(Gaspack jar). 2-
Fluid media in deep tubes containing either fresh
animal tissue(chopped cooked medium) or o.1
agar and a reducing agent(fluid
thioglycolate). Colony Forms Growth
Characteristics.
Clostridium botulinum
Causes botulism, found in soil and occasionally
in animal feces. Toxins Seven varieties(A-G).
Types A B and occasionally F cause human
illness.
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PathogenesisClinical Finding Symptoms begin
18-24 hours after ingestion of the toxic food.
GI symptoms are not regularly prominent. No
fever, with visual disturbances, inability to
swallow and speech difficulty, paralysis and
death due torespiratory paralysis or cardiac
arrest.Diagnostic Laboratory TestsTreatment
Clostridium tetani
Causes Tetanus, worldwide in distribution in the
soil,and in the feces of horses and other
animals. Toxins Tetanospasmin Pathogenesis
Wound contamination, not an invasive organism.
The toxins released from vegetative cells reaches
the CNS and rapidly becomes fixed to receptors in
the spinal cord and brain stem and exerts their
action. Clinical Findings Incubation period
4-5 days to many weeks. The disease is
chacterized by tonic contraction of voluntary
muscles. Diagnosis Prevention and Treatment
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Clostridia Invasive Infections
Many different- toxin producing clostridia can
produce invasive infections(including myonecrosis
and gas gangrene) if introduced into damaged
tissue. About 30 species of clostridia may
produce such an infection, but the most common in
invasive disease is C. perfringens(90). An
enterotoxin of C. perfringens is a common cause
of food poisoning. Toxins produce different
types of toxins and enzymes that result in
spreading infection. They have lethal,
necrotizing, and hemolytic properties.
Pathogenesis Wound contamination. Clinical
Findings Infection spreads in 1-3 days.
Crepitation in subcutaneous tissue and muscle,
fever, tissue necrosis, hemolytic anemia, severe
toxemia and death. Laboratory Diagnosis Treatment
Prevention and Control
Clostridium difficile
Pseudomembranous colitis(Antibiotic Associated
Diarrhea).
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The Genus ClostridiumLeft. Stained pus from a
mixed anaerobic infection. At least three
different clostridia are apparent. Right.
Electron micrograph of Clostridium tetani
C.perfringens
C. difficile
C. botulinum
C. tetani
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Non-Spore-Forming Gram-Positive
Bacilli Corynebacterium Propionibacterium Listeria
Erysiplothrix Actinomycetes
These are a diverse group of bacteria, many
members of which are normal flora of the skin and
mucous membranes.
Corynebacterium diphtheriae
Morphology and Identification Corynebacteria are
0.5-1u in diameter and several micrometers long..
Metachromatic granules(metaphosphate) are
irregularly distributed within the rods giving
them beaded appearance. The rods tend to be
parallel or at acute angles to one another.
Colonies on blood agar are small, granular and
gray and may have small zone of haemolysis. Four
biotypes Gravis, mitis,intermedius and
belfanti. Pathogenesis The disease Diphtheria is
caused by lysogenic C. diphtheriae(toxin
producer). It is a droplet infection in which
the organism pass through the nasopharynx .
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C. diphtheriae
Stained Corynebacterium cells. The "barred"
appearance is due to the presence of
polyphosphate inclusions called metachromatic
granules. Note also the characteristic
"Chinese-letter" arrangement of cells.
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PathologyPseudomembrane over the tonsils,
pharynx, larynxDamage by toxins to heart muscle,
liver, kidneys, and adrenals. Also nerve damage
resulting in paralysis of the soft palate, eye
muscles or extermities.Clinical FindingsFever,
sore throat, dyspnea because of the obstruction
caused by the membrane. Later ondifficulties
with vision, soeech, swallowing, or movement of
the arms or legs. Var gravis is more severe.
Symptoms ten to subside spontaneously.Laboratory
DiagnosesSpecimen Throat swabGram stainMedia
for Culture Blood agar, potassium tellurite,
Loefler slant.Toxigenicity test Invitro and
Invivo test.Treatment Antitoxin and
antibiotics(penicillin).Epidemiology, Prevention
and controlDPT Vaccine.
Listeria monocytogenes
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Morphology and Identification
Listeria monocytogenes
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Erysipelothrix rhusiopathiae
Causes erysipelas in animals specially swine.
Human is infected directly by contact. The
disease is called erysipeloid usually occurs on
the fingers.
Actinomycetes
Large diverse group of gram positive bacilli with
a tendency to form chains and filaments. Most
are saprophytes that live in the soil. Members
are responsible for three humen infections 1-
Actinomcosis Chronic suppurative granuolomatous
infection. Caused by Actinomyces israeli.
Cervicofacial, thoracic, and abdominal 2-
Nocardiosis Caused by Nocardia asteroides , gram
positive, weakly acid fast. Present as subacute
and chronic pulmonary infection that may
disseminate to other organs, usually the brain or
skin. ,3- Actinomycetoma Mycetoma(Madura foot)
is a localized slowly progressive , chronic
infection that begins in subcutaneous tissue and
spread to adjacent tissues. It is destructive
and often painless
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The Staphylococci
Gram positive cocci1 um in diameter arranged in
irregular clusters, single,pairs, chains,
tetrads, nonmotile, uncapsulated, non-spore
formers, facultative anaerobes, grow most rapidly
at 37c. They grow readily on many types of media
and active metabolically, fermenting
carbohydrates and produce pigment that range from
white to deep yellow. All staphylococci are
catalase positive. The genus Staphylococcus has
at least 30 species. The three main species of
clinical importance are Staphylococcus aureus,
Staphylococcus epidermidis and Staphylococcus
saprophyticus.
Staphylococcus aureus
Can produce disease both through their ability to
multiply and spread widely in tissues and through
their production of many intracellular
substances. Some are enzymes, others are
toxins. Catalase, Coagulase, hyaluronidase,
staphylokinase, exotoxins, leukocidin,
exfoliative toxin, toxic shock syndrome toxin,
entertoxins. Pathogenesis and pathology Clinical
findings Laboratory diagnosis Treatment
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Usually present as normal flora on the skin,
nonpathogenic.
Staphylococcus epidermidis
Staphylococcus saprophyticus

• Urinary tract infection specially in sexually
  active young women

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Gram stain of Staphylococcus aureus
    Negative tube coagulase test     Positive
tube coagulase test
Mannitol negative Mannitol positive
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Streptococci
Streptococci
Dividing Streptococci M protein
Impetigo Tonsillitis

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The Streptococci

• Morphology and Identification
• Individual cocci are spherical or ovoid arranged
  in chains and diploes, non-motile, some are
  capsulated, anaerobes, facultative anaerobes,
  non-spore formers. Some require 5-10 CO2 for
  growth. Streptoccci are alpha hemolytic, Bata
  hemolytic or nonhemolytic.
• Antigenic structure
• 1- Group specific cell wall antigen
  Carbohydrate present in the cell-wall of many
  streptococci and forms the basis of serological
  groupings( Lancefield groups A-H, K-U ).
• 2- M protein Major virulence factor of group A
  Streptococcus pyogenes.
• 3- T substance Has no relation to virulence.
• 4- Nucleoprotein Called P substances which
  probably make up most of the streptococcal cell
  body.
• Toxins and Enzymes
• A- Streptokinase(Fibrinolysin).
• B- Streptodornase.
• C- Hyaluronidase.
• D- Erythrogenic Toxins.
• E - Diphosphopyridine nucleotidase.
• F- Hemolysins
• S. pyogenes elaborates two hemolysins(streptolysin
  s) Streptolysin O (ASOT) and Streptolysin S(B
  hemolysis)

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Classification of Streptococci of Medical
Importance

• A- Streptococcus pyogenes( Group A B Hemolytic
  Streptococci).
• B- Streptococcus agalactiae These are group
  streptococci.
• C- Groups C and G.
• D- Enterococcus fecalis(E. faecum, E durans)
  Group D.
• E- Streptococcus bovis Nonenterococcal group D
  streptococci.
• F- Streptococcus anginosis.
• G- Group N Streptococci.
• H- Groups E,F,G, H and K-U Streptococci.
• I- Streptococcus pneumoniae.
• J- Viridans Strepococci (S. mitis, S. mutans,
  S. salivaris, S. sanguis).
• K- Nutritionally Variant Streptococci.
• L- Peptostreptococcus (Many Species).
• Pathogenesis and Clinical Findings
• Infections can be divided into several
  categories
• A- Diseases caused by S. pyogenes
• 1- Erysipelas
• 2- Cellulitis
• 3- Necrotizing fasciitis(streptococcal
  gangrene).
• 4- Puerperal fever.

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Beta hemolytic
Alpha haemolytic streptococci
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7- Streptococcal pyoderma8- Infective
endocarditis acute and subacute.9-
Streptococcal toxic shock syndrome10- Scarlet
fever.Poststreptococcal Diseases1- Rheumatic
Fever2- Acute Glomerulonephritis

• Laboratory Diagnosis
• !- Specimen
• 2- Smear
• 3- Culture
• 4- Antigen Detection Test
• 5- Serology
• Streptococcal pneumoniae
• Pathology and Clinical Findings
• Laboratory Diagnosis
• Treatment

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Gram Negative Bacteria
The Neisseriae

• Gram negative cocci usually in pairs, nonmotile,
  nonspore forming o.8u in diameter, facultative
  anaerobes, or aerobes. All neisseriae are
  oxidase positive.
• Nonpathogens
• N. flavescens, N. flava, N. subflave, N. sicca,
  N. lactamica.
• Two important pathogens
• N. gonorrhoeae(gonococcia)
• N. meningitidis(meningococcia)
• N. Gonorrhoeae
• Antigenic structure
• Pathogenesis and clinical findings
• Gonococci attack mucous membranes of the
  genitourinary tract, eye, rectum, and throat,
  producing acute suppuration that may lead to
  tissue invasion, this is followed by chronic
  inflammation and fibrosis.

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Disease in Males
Disease in Females
Disease of the Newborn
Ophthalmia neonatorum Diagnostic Laboratory
test 1- Specimen 2- Smear 3-
Culture Immunity Treatment Epidemiology
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N. meningitidis
Antigenic Structure Pathogenesis and Clinical
Findings Diagnostic Laboratory Tests 1-
Specimens 2- Smears 3- Culture 4-
Serology Immunity Treatment Epidemiology
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Enteric Gram Negative Rods
Family Enterobacteriaceae
Large heterogeneous group of gram negative rods
whose natural habitat is the intestinal tract of
humans and animals. Facultative anaerobes,
oxidase negative, ferment glucose with the
production of acid or acid and gas, reduce
nitrate to nitrite. Most are motile with
peritrichous flagella, some have a polysaccharide
capsule. According to lactose fermentation,
enterobacteriaceae are classified into 1- Rapid
lactose fermenters ferment lactose in 24
hours. Escherichia coli Klebsiella
pneumoniae Enterobacter aerogenes 2- Late
lactose fermenters ferment lactose in 48 hours
or do not ferment lactose. Edwardsella, Serratia,
Citrobacter, Arizona, Providencia, Erwinia. 3-
Non-lactose fermenters Shigella, Salmonella ,
Proteus
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Some enteric organisms are present as normal
flora in the intestinal tract of human and
animals causing infections in other tissues and
organs. Others are pathogens 1- E. coli
associated with diarrheal disease. 2-
Shigella. 3- Salmonella. Antigenic
Structure Enterobacteriaceae have a complex
antigenic structure. gt 150 different heat stable
somatic O Ag. gt 100 heat labile K (capsular )
Ag. gt 50 H (flagellar ) Ag. Bacteriocines Protein
antibiotics like substance produced by many gram
negative bacteria in which their production is
controlled by a plasmid. They are active against
strains of the same species and closely related
species but not the producer strain. Colicins by
E. coli. Marcescins by Serratia
marcescins. Pyocins by Pseudomonas aeruginosa.
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Diseases Caused by Enterobacteriaceae Other Than
Salmonella and Shigella A- E. coli 1- Urinary
tract infection. 2- E. coli associated diarrheal
diseases a- EPEC b- ETEC C- EHEC d- EIEC e-
EAEC 3- Sepsis. 4- Meningitis. 5- Otitis
media 6- Wound infection B- Klebsiella-Enterobac
ter-Serratia Proteus-Morganella-Providencia
and Citrobacter Respoiratory tract, urinary
tract, sepsis, otitis media
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The Shigellae
S. dysenteriae, S. sonnei, S. flaxonari, S.
boydii. Bacillary dysentery Morphology and
Growth Characteristics Pathogenesis and
Pathology Toxins Clinical Findings Diagnostic
Laboratory Tests Immunity Treatment Epidemiology,
prevention and control.
The Salmonella
S. typhi, S. paratyphi A and B , S. cholerasuis,
S. typhimurium, S. entertidis. Morphology and
Identification. Classification.
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Pathogenesis and Clinical Findings S. typhi, S.
paratyphi A and B , S. cholerasuis, S.
typhimurium, S. entertidis are of human origin.
The vast majority are animal pathogens that
constitute the reservoir for human
infection. Three main types of disease in
human A- The Enteric Fevers B- Bacteremia with
Focal Lesions C- Enterocolitis Diagnostic
Laboratory Tests 1- Specimens. 2- Culture. 3-
Identification by biochemical tests and
serology. 4- Agglutination test( Widal
test). Immunity Treatment Epidemiology