Gram positive bacteria

Bacteria consist of how many cells

Bacteria consist of how many cells

One

Bacteria fall in which category of life

Prokaryotes

Basis of which classification of bacteria are made

Shape: Bacilla,cocci,spiral

Ability to form spores

Nutritional requirements

Reaction to gram staining

Method of energy production ( glycolysis-anaerobes, cellular respiration-Aerobe )

Classification of bacteria based of gram staining

Gram positive

Gram negative

Examples of gram positive cocci

Streptococcus

Staphylococcus

Enterococcus

Examples of Gram positive rods

Corynebacterium

Listeria

Bacillus

Clostridium

Erysipelothrix

The Genus streptococcus

Alpha Haemolytic streptococcus

Beta Haemolytic streptococcus

Non Haemolytic streptococcus

Alpha Haemolytic Streptococcus

Streptococcus pneumoniae ( pneumococcus)

Streptococcus viridans (bacterial endocarditis)

Beta Haemolytic streptococcus

Group A (streptococcus pyogenes)

Group B (streptococcus agalactiae)

Group C

Group G

Non Haemolytic streptococcus

Certain members of

Group B

Group C

Group D

Group H

Group O

Streptococcus Pyogenes

Major virulence factors

Extracellular toxins

Extracellular enzymes

Streptococcus Pyogenes

Habitat

Throat

Nasopharynx

Streptococcus Pyogenes

Extracellular toxins

Streptolysin: SLO(rapidly injurious to cell memebranes of many cell types.damage in rheumatic fever) SLS ( multiple cytotoxic effects on leukocytes,liver,heart muscle)

Erythrogenic/pyrogenic toxin:

Streptococcus Pyogenes

Extracellular enzymes

Streptokinase: Plays role in invasion by digesting fibrin clot.

Hyaluronidase: promotes spreading pathogen by intracellular glue breakdown.

Streptococcus Pyogenes

Infections

Skin infections:pyoderma,Erysipelas

Streptococcal pharyngitis(tonsillitis):

Streptococcus Pyogenes

Skin Infections

Pathogenesis

Pyoderma:

Invades nick of skin

Inflammatory primary lesion is produced

Characterized by itchy papule that breaks and form highly contagious crust

Streptococcus Pyogenes

Skin Infection

Pathogenesis

Erysipelas:

More invasive

The pathogen enters through wounds and spreads to the dermis and subcutaneous tissues

Characterized by edema,fever,chills,redness of skin near entry point

Depending on the depth of lesion and how the lesion progresses, it may remain superficial or produce long term systemic complications

Streptococcus pyogenes Infections

Streptococcal Pharyngitis

Organism multiplies in tonsils

Characterized by redness,edema,enlargement and extreme tenderness,headache,nausea ,swollen cervical lymph nodes,white pus filled nodules on tonsils

Throat infection leads to

scarlet fever

Systemic spread of erythrogenic toxin results in

High fever

Bright red diffuse rash over face, trunk inner arms,legs and tongue

Desquamation of epidermis after rash and fever disappear (10 days)

Streptococcus pyogenes infection

Systemic infections

Septicemia

Pneumonia

Puerperal fever: postpartum disease(abdominal sepsis)

Streptococcus pyogenes infection

Complications

Rheumatic fever(RF): joints,heart and subcutaneous tissues. Major clinical features: painful arthritis, nodules under skin,carditis,abnormal electrocardiogram

Acute glomerulonephritis (AGN): disease of the kidney glomerulus and tubular epithelia. Symptoms: Increased blood pressure,occasional heart failure,nephritis(swollen hands and feet and low urine output).

Streptococcus pyogenes infection

Treatment

Penicillin

Erythromycin or cephalosporin (incase of allergy)

Streptococcus Agalactiae

Epidemiology

Habitat:vagina,pharynx,large intestines

Most common cause of neonatal sepsis,meningitis and endocarditis

Wounds and skin infections

Steptococcus agalactiae

Lab diagnosis

Culture

Steptococcus agalactiae

Management

Penicillin G

Sepsis(10-14 days)

Meningitis(14-21 days)

Streptococcus agalactiae

Prevention

Perinatal Group B streptococcus prophylaxis

Streptococcus agalactiae

Prognosis

Mortality 10-40%

Streptococcus pneumonia (pneumococcus)

epidemiology

In normal flora of 5-50%of all persons nasopharynx

Most common cause of community acquired pneumonia

Common cause of URTI in children leading to meningitis

Otitis media

Streptococcus pneumonia (pneumococcus)

Risk factors

Old age

Season

Underlying infections

Streptococcus pneumonia (pneumococcus)

Major virulence factors

All pathogenic strains form large capsules

Only encapsulate strains cause disease

Streptococcus pneumonia (pneumococcus)

Classic symptoms

Shaking

Fever

Abnormal breathing

Pleuritic chest pain

Dyspnea

Streptococcus pneumonia (pneumococcus)

Lab

Culture: blood,sputum,spinal fluid,pleural fluid

Streptococcus Pneumoniae (pneumococcus)

Serological test

Quelling reaction

Streptococcus Pneumoniae (pneumococcus)

Blood culture

33% cases positive

Streptococcus Pneumoniae (pneumococcus)

Sputum culture

40% pneumococcal pneumonias positive

Streptococcus Pneumoniae (pneumococcus)

Radiology

Chest X ray:

lobar consolidation

Patchy infiltrates

Streptococcus Pneumoniae (pneumococcus)

Treatment

Penicillin

Penicillin G IV

Erythromycin

Azithromycin

Clarithromycin

Doxycycline

Ampicillin IV

Amoxicillin

Oral 2nd generation cephalosporin

Parenteral 3rd generation cephalosporin

Streptococcus pneumoniae

High level of penicillin resistance

High dose of Ampicillin

Parenteral 3rd generation cephalosporin

Vancomycin IV with or without rifampin

Broad spectrum of flouroquinolone: levofloxacin,gatifloxacin,grepafloxacin,moxifloxacin,sparfloxacin.

Streptococcus Viridans

Epidemiology

Habitat:nasopharynx,oral cavity,genital tract and skin.

Entry: dental or surgical instruments (not invasive)

Dental procedures can lead to bacteraemia,meningitis,abdominal infections

Causes: dental caries

Complications: subacute endocarditis

Treatment: Vancomycin

The Genus staphylococcus

Organism

Staphylococcus aureus

Staphylococcus epidermis

Staphylococcus saprophyticus

Staphylococcus aureus

Skin and mucus membrane

It is found in over half the population , higher in paramedics and hospitalized patients

Widely present in in the environment (resistance to pH and high temperature and months of air drying and disinfectants)

Staphylococcus aureus

Virulence factors

Enzyme: coagulate,hyaluronidase,DNAse and lipase

Toxins:

Staphylococcus aureus infection

Local: inflamed lesion with abscess

Systemic

Staphylococcus aureus infection

Localized infections

Folliculitis

Furuncles

Carbuncle

Impetigo

Cellulitis

Staphylococcus aureus infection

Systemic infection

Osteomyelitis

Bacteraemia

Pneumonia

Meningitis

Staphylococcus aureus infection

Toxigenic infection

Food intoxication

Scalded skin syndrome(SSS)

Staphylococcus aureus infection

Lab

Pus

Blood

CSF

Tracheal fluid

Wound swab

Staphylococcus epidermidis

Skin ,hair follicles ,mucous membrane

Not as invasive as S.aureus

Causes endocarditis,bacteraemia and UTI infections

Susceptible to novobiocin

Staphylococcus saprophyticus

Skin , lower intestinal tract and vagina

UTI infection

Enterococcus

Enterococcus faecalis: Affects elderly undergoing surgery. The urinary tract, wounds , appendix , endocardium

Enterococcus faecium

Gram positive rods

Corynebacterium

Listeria

Bacillus

Gram positive rods

Corynebacterium

Rare due to immunization (DTP)

Etiology: corynebacterium Diphtheriae

Symptoms: sore throat , dysphagia, weakness, malaise

Signs:cervical lymphadenopathy,fever,tachycardia , gray/white tenacious exudate, occurs at tonsillar pillars and posterior Pharynx

Gram positive rods

Corynebacterium

Lab: leukocytosis, blood agar,leoffler medium

Management:Diphtheria antitoxin,Erythromycin 20-25mg/kg IV 7-14 days

Prevention: Immunization (DTP)

Listeria monocytogenes

widely distributed (water,soil,intestines of healthy mammals,bird,fish)

Contaminated milk ,cheese,ice cream,meat

Risk factors: weak immune systems,listeriosis with non specific symptoms (fever diarrhea sore throat)

Infection in neonates localize in the meninges and causes extensive damage to nervous system

Listeria monocytogenes

Diagnosis hampered by difficulty in isolation(cold enrichment)

Treatment:Ampicillin and penicillin, Erythromycin

Prevention: Adequate pasteurization of milk,cooking food that may be contaminated with animal manure

Bacillus Anthracis (Anthrax)

Contact with animal hide, Ingestion of contaminated meat, inhalation of spore(8,000-50,000 spores)

Spores are viable for >40 years

Cutaneous Anthrax

Enters a small cut

Painless pustules develop

Erythematous papule forms

Vasculates and ulcerates

Surrounded by a ring of non tender edema

Pulmonary Anthrax