More Related Content Similar to Overview of bacterial infections Similar to Overview of bacterial infections (20) More from THERESE MARY DHASON More from THERESE MARY DHASON (7) 2. SYNOPSIS
• Types of Bacteria(GPC,GNC,GNB,GPB)
• Various infectionscaused by Bacteria
• Types of infections
• Morphology of Bacteria
• Gram stain
• Gram positive cocci –Staph, Strep, Enterococcusspp.
• Gram negativecocci-N.meningitidis,N.gonorrhoea
3. TYPES OF BACTERIA
• Gram positive cocci
• Gram Negative cocci
• Gram negative bacilli
• Gram positive bacilli
• Others
8. GRAM POSITVE COCCI
• MICROCOCCACEAE- Catalase positive, GPC in clusters or tetrads
• Tetrads-Micrococci(Non pathogenic)
• Clusters-Staphylococci(Pathogenic)
• STREPTOCOCCACEAE-Catalase negative, GPC in pairs or chains
• Pairs-Enterococci, Streptococcus pneumoniae(Pathogenic)
• Short chains-Beta hemolytic streptococci, short chains(Pathogenic)
• Long chains-S.viridans (commensals, occasionally pathogenic)
9. GRAM POSITIVE COCCI (AEROBIC)
• Staphylococcus aureus
• Coagulase negative staphylococcus
• Streptococcus pyogenes
• Streptococcus viridans
• Streptococcus agalactiae
• Streptococcus pneumoniae
• Enterococcus spp
12. VIRULENCE FACTORS&CLINICAL
MANIFESTATIONS
• Toxins (Hemolysins, exfoliative toxin,enterotoxin,TSS toxin)
• Enzyme(coagulase)
Clinical features
• Skin and soft tissue infections, Musculoskeletal infections
• Respiratory, UTI
• Sepsis,Toxin mediated(SSSS, food poisoning, TSS)
17. STREPTOCOCCUS SPECIES
• Gram positive, pairs or chains
• Catalase Negative
• ꭤ hemolysis(S.viridans, S.pneumoniae)
• ꭤ (S.pyogenes, S.agalacatiae)
• ℽ(Enterococcus spp)
20. VIRULENCE FACTORS
• Cell wall antigen;M proteins
• Toxins-Streptococcal pyrogenic exotoxin
• Enzymes-Streptokinase, Streptodornase, Hyaluronidase
22. LABORATORY DIAGNOSIS &TREATMENT
Lab Diagnosis
• Direct Gram Stain
• Culture-BAP(pinpoint colonies with wide zone of beta hemolysis)
• Bacitracin sensitive
• CAMP test negative
Treatment
• Penicillin, Erythromycin
23. Streptococcus agalactiae(Group B Streptococcus)
• Colonizes female genital tract
• Neonatal meningitis, sepsis
• Puerperal fever
• CAMP test positive
• Bacitracin resistant
Treatment
• Penicillin
24. S.viridans
• Commensals of mouth and respiratory tract
• Gram positive, long chains
• Alpha hemolysis on BAP
• Dental caries, Infective endocarditis &suppurative infections
• Penicillin & Vancomycin
25. S.pneumoniae (PNEUMOCOCCUS)
• Capsulated, Gram positive cocci in pairs, lanceolate shaped
Clinical manifestations
• Invasive infections: Pneumonia, Septicemia, Pyogenic meningitis
• Non invasive: Otitis media, Sinusitis
26. LABORATORY DIAGNOSIS
• Gram stain-Capsulated Gram positive
lanceolate shaped diplococci
• Culture-Draughtsman or carrom coin
shaped alpha hemolytic colonies
• Bile soluble
• Optochin sensitive
27. TREATMENT & PREVENTION
• Penicillin G
• Ceftriaxone
• Vancomycin
Vaccines
• Pneumococcal conjugate vaccine(PCV 13)
• 23 valent Pneumococcal polysaccharide vaccine(PPSV 23)
28. ENTEROCOCCUS
• Normal flora of human intestine
• Gram positive oval cocci in pairs
• UTI, Bacteremia, Endocarditis, Intra-abdominal infections
Lab.Diagnosis
• Gram stain
• Culture-Non hemolytic translucent, tiny colonies(BAP)
MAC- Magenta colored LF colonies
• Bile esculin positive
• Treatment; Ampicillin, Vancomycin, Fosfomycin
29. GRAM NEGATIVE COCCI
• Neisseriae- Gram negative diplococci
• Pathogens- N. meningitidis, N.gonorrhoea
• Others are commensals of oral cavity or genital tract
30. N. meningitidis(Meningococci)
• Capsulated, Gram negative lens shaped Diplococci
• Virulence factors ;polysaccharide capsule, endotoxin, outer membrane
proteins
• Clinical features; pyogenic meningitis and septicemia
31. LABORATORY DIAGNOSIS
• Specimen-CSF, Blood, Nasopharyngeal swabs
• Gram stain
• Culture-BAP, CAP, Muller-Hinton starch casein hydrolysate agar(translucent ,round, convex,
bluish grey colonies, easily emulsifiable)
• Oxidase Positive, Catalase positive
• Ferments glucose and maltose
32. TREATMENT AND PREVENTION
• 3rd generation Cephalosporins
Vaccines
• Capsular polysaccharide vaccine
• Conjugated capsular vaccine
• Recombinant Vaccines
34. LABORATORY DIAGNOSIS
• Specimen-Urethral swab for Male, Endocervical swab for Female(Stuart’s transport
medium)
• Gram Stain-Gram negative intracellular kidney shaped diplococci
• Culture-Thayer Martin medium, Modified New York City medium(small, round, convex
or umbonate, easily emulsifiable )
• Oxidase positive, Ferments glucose not Maltose
35. SUMMARY
• Majority of cocci are Gram positive except few.
• They can be either commensals or pathogens
• Virulence factors are toxins, enzymes, proteins
• Pneumonia can be caused by Staphylococcus aureus, S.pneumoniae
• Meningococci and Pneumococci can cause pyogenic meningitis
• Gonococci cause STD, Conjunctivitis in newborn
• Lab diagnosis is by Gram stain, culture and biochemical tests
• Antibiotics of choice – Penicillins, Cephalosporins
• Prevention-vaccines
36. EXERCISE
• Name 2 pathogenic gram positive cocci
• How will you differentiate Staphylococcus aureus from Streptococcus pyogenes?
• Name 2 commensal gram positive cocci
• How will you differentiate Group A –beta hemolytic Streptococcus from S. agalactiae.
• Name 2 cocci which cause Meningitis
• Name 2 cocci which cause Pneumonia
37. CASE STUDY
• A 5 yrs. old male child was brought to Paediatrics OPD with the C/O fever,
headache, vomiting for 4 days with altered sensorium. What is the probable
diagnosis? How will you proceed to detect the causative agent?
