Download - Streptococcus pneumoniae pneumococus
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Streptococcus pneumoniaeStreptococcus pneumoniaepneumococuspneumococus
PneumoniaPneumoniaMeningitisMeningitis
bacteraemiabacteraemia
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Description Description Gram-positive diplococci (in pairs)Gram-positive diplococci (in pairs)Encapsulated ovoid or lanceolate coccusEncapsulated ovoid or lanceolate coccusNon-motileNon-motileFastidious (enriched media)Fastidious (enriched media)– Blood or chocolate agarBlood or chocolate agar– 5-10 % CO25-10 % CO2Alpha haemolysis + draughtsman appearance Alpha haemolysis + draughtsman appearance Some strains are mucoidSome strains are mucoidSoluble in bileSoluble in bileOptochin sensitive Optochin sensitive
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Pathogenesis Pathogenesis Virulence factors Virulence factors – Capsular polysaccharide Capsular polysaccharide
The major factorThe major factor84 serotypes84 serotypesBoth antigenic and type specificBoth antigenic and type specificAntiphagocyticAntiphagocyticSerotype 3 , 7 are most virulent Serotype 3 , 7 are most virulent 90% of cases of bacteraemic pneumococcal 90% of cases of bacteraemic pneumococcal pneumonia and meningitis are caused by 23 pneumonia and meningitis are caused by 23 serotypes serotypes Quellung reaction , india ink Quellung reaction , india ink
– PneumolysinPneumolysinMembrane damaging toxinMembrane damaging toxin
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Carrier rate Carrier rate – Oropharyngeal flora of 5 – 70% of theOropharyngeal flora of 5 – 70% of the populationpopulation
– Significance in respiratory infectionSignificance in respiratory infection
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Predisposing factorsPredisposing factors– Aspiration of upper airway secretions ( endogenous )Aspiration of upper airway secretions ( endogenous )– No person-person spread No person-person spread – Disturbed consciousness , general anaesthesia , Disturbed consciousness , general anaesthesia ,
convulsions , CVA , epilepsy , head trauma convulsions , CVA , epilepsy , head trauma – Prior LRT. VIRAL infection Prior LRT. VIRAL infection – Preexisting respiratory diseases , smoking Preexisting respiratory diseases , smoking
Chronic bronchitis , bronchogenic malignancy Chronic bronchitis , bronchogenic malignancy – Chronic heart disease Chronic heart disease – Chronic renal disease ( nephrotic syndrome )Chronic renal disease ( nephrotic syndrome )– Chronic liver disease ( cirrhosis)Chronic liver disease ( cirrhosis)– Diabetes mellitus Diabetes mellitus – Old age , (extreme of age )Old age , (extreme of age )– Malnutrition , alcoholism Malnutrition , alcoholism
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Specific deficiencies in host defence Specific deficiencies in host defence – HypogamaglobulinaemiaHypogamaglobulinaemia– Asplenia , hypospenism ( tuftsin )Asplenia , hypospenism ( tuftsin )– Homozygous sickle cell disease Homozygous sickle cell disease – Coeliac disease Coeliac disease – Multiple myeloma , leukaemia , lymphomasMultiple myeloma , leukaemia , lymphomas– Neutropenia Neutropenia – HIVHIV
Relative or absolute deficiency of opsonic Relative or absolute deficiency of opsonic antibody or inadequate manufacture of type antibody or inadequate manufacture of type specific antibody specific antibody
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Diseases Diseases Respiratory tract infectionsRespiratory tract infections– Lobar pneumonia ( commonest cause of CAP )Lobar pneumonia ( commonest cause of CAP )– EmpyemaEmpyema– Otitis media (6 months – 3 yrs )Otitis media (6 months – 3 yrs )– MastoiditisMastoiditis– SinusitisSinusitis– Acute exacerbation of chronic bronchitis Acute exacerbation of chronic bronchitis MeningitisMeningitisConjunctivitisConjunctivitisPeritonitis ( primary )Peritonitis ( primary )Bacteraemia ( 15 % of pneumonia )Bacteraemia ( 15 % of pneumonia )septicaemiasepticaemia
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Clinical feature Clinical feature
Lobar pneumoniaLobar pneumonia– Sudden onsetSudden onset– FeverFever– rigorrigor– Cough , rusty sputum Cough , rusty sputum – Pleural painPleural pain– Signs of lobar consolidationSigns of lobar consolidation– Polymorphonuclear leucocytosis Polymorphonuclear leucocytosis – Empyema , pericarditis Empyema , pericarditis
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MeningitisMeningitis– The most virulent pathogen of meningitisThe most virulent pathogen of meningitis– Mortality ( 20% )Mortality ( 20% )– Primary Primary – Complicate infections at other site ( lung )Complicate infections at other site ( lung )– Bacteraemia usually coexists Bacteraemia usually coexists – Bimodal incidence ( < 3 yr - > 45 yr )Bimodal incidence ( < 3 yr - > 45 yr )
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Mortality Mortality
Age (> 65 yr ) Age (> 65 yr ) Preexisting diseasePreexisting diseaseBacteraemiaBacteraemiaSerotype 3 , 7Serotype 3 , 7
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Laboratory diagnosisLaboratory diagnosis
SpecimenSpecimen– SputumSputum– CSFCSF– SwabsSwabs– PusPus– Blood cultureBlood culture– Aspirate Aspirate
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Microscopy Microscopy – Gram stained smear Gram stained smear
Gram-positive diplococci + pus cellsGram-positive diplococci + pus cells
cultureculture
Blood agar , chocolate agar + 10 % CO2Blood agar , chocolate agar + 10 % CO2
identificationidentification
Alph-haemolytic colonies Alph-haemolytic colonies Optochin sensitive Optochin sensitive Bile soluble Bile soluble
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Sensitivity testingSensitivity testing– PenicillinPenicillin– susceptiblesusceptible
Sensitive Sensitive – Nonsusceptible Nonsusceptible
Intermediate Intermediate Resistant Resistant
– Ampicillin , amoxicillin Ampicillin , amoxicillin – Erythromycin Erythromycin – Ceftriaxone , cefuroxime Ceftriaxone , cefuroxime – ClindamycinClindamycin– Fluroquinolones Fluroquinolones – tetracyclinestetracyclines– Vancomycin Vancomycin
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Treatment Treatment
MeningitisMeningitis– Parenteral ceftriaxone + vancomycinParenteral ceftriaxone + vancomycin
pneumoniapneumonia– Outpatients Outpatients
ErythromycinErythromycinAmoxacillin – clavulanic acidAmoxacillin – clavulanic acidCefuroxime or ceftriaxone (IV) + oral Cefuroxime or ceftriaxone (IV) + oral b- lactamb- lactam
– Inpatients Inpatients Parenteral cefuroxime or ceftriaxone Parenteral cefuroxime or ceftriaxone
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Prevention Prevention
23 polysaccharide vaccine 23 polysaccharide vaccine – Not effective in children < 2 yrsNot effective in children < 2 yrs– >65 yrs>65 yrs– Functional or anatomical asplenia Functional or anatomical asplenia – SCDSCD
7-valent – protein- conjugated vaccine7-valent – protein- conjugated vaccine– Children < 3 yrs Children < 3 yrs
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