Streptococcus pneumoniae pneumococus

Streptococcus pneumoniaeStreptococcus pneumoniaepneumococuspneumococus

PneumoniaPneumoniaMeningitisMeningitis

bacteraemiabacteraemia

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

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

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

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

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

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

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

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 )

Mortality Mortality

Age (> 65 yr ) Age (> 65 yr ) Preexisting diseasePreexisting diseaseBacteraemiaBacteraemiaSerotype 3 , 7Serotype 3 , 7

Laboratory diagnosisLaboratory diagnosis

SpecimenSpecimen– SputumSputum– CSFCSF– SwabsSwabs– PusPus– Blood cultureBlood culture– Aspirate Aspirate

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

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

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

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