Dr. Husni SamadinMikrobiologi .FK.Unsri

Microbes Benefit Humans1.Bacteria are primary decomposers - recycle nutrients back into the environment (sewage treatment plants)2. Microbes produce various food products cheese, pickles, sauerkraut, green olivesyogurt, soy sauce, vinegar, breadBeer, Wine, Alcohol

3. Microbes are used to produce AntibioticsPenicillin

Mold Penicillium notatum

1928 Alexander Fleming

Bacterial classification based on several major properties Gram Staining characteristicsMorphologyMetabolic behaviorDNA sequence

Bacterial classificationCell morphologyShapesRodCocciSpiralAssociationsIndividualDiplo-Staphylo-Strepto-Filaments

Bacterial classificationGrowth characteristicsOxygen requirementAerobicAnaerobicMicroaerophilic, aerotolerantFacultativeSpore formationIntracelular/extracellularFastidious/non-fastidious

ArrangementsStaphyloStreptoDiploSarcinaeTetrad

Vibriocomma shapedbacter bacillibacterium bacilli

Bacteria

Aerobes (Common)AnaerobesRodsCocciG+G-ListeriaCorynebacteriaBacillusEnterobacteria-Many generaprimarily from the gut e.g E. coliKlebsiella

PseudomonadsHemophilusBordetellaYersiniaPasteurellaFranciscellaBrucella

G +StaphylococciStreptococciEnterococciG-GonococciMeningococciFilamentousG+Nocardia

G-Dental plaque bacteria

Anaerobes (Common)RodsCocciGm-BacteroidesFusobacteriumG+ClostridiaG+StreptococciPeptococciPeptpstreptococciG-VeillonellaFilamentousG+ActinomycesGm-Various gut organisms

4. Bacteria synthesize chemicals that our body needs, but cannot synthesizeExample: E. coliB vitamins - for metabolismVitamin K - blood clotting

Escherichia coliDr. EscherichColon (intestine)

PurposeTo provide an overview of how we think when confronted with a bacterial infectionTo alert you to the importance of bacterial classification in treatmentThe importance of knowing the etiology of organ system based infection and the gram stain

How does an experienced Physician approach bacterial diseasesOrgan system approachWhich bacteria cause disease in a certain locationE.g. lungs, skin, subarachnoid space.With experience the answer comes easilyGram stain approachWhat does the gram stain show--used to treat empirically before cultures are completedRequires that one is able to get a gram stain, which is not always the case

ChestPneumoniaPneumococcus, H. influenzaePleural cavityPneumococcus, Staphylococcus, Anaerobic bacteriaEndocarditisStreptococcus, Staphylococcus, Enterococci

AbdomenLikely organisms in intraabdominal infections come from the GI tractTherefore all enteric flora need to be consideredNot respiratory flora as in Head and ChestAerobic (Enterobacteriaceae) and anaerobic (Bacteroides, Fusobacteria) gram negatives rods. Aerobic (Enterococci and Streptococci) and anaerobic gram positives cocci (Streptococci)Anaerobic gram positive rods (Clostridia)

Peritonitis-fecal flora spilled into abdominal cavity from surgery or perforationAll morphological forms and all metabolic typesLiver abscessesAll typesBiliary tract infectionsFewer types of organismsAerobic gram negative rods and gram positive cocci predominate

Add in the gram stainPneumonia-sputum gram stainGram positive coccus as the predominant organismLikely organism Pneumococcus--the most common gram positive coccus found in pneumoniaTherapy can be chosenEndocarditis-blood culture positiveGram positive coccus on the stainMay be Streptococci, Enterococci or StaphylococciTreatment decision made on this basis- Vancomycin +

SkinSkin infectionsSkin flora-Gram positive cocciStaphylococcus aureus and Strep. pyogenesThis is of immediate help in therapyComplex skin infectionsSkin flora plus enteric flora and environmental flora.

Urinary tract infectionBecause of proximity to GI tract Enteric flora are the prime suspects in most casesUnusual to find Staphylococci and streptococci or anaerobesAerobic Enteric gram negative rodsAerobic gram positive cocci from the gutWhat are these

Classification & DiagnosisType of coloniesAppearanceColor, shape, size and smoothnessOn differential mediaBlood, MacConkey, EMB, Manitol salt agarOn selective mediaMacConkey, EMB, Manitol salt agar

Dr. Husni SamadinMikrobilogi FK. Unsri

Basic techniques needed to study Bacteria1. Grow Bacteria2. Isolate Bacteria3. Grow Bacteria in pure culture4. Observe Bacteria 5. Identify Bacteria

Preparing smears for staining1. Bacteria on slide2. Air Dry3. Bacteria are HEAT FIXED to the slide4. Stain is applied

Differential StainsReact differently with different types of bacteria

2 Most CommonGram StainAcid-Fast Stain

Gram Stain1884 Hans Christian Grammost important stain used in Bacteriology

Divides all Bacteria into 2 groups:Gram (+)Gram (-)

Gram Stain1. Crystal violet

Gram Stain2. Grams Iodine (mordant)

Gram Stain3. Alcohol

Gram Stain4. Safranin (Counterstain)

ResultsGram (+)Purple

Gram (-)Red

Difference - due to structure of cell wallGram (+) Thick cell wallGram (-) Thin cell wall

Acid - Fast StainDifferential Stain - divides bacteria into 2 groups

Acid - FastNon Acid - Fast

Used to identify organisms in the Genera Mycobacterium (high lipid and wax content in cell wall)

Acid - Fast Stain1. Carbolfuchsin (Red)2. Acid Alcohol3. Counterstain with Methylene Blue

Acid - Fast Cells RedNon Acid - Fast Blue

Special StainsCapsule Stain Klebsiella pneumoniae

Flagella Stain Spirillum volutans

Endospore Stain Bacillus cereus

Prokaryotic Cell StructureGlycocalyx - term to describe substances that surround bacterial cells1. Capsuleif substance is organized and firmly attached to cell wall2. Slime Layerif substance is unorganized and loosely attached to cell wall

Function of Capsule1. Contribute to Virulence of bacteria by preventing phagocytosis by WBCsA. Streptococcus pneumoniaeB. Bacillus anthracis

Functions of Capsules2. Prevents drying out or dessication

3. Allows bacteria to adhere to various surfacesStreptococcus mutans - enamel on teeth to cause dental carriesKlebseilla pneumoniae - attaches to respiratory tract

MotilityAlmost all Spiral bacteria are motile

About 1/2 of Bacilli are motile

Almost all Cocci are non-motile

Flagella1. Monotrichous

2. Amphitrichous

3. Lophotrichous

4. Peritrichous

Axial Filament - found only in spirochetes (flexible spirals) Treponema pallidum

FimbriaeFilamentous appendages that are shorter, straighter and more numerous that flagella

found mostly in Gram (-) Bacteria

used for attachment not motility

Bacterial cell wall - chemically unlike any other structure in Animal cellsTarget for drugs that can attack and kill bacteria without harming the host cell

MANY ANTIBIOTICS are specifically directed at Cell Wall SynthesisPenicillinworks by damaging the pentaglycine crossbridges of the peptidogylcan layerWorks best against Gram (+) bacteria

lysozymeDigestive enzyme that damages bacterial cell wallsfound in tears, saliva & mucusattacks the bond between NAM & NAGWorks best on Gram (+) bacteria

Cell Membrane (Plasma Membrane)2 structural componentdouble layer of phospholipidsproteins

Fluid Mosaic Model

Functions of Cell Membrane1. Selective barrier (selectively permeable)2. Secretes exoenzymesamylaseslipasespeptidasesCAN NOT UNDERGO PHAGOCYTOSIS

Functions of Cell Membrane3. E.T.S. is located here4. Enzymes for cell wall synthesis5. If photosynthesis, enzymes are located on membranous structures called thylakoids6. Mesosomes - invagination of cell membrane attached to DNA (Binary Fission)?

Endospores - formed under periods of environmental stressOnly found in Gram (+) BacteriaBacillusBacillus cereusBacillus anthracisClostridiumClostridium tetaniClostridium botulinumClostridium perfringens

EndosporesExtremely resistant to heat, cold, chemicals, lack of water, etc.

Most vegetative bacterial cells are killed at temps. above 70 C (160 F)Endospores can survive boiling water for several hours (some for as long as 20 hours)

Dr. Husni Samadin

Pathogenicity - ability to cause diseaseVirulence - degree of pathogenicityMany properties that determine a microbes pathogenicity or virulence are unclear or unknown

But, when a microbe overpowers the hosts defenses, disease results!

Portals of Entry1. Mucus Membranes

2. Skin

3. Parentarel

Common Diseases contracted via the Respiratory TractCommon coldFluTuberculosisWhooping coughPneumoniaMeaslesStrep ThroatDiphtheria

Mucus MembranesB. Gastrointestinal Tractmicrobes gain entrance thru contaminated food & water or fingers & hands

most microbes that enter the G.I. Tract are destroyed by HCL & enzymes of stomach or bile & enzymes of small intestine

Common diseases contracted via the G.I. Tract SalmonellosisSalmonella sp.ShigellosisShigella sp.CholeraVibrio choloreaUlcersHelicobacter pyloriBotulismClostridium botulinum

Fecal - Oral DiseasesThese pathogens enter the G.I. Tract at one end and exit at the other end.

Spread by contaminated hands & fingers or contaminated food & water

Poor personal hygiene.

2nd Portal of Entry: SkinSkin - the largest organ of the body. When unbroken is an effective barrier for most microorganisms.

Some microbes can gain entrance thru openings in the skin: hair follicles and sweat glands

3rd Portal of Entry: ParentarelMicroorganisms are deposited into the tissues below the skin or mucus membranesPuncturesinjectionsbitesscratchessurgerysplitting of skin due to swelling or dryness

How do Bacterial Pathogens penetrate Host Defenses?1. Adherence - almost all pathogens have a means to attach to host tissue

Binding Sitesadhesinsligands

Adhesins and ligands are usually on FimbriaeNeisseria gonorrhoeaeETEC (Entertoxigenic E. coli)

Bordetello pertussis

2. CapsulesPrevent phagocytosis attachmentStreptococcus pneumoniaeKlebsiella pneumoniaeHaemophilus influenzaeBacillus anthracisStreptococcus mutansYersinia pestis K. pneumoniae

3. EnzymesMany pathogens secrete enzymes that contribute to their pathogenicity

A. LeukocidinsAttack certain types of WBCs

1. Kills WBCs which prevents phagocytosis2. Releases & ruptures lysosomeslysosomes - contain powerful hydrolytic enzymes which then cause more tissue damage

B. Hemolysins - cause the lysis of RBCsStreptococci

2. Beta Hemolytic Streptococci - secrete hemolysins that cause the complete lysis of RBCs

C. Coagulase - cause blood to coagulateBlood clots protect bacteria from phagocytosis from WBCs and other host defenses

Staphylococci - are often coagulase positiveboilsabscesses

D. Kinases - enzymes that dissolve blood clots1. Streptokinase - Streptococci2. Staphylokinase - Staphylococci

Helps to spread bacteria - Bacteremia

Streptokinase - used to dissolve blood clots in the Heart (Heart Attacks due to obstructed coronary blood vessels)

E. HyaluronidaseBreaks down Hyaluronic acid (found in connective tissues)Spreading Factor

mixed with a drug to help spread the drug thru a body tissue

F. CollagenaseBreaks down collagen (found in many connective tissues)

Clostridium perfringens - Gas Gangreneuses this to spread thru muscle tissue

G. Necrotizing Factor- causes death (necrosis) to tissue cells Flesh Eating Bacteria Necrotizing fasciitis

Summary of How Bacterial Pathogens Penetrate Host Defenses1. Adherence2. Capsule3. EnzymesA. leukocidinsB. HemolysinsC. CoagulaseD. KinasesE. HyaluronidaseF. CollagenaseG. Necrotizing Factor

4. ToxinsPoisonous substances produced by microorganisms toxins - primary factor - pathogenicity220 known bacterial toxins 40% cause disease by damaging the Eukaryotic cell membraneToxemia Toxins in the bloodstream

2 Types of Toxins1. Exotoxinssecreted outside the bacterial cell

2. Endotoxinspart of the outer cell wall of Gram (-) bacteria

ExotoxinsMostly seen in Gram (+) Bacteria

Most gene that code for exotoxins are located on plasmids or phages

3 Types of Exotoxins 1. Cytotoxinskill cells2. Neurotoxinsinterfere with normal nerve impulses3. Enterotoxinseffect cells lining the G.I. Tract

Response to ToxinsIf exposed to exotoxins: antibodies against the toxin (antitoxins)Exotoxins inactivated ( heat, formalin or phenol) no longer cause disease, but stimulate the production of antitoxinaltered exotoxins - ToxoidsToxoids - injected to stimulate the production of antitoxins and provide immunity

Response to ToxinsIf exposed to exotoxins: antibodies against the toxin (antitoxins)Exotoxins inactivated ( heat, formalin or phenol) no longer cause disease, but stimulate the production of antitoxinaltered exotoxins - ToxoidsToxoids - injected to stimulate the production of antitoxins and provide immunity

Type of VaccinesDPTMMRPolioSalkSabinHibHBV

Chicken PoxToxoidAntigenToxoidAttenuatedAttenuatedAttenuatedIPV Inactivated Polio virus (Killed) 1953OPV Oral Polio vaccine (attenuated) 1964Conjugated vaccineRecombinant vaccine (antigen) yeastCapsid produced by genetically engineered yeastAttenuated

Diseases caused by NeurotoxinsBotulism Clostridium botulinumGram (+), anaerobic, spore-forming rod, found in soilworks at the neuromuscular junctionprevents impulse from nerve cell to muscle cellresults in muscle paralysis

Tetanus (Lock Jaw)Clostridium tetaniGram (+), spore-forming, anaerobic rodneurotoxin acts on nerves, resulting in the inhibition of muscle relaxationtetanospasmin - spasms or Lock Jaw

Diseases caused by EnterotoxinsCholeraVibrio choleraeGram (-) comma shaped rods

Cholera toxinConverts ATP into cAMPcauses cells to excrete Cl- ions and inhibits absorption of Na+ ionsElectrolyte imbalanceH2O leaves by osmosisH2O Loss (Diarrhea)

EHEC (Enterohemorrhagic E. coli)E. coli (0157:H7)enterotoxin causes a hemolytic inflammation of the intestinesresults in bloody diarrheaToxinalters the 60S ribosomal subunitinhibits Protein SynthesisResults in cell deathlining of intestine is shedBloody Diarrhea (Dysentary)

Endotoxins - part of the Gram (-) Bacterial cell wallLPS (Lipopolysaccharides)O AntigenLipid ALipid A - Toxin portion of the LPSresponsible for Fever that is associated with many Gram (-) Bacterial infectionsGram (-) cells are digested endotoxins are released - feverAntibiotics

Salmonella Salmonellosis = Generic term for disease

Clinical Syndromes

Enteritis (acute gastroenteritis)

Enteric fever (prototype is typhoid fever and less severe paratyphoid fever)

Septicemia (particularly S. choleraesuis, S. typhi, and S. paratyphi)

Asymptomatic carriage (gall bladder is the reservoir for Salmonella typhi)

Coliform bacilli (enteric rods)

Motile with peritichous flagellaGram-negative facultative anaerobes

Non-lactose fermenting

Resistant to bile salts H2S producing, survive freezing in water.Resist chemicalsGeneral Characteristics of Salmonella

Antigenic structureAntigens OHK - Vi Ag invasiveness

Classification - Complex - Kauffmann White SchemeEx: S typhiS. paratyphi A/B India and AsianS. choleraesuisS. typhimuriumS. enteritidis

SO MANY OTHER SPECIES

INCUBATION STAGEIncubation period 10-14 daysFaecal oral routeMost of the cells will get killedID should be highReach the duodenumMultiply in alkaline mediumadhere to villito the sub mucous coatwill be phagocytosed by Macro and Neutro

Virulent bacilli resist intracellular killing and multiply

Enters the mesenteric lymhnodes and multiply there and then to the blood (primary bacteraemia) 1-7 days

bacilli will be cleared by MPS in the liver/spleen/bone marrow/lungs/lymhnode

Epidemiology & Clinical Syndromes (cont.) Enteric Fevers S. typhi causes typhoid feverS. paratyphi A, B (S. schottmuelleri) and C (S. hirschfeldii) cause milder form of enteric fever Infectious dose = 106 CFU Fecal-oral route of transmission Person-to-person spread by chronic carrier Fecally-contaminated food or water 10-14 day incubation period Initially signs of sepsis/bacteremia with sustained fever (delirium) for > one week before abdominal pain and gastrointestinal symptoms

Invasiveness in Enteritis (cont.)Penetrate mucus, adhere to and invade into epithelial layer (enterocytes) of terminal small intestine and further into subepithelial tissueBacterial cells are internalized in endocytic vacuoles (intracellular) and the organisms multiplyPMNs confine infection to gastrointestinal (GI) tract, but organisms may spread hematogenously (through blood, i.e., septicemia) to other body sites Inflammatory response mediates release of prostaglandins, stimulating cAMP and active fluid secretion with loose diarrheal stools; epithelial destruction occurs during late stage of disease Pathogenesis of Salmonella (cont.)

Virulence attributable to: Invasiveness Intracellular survival & multiplication Endotoxin Exotoxins: Effects in host have not been identified Several Salmonella serotypes produce enterotoxins similar to both the heat-labile (LT) and heat-stable enterotoxins (ST), but their effect has not been identified A distinct cytotoxin is also produced and may be involved in invasion and cell destruction Pathogenesis of SalmonellaEnteritis (cont.)

SEPTICAEMIC STAGE

Primary bacteraemia - where bacilli will be multiply in the cells of MPS

10th day parasitised cells undergo necrosis leads to seondry bacteramia, results in clinical symptoms thats about on the 14th day after the ingestionsome bacilli lyse and release endotoxinsbacteraemia and toxaemia causes fever and other signs

STAGE OF LOCALIZATION

Bacteraemia-gall bladder/liver/spleen/bone

bacilli can be discharge into the intestine from the gall bladder and cause inflammation of the Payers patches in the intstine and lymphoid follicles

Necrosis/sloughing---ulcers--haemorrhage

Severe mental cloudingheadache

anorexia -cannot eat

High fever (Step ladder pyrexia) spleen and liver enlargement

Splenohepatomagaly

Rose spots (1-2mm) on skin of chest and abdomen 2nd and 3rd week

bacilli appear during 2nd and the 3rd week in stools - diagnostic

4th week in urine - diagnostic

The disease lasts 4 to 5 weeks

WBC normal or low

Treatment - chloramphenicoal

ComplicationsIntestinal hemorrhage & perforationHyperplasia and necrosis of Payers pachesHepatitis, focal liver necrosisgall bladder inflammationbone ,lungs and other organs can be affected.

Isolation of bacteria

Specimens - stools/urine/blood

Blood culture - before giving chloramphenicol - repeat the culture - 80-90% +ve 1st week up to10days - +ve during relapses - can culture bone marrow +ve 1-2 days after drug therapy ? good -

Blood (5 - 10 ml)

BHI

Incubate 37 0C

Subculture(18-24hrs/every 2nd day for 7days)

MacConkeyStools and urine first should be cultured in enrichment media

MacConkey agar plate inoculated with the gram-negative lactose fermenter and the gram-negative non-lactose fermenter

Serological testDetection of antibodies to H and O antigens

Widal testAntibodies appear at the end of the first weekRises during the 3rd week of the enteric feverTwo specimens are taken at interval of 7 to 10 days

Interpretation of Widal test1. Antibody appears at the end of 1st week/rises during 2nd and 3rd/steady at the 4th week then decline

2. Four fold rise of both H and O antibody in an interval of 7 - 10 days (between 1st and the 3rd week is highly significant)

Widal interpretationHigh titer > 1:160 against O antigen suggest infectionHigh titer > 1:160 against H antigen suggest past infectionJawetzSerology limited role

Widal interpretationActive typhoid if titers above 1:180 or 1:200 against O or H or both agglutinins is presentIn acute infection, O antibody appears first, H antibody appears slightly later but persists longer and can be used to distinguish between various types of enteric fever.

Asymptomatic Carriage Chronic carriage in 1-5% of cases following S. typhi or S. paratyphi infection

Gall bladder usually the reservoir

Chronic carriage with other Salmonella spp. occurs in

Streptococci

Morphology and IdentificationGram-positive cocci arranged in chains.Most group A, B, and C strains produce capsules. Most strains grow as discoid colonies, 1-2 mm in diameter.Catalase-negative.Grow better in media enriched with blood or tissue fluid.Most are facultative anaerobic and some are capnophilic. For most species growth and hemolysis are aided by incubation in 10% CO2.

Hemolysis a-hemolysis: incomplete lysis of RBC with the formation of green pigment. b-hemolysis: complete hemolysisNo hemolysisLancefield classification: a serologic classification (A to V)Biochemical reactions (used for species that can not be classified into the Lancefield classification, e.g. viridans streptococci) Classification

Antigenic StructureCapsule: antiphagocytosis. The capsule of group A streptococci is composed of hyaluronic acid. The group B streptococci contain type-specific capsular polysaccharides. Group-specific cell wall antigen (Lancefield groups A-V)CarbohydrateSpecificity is determined by an amino sugar. M protein T protein: type-specific; function unknown.M-like proteins: binds IgM, IgG and a2-macroglobulin; interfere with phagocytosis.Lipoteichoic acid: binds to epithelial cells.F protein: a major adhesin of S. pyogenes, binding with fibronectin.

PathogenesisPathogenesis of group A streptococciAdherence to the epithelial cells;>10 adhesion moleculesinvasion into the epithelial cells;mediated by M protein and F proteinimportant for persistent infections and invasion into deep tissuesavoiding opsonization and phagocytosis;M protein, M-like proteins, and C5a peptidaseproducing enzymes and toxins

Enzymes and toxinsStreptokinase (fibrinolysin)Can lyse blood clots and may be responsible for the rapid spread of the organism.Used (IV injection) for treatment of pulmonary emboli, coronary artery thrombosis and venous thrombosis.Streptodornase (DNases A to D)Decreases viscosity of DNA suspension. A mixture of this and streptokinase is used in enzymatic debridement-liquifies exudates and facilitates removal of pus and necrotic tissue.Hyaluronidase (spreading factor): Destroys connective tissue and aids in spreading infecting bacteria.C5a peptidase Prevents streptococci from C5a-mediated recruitment and activation of phagocytes, and is important for survival of S. pyogenes in tissue and blood.

Streptococcal pyrogenic exotoxins (Spe): Produced by both the scarlet fever strains and new invasive S. pyogenes strains.More than four serologically distinct toxins (SpeA, B, C and F).Biological activities (except SpeB, which is a cysteine protease):PyrogenicityCytotoxicityImmunosuppressionSuperantigenSpe is associated with toxic shock-like syndrome or other invasive S. pyogenes diseases.

HemolysinsStreptolysin O: O2-labile; causes hemolysis deep in blood agar plates. ASO (antistreptolysin O) titer >160-200 units suggests recent infection or exaggerated immune response to an earlier respiratory infection. Inhibited by cholesterol in skin lipids, therefore, skin infection does not induce ASO.Streptolysin S: O2-stable. Causes b-hemolysis on the surface of blood agar plates. Cell-bound, not antigenic. Produced in the presence of serum. Kills phagocytes by releasing the lysosomal contents after engulfment.

Clinical Diseases1. Local infection with S. pyogenes Streptococcal sore throat (pharyngitis), and scarlet fever.Streptococcal pyoderma (impetigo, local infection of superficial layers of skin).Strains that cause skin infections are different from those that cause pharyngitis.

2. Invasion by S. pyogenes Invasion from respiratory tract: otitis media, sinusitis, pneumonia, meningitis, osteomyelitis, and arthritis.Invasion from skin: erysipelas, cellulitis, and necrotizing facitis. Diffuse and rapidly spreading infection that extends along lymphatic pathways with only minimal local suppuration.Sepsis (toxic shock-like syndrome, TSLS): the organism is introduced into the subcutaneous tissue through a break in the skin cellulitis necrotizing faciitis systemic toxicity, multiple organ failure, and death (mortality > 40%).

3. Poststreptococcal diseases (occurs 1-4 weeks after acute S. pyogenes infection, hypersensitivity responses)Rheumatic fever: most commonly preceded by infection of the respiratory tract. Inflammation of heart (pancarditis), joints, blood vessels, and subcutaneous tissue. Results from cross reactivity of anti-M protein Ab and the human heart tissue. This disease can be reactivated by recurrent streptococcal infections, whereas nephritis does not. Acute glomerulonephritis: preceded by infection of the skin (more commonly) or the respiratory tract. Symptoms: edema, hypertension, hematuria, and proteinuria. Initiated by Ag-Ab complexes on the glomerular basement membrane.

S. agalactiae (group B, b-hemolytic, contains type-specific capsular polysaccharides which induce protective antibodies; may colonize at lower gastrointestinal tract and genitourinary tract)Neonatal sepsis or meningitis Early-onset (during the first week of life): infection acquired in utero or at birth.Late-onset (older infants): infection acquired from an exogenous source.(Premature infants are at greater risk.)Infection of pregnant womenUrinary tract infections, amnionitis, endometritis, and wound infectionsInfection in men and nonpregnant womenPatients are generally older and have underlying conditions. Bacteremia, pneumonia, urosepsis (UT infection with bacteremia), skin and soft tissue infections. Mortality: 15%-32%.

Viridans streptococci (a-hemolytic or nonhemolytic, most are nongroupable)These streptococci colonize the oropharynx, GI tract, and GU tract; rarely on the skin surface.Diseases:Subacute endocarditisIntra-abdominal infectionsDental caries (mostly associated with S. mutans)Cariogenicity of S. mutans is related to its ability to synthesize glucan from fermentable carbohydrates as well as to modify glucan in promoting increased adhesiveness. S. pneumoniae

Laboratory DiagnosisSmears: useful for soft tissue infections or pyoderma, but not for respiratory infections.Antigen detection tests: commercial kits for rapid detection of group A streptococcal antigen from throat swabs. Culture: Specimens are cultured on blood agar plates in air. 10% CO2 although speeds hemolysis, the growth of inhibitory bacteria is also enhanced.IdentificationSerological test ASO titration for respiratory infections.Anti-DNase B and antihyaluronidase titration for skin infections.Antistreptokinase; anti-M type-specific antibodies.

Identification of Gram-positive cocciNone

Pathogenesis and ImmunityS. pneumoniaePneumococci produce disease through their ability to multiply in the tissues (invasiveness). Virulence factors: capsule, cell wall polysaccharide, phosphorylcholine, pneumolysin, IgA protease, etc.40-70% of humans are at sometimes carrier of virulent pneumococci. Major host defense mechanisms: ciliated cells of respiratory tract and spleen. The normal respiratory tract has natural resistance to the pneumococcus. Loss of natural resistance may be due to:1. Abnormalities of the respiratory tract (e.g. viral RT infections).2. Alcohol or drug intoxication; abnormal circulatory dynamics.3. Patients undergone renal transplant; chronic renal diseases.4. Malnutrition, general debility, sickle cell anemia, hyposplenism or splenectomy, nephrosis or complement deficiency. 5. Young children and the elderly.

Sudden onset with fever, chills and sharp chest pain. Bloody, rusty sputum. Empyema (mostly caused by type 3) is a rare but significant complication.Complications caused by spreading of pneumococci to other organs: sinusitis, meningitis, endocarditis, septic arthritis, middle ear infection. Clinical diseases S. pneumoniaePneumococcal pneumonia develops when the bacteria multiply rapidly in the alveolar space after aspiration. The affected area is generally localized in the lower lobes of the lungs (lobar pneumonia). Children and the elderly can have a more generalized bronchopneumonia. Resolution occurs when specific anticapsular antibodies develop.

S. pneumoniaeLaboratory diagnosis Examination of sputumStained smears of sputum: a rapid diagnosis.Quellung test with multivalent anticapsular antibodies.CultureSpecimen: sputum, aspirates from sinus or middle ear, CSF.cultured on blood agar plate in 5-10% CO2.Identification: bile solubility, optochin sensitivity, etc. for differentiation from other a-hemolytic streptococci. Additional biochemical, serologic or molecular diagnostic tests for a definitive identification.Antigen detection: detect capsular polysaccharide in body fluids.

*Aerobic: SOD and catalase positive (important for survival)Mouth full of both aerobics and anaerobics (ask why?)Microaerophilics: H. pylori discovery story (2005 Nobel Prize in Medicine)Endospores are formed by certain Gram positives--to overcome adverse growth condition (B. anthracis)Exospores formed by fungi are for the purpose of replicationTCBS medium for Vibrio (enrich and differentiate)

Rikettissa: typhus, Rocky mountain spotted feverCoxiella: Q feverErlichia: ehrlichiosmYellow color by S. aureus de[ends on culture mediaSeritia marcesens: red pigmentMacConkey: bile salt kills Gram positivesEMB: eosin-methylene blue agar, select for enterics (mechanism?), differentiate lac+/-Mannitol salt: high salt (7.5% NaCl) select for certain bacteria, especially Staphylococcus sp., differentiate mannitol+/-Thyayer-Martin medium: contains several antibiotics, select for Nieseria. **Botulus latin word for sausage (first known as sausage disease) C. botulinum does not grow in sausage today mainly due to nitrites added. Infant botulism 250 per yr., most associated with honey (due to unestablished microbial flora in G.I.*About 50 cases a yr. In U.S. World wide 1 million per yr. (50% in newborns because they dress severed umbilical cord with soil, clay or cow dung) Tetanospasmin inhibits the release of acetylcholine by interfering with activity of cholinesterase (enzyme that normally breaks down acetylcholine)*H Hauch (film) seen on growth media if bacteria are motile FLAGELLAO Ohne Hauch (without film) no flagella CELL WALLK Kapsel**rising progressively, later falling, and often disappearing within a few months