Campylobacter

CampylobacterAmong the most widespread cause of infection in the world.Cause both diarrheal and systemic diseasesCampylobacter jejuni

Typical Organisms Gram-negative rods with comma, S, or gull-wing shapes.Motive, with a single polar flagellumNo spore & no capsule

CultureAn atmosphere with reduced O2 (5% O2) with added CO2 (10% CO2)At 42 (for selection)Several selective media can be used (eg, Skirrows medium)Two types of colonies: watery and spreading round and convex

Virulence FactorLipopolysaccharides (LPS) with endotoxic activityCytopathic extracellular toxins and enterotoxins have been found

PathogenesisThe infection by oral route from food, drink, or contact with infected animals or animal products(Milk, meat products ).Susceptible to gastric acid (about 104 organisums) Multiply in the small intestine invade the epithium produce inflammation cause bloody stoolsOccasionally, the bloodstream is invaded

diarrhea malaise fever abdominal pain usually self-limiting antibiotics occassionally bacteremia small minorityCampylobacter - symptomsIncubation: 4-8dAcute enteritis: 1w, stools remain positive for 3 wAcute colitisAcute abdominal painBacteremia:

Diagnostic Laboratory TestsSpecimens: Diarrheal stoolsSmears: Gram-stained smears of stool may show the typical gull-shaped rods.Culture: (have been described above)

ControlThe source of infection may be food (eg, milk, under-cooked fowl) or contract with infected animals or humans and their excreta.

Curved bacilli Former name - Campylobacter pylori, H. pylori

Helicobacter pylori

Helicobacter pyloriHelicobacter pylori is the prototype organism in this group. It is associated with antral gastritis, gastric ulcers, and gastric carcinoma.

MicrobiologyGram negative rod, curved, Very Motile corkscrew motionMicroaerophilic, use amino acids and fatty acids rather than carbohydrates to obtain energy needs 10% CO2 and 5% O2Urease productionCatalase productionOxidase positiveGrowth at 370C, not 250C or 420C

Virulence factorsvacA (vacuolationg associated) cytotoxin, Pathogenicity island: cag, cytotoxin associated gene A+genes related to bacterial secretion Cag+ HP is much more associated with peptic ulcer disease than Cag(--) HP.

PathogenesisMotility it moves into the mucus and produces adhesins on gastric epithelial cells (not intestinal epithelial cells)Urease production, breaks down the urea to ammonia which buffers the pH around the bacterium.Persists, escape defense mechanisms SOD, catalase, Urease. Breack down free radicals

PathogenesisH pylori invade the epithelial cell surface to a certain degreeToxins and LPS may damage the mucosal cellsNH3 produced by the urease activity may also damage the cells

Epidemiology

EpidemiologyPrevalence related to socioeconomic level during childhood.Infection occurs in childhood, persists for decadesPrevalence among adults 20%-100%Source stomach of humansMode of transmission? Fecal-oral? Oral-oral? Vomiting and aerosols ?Incidence of HP colonization is declining in developed countries

EpidemiologyUnder age 30 80% in adultsAcute epidemics of gastritis suggest a common source for H pylori.

Clinical featuresAcute acquisition - nausea, vomiting, abdominal painlast for 1w, later gastritis.Persistent colonization - after acquisition, persist for years. Asymptomatic. Duodenal ulcer more than 90% with DU - carry HP. antimicrobial therapy response, eradication of HP - less recurrences

Gastric ulcer - 50-80% HPGastric carcinoma -HP induces gastritis, gastritis is risk factor for Carcinoma.Gastric lymphoma - MALToma: mucosa associated lymphoid tumors, strong association with HP. Stage 1 is cured by antibiotics.Esophageal diseases - HP protects against: gastroesophageal reflux, Barrette's esophagus and carcinoma of esophagus.

Immunity An IgM antibody response to he infection is developedSubsequently, IgG and IgA are produced

Laboratory diagnosisEndoscopy and biopsy.Urease detection CultureUrea breath test - samples of breath air are collected by having the patient blow into a tube before and 30 min after ingestion of 13C-labeled urea, rapid, noninvasive, for assessing response 4-8w post therapy, expensive but non invasive!! Serology

Principles of therapyCombination chemotherapy Some drugs are effective in vitro, not in vivo - due to acidic pH - erythromycin Resistance - not to bismuth salts or tetracyclines, 10-30% to metronidazole, Response - 1 month after cessation of therapy for breath test or biopsy, 6 month for serology

Principles of therapyTriple therapy: Bismuth+metronidazole+amoxicillin: eradication 60-90%, tetracyclines, macrolides - clarithromycinPPI proton pump inhibitors therapy: omeprazolone lansoprazole: inhibit HP, urease, acidPPI+amoxicillin+clarithromycin or metronidazolePPI+ Bismuth+metronidazole+amoxicillin-very effective

PSEUDOMONAS

Common CharacteristicsGram-negativeMotileAerobic rodSome produce water-soluble pigmentsWidely in soil, water, plants and animalsMore than 200 (up to now)

Some of the medically important pseudomonas

rRNA Homology Group and SubgroupGenus and SpeciesI. Fluorescent Group

Nonfluorescent GroupPseudomonas aeruginosaPseudomonas fluorescensPseudomonas putidaPseudomonas stutzeriPseudomonas mendocinaII. Burkholderia pseudomalleiBurkholderia malleiBurkholderia cepaciaRalstonia pickettiiIII. Comamonas speciesAcidovorax speciesIV. Brevundimonas speciesV. Stenotrophomonas maltophilia

Pseudomonas aeruginosa

Pseudomonas aeruginosaWidely distributed in natureFrequently present in small numbers in the normal intestinal flora and on the skinCommonly present in moist environments in hospitals It is primarily a nosocomial pathogen

Typical Organisms Gram-negative rod ---- 0.62 mUnipolar flagellum (1~3) ---- actively mobile Occurs as single bacteria, in pairs, and occasionally in short chainCapsule Pili in strains obtained from clinical specimens

Culture Grow readily on many types of culture mediaSmooth and round coloniesMultiple colony types in one cultureFluorescent greenish colorSometimes produce a sweet or grape-like or corn taco-like odor

Culture Obligate aerobicGrow well at 37~42and no growth at 4 Produce water-soluble pigments Pyocyanin; Pyoverdin; Pyorubin; PyomelaninProduce hemolysinOxidase-positiveFerment glucose but not other carbohydrates

Virulence Determinants

Virulence Determinants Adhesins fimbriae (N-methyl-phenylalanine pili) polysaccharide capsule (glycocalyx) alginate slime (biofilm)Invasins elastase alkaline protease hemolysins (phospholipase and lecithinase) cytotoxin (leukocidin) siderophores and siderophore uptake systems pyocyanin diffusible pigment

Virulence DeterminantsMotility/chemotaxis FlagellaToxins Exoenzyme S Exotoxin A LipopolysaccharideAntiphagocytic surface properties Capsules, slime layers LPSDefense against serum bactericidal reaction Slime layers,capsules LPS Protease enzymes

Virulence DeterminantsDefense against immune responses Capsules, slime layers Protease enzymesGenetic attributes Genetic exchange by transduction and conjugation Inherent (natural) drug resistance R factors and drug resistance plasmidsEcologic criteria Adaptability to minimal nutritional requirements Metabolic diversity Widespread occurrence in a variety of habitats

Inhibition of protein synthesis in susceptible cells ----Toxin AThe resultant ADP-ribosyl-EF-2 complex is inactive in protein synthesis. This intracellular mechanism of action of toxin A is identical to that of diphtheria toxin fragment A .

Diverse sites of infection by P aeruginosa

Disease caused by Pseudomonas aeruginosa EndocarditisRespiratory infectionsBacteremiaCentral Nervous System infectionsEar infections including external otitisEye infectionsBone and joint infectionsUrinary tract infectionsGastrointestinal infectionsSkin and soft tissue infections, including wound infections, pyoderma and dermatitis

Who are at risk?People with cystic fibrosisBurn victimsIndividuals with cancerPatients requiring extensive stays in intensive care units

DiagnosisIsolation and laboratory identification. blood agar plates eosin-methylthionine blue agar.Gram morphology, Inability to ferment lactosePositive oxidase reactionFruity odorAbility to grow at 4 2 Fluorescence under ultraviolet radiation helps in early identification of P aeruginosa colonies and also is useful in suggesting its presence in wounds.

Control and TreatmentThe spread of Pseudomonas is best controlled by cleaning and disinfecting medical equipment. In burn patients, topical therapy of the burn with antimicrobial agents such as silver sulfadiazine, coupled with surgical debridement, has markedly reduced sepsis. Susceptibility testing is essential. The combination of gentamicin and carbenicillin can be very effective in patients with acute P aeruginosa infections.

ReviewGeneral characteristics: Gram negative rod, unipolar flagellum, actively motile; produce diffusible pigments -- pyocyanin,gluorescin and pyorubin; aerobic, produce hemolysin. Pathogenicity: cause suppurative infections in burn, trauma, etc. Endotoxin: main pathogenic substance Exotoxin A Extracellular enzymes:phospholipase, proteinase, etc. Bacteriological diagnosis: Specimens Culture and identification Unusual bacteria

Haemophilus influenzae

Common CharacteristicsSmall, gram-negativePleomorphic Require enrich media (usually containing blood for isolation)No flagellum, no sporeDivided into 17 species according to different requirement to X and V factor

HaemophilusSmall Gram-negative coccobacilli, facultative anaerobes, non motile often resemble cocci, eg pneumococci, most non-encapsulated strains --- virulent forms encapsulated fastidious (require blood factors) X factor = hematin V factor = NAD Organisms: H. influenzae: H. ducreyi --( soft chancre); H. aegypticus -- (purulent conjunctivitis)

Characteristics and growth requirements of some haemophilus speciesX=heme; V=nicotinamide-adenine dinucleotide

SpeciesRequires Hemolysis XVH influenzae (H aegyptius)H parainfluenzaeH ducreyiH haemolyticusH parahaemolyticusH aphrophilus+-++--++-++----++-

Haemophilus influenzaePresent in the nasopharynx of approximately 75 percent of healthy children and adults (non encapsulated strains as the normal flora)Rarely encountered in the oral cavity Has not been detected in any other animal species 6 types(a-f) according to capsular polysaccharide type in the encapsulated strainsH. influenzae type b (Hib) encapsulated strain is the most common cause of meningitis in children between the ages of 6 months and 2 years.

Biological Characteristics ----Morphology of organismIn specimens of acute infections: short (1.5m) coccoid bacilli sometimes in pairs or short chainIn culture: At 6~8 h on rich medium: small coccoid bacilli Later: longer rods, lysed bacteria, pleomorphic

Biological Characteristics---- ColoniesOn brain-heart infusion agar with blood: Small, round, convex, iridescence (24h)On chocolate agar: Takes 36~48h to develop 1mm colonySatellite phenomenonNot hemolyticsatellite phenomenon

Biological Characteristics---- GrowthAerobic or facultative anaerobicGrow well at 33~37Require X and V factorsGrow better on chocolate agar than on blood agar

Virulence factor Endotoxin Lipooligosaccharide Neuraminidase IgA proteaseFimbriae Polyribosyl ribitol phosphate (PRP) capsule (the most important)

Disease caused by H. influenzaeNaturally-acquired disease caused by H. influenzae seems to occur in humans only.BacteremiaAcute bacterial meningitisEpiglottitis (obstructive laryngitis), CellulitisOsteomyelitisJoint infectionsEar infections (otitis media) Sinusitis associated with respiratory tract infections (pneumonia)

An infant with severe vasculitis with disseminated intravascular coagulation (DIC) with gangrene of the hand secondary to Haemophilus influenzae type b septicemia - prior to the availability of the Hib vaccine Child has swollen face due to Hib infection, tissue under the skin covering the jaw and cheek is infected, infection spreading into her face.

Immunity Relation of the age incidence of bacterial meningitis caused by H influenzae to bactericidal antibody titers in the blood

Host resistance to infectionBactericidal antibody directed against PRP capsule of H. influenzae type b Antibody to somatic (cell wall) antigens

Who is at risk?Young children under 5 years (most cases occurring in infants between 6-11 months of age) Day-care attendees Those in contact with household cases of Hib diseaseImmune deficiencies that lower the body's resistance to infection

DiagnosisThe history and the physical exam.Detecting the bacteria in blood, spinal fluid, or other body fluidSatellite phenomenon

TreatmentH. influenzae meningitis: ampicillin for strains of the bacterium that do not make -lactamase; a third-generation cephalosporin or chloramphenicol for strains that do. Chloramphenicol for penicillin-resistant H. influenzaeThird-generation cephalosporins, such as ceftriaxone or cefotaxime: effective against H. influenzae and penetrate the meninges wellTetracyclines and sulfa drugs: sinusitis or respiratory infection caused by nontypable H. influenzae. Amoxicillin plus clavulanic acid (Augmentin): effective against -lactamase producing strains.

ControlHib conjugate vaccines licensed for use among children

Gram stain and Laboratory GrowthGrowth REQUIRES X (hemin) factor only (H. influenzae needs X and V)Organisms also grow best in an increased CO2 environment. DIAGNOSIS: Generally made on presentation only.Soft, very painful chancre.

Legionella46 species of Legionella and 68 serogroups. 1976 outbreak of pneumonia occurred among persons attending a convention of the American Legion in Philadelphia.First defined Legionella pneumphila.

MorphologyAerobic ,gram-negative, motile, catalase-positive Stain poorly by grams method,basic fuchsin should be used as the counterstainGrow on BCYE(buffered charcoal-yeast extract agar) with -ketoglutarate,at pH 6.9, 35 C,90% humidity3 days of incubation,colonies are round or flat with entire edges.Color vary from colorless to pink or blue

0.5-1 um wide ,2-50 um long

Cell productsProduce distinctive 14-17 carbon branched-chain fatty acid.Produce proteases, phosphatase, lipase, Dnase,& RnaseProduce a metalloprotease

Transmissioncontaminated air infected water supply

not spread person-person

PathogenesisAttach to phagocytic cell surface 1).no antibody : C3 deposite on the bacterial surface,attached to CR1 or CR3 2).antibody is present : Fc-mediated phagocytosisfail to fuse with lysosomal granules and ribosomes,mitochondria around vacuoles containing L pneumophila, Then cells are destroyedPontiac fever marked by fever, chills, headache and malaise that lasted 2-5 days Legionnaire's disease the more severe form of infection which includes pneumoniaImmunityAntibodies 4-6 weeks after infectionCell-mediated response is important

Epidemiology1)When legionellosis occur?they are are usually occur in the summer and early fall, but cases may occur year-round. About 5% to 30% of people who have Legionnaires' disease die.2)How is legionellosis spread?Legionella are typically associated with aerosolized water (central air conditioning, cooling towers, showers, whirlpool spars). Disease is generally waterborne; transmission occurs via airborne droplets.3)Where is the Legionella bacterium found?The organisms exist in many types of water systems in nature; humans are an accidental host.

Risk Groups The elderly, cigarette smokers, persons with chronic lung or immuno-compromising disease, and persons receiving immunosuppressive drugs

DiagnosisClinical: Symptoms include headache, malaise, rapid fever, nonproductive cough, Chest X-rays show pneumonia Laboratory: immunofluorescent(IF) ,silver stain. Legionella antigens in urine samples Legionella-specific serum antibody ErythromycinRifampicinPontiac fever requires no specific treatmentTreatmentControlRegular maintenance of air conditioning or the inclusion of biocidal compounds into water cooling towers reduces the reservoir. Similarly, hyperchlorination of the water supply eliminates the source.

BordetellaClassification the genus contains three medially important speciesB. pertussisB. parapertussisB. bronchosepticaBordetella pertussis

Virulence factorsPili for attachmentPertactin, an outer membrane protein also acts as an adhesionFHA: Filamentous hemagglutininPT: Pertussis toxin Bacterial adenylate cyclase Dermonecrotic toxin causing strong vasoconstrictive effects. Tracheal cytotoxin the killing and sloughing off of ciliated cells in the respiratory tract.Lipooligosaccharide associated with the surface of the bacteria and has potent endotoxin activity

pertussis toxin

Pertussis is generally a disease of infants (50% of cases occur in children less than 1 year old). Acquired by inhalation of droplets containing the organismThe organism attaches to the ciliated cells of the respiratory tract. During an incubation period of 1-2 weeks, the organism multiplies and starts to liberate its toxins.Next the catarrhal stage occurs - This last ~ 2 weeks.Next is the paroxysmal stage that lasts ~ 4 weeks. The patient has rapid, consecutive coughs with a rapid intake of air between the coughs (has a whooping sound). The ciliary action of the respiratory tract has been compromised, mucous has accumulated, and the patient is trying to cough up the mucous accumulations. The coughs are strong enough to break ribs! Other symptoms due to the activity of the released toxins includeFinally there is a convalescent stage during which symptoms gradually subside. This can last for months.B. pertussis rarely spreads to other sites, but a lot of damage may occur, such as CNS dysfunction which occurs in ~10 % of the cases and is due to an unknown cause. Secondary infections such as pneumonia and otitis media are common.

B. Parapertussis & B. bronchoseptica B. parapertussis causes a mild form of whooping coughB. bronchoseptica Widespread in animals where it causes kennel cough.Occasionally causes respiratory or wound infections

CONTROLSanitary: This very contagious disease requires quarantine for a period of 4-6 weeks. Immunological: Pertussis vaccine is a part of the required "DPT" schedule. Chemotherapeutic: Antibiotic prophylaxis (erythromycin) may be used for contacts. Treatment of disease with antibiotics does not affect its course