Respiratory Pathogens Bacteria Flashcards
Acinnetobacter Baumannii
- gram neg. coccobacilli (small rods), non motile, aerobic, oxidase neg, highly resistant to antibiotics
- blood agar
Ubiquitous (like pseudomonas). resistant to dryness, normal flora oropharynx of some people. Inhalled, ski trauma, hospital pathogen. High Risk: ventilators, catheters, surgery, elderly, ICU.
PATIENT: typical pneumonia, UTI, septicemia, soft tissue infection (gun shot Iraq-bacilllus)
TX. multi drug resistant
Bacillus Anthracis
- gram pos, spore forming, bacilli, chain formatin, aerobic, poly-glutamic acid capsule
- sputum, lesion pus, blood (no spores)
- blood agar. non hemolytic, white-grey rough colonies look like grounded glass
- PCR diagnonsis
Ubiquitous in soil and animals. Animal aquire by grasing. Humans aquire thru animal contact. Spores enter sutaneous, inhalation, ingestions. High Risk: animal workers, taners, taxidermi (biowarfare)
- antiphag poly-glutamate capsule
- toxin: AB-toxin coded by plasmid genes.
- protective agent (PA): binds mediates entry into many cell types. monomers elf associate to heptamers that act as pores allowing toxin entry to cell.
- edema antigen (EF): adenylate cyclase elevates cAMP resulting in edema
- lethal factor (LF): Zn-dependant protease inhibits several kinases causing cell death
PATIENT: three disease based on route of entry. black necrosis with raise edematous edges. intestinal anthrax rare in humans. wool sorter’s disease incubates >2months while macrophages engiulf and carry to mediastinal lymph nodes. atypical pneumonia. massive chest edema, hemorrhagic mediastinal lymphadenitis (widened mediastinum). hemorrhagic pleural effusions, bacteremia and toxemia (cyanosis, shock, death within 3 days). Meningeal symptoms.
Tx. ciprofloxacin or doxycycline plus two other (rifampin//vancomycin etc). Post exposure prophylaxis for 60 days. Vaccine for at risk and animals (partial purified protein)
Bordetella Pertussis
gram neg. rod.strict aerobic. encapsulated.
Human only, aerosol treansmission/direct contact Risk: adults, unvaccinated children (wanning immunity from old vaccine)
PATIENT: Whooping cough. paroxysms of coughing often follwed by emesis.
- multiplies rapidly Adheres to epithelial surface trachea and bronchi interfering with ciliary function.
- Filamentous hemagglutinin (FHA) adheres and pertactin. both bind to integrins on ciliated cells, both bind CR3 on macrophages and induce phagocytosis without initiating resp burst.
- Grows intracellularly in macrophages protected from humoral immunity.
- Toxin AB type: ADP rybosylates Gi protein (remove inhibition) increase cAMP.
- increasing secretions
- increased insulin leading to hypoglycemia
- lymphocytosis: inhibit signal transduction of cytokine receptors and chemotaxis (blocking immune effector cells)
- increase histamine sesitivity
- Tracheal cytotoxin (peptidoglycan subunit) interfers with DNA synthesis, kills ciliated respiratory cells
- adenylate cyclase toxin/hemolysin secreted by the bacteria,
- absorbed by the host cells and get activvated to convert ATP to cAMP (impair chemotaxis/phagocytosis)
- Patient may develop encephalopathy due to lack of O2 in the brain symptoms like convulsions and seizures (infrequent)
- stages:
- -incubation (7-10days) asymptomatic
- -catarrhal (1-2 wks: contagious) rhinorrhea,malaise, fever, sneezing, anorexia.
- -paroxysmal (2-4wks) repetitive cough with whoops, vomitting, leukocytosis
- -convalescnet (3-4wks) diminished paroxysmal cough development of secondary complications (pneumonia,seizures, encephalopathy)
TX. macrolides. erythromycin or azithromycin in early stage. supposrtive care in late stages
- Micro: fluorescent Ab on aspirated specimen (high false positives - not very specific)
- Culture: not very sensitive
- BORDET GENOU enriched potato-blood-glycerol agar media resistant to penicillin (can add to make selective media)
- -charcoal-cephalexin blood agar, -
- regan lowe agar nicotinic acid supports growth while charcoal and starch removes fatty acids melecular methood:
- PCR (most used) serology: ELISA titers
- Tx.
- PREVENTIONl: DPT vaccine (diphteria, pertusis tetanus). whole cell inactivated (has side effects no longer used in USA)
- DaPT vaccine multivalent acellular vaccine Erythromycin prophylaxis
Burkholderia Capecia
nine burkholderia spp. capecia best known.
- gram neg, bacilli, aerobic non-fermenter, oxidase pos, NO pigments.
- BAP or with polymyxin medium resistant
Moist environments surfaces (similar to pseudomonas). Inhaled. opportunistic pathogen. High risk in CF/chronic granulomatous disease/chronic pulm disease. aquired thru respirators/catheters. (not pathogen in healthy indivicuals)
PATIENT: UTI catheterized patients. Typical pneumoni
TX. trimethoprim sulfamethoxazole (less resistant than pseudomonas)
Chlamydiaceae - Chlamydophila Pneumoniae
- energy parasites (use host cell ATP). obligate intracellular
- cell wall but lack muramic acid. grow in HE-p2 cell line.
- do not gram stain
- biphasic growth cycle: elementary body (infectious/ met inactive) and reticulate body (met active)
- Serology microinmmunoflurescent (MIF) or complement fixations test
- ER body adhesion cell surface, endocytosis, endosome deos not fuse lysosome, reorganizes to RB. binary fision replication, reorg to EB, inclusion granules with both EE and RB. Reverse endocytosis. (except psittaci lyses cell and inclusions)
Human resp tract thru resp droplets. High Risk: elderly
- intracellular groth, infects macrophages, endothelial cells, coronary artery and smooth muscle
PATIENT: assymptomatic or pharyngitis, sinitis, bronchitis, walking pneumona, also linked to ATH, ALZ, asthma, reactive arthritis.
Tx. prolongued treatment due to high recurrence. doxycycline, fluoroquinolones, erythromycin
Chlamydiaceae - Chlamydophila Psittaci
- energy parasites (use host cell ATP). obligate intracellular
- cell wall but lack muramic acid. grow in HE-p2 cell line.
- do not gram stain
- biphasic growth cycle: elementary body (infectious/ met inactive) and reticulate body (met active)
- ** Serology microinmmunoflurescent (MIF) or complement fixations test**
ER body adhesion cell surface, endocytosis, endosome deos not fuse lysosome, reorganizes to RB. binary fision replication, reorg to EB, inclusion granules with both EE and RB. Reverse endocytosis. (except psittaci lyses cell and inclusions)
Birds (turkeys) in tissue, feathers, fecces, urine. respiratory droplets and dust (not person-person). High Risk: abatoir workers etc.
PATIENT: parrot fever, ornithosis, psittacosis, atypical pneumonia, brochitis, pharyngitis, sinusitis, (rarely death). in severe cases involves hepatosplenomegaly, GI, CNS.
TX. doxycycline, macrolides, fluoroquinolones. (tx bird with chlortetracycline)
Corynebacterium Diphteriae
gram+. pleomorphic (snapping divisions - chinese letters) coryneform (clubbed end shaped) arranged in pairs of V or L shapes form granule (volutin) beaded appearance
Human only host. nasopharynx, upper resp, GI, skin (normal flora). Risk. unvaccinated, crowded, children (found in the tropics)
PATIENT: fibrinous pseudomembranes on uvula and upper airways, bull neck, cardiac arrythmias, neuropathies.
- Aquires toxic gene from phage (lysophagenized bacteria). spread thru lysogenized bacteria.
- carried by beta phase lysogenised corynebacteria binds to heparin-binding epidermal growth factor (HB-EGF) found on many cells ( like heart and nerve) regulation via DTxR (iron dependant repressor protein) on chromosome which responds to tissue iron levels
- LOW iron = toxin gene expression
- HIGH iron represses toxin gene (no toxin)
- Diphteria: incubation 2-6 days. sore throat, fever, dyspnea. local inflammation with fibrinous exudates that form though, adherent gray/green/black pseudomembrane. -exudate filed with neutrophils, necrotic epithelial cells, erythrocytes, bacteria in fibrin mesh -difficult to detach without damaging underlying tissue (bleeds when removed and hard to the touch) - located on anterior nasal, tonsils, pharynx (airway obstruct) *bull neck Appearance* enlarged anterior cervical lymph nodes and edema of soft tissue skin diphteria possible.
- Toxin may be carried to other organs (heart, liver, kidney, and cause necrossis) not all strains produce toxin! (need phage)
- Myocarditis (arrythmias and circulatory collapse)
- nerve weakness/paralysis (cranial nerves) can lead to regurge fluids thru nose.
- can lead to perforation of soft palate, skin lesions,
- Virulence: DT A-B exotoxin inhibits protein synthesis thru ADP ribosylation of EF2.
- DGX:. cystine-potassium tellurite plate (inhibits most normal flora and grown blackgrey diphteria colonies in 24-48 hrs)
- blood agar: small grey (may have zones of hemolysis)
- loeffer’s serum plate for granule formation stain metachromatic stain
- Ouchterlony immunodiffusion line of precipitin (ELEK) antitoxin strip
- PCR to detect toxin gene
- TX: diphteria anti-toxin (passive immunity)
- penicillin/erythromycin respiratory support
- PREVENTION: DPT vaccin with boosters
Epiglottitis
- Haemphilus influenzae (thumb sing)
- gram neg (pink), pleomorphic rod/coccobacilli, capsulated capsular types a thru f (type B most virulent many non-typabeale are normal flora).
medical emergency acute onset, fever, sore throat. dysphagia dysphonia drooling distress stridor (high pitch inhale) muffled voice pharynx inflammed beefy, cherry red, stiff, swollen epiglottis.
Dgx. lateral x-ray of neck, *thumb sign*, laryngoscopy
dd: strep throat (strep pyogens GAS), croup (parainfluenza), corynebacterium diphteria, peritonsillar abscess, infectious mononucleosis acute herpesviridae ebstein barr virus.
Haemophilus Influenzae
- gram neg (pink), pleomorphic rod/coccobacilli, capsulated capsular types a thru f.
Human only. nasopharynx, capsular type B most virulent (many non typabeale types are normal flora). respiratory droplets Risk: unvaccinated 2-4year olds.
PATIENT: ottis media, sinusitis, lower resp infection. *HiB* causes invasive meningintis and epiglottitis (thumb sign) (may cause complete airway obstruction)
- polysaccharide capsule type B of polyribose-ribitol phosphate (HiB)
- IgA protease
- Endotoxin. lipo-oligosaccharide (LOS) similar to neiseria adherence toxic to ciliated eclls induce inflammation
- Dg. Ag detection on latex agglutination or rapid capsular antigen type B.
- Chocolate Agar (or growth factors X-hemin and V-NAD. Or satellite to S. Aureus.
- Tx. cricothyrotomy if necessary,
- antibiotics broad-spectrum caphalosporin (or in mild cae amoxicillin/doxycycline)
- Prevention. HiB vaccination conjuated with tetanus ordiphteria.
- chemoprophylaxis: rifampin to eliminate carriage in high risk groups or outbreaks
Klebsiella Pneumoniae
gram–, rod/bacillus, facultative anaerobe, lactose fermentoer (MacConkey agar pink), enterobacteriaciae, non-motile,oxidase neg, indole negative, highly mucoid colonies with large capsule
Normal GIT, URT flora. aspiration, endogenous, resp droplets, top ten nosocomial infections. High risk in chronic lung disease ,alcoholism, diabetes, resp equipment…
PATIENT: necrotic destruction of alveolar spaces, cavity formation, lobular consolidations. Thick current jelly blood tinged sputum. may lead to septecemia. Causes UTI.
- Antiphagocytic capsule
- LPS endotoxin (inflammations, septic shock)
TX. antibiotic resistant (vancomycin resistant)
Legionella penumophila
- gram neg, bacilli (pleomophic), hard to stain (use silver impregnation or other stain), use direct fluorecnet Ab to detect.,
- fastidious growth (cystein, iron enriched media). Buffered Charcoal Yeast Extract Agar (BCYE)
- charcoal neutralizes toxic fatty acids in media
- Urine Ag test: immunoassay test for LP specific LPS antigen (most sensitive)
- NAA nucleic acid amplification test not often used
- Ab detection: (4 fold increase to determine current infection). ELISA or Direct Fluorecnet Ab stain (1:128 or greater)
Aquatic habitat. survives inside amoeba in water, misted grocery veg, cooling towers, showerws, hottubs, decorative fountains, resistant to chlorine and 45degF (7degC). inhalled aerosol/water. (no person-person). High Risk: alcoholic, smokers, COPD, diabetics, older immunocompromised.
- facultative intracellular pathogen of alveolar macrophag, monocyte, epithelial cells
- C3b deposition facilitates phagocytosis
- no fusion phago-lysosome
- infected macrophages produce cytokynes (inflammation)
- PATIENT: assymptomatic is common.
-
Pontiac fever: flu-lke.
- incubate 2 days. flu 2-5 days
- fever, chills, myalgia, malaise, headache (some have dry cough)
- no pneumonia evidence
- Tx self limiting
-
Legionnaires disease: atypical pneumonia
- incubation 2-10 days
- severe toxic pneumonia. rapid onset from flu-like symptoms
- patchy interstitial infiltration with tendency to develop into consolidation and micro-abseces
- may become multi rgan disease (CNA, GI, Liver, Kidney)
- mortality up to 15% in healthy
TX. antibiotic must penetrate human cells. Macrolides (azithromycin or clarithromycin). Fluoroquinolones (ciprofloxaci or levofloxacin). Copper-silver ionization of water supply.
Moraxella Catarrhalis (used to be called branhamella)
- gram neg, diplococci-bean shaped, oxidase positive,
- like neisseria family but does NOT ferment glucose, maltose, or sucrose
- attach to or reside in PMNs in sputum specimen
Human normal pharyngeal flora. Tx by aerosol. immunocompromised (elderly and children) for the sever pathogenesis effects.
- Patient: ottitis media (3rd most common). sinusitis in children and bronchitis/pneumonia in elderly
- Tx: most are betalactamase positive and p_enicillin resistant_. ampicillin/clavulanate (augmentin) 2nd or 3rd gen oral cephalosporins (TMP/SMX)
Mycoplasma Pneumoniae
smallest living creature. cell wall-less, pleomorphic, sterol cell membrane. requires cholesterol in culture.
- bronchial washings.
- cuture mulberry (fried egg) colonies on A8 agar providing cholesteroland antibiotics to kill others (>6weeks to grow)
- cold agglutinin test: IgM Ab bind RBC O blood at 4degC (epstein barr, CMV, and lymphoma: low specificity)
- NAA nucleic acid amplification test and antigent detection
- ELISA (4 fold increase) detect Ab against P1-Ag
Human resp tract. Aerosol spread. incubates 1-4 weeks. High Risk: teenagers/young adulst. outbreaks in college/military
- Adhesion: surface P1 protein binds to sialic acid on celiated resp epithelial cells
- can also bind sialic acid containing glycoproteins of RBC causing agglutination.
- binding site not on goblet or nonciliated cells.
- tissue damage: produces hydropen peroxide, superozide radicals and cytolytic enzymes. kills cellsand destroys ciliar action.
PATIENT: pharyngitis, tracheobronchitis (low gade fever, dry cough), pneumonia (atypical/walking) patchy bronchopneumnia. complications include hemolytic anemia, neuro abnormalities.
TX. beta lactams. tetracycline, erythromycin and quinolones
Mycobacterium Tuberculosis
Acid fast bacteria (auramine-rhodamine) (130 spp. including atypical pneumonia M.Avium, M.Kansasi in HIV patients from soil/water, and M.Bovis in animals/unpastured milk. Skin manifestations in M.leprae, M.marium, M.ulcerans)
- strictly human pathogen
- acid fast, rod, obligate aerobic, non-spore forming, facultative intracellular, slow grower (up to 24hrs)
- high guanine/cytosie ration,
- produces niacin (unlike other M.spp.)
- acid fast: lipoarabinomannan and phosphatidylinositol mannosides (PIM), mycolic acid, peptidoglycolipids linked to arabinogalactan. (high lipid-wax content) and surface proteins (PPD Ag source)
- resistant to stain, antibiotics, acid/alkaline, osmotic lysis via complement deposition, oxidation -survives in macrophages
- Cord factor (trehalose dimycolate) part of lipid in virulent strains only responsible for serpentibe appearance (parallel clumping) of cells in culture.
strict human pathogen, inhalation, can survive 8 months in air. Risk Factor: malnutrition, crowding, drug users. 33% seropositive worldwide.
- no capsule, no exo or endotoxin
- survives within macrophages by preventing fusion phagolysosome and resisting oxidative killing
- affects the lung but may spread to other organs
- first exposure no specific immunity. innate immunity macrophage engulfs bacteria which resist intracellular killing. macrophage secrete IL-12 nd TNF alpha (recruit infamm cells). Macrophages present to T-cells differentiate to Th1 cells secreting TNF-gamma activating the macrophages.
- granulomatous lesions epitheliod cells, giant cells, T lymphocytes, central caseous necrosis where bacteria may remain viable for long time (reactivation when immune system is lowered)
- tubercle granuloma surrounding fibrous tissue.
- Ghon complex formed as macrophage carry organism to nearby lymph nodes cusing it to swell.
PATIENT: asymptomatic granuloma formations. impairment of immune system can re-activate (upper lung). gradual onset, cough, bloody sputum, fever, chills, night sweats, weight losss (lower part of lung) Tubercle may burst causing caseous cavity which both disseminates blood stream to other organs (miliary tuberculosis) and enables opportunistic pathogens.
- chrinic meningitis,
- scrofula lyphatics of the neck,
- Pott’s disease in bones and joints,
- urogenital tuberculosis.
- Tuberculin/Mantoux test/PPD (purified protein derivative) test: delayed HSR to tuberculin proteins to past, latent, current infection. measure induration.
- >5mm positive
- >10mm incresaed risk person positive.
- >15mm positive in person with no known risk factors
- Xray looking for tubercles, ghon, cavitary lesions
- staining microscopy: acid fast, ziehl-neelsen stain, immunofurescent staining with auramin-rhodamine stain. binds acid fast bacteria.
- INF-gamma release assay (IGRA) how the immune system reacts to the bacteria. patient blood mised with TB Ags, incubated, then INF-gamma is measured. If present then the patien’s WBCs are already sensitized to TB.
- culture: inoculated into egg based media middlebrook 7H10 or lowenstein-Jensen (up to 8 weeks for results) using sodium hydroxide to reduce contaminants.
- DNA probes
TX. treatment for 6-9 months (or chemoprophylaxis for at risk), isoniazid, rifampin, pyrazinamide, ethambutol. Resistant strains have emerged MDR-TB and XDR-TB. immunoprophylaxis BCG-Bacille Calmette-Guerin attenuated bovine strain.
Glomerulonephritis
Streptococcus Pyogenes
Genus: Grm POS. cocci (chains). catalase neg. lactobacillale (facultative anaerobe)
Spp: hemolytic B. Lacefield A (GAS). bacitracin senstitive. PYR positive
immune mediated (Type III HSR) Ab/Ag depositions
- >150 serotypes * M protein types (immunogenesity and virulence factor)
- Acute post streptococcal glomerulonephritis
- triggers inflammatory reaction leading to tissue damage and impairmemt of normal kidney function usually follows skin infection.
- Patient: edema, hematuria, proteinuria, smoky urine.
- Dgx. clinical hx of skin or throat infection and serology of Anti-ASO and anti-DNAase
