Week 10 Flashcards

Question

What is the specimen collection like for Neisseria meningitidis

Answer 1

-direct gram stain - NOT good for nasopharyngeal -Intracellular and extracellular GNDC ◦ inside or outside the PMNs Use cytocentrifugation of CSF (cerebrospinal fluid) to enhance detection

Answer 2

- same as GC but less fastidious and will grow on BA -needs increased CO2 and humidity -best at body temp ◦ Gray, transparent, smooth, round, convex ◦ 1-1.5 mm @ 24hrs incubation ◦ Mucoid with capsule

Answer 3

GNDC -Oxidase positive Bacticard= GLUT + -gonogen -neg -acid from carb metabolism = GLU/Malt -serology must be done -work must be done in a BSC if isolated from invasive sample -treatment failure is rare -AST not usually done -send to PHL for broth and agar Note that Neisseria lactamica G+M+L+ (can use ONPG)

Answer 4

-vaccine with 1 dose+booster -group B if high risk -Contacts of primary disease receive prophylactic antibiotic therapy (chemoprophylaxis), or a vaccine (immunoprophylaxis) depending on risk level. *Unprotected healthcare worker *Household contact *Airline passenger *Shared food, cigarettes, etc.

Answer 5

-found in RT of children and old people -PATHOGEN causing otitis media, sinusitis , Bronchopneumonia, endocarditis, meningitis, LRTI in old people with COPD -Bacteremia 2nd to pneumonia in immunocompromised

Answer 6

Pili - adherence to pharyngeal epithelial cell -Presence of intracellular GNDC in respiratory specimens (sputum) may be possible infection with M. catarrhalis

Answer 7

-less fastidious than GC or meningococci -NON SPORE FORMING NON MOTILE -growth on BA or CHOC strict AEROBE but grows more at CO2 -grey -creamy white and raised -FRIABLE can push like a hockey puck -Oxidase and catalase positive -No acid production (glucose, maltose, lactose, sucrose negative) -DNase positive -Tributyrin hydrolysis positive SAME AS BactiCard Neisseria- first well AST -chromogenic cephalosporin method to detect βlactamase (e.g. cefinase)

Answer 8

blood lover Pathogenic ◦ Haemophilus influenzae ◦ H. ducreyi Non-pathogenic or opportunistic ◦ H. parainfluenzae ◦ H. hemolyticus ◦ H. parahemolyticus ◦ H. aphrophilus ◦ Aggregatibacter sp.

Answer 9

always look at CHOC plate to see if difference between the types -GNB, pleomorphic, coccobacilli ◦ Small coccobacilli (direct smears of clinical specimen) ◦ Thin GNB (picking of colonies) -non motile, non spore forming -facultative ANO2 -Ferments carbs -reduce nitrates to nitrites - oxidase +, catalase + -require X factor (hemin or hematin), V factor (nicotinamide adenine dinucleotide [NAD]), or both -sensitive to drying and cold

Answer 10

-found in NF of resp tract of humans and animals -Non-typeable (no capsule) -serotypes by CAPSULAR AG -◦ *Type b most virulent (HiB) – once leading cause of meningitis

Answer 11

Nonencapsulated strains - Otitis media - Conjunctivitis - Bacteremia - Pneumonia (LRTI) - Meningitis (immunocompromised, elderly) Encapsulated strains - Meningitis - Between 3mos-6yrs: type b - Septicemia - Osteomyelitis - Cellulitis in children (neck/face) - Septic arthritis - Pneumonia - Epiglottitis (peak: 2-4 yrs) - Bacteremia Vaccine for H. influenzae type b works very well

Answer 12

-Capsule but not all H flu has one IgA protease ◦ Only produced by H. flu ◦ Cleave secretory IgA Adherence by fimbriae ◦ found in nonencapsulated strains (more localized infections) Outer membrane protein (OMP) LPS – paralyzing effect on cilia in respiratory epithelials B-lactamase

Answer 13

-deep infection of the skin, with (systemic) symptoms such as fever and chills -redness increases as infection spreads

Answer 14

-always treated as NF -found in oral cavity -low pathogenicity -if there is disease itll be endocarditis but first there will be no symptoms but they will start later -first symptom will be a month AFTER dental procedure -MITRAL VALVE primary site of infection

Answer 15

- HUMAN PATHOGEN -CHANCROID - a VD -4-14 day incubation period ◦ Highly communicable genital ulcer disease; can infect non-genital skin ◦ Lesion (soft chancre) that resembles a syphilitic chancre (hard chancre) ◦ Painful, pus forming; associated with swelling of lymph nodes in the inguinal area (buboes)

Answer 16

-facultative anaerobe -CHOC mostly used for incubation -Chocolate agar with bacitracin used for selective medium also known as Haemophilus selective agar (HSA) - Blood agar with Staph streak (CO2)- satelliting colonies -wont see in ANO2 unless another org provides the V factor

Answer 17

X factor : hemoglobin degradation products hemin and hematin (X=unknown) V factor : nicotinamide adenine dinucleotide (NAD) or coenzyme I (V=vitamin) -both factors are present in CHOC which is why its the medium of choice -we use horse/rabbit blood instead of sheep because Sheep RBCs release NADase which can inactivate NAD in the medium therefore no V factor V factor also produced by ◦ some bacteria e.g. Staphylococcus aureus - hence satelliting in BA ◦ Some Yeasts H flu needs both X and V PARA needs only V Ducreyi needs X

Answer 18

done on TSA agar or BHI plate -look for cloud of growth -if there is growth it is positive -streak with 0.5McF and make a CHOC PURITY PLATE disks x v xv

Answer 19

-test looks for the ability of the organism to convert substrate δ-aminolevulinic acid (ALA) to porphyrin, an intermediate in synthesis of X factor ◦ Porphyrin detected by UV light with 360nm wavelength (Wood’s lamp) – fluoresces reddish-orange ◦ No fluorescence – Negative test ◦ i.e. X factor not synthesized H. influenzae : ALA Negative (X factor required) as it cannot synthesize heme H. parainfluenzae ALA Positive (X factor not required)

Answer 20

-direct gram stain then culture -GNCB -WEAK oxidase and catalase positive -Requires both X and V Direct Antigen Test ◦ antisera for direct detection of H. flu antigen in clinical specimens e.g. CSF ◦ Not considered very sensitive and specific – false positive results after vaccination on CHOC -Small, translucent, tan, moist, smooth -“mousy” or “bleach-like” odor

Answer 21

-Amplicillin - because there was penicillin resistance because of beta lactamase production -Beta lactamase on H flu (not para because its NF) using Nitrocefin or acidometric methods - Negative beta-lactamase does not rule out penicillin resistance by other mechanisms

Answer 22

-Bordetella pertussis – in humans only- causes pertussis, “whooping cough” -B. parapertussis – both humans and lambs, may cause mild pertussis -Small GNCB, nonmotile (except B. bronchiseptica), non-spore forming -obligate aerobe - growth at body temp -Grow well on ordinary media except B. pertussis

Answer 23

-HUMANS ONLY host -Affinity for ciliated epithelium of the respiratory tract = nasopharynx Virulence pertussis toxin and hemolysin; and has a capsule =Causative agent of pertussis (“whooping cough”)

Answer 24

-very contagious through respiratory droplets during the incubation period Classic pertussis has 3 stages Stage I: Catarrhal or Prodromal (1-2 weeks) - Cough, cold, low-grade fever Stage II: Paroxysmal (2-4 weeks) ◦ Severe and spasmodic cough with “whoop”; absolute and lymphocytosis Stage III: Convalescent (1-3 weeks or more)- Cough slowly subsides Complications: Bronchopneumonia, acute encephalopathy, asphyxia followed by death

Answer 25

-declined since vaccination but there are still spikes every year -part of DPT vaccine -adults are harder to diagnose

Answer 26

-special media for growth – unsaturated fatty acids, metal ions toxic Bordet-Gengou (B-G) medium with potato, glycerol, blood – made selective by adding methicillin or cephalexin- medium must be used in <5days Regan-Lowe – horse blood, charcoal, antibiotics – lasts for 8 weeks -incubate 35 aerobically with moisture -on RL the colonies are shiny like mercury droplets and then turn white grey as they age on BG agar they are hemolytic

Answer 27

Gram stain, motility, pigment, oxidase, urease B. pertussis : small GNCB hard to stain, non-motile, oxidase positive, urease negative. B. parapertussis : oxidase negative, non-motile, urease positive in 18 hours B. bronchiseptica (rarely a human pathogen): oxidase positive, motile, urease positive in 4 hours

Answer 28

◦ Nasopharyngeal swab ◦ Nasopharyngeal aspirate -done by PCR or DFA (Direct fluorescent antibody) Test Bordetella AG in the specimen plus Specific AB with fluorescent label : Fluorescence – Positive test Advantages - quick and detects non viable orgs DIS- can cross react with other bordetellae, false neg can occur ahrd to read due to non specific fluorescence

Answer 29

-Erythromycin or azithromycin -prophylaxis for contacts no standard treatment -use vaccines but a failure to maintain the booster schedule can cause outbreaks. Adults can become colonized and contribute to source

Answer 30

Zoonotic in people B. abortus – in cattle B. melitensis – in sheep, goats B. suis – in pigs B. canis – in dogs

Answer 31

-extremely infectious; -level 3 for cultivation ◦eating contaminated meat ◦ Through skin, mucous membranes by contact with infected animal/ carcass ◦ Inhalation How to reduce -mandatory pasteurization of dairy products, -immunization of cattle

Answer 32

◦ Obligate intracellular parasites; survive in phagocytes ◦ Circulated throughout the body by cells of the RE system Phases: acute, chronic, convalescent ◦ Chronic recurring fever (undulant fever), chills, headache, malaise, weight loss, anorexia – organisms intermittently in blood ◦ Complications: osteomyelitis, endocarditis, lung lesions, meningoencephalitis

Answer 33

-Class III safety cabinet – sent to a reference lab (PHL) -Blood – specimen of choice- during febrile period of acute illness multiple samples ◦ Automated culture systems or bi-phasic Castaneda bottle used Other specimens: lymph node aspirate, joint fluid, urine, CSF, liver/spleen biopsies

Answer 34

-CO2 incubation for 3 weeks at 35 -enriched media BA, CHOC best on Brucella agar-enriched with casein -NO GROWTH ON MAC -convex colonies -NH -serology with blood -Strict aerobes, capnophilic -some have affinity for placenta (erythritol) -GNCB (faintly staining) ▪ Catalase, oxidase, urea pos ▪ Nitrate to nitrites ▪ Potential bioterrorism agent ▪ Reportable to MOH

Answer 35

Habitat: Many wild animals, mainly rabbits, rodents, beavers, Francisella tularensis – ◦ human pathogenic species causing tularemia Transmission -low effective dose -handling dead infected animals like rabbit -insect vectors deerflies, ticks -eat infected carnivores -hunters at risk Small pleomorphic GNB

Answer 36

can turn typhoidal Virulence factors: ◦ Capsule ◦ invasive, can invade intact skin ◦ Intracellular, survives in RE cells Symptoms: ◦ Granulomatous lesions in many organs ◦ High fever, headache ◦ Lymphadenopathy ◦ Ulcerative lesion at the site of invasion ◦ Heals poorly ◦ Pneumonia, rhabdomyolysis ◦ High mortality rate without treatment

Answer 37

Level 2 pathogen for clinical specimens Level 3 for handling cultures Preventing aerosols is important

Answer 38

-Strict aerobe, no growth on MacConkey -Needs a special medium, cystine-glucose with thiamine, or charcoalyeast extract medium (Legionella medium) - 2-4 days, to 2 wks to grow

Answer 39

Identification ◦ Small pleomorphic gncb ◦ catalase weak positive ◦ oxidase negative ◦ Serological identification from blood specimens ◦ Direct fluorescent antibody tests ◦ Immunohistochemical staining ◦ PCR ◦ Streptomycin

Answer 40

L. pneumophila causes most diseases Habitat: -found in nature -aquatic environement , AC, plumbing, water cooling tower Pathogenicity: Legionnaire’s disease -◦ Inhibits destruction by phagocytes

Answer 41

Subacute illness – asymptomatic Pontiac fever: fever, cough, no lung involvement Legionnaire’s disease: high fever with pneumonia, cough with lung involvement , sporadic/epidemic, nosocomial Extrapulmonary: bacteremia, pericarditis, cellulitis, GI/liver abscess

Answer 42

erology –Serum Antibody detection ◦ 2 blood samples –initial & 4-6 weeks after ◦ IFA test -Seroconversion (increase in titre) Direct examination ◦ DFA: not very useful, replace with PCR Lower Respiratory Tract PCR & Culture ◦ If PCR (Real time PCR) positive, then cultured Urine antigen test ◦ Only 1 serotype, but effective for that one ◦ acute phase sample preferred class 2 path- sputum , bronch washings, urine . No transport medium -inhibitory -vortex and centrifuge

Answer 43

◦ Dies very quickly so process immediately ◦ NG on ordinary media ◦ BCYE agar – buffered charcoal, yeast extract ◦ BCYE agar with antibiotics as a selective medium -O2 incubation at 35 for 3-4 days -colonies are smooth GLASS SHINE, and FLUORESCE blue white in UV light -can grow between 25-43 AROBIC MOTILE SLENDER GNB OXIDASE AND CATALASE POSITIVE

Answer 44

-Haemophilus aphrophilus (now called Aggregatibacter aphrophilus) -Aggregatibacter actinomycetemcomitans -Cardiobacterium hominis -Eikenella corrodens -Kingella kingae

Answer 45

-NF HUMAN oropharyngeal, urogenital flora -associated with endocarditis, bacteremia, and polymicrobic wound infections -Slow growers; NG on MAC -cultures can take over 2 weeks -need enriched media -hemin enhances recovery in culture

Answer 46

fastidious -Dental plaque, gingival scrapings -Endocarditis; periodontal disease in teens - V factor dependent/independent - Small GNCB, yellow colonies opaque centre, catalase negative

Answer 47

-related to Haemophilus; small GNCB -Colonies stick to agar; old colonies look like stars Nitrate positive; negative for oxidase, catalase and urea

Answer 48

-Infects diseased heart valves, endocarditis -History of dental work preceding endocarditis -Isolated from blood cultures - aerobic and anaerobic, (CO2 enhances growth) -Gram variable, retains crystal violet at poles of cell; GNB -Cells pleomorphic: "tear-drop", "dumbbell" , "lollipop" shapes; rosette clusters or picket fence formations Oxidase positive, negative for catalase, nitrate, urea

Answer 49

fight bite -human bites, dental and periodontal infection, root canals, mixwed wound

Answer 50

-Facultative anaerobe, capnophile -Pits (corrodes) agar; "bleach smell“; produce yellow pigment after extended growth -NH -Slender GNB or GNCB -No carbohydrate utilization -Oxidase positive; negative for catalase and urea

Answer 51

PLUMP GNB/GNCB in pairs and short chains -Facultative anaerobe, NG on MAC -B-hemolytic; pits agar -Oxidase positive -Negative for catalase and urea -Osteoarthritis in children <4 -endocarditis in teens and adults -related to poor oral hygiene

Answer 52

NORMAL ORAL FLORA -associated also with bite wounds and oral cavities -Gram-negative fusiform bacilli -Gliding motility -growth on BA and CHOC not MAC -Colonies yellowish-tan; film around colony -juvenile periodontitis -sepsis in immunosuppressed and pt with no spleen