fall microb week 2 and 3

importance of graim stain

confirm material submitted us acceptable, ID cellular components, inflamm cells, suspected pathogens, gives rapid results, presumptive id, improper treatment could kill

specimens used for direct exam

sputum, BAL, bronchial washings, wounds, tissues, sterile body fluids, NOT stool blood or clean catch urine

gram stain steps

heat fix, primary stain (15 s), mordant iodine (105 s), decolorizer alc 1s, counter stain safranin 25 s

10x organism check

distribution and consistency, stain, scan in many areas

10x cellular check

quantitation, infection clue, contaimination- squamous EC, inflam- polymorphonuclear cells PMNs or wbcs, good- columnar EC

100x

quantitation of cells and bacteria, infec- single or mixed morph,

quantitation

rare less than 1, few 1-10, mod 11-25, many more than 25

anaerobes

rep in absence of oxygen, differ in response to oxygen, low redox potential

redox potential

measure of how much an environment tends to accept electrons

high redox potential

lost of oxygen or strongly oxidizing environment, unfavorable for anaerobes

low redox potential

little oxygen or reducing environment, favorable for anaerobes, repilcate this environment in certain media agars

obligate anaerobes

strict, killed in presence of oxygen immediately, bacteroides spp, clostridium, eubacterium, fusobacterium, peptostrep, porphyromonas

capnophilic

increased CO2 5-10%, reduced oxygen 15%, aerobes can still rep, some anerobes, neisseria

microaerophilic

oxygen reduced to 5% or less, campylobacter, helicobacter

facultative anaerobe

prefer oxygen as an electron acceptor, can grow without but slower, Enterobacteriaceae

aerotolerant

moderate anaerobes, survive in short exposure to O2 but cannot perform metabolic process unless placed into anaerbic environment, strep, propionibacterium, clostridium

clostridium spp

lower GI tract, GPR spores

Cutibacterium (formerly Propionibacterium)

skin, nasopharynx, oral cavity, gastrointestinal and genitourinary tract, GPR no spores

actinomyces spp.

mouth and genitourinary tract, GPR no spores

bacteroides spp.

Mouth, upper respiratory, gastrointestinal and urogenital tract, GNR no spores

prevotella spp., Fusobacterium spp., Porphyromonas spp.

Oral cavity, gastrointestinal and genitourinary tract, GNR no spores

Peptostreptococcus spp.

Skin, mouth, upper respiratory, gastrointestinal and urogenital tract, GPC no spores

Veillonella spp.

Upper respiratory, gastrointestinal and urogenital tract, GNC no spores

lactobacillus spp

gram pos, highly pleomorphic bacilli, aerotolerant anaerobe, good bacteria in vaginal canal, GPR no spores

mobiluncus spp

curved, gram variable bacilli, anaerobe, overgrowth can cause vaginal issues, bacterial vaginosis, GPR no spores

exogenous

outside body, ingestion, trauma, soil, water

endogenous

inside body, skin, mucosal surface, colonized with normal flora, reduce redox potential allowing ANA growth

collagenases

catalyze the degration of collagen, clostridium spp

cytotoxins

toxic to specific cell types, C. difficile

DNase

destroy dna, clostridium spp

enterotoxins

toxic to intestinal mucosa cells, c. difficile

hemolysins

lyse rbcs liberating hemoglobin, clostridium spp.

hyaluronidase

catalyzes hydrolysis of hyaluronic acid (cement substance of tissues), clostridium spp.

lipases

catalyze hydrolysis of ester linkage between fatty acids and glycerol of triglycerides and phospholipids, clostridium spp

neurotoxins (botulinum toxin, tetanospasmin)

destroy or disrupt nerve tissue, C. botulinum, C. tetani

phospholipases

catalyze the splitting of host phospholipids (lecithinase), clostridium spp

proteases

spit host proteins by hydrolysis of peptide bonds, clostridium spp

clostridium perfringens

gas gangrene (myonecrosis), NEC (gastrointestinal disease, bowel necrosis and inflamm, low birth weight, premature infant)

clostridium septicum

linked to underlying colonic malignancy, hematologic malignancies, neutropenia, diabetes

clostridium soredllil

gas gangrene of the uterus due to abortion, normal delivery, or cesarean section

clostridium tetani

tetanus, lockjaw- muscles contract

clostridium botulinum

3 types, foodborn- muscles paralyzed, infant, wound

clostridium (clostridiodes) difficite

established in gut of hosp pt after diminution of normal gut flora, diarrhea, pseudomembranous colitis (necrotic debis, wbc, fibrin on inflamed bowl), toxins A or B cause infec

Cutibacterium (formerly Propionibacterium)

inflam acne, systemic opportunistic infec (endocarditis, CNS, osteomyelitis, arthritis), normal skin flora

Actinomyces spp.: A. israelii, A. meyeri, A. naeslundii, and A. odontolyticus

mixed oral or cervicofacial, thoracic, pelvic, and abdominal infections caused by patient's endogenous strains abscesses

Bacteroides fragilis group,

anaerobic infec, throughout body localized or enclosed abscess, foul odor, below diaphram

Prevotella spp., Porphyromonas spp. Fusobacterium nucleatum

anaerobic infec, throughout body localized or enclosed abscess, foul odor, head neck pleuropulmonary infec

Fusobacterium nucleatum

anaerobic infec, throughout body localized or enclosed abscess, foul odor, Lemierre’s syndrome (oropharyngeal infection leading to septic thrombophlebitis of internal jugular vein)

Peptostreptococcus sp

polymicrobic infec, abscesses, contaminant in blood culture

Veillonella sp

mixed infec, periodontal/bite wounds, serious infections

Bacterial vaginosis is a synergistic infectious process involving

Gardnerella, Bacteroides., and Peptostreptococcus.

Based on the normal role of Lactobacillus in the vagina, which change would most directly contribute to the development of BV, and why?

Decreased Lactobacillus activity reduces lactic acid production, making the vaginal environment less acidic and more favorable for diverse bacteria

What substances do organisms that use oxygen have to protect themselves from superoxide anions?

Superoxide dismutase and catalase

specimen collection

aerobic culture orders, limit O2 exposure, improper wastes time, effort, issue for pt, colony vs contaiminant

anaerobic culture specimen types

sterile body fluids, aspirated exudates from deep abscesses, transtrachial aspirates, direct lung aspirates, lung tissue, tissue biopsies, suprapubic aspirates, nephrostomy urine specimen

not anaerobic culture specimen types

swabs, O2 or normal flora exposure, throat/sputum/upper resp, stool, superficial wound swabs, urine/genital

anaerobic transport systems

tube, biobag, syringe with cap, blood culture bottle (1 aerobic 1 anaerobic)

anaerobic processing

immediately grind tissues and centrifuge clear body fluid specimens pellit at bottom

gram stain

indicates anaerobic infec or contaimination, determine additional selective media to plate, neg can stain poorly pink, pos can stain pink, improve by staining in anaerobic envir

anaerobic agar media

reducing agents, vitamin K, hemin and yeast extract, thio broth, enriched

Anaerobic (Brucella) blood agar (anaBAP)

Nonselective for anaerobes and facultative anaerobes, preo with Columbia, Schaedler, CDC, Brucella, or brain-heart infusion base supplemented with 5% sheep blood, 0.5% yeast extract, hemin, L-cystine, and vitamin K1

bacteroides bile esculin agar BBE

selective and differential for Bacteroides fragilis group, good presumptive identification, Trypticase soy agar base with ferric ammonium citrate and hemin, bile salts and gentamicin inhibit

laked kanamycin-vancomycin LKV

selective for prevotella and bacteroides spp, Brucella agar base with kanamycin (75 μg/ mL), vancomycin (7.5 μg/mL), vitamin K1 (10 μg/mL), and 5% laked blood

anaerobic phenylethyl alc agar ANA PEA

selective inhib of enteric GNRs and swarming by clostridia, nutrient agar base, 5% blood, phenylethyl alc

egg yolk agar EYA

nonselective for determination of lecithinase and lipase production by clostridia and fusobacteria, egg yolk base

cycloserine cofoxitin fructose agar CCFA

selective for C. diff, egg yolk base with fructose, cycloserine (500mg/L), and cefoxtin (16mg/L), neutral red indicator

thio broth

nonselective for anaerobes, facultative anaerobes, and aerobes, pancreatic digest of casein, soy broth, and glucose to enrich growth of most bacteria, reduce Eh, may supplement with hemin and vit K1

anaerobic chamber or glove box

best envir, inoculation and incubation of media to limit O2 exposure, anaerobic gas mixture maintains anaerobic conditions

anaerobic jar and pouch

seals tight, 85% N, 10% H, 5% CO2, active catalyst removes O2 by producing water, reduction conditions in 1-2 hrs

incubation

35-37 C for 48 hr exam, reincubate NG for at least 5 days, inspect thio broth daily for 7 days

confirm anaerobic atmosphere by

methylene blue (white, blue o2), resazurin (white, pink o2)