E3 AMM

what is the most likely transmission mode of skin and soft tissue infections

direct contact

abscess

collection of pus

pyoderma and what it includes

pus in the skin, includes folliculitis, furuncles, carbuncles

folliculitis and most likely pathogen

infected hair follicle, S. aureus

furuncles

small abscesses located deep in hair follicles

carbuncles

connected furuncles

cellulitis

infection of lower dermis, subcutaneous fat

impetigo and usual pathogens

superficial pus filled vesicles, crust over into honey colored lesions - GAS or S. aureus

erysipelas

red raised w/ defined borders that affects dermis and superficial lymphatics, can progress from impetigo

what are some typical pathogens for general wound infections

S. aureus, Streptococci, GN bacteria, Mycobacteria

what are some typical pathogens for surgical wound infections

S. aureus, Streptococci, GN and anaerobic bacteria

what are some typical pathogens for burn wound infections

S. aureus, P. aeruginosa and other GN bacteria, yeast

what is an ulcer

lesion where tissue has been mechanically eaten away - necrosis

what are common types of ulcers that become infected

diabetic foot ulcers and decubitus ulcers (bed/pressure sores)

what are common pathogens associated with diabetic foot ulcers

S. aureus, GBS

what is myonecrosis (gas gangrene) and its usual pathogen

severe muscle infection, Clostridium perfringens

what is necrotizing fasciitis and its usual pathogens

severe infection of fascia, GAS and S. aureus

what are characteristics of Staphylococcal scalded skin syndrome

exfoliative exotoxin produced by S. aureus - causes skin peeling

what is the transmission of SSSS

infection of umbilical stump or eyes

what specimen types are ideal and not ideal for skin/wound infections

want tissue and fluid/pus aspirates, swabs not ideal

time period for bacterial culture/smear and what its plated on

BAP, CHOC, CNA, MAC, 2-3 days

when is an anaerobic bacterial culture/smear ordered and how long does it take

for closed wounds/abscesses- 7 days

how long does a fungal culture and smear take

2-4 weeks

how long does an acid fast culture and smear take

2-8 weeks

characteristics of S. aureus

GPC, clusters, catalase and coagulase positive

what skin diseases are caused by S. aureus

impetigo, erysipelas, cellulitis, folliculitis, SSS, surgical wound infections

what is the transmission of S. aureus

direct contact, normal skin microbiota

what is the function of alpha toxin in S. aureus

hemolysin, pore forming cytotoxin

what is the function of Panton-Valentine leukocidin in S. aureus

pore forming cytotoxin, targets PMN and platelets

what is the function of exfoliatin in S. aureus

protease that targets keratinocytes - in SSSS to cause peeling

what is the Staphylococcal superantigen toxin (SAgs)

toxic shock syndrome toxin 1 that triggers systemic immune response

describe a lab diagnosis of S. aureus

culture/smear with GPC, beta hemolysis, large yellow colonies, NAAT testing

treatment for MSSA and MRSA

penicillin (beta lactams) and vancomycin

what is the mutation and resistance in MRSA strains

mutation in transpeptidase, resistant to all beta lactams

what are the characteristics of Streptococcus agalactiae (GBS)

GPC, chains, beta hemolysis (big beta baby)

what diseases are associated with

sepsis, meningitis, skin/soft tissue infections (elderly, newborns, feet)

what is the transmission of Streptococcus agalactiae

direct contact, vertical peripartum

where is Streptococcus agalactiae normal microbiota

GI and vaginal tract

what is the treatment for GBS

penicillin or cephalosporin

what is the prevention method for GBS in newborns

screening at 35 weeks pregnant and IV antibiotics during labor

characteristics of Pasteurella multocida

GNCB, no growth on MAC

diseases associated with Pasteurella multocida

sepsis, meningitis, skin/soft tissue infecctions

what is the transmission of Pasteurella multocida

direct contact and animal bites

treatment for Pasteurella multocida

penicillin sensitive and augmentin for polymicrobial infections

characteristics of Streptococcus pyogenes (GAS)

GPC, chains, beta hemolytic, pinpoint colony

diseases associated with GAS

pharyngitis, scarlet or rheumatic fever, skin infections, TSS

transmission of GAS

respiratory droplets and direct contact

function of Streptolysins O and S in GAS

causes beta hemolysis, is oxygen labile

function of M protein in GAS

causes type II hypersensitivity

function of C5a peptidase in GAS

degrades complement

function of hyaluronidase in GAS

degrades hyaluronic acid, spreading factor

what type of GAS is on the concerning threat list

erythromypcin resistant GAS

what genes are present in erythromycin resistant GAS

erythromycin ribosome methylation (erm) genes and macrolide efflux pump (mef) genes

characteristics of Pseudomonas aeruginosa

GNB, oxidase positive, lactose negative on MAC, pigment production

diseases associated with Pseudomonas aeruginosa

pneumonia, wound/eye/ear infections, UTI

transmission of Pseudomonas aeruginosa

direct contact or reservoirs in water and soil

4 virulence factors in Pseudomonas aeruginosa

adhesins, exoA, T3SS, elastase

exoA function

ADP ribosylation of EF-2

function of elastase

breaks down collagen, IgG, IgA, complement proteins

what pathogen has quorum sensing and alginate in its pathogenicity

P. aeruginosa

function of alginate

biofilm and mucoid formation

what pigment does P aeruginosa produce

pyocyanin and pyoverdin

describe pyocyanin

blue green pigment with inc oxidative stress, alters calcium homeostasis

describe pyoverdin/fluorescin

yellow fluorescent pigment, high exoA and siderophore acts to sequester iron

presumptive lab ID for P aeruginosa

GNB, oxidase positive, green and grapey

treatments for P aeruginosa

MDR common, 3rd gen cephalosporins

what skin infection pathogen is a member of ESKAPE

P aeruginosa and S aureus

what are 3 mechanisms of resistance in P aeruginosa

beta lactamases (intrinsic AmpC), efflux pumps, metallo beta lactamases (verona integron encoded/VIM)

describe the vaginal microbiome during child-bearing years

glycogen produced by vag epithelial cells, Lactobacillus spp. makes lactic acid to lower pH

what is the most common cause of vaginal discharge

bacterial vaginosis

what characterizes bacterial vaginosis

dec lactobacilli, inc GN/gram variable/clue cells

what risks are associated with bacterial vaginosis

inc risk of preterm birth and STI

what is used for the clinical and lab diagnosis of bacterial vaginosis

amsel criteria for clinical, nugent score for lab

what bacteria is associated with STI in the vagina

G. vaginalis

what happens to the pH in bacterial vaginosis

increase pH

what are the gram morphology characteristics of Gardnerella vaginalis

gram variable CB, facultative anaerobe

what are the virulence factors of Gardnerella vaginalis

sialidase and biofilm formation

what is the gram morphology of Mobiluncus spp

curved gram variable bacillus

why don't you order culture of a vaginal specimen

there is a lot of normal flora, hard to distinguish what is an actual pathogen

what is looked for in Nugent's criteria

on gram stain, lactobacilli should be present with few to no other organisms

what does the scoring system look like for Nugent's criteria

0-3 is good

4-6 is intermediate

7-10 is bacterial vaginosis

list some common STI's in the US

HPV, chlamydia, trichomoniasis, gonorrhea

what is the gram morphology and characteristics of the Chlamydiaceae family

GN, non-motile, obiligate intracellular (need host ATP)

describe the cell wall of the Chlamydiaceae family

LPS but no PG layer, intrinsic penicillin resistance

describe the developmental cycle of the Chlamydiaceae family

biphasic, alternates between reticulate (met. active/non infectious) and elementary (infectious/met. inactive) body

what type of infection is associated with Chlamydia trachomatis strains A-C

Trachoma/eye infection, a neglected tropical disease transmitted by contact, fomites, and flies

what type of infection is associated with Chlamydia trachomatis strains L1-3

Lymphogranuloma venereum that presents with bubo- swollen lymph nodes

what type of infection is associated with Chlamydia trachomatis strains D-K

genital tract and newborn infections- nongonococcal urethritis and inclusion conjunctivitis

what culture methods are used for exam and ID of Chlamydia trachomatis

direct fluorescent ab and iodine stain for glycogen

what are some non-culture detection methods of Chlamydia trachomatis

Giemsa-stained smears, serology, NAAT

what are the most common symptoms of Chlamydia

mostly asymptomatic, discharge and dysuria

what are the 3 major complications of chlamydia

epididymitis (male), Pelvic inflammatory disease (female), nionatal conjunctivitis

what are the 2 etiological agents of pelvic inflammatory disease

C. trachomatis and N. gonorrhoeae

what are the internal signs of PID

salpingitis, oophoritis, endometritis, basically inflammation of all that stuff

complications of PID

chronic pelvic pain, ectopic pregnancy, infertility

treatment for PID

antibiotic therapy

how do the stages of lymphogranuloma venereum progress

painless lesions, swollen LN, progressive edema and fibrosis/necrosis

gram morphology characteristics of Neisseria gonorrhoeae

GNDC, fastidious(only grows on CAP)

transmission of Neisseria gonorrhoeae

sex or vertical

diagnosis and treatment of Neisseria gonorrhoeae

NAAT, many resistant strains - urgent threat list