path bac exam 4 (copy)

staph aureus basics

gram positive commensal cocci

opportunistic pathogen

low G+C content genome 33%

non-spore forming

non-motile

resident in approx 30% human population

all vaccines have failed up to phase 3

staph aureus natural environment

human microbiome

natural environment: skin + nares

20% human population persistently colonized

30% human population transiently colonized

brain: meningitis/ abscesses

heart: endocarditis

lungs: necrotizing pneumonia

stomach: food poisoning

uterus: toxic shock syndrome

knee: septic arthritis

foot: osteomyelitis

basically can infect any part of the body

staph aureus infection severity

mild: soft tissue infections, boils and skin abscesses

moderate: impetigo, cellulits, scalded skin syndrome

severe: toxic shock syndrome, septicemia, necrotizing fasciitis

what makes it MRSA

acquisition of the SCCmec element turns MSSA into MRSA

mecA gene encodes PBP2a which confers resistant to beta-lactam antibiotics

specification of s.aureus

s.aureus → MRSA → hospital associated MRSA + community associated MRSA

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HA-MRSA v CA-MRSA

hospital acquired MRSA:

* found in health care settings
* infect immunocompromised
* **HIGH** levels of AB resistance
* produce **LOW** levels of toxins
* cause disease in sick people

community associated MRSA:

* found in community
* infect immunocompetent
* **LOW** level of AB resistance
* produce **HIGH** levels of toxins
* cause disease in healthy people

VRSA

NO cases seen in spread from patient to patient

s.aureus secreted VF’s

exoenzymes: metalloproteases, V8 protease, nuclease, lipase, PLC, coagulase, staphylokinase, staphopains, hyduronidase

immune evasion: protein A, capsule, CHIPS, complement inhibitor

adhesins: MSCRAMMs, clumping factors, fibrinogen binding, fibronectin binding, collagen binding, extracellular adherence, Ser-Asp rich

toxins: a-toxin, beta/gamma/sigma-hemolysin, PVL, leukocidins, phenol soluble modulins

superantigens: enterotoxins, TSST-1, exfolative toxin

staphylocoocal pore forming toxins

staph aureus employs numerous pore-forming toxins

different PFTs use different proteinaceous receptors to target host cells

receptors explain cell-type specificity exhibited by s.aureus toxins

alpha-toxin: builds pore, inserts

leukocidin: two components, mulitple bind to create pore, insertion

L19 slide 22

superantigens

TSST-1:

* toxic shock syndrome
* associated with use of ultra-absorbent tampons

enterotoxin:

* multiple types
* associated with S.aureus food poisoning
* Heat stable toxins
* ingested and stimulates vagus nerve
* projectile vomiting
* rapid onset
* subsides quickly
* non-fatal

exfoliative toxin

sole toxin responsible for staphylococcal scalded skin syndrome

toxin separates epidermis from underlying dermis

toxin target is (Dsg-1) on epidermal surface of skin only

normal role is to maintain keratinocyte cell-cell adhesion

contributes to spread

s.aureus exoenzymes

aureolysin: protease, multiple functions, cleave human plasma proteinase inhibitors

staphopain: protease, broad substrate specificity, unclear role in pathogenesis

V8 protease: degrades bacterial cell surface fibronectin-binding protein

nuclease: degrades neutrophil extracellular traps

hyaluronidase: degradation of hyaluronic acid, contribute to local dissolution of the extracellular matrix and connective tissue

lipase: enable the bacteria to persist in the fatty secretions of the human or mammalian skin

staphylocoagulase: causes blood clots - binds prothrombin and activates it resulting in cleavage of fibrinogen to fibrin

staphylokinase

Staphylokinase (Sak) is an exoenzyme that contributes to spread of S. aureus

Dissolves blood clots

Blood clots are platelets held together by fibrin mesh (contains plasminogen)

Normally tPA (tissue plasminogen activator) cleaves plasminogen into plasmin

Plasmin degrades fibrin mesh (in a controlled manner)

Sak activates plasminogen to plasmin which degrades fibrin mesh in an uncontrolled manner

Allows bacteria to move through tissues and escape from abscesses

s.aureus cell wall associated virulence factors

MSCRAMMs (Microbial surface components recognizing adhesive matrix molecules)

cover the cell in fibrinogen = cell cannot recognize it as foreign

protein A:

* Binds IgG
* binds heavy chain Fc region
* IgG molecules are bound in the wrong orientation
* Disrupts opsonization and prevents phagocytosis

lecture 19 slide 29

S.aureus regulation

complicated

125-150 DNA binding proteins in S. aureus genome

Regulatory proteins

* Activators
* Repressors
* TCSTSs
* Sigma factors

\~300 sRNAs in S. aureus genome

Regulatory RNAs:

* Riboswitches
* Trans acting sRNAs
* Cis acting sRNAs
* Ribozymes

virulence gene regulation in s.aureus

majority of virulence gens in S. aureus are regulated by the **agr system**

includes:

* Quorum sensing system
* Two-component system
* Small RNA
* DNA binding repressor protein

agr system:

* P2 P3 = promoters
* P2 drives expression of operon,
* ArgC+A: TCS,
* C= kinase, A=response protein,
* AgrB: takes AgrD and secretes and cleaves it from the cell,
* agrD turns into AIP AIP binds aprC
* P3: promoter for RNAIII which regulates gene expression

RNAIII

514 nt sRNA

regulates gene expression via antisense base pairing with target mRNAs

RNAIII binds to regions containing the RBS sequence or AUG start codon of the target mRNA

Results in negative control of translation

RNAIII regulation of Rot

Rot is a DNA-Binding protein that represses transcription of toxins and secreted virulence factors

Rot stands for Repressor of Toxins

Rot regulates 146 genes

The RNAIII molecule interacts with the rot mRNA


1. Preventing translation of the rot mRNA
2. Causing the rot mRNA to be degraded

RNAIII causes the Rot mRNA to be degraded

* No repression of toxins
* Toxins produced

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Rot in cell = no toxins products

RNAIII represses Rot = toxin production turned back on

Agr control of virulence gene expression

low density = staph tries to attach to things

high density = staph produces toxins

lag phase

exponential phase: expression of surface associated binding proteins MSCRAMMs

post-exponential: quorum reached

stationary phase: expression of extracellular virulence determinants (toxins

CRISPR systems and what kind is staph aureus

Type 1: 1 RNA = crRNA, Cas nucleases typically consist of many protein subunits

Type 2: 2 RNA = crRNA + tracrRNA = guide RNA, Cas nuclease typically consists of one protein Cas9

staph aureus encodes a type 2 CRISPR system, encodes CAS9

staph aureus CRISPR-Cas9

S. aureus encodes one of the smallest Cas9 proteins

In order for CRISPR-Cas9 complex to reach the target DNA, it has to be delivered via plasmids or viruses

S. aureus Cas9 is one of the most commonly used Cas proteins for gene editing

It is 1,053 amino acids, so it can just fit inside the adeno-associated viruses AAV, commonly used to deliver CRISPR-Cas

Streptococcus agalactiae general characteristics

group B strep

beta hemolytic - complete hemolysis

gram positive

GI and genital tract

capsule

main reservoir = vagina

Streptococcus agalactiae disease definition

a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury

Streptococcus agalactiae common and rare disease types

common: bacteremia, sepsis, pneumonia, meningitis in newborn

rare: meningitis in adults + UTI

Streptococcus agalactiae common symptoms

bacteremia and sepsis: fever, chills, low alertness

pneumonia: fever, chills, cough, rapid/difficult breathing, chest pain

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skin/ soft tissue infections: red, swollen/painful touch, warm to the touch, full of pus or other drainage

bone and joint infections: fever, chills, swelling, stiffness or inability to use limb/joint

Streptococcus agalactiae risk factors for newborn

newborn risk factors stem from the pregnant individual

increase risk associated with

* testing positive for Group B strep late in pregnancy
* developing a fever during labor
* having 18 hours of more pass between when the water breaks + delivery

Streptococcus agalactiae 2 main types of infant infection

early onset:

* antibiotics penicillin, ampicillin, cefazolin
* occurs during the first week of life

late onset:

* no prevention methods
* occurs from the week 1 - 3 months life

Streptococcus agalactiae risk factors for adults

infection of GBS in adults RARE

risk factors: diabetes, heart disease, congestive heart failure, cancer/history cancer, obesity

Streptococcus agalactiae how it spreads

not known in non-pregnant individuals

most common ways of spreading GBS = pregnancy = moms → babies

CDC says no evidence of GBS spreading through food, water, surfaces

Streptococcus agalactiae characteristics -facts

leading cause of meningitis and bloodstream infections during the first 3 months of life

2-3 / 50 babies who develop GBS disease die

1/4 pregnant individuals carry GBS

1/20 non-pregnant adults with GBS die

Streptococcus agalactiae active bacterial core surveillance

infection survival on the rise

deaths relatively stable

Streptococcus agalactiae national stats

28,010 cases invasive GBS annually all ages

2020, early-onset infection 0.2 per 1,000 live births

app called Prevent GBS

Streptococcus agalactiae

listed as a concerning threat

penicillin and ampicillin to mothers

clindamycin for allergies to penicillin

Streptococcus agalactiae virulence factors

vaginal colonization:

* adhesins Srr1/2, FbsA/B/C, PbsP, ScpB
* pili
* hemolytic pigment

cervial colonization: alpha C protein, capsule

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Srr1/Srr2 = Serine rich repeats

FbsA/FbsB/FbsC = Fibrinogen binding proteins

PbsP = plasminogen binding proteins

ScpB = C5a peptidase

Streptococcus agalactiae ScpB

C5a peptidase

surface associated serine protease

inactivate C5a, GBS can prevent complement activation and help bacteria bind to fibrinogen

Streptococcus agalactiae HvgA

hypervirulent GBS adhesin

very important in newborn disease

enhances adherence to intestinal epithelial and endothelial cells

important for translocation across the intestinal barrier

mediates crossing of the Blood Brain Barrier to cause meningitis

Streptococcus agalactiae membrane vesicles

NA, lipids, hyaluronate lyases, sialidases, C5a peptidase

can assist with infiltration of neutrophils and lymphocytes

have protease activity that breaks down collagen

release hemolytic pigments to destroy ROS

Streptococcus agalactiae QUESTIONS


1. What are the two categories of infections in infants? How do they differ and are they preventable?
2. What is Group B Streptococcus’s natural environment, how does this lead to spreading of GBS?
3. How is Streptococcus agalactiae separated from other types of streptococcus?
4. Can you name 5 virulence factors of Streptococcus agalactiae? What does one of them do to cause virulence?
5. A healthy college aged student is presenting symptoms of bacterial infection including fever, chills, difficult breathing and chest pain. The student mentions that their sibling had a streptococcal infection. Do you think it could be Group B Strep, why or why not?

1. The two categories of infections in infants includes early onset disease, within the first week of life, and late onset disease, between the first week and 3 months of living.



Early onset disease can be treated with antibiotics, however late onset disease cannot.


2. The main reservoir of Group B Strep is the vagina. This leads to transmission when a colonized pregnant individual gives birth. The newborn is then susceptible to infection.

\*GBS can also colonize the GI tract of adult \*It is unknown how GBS spreads between adults s
3. Group B Streptococcus is gram positive, catalase negative, _-hemolytic, and is not sensitive to bacitracin.
4. - Adhesins - Pili - Hemolytic Pigment - Capsule - Membrane Vesicles 

HvgA (Hypervirulent GBS adhesin) Is an adhesin that assists attachment of GBS to epithelial/endothelial cells. It also helps with invasion of intestinal barriers and the Blood Brain Barrier to cause severe disease
5. It most likely is not GBS, infections in adults are rare and usually are due to other health complications. Group A streptococcus on the other hand spreads through talking, sneezing or coughing.

\*Healthy adults are usually unaffected by this bacterium. \*It is unknown how GBS is transmitted between adults

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Clostridium perfringens introduction

Gram positive

spore

gas producing

anaerobic

bacillus

**1891 William H Welch**

**aka: Bacillus aerogenes capsulatus, Bacillus perfringens, Bacillus welchii, Clostridium welchii**

soil, sewage, food, animal GI’s

**next-gen sequencing in Otzi iceman**

**generation time: 12-17 minutes @37C**

Clostridium perfringens diseases

causes about 1 million cases of foodborne illness in the US

non-foodborne diarrhea

Darnbrand: 1944-1949 northern germany

* necrotic inflammation of small intestine datal
* unusually heat-resistant spores

necrotizing enterocolitis

* leading cause of gastrointestinal morbidity and mortality in premature infants
* pig-bel: abdominal pain after pig feast

gas gangrene: clostridial myconecrosis

necrotic enteritis - causses 6 billion loss to poultry industry

Clostridium perfringens AB resistance

obtain plasmids carry tetracycline resistance

resistance to lincosamides and macrolides - most widespread

MDR-C perf in 1977 → resistant to tetracycline, erthromycin, clindamycin, lincomycin

Clostridium perfringens toxin production

makes 20+ toxins & degradative enzymes

7 toxin types

most toxins encoded on plasmids

clostridium perfringens alpha-toxin

Present in all toxin types

major player in gas gangrene infections

is a metallophospholipase

targets host membranes

two enzymatic activities: Phospholipase C Sphingomyelinase

N-domain: catalytic domain

C-domain: bilayer-binding domain

Inhibits neutrophil differentiation

infection is characterized by an absence of PMNs at the site of infection

Muscle fibers are most susceptible to CPA, which causes membrane damage and lactate dehydrogenase release

clostridium perfringens epsilon-toxin

Found in type B and D toxin types

Plasmid-encoded

LD50 of \~70 ng/kg

Primarily responsible for enterotoxemia in animals, primarily sheep (Lambs, pulpy kidney disease)

High levels of toxin production in the intestines

Toxin can pass the intestinal barrier and disseminate to other tissues and organs via the circulatory system

Can cross the blood-brain barrier

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Heptameric beta-pore-forming toxin

Secreted but must be cleaved by an extracellular protease to become active

Forms a pore in eukaryotic cell plasma membranes

Induces perivascular edema, leading to accumulation in various tissues, the kidney, and the brain

Causes edema and necrotic lesions in the brain

Once in the brain, ETX stimulates the release of glutamate

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Treponema pallidum general characteristics

spirochete

gram-negative

OM lacks LPS

anaerobe

non-spore forming

motile

* presence of endoflagella located in the periplasmic spaces

Treponema pallidum history

1905 by Schaudinn and Hoffman

originally named ‘Spirochaeta pallida’

1906 Landsteiner introduced the use of dark-field microscopy method for the detection of this spirochete

1910 the German bacteriologist Wasserman came up with the first serologic test for this bacterium

Was among the first major bacterial pathogens of humans to be identified

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Treponema pallidum disease

Syphilis

3 stages of infection


1. Primary Stage – initial genital tract lesion (chancre)
2. Secondary Stage – disseminated lesions
3. Tertiary Stage – formation of gummas, as well as cardiovascular and neurological problems

Treponema pallidum Transmissibility and Prevalence

Direct contact

Sexual contact

ID50 \~57 organisms

\~12 million new cases worldwide each year,

\~6,498 deaths

Mostly found in men Re-emerging bacterium

In 2020, 133,945 cases of all stages of syphilis were reported in the U.S.

high cases in africa and western pacific region

Treponema pallidum VF

adhesins for fibronectin (TP0155 and TP0483) and laminin (TP0751)



TP0751 is a zinc-dependent metalloprotease (also known as pallilysin) that forms a complex with TP0751 (which contains a Von Willebrand factor type A domain) capable of degrading clots and extracellular matrix, which could facilitate both dissemination and attachment



TP0751 is a primary target of opsonic antibodies, and thus is predicted to be surface-exposed on outer membrane

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T1SS → ABC transporters

Treponema pallidum treatment

penicillin syphilis treatment

oral doxycycline or tetracycline as alternative treatments in the case of penicillin allergy (except for pregnant women)

Growing resistance to macrolides - associated with a single base mutation in the 23S rRNA gene

Nesseria meningitidis general characteristics

Gram negative

Aerobic

Humans are the only host

Capsule formation is key for most infections

1 in 10 people carry N. meningitidis in their nose and throat

Serotypes that most commonly cause disease: A, B, C, W, X, and Y

Nesseria meningitidis epidemiology

Rates of infections have been decreasing in US

most often in \*infants, young adults, and elderly patients

Serotype B is the most common cause of meningococcal disease

Sub-Saharan Africa is called the “meningitis belt” due to frequent cycles of meningococcal meningitis epidemics

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Nesseria meningitidis transmission

Spread through respiratory and throat secretions

close contact with other people - roommates, oral secretions

Nesseria meningitidis VF

Capsule

* protection from complement-mediated killing
* prevents phagocytosis
* Genes are located on the IHT-A1 virulence island

Opacity genes

* Opa and Opc proteins
* Opa interacts with carcinoembryonic antigen-related cell-adhesion molecules
* Helps with cellular attachment and invasion

Nesseria meningitidis diseases - 2

Meningococcal meningitis

Meningococcal septicemia

Meningococcal meningitis

infection of the lining of the brain and spinal cord

Common symptoms in adults: 7 Fever Headache Stiff neck Nausea Vomiting Photophobia Confusion

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Meningococcal septicemia

An infection of the bloodstream that causes damage to the walls of blood vessels.

Common symptoms: Fever and chills Fatigue Vomiting Cold hands and feet Severe aches or pain in the muscles, joints, chest, or abdomen Rapid breathing Diarrhea Dark purple rash in later stages of disease

Nesseria meningitidis treatment

infected? antibiotics are administered Extended-spectrum cephalosporins, penicillin, and ampicillin

exposed? a prophylactic round of antibiotics are administered

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Nesseria meningitidis morbidity and mortality

10-15% of people infected will die

20% of people that survive meningococcal disease will have life altering disabilities

* Loss of limb(s)
* Deafness Nervous system damage
* Brain damage

Nesseria meningitidis prevention

Vaccines MenB and MenAcwY

Both provide protection against the most common serotypes that cause meningococcal disease

As with other vaccines, they are not 100% effective and there is still a risk for infection.

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Nesseria meningitidis AB

Resistance is uncommon, but not rare

Some isolates belonging to serogroup Y have obtained resistance to penicillin and ciprofloxacin

β-lactamase gyrA

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Francisella tularensis

Gram-negative

Coccobacilli

Split into A and B variations (F. tularensis vs F. holarctica)

Causes tularemia

tularemia - spread and symptoms

Wide range of host species & vectors

A1 prefers lagomorphs and ticks

A2 prefers deer flies

Symptoms can vary based on infection vector

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flu like symptoms

inflamed lymph nodes close to the site of inoculation

6 categories of symptoms

Francisella tularensis 6 categories of symptoms

ulceroglandular: animal/vector bite, ulcerated lesion, enlarged lymph nodes

glandular: animal/vector bite, enlarged lymph node, lacks ulcerated lesion

oculoglandular: conjunctiva, self inoculation, bacteria on hands

oropharyngeal: contaminated food/water, sore throat, tonsils and cervical lymph node swell, most common

pneumonic: most severe, inhalation of bacteria, OR septic spread from another infection site

typhoidal: systematic disease, lacks identifying features, confused + flu

Francisella tularensis AB

streptomycin: block 30S rRNA

gentamicin: block 30S rRNA

doxycycline: block 30S rRNA

ciprofloxacin: inhibit DNA gyrase

fluoroquinolone: inhibits DNA gyrase

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generally resistant to beta-lactam inhibition antibiotics

Francisella tularensis - found where

Americas Japan USSR (Russia) Norway Canada Sweden

Francisella tularensis VF pathogenesis

stealth pathogen

lacks VF, T3SS, exotoxins DO NOT HAVE

HAS capsule

modified LPS: modified lipid A and core

Francisella tularensis LPS

Lipid A:

* usually has 12-14 long carbon chains and 6 acyl chains (like in *Escherichia coli*)
* modified Lipid A has 16-18 long carbon chains and 4 acyl chains

Core:

* Usually has two molecules of KDO
* Modified core only has one molecule of KDO

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O-antigen: no change



All of these modifications lead to a harder-to-detect pathogen. This along with its high morbidity and mortality rate make it a Tier 1 selective agent

Francisella tularensis pili

type IV pili

changes based on medium:

* agar medium, the pili on F. tularensis tend to be short and horn-like
* liquid medium, the same pili are long and fiber-like
* Environment can play a role in pili gene expression

changes based on strain:

* pilE1, pilE2, pilE3, pilE4
* Type B has modifications

strain expression

* type A: has pilE1-3, has shortened pilE4 gene
* type B: has shortened pilE1-3 genes, shortened genes = less virulent, has full pilE4
* the longer pilE1-3 the more virulent, the shorter pilE4 the more virulent

Enterococcus faecalis basics

•Gram Positive

•Diplococci in chainlike arrangement

•Catalase Negative

•Gamma Hemolytic species

•Most common in enterococci family(18 species)

•Thermophilic

•Environmental conditions: Salty (6.5 NaCl)

•pH resistant (acidic environments)

Enterococcus faecalis Spread/Transmission

•Enterococci  Faecalis live harmlessly in human gut microbiota, oral cavity and urinary tract microbiota/vagina.

•Commensal; however opportunistic pathogens.

•Regions of Infection: urine, blood, surgical sites/wound infections

•Both community acquired and hospital acquired

•Spreads via person-person contact (especially in hospitals).

•Medical devices (abiotic/biotic) if improperly cleaned.

Enterococcus faecalis DISEASES/Symptoms

•Diseases: meningitis, bacteremia, sepsis, UTIs, ineffective endocarditis, periodontitis

•UTIs: most common infection, 110,000 cases, affects kidney's, bladder, urethra

•Ineffective endocarditis (IE): third leading cause. Symptoms include heart murmur and spots in the white of the eyes and roof of the mouth.

•Many symptoms depend on the type of infection/location

•General symptoms Include: headache, diarrhea, dysuria, chest pain when breathing, SOB, swollen/red, tender gums, flu-like symptoms(fevers, chills, fatigue, nausea, vomiting, aches, night sweats)

Enterococcus faecalis Virulence Factors

•**Biofilm Formation**

•Adhesin proteins, aggregation substance

•Toxins/Enzymes: **gelatinase,** cytolysin 

•Crosses epithelial barriers (cuts) and intracellular routes

•Multiple immune evasion strategies

•Translocation to new environments

•Undergoes transcriptional changes to adapt to new niche.

Enterococcus faecalis Biofilm Formation

•Uses quorum sensing to regulate biofilm formation

•Fsr-QS system: a two-component system that is controlled by a four-gene locus *fsr*ABCD.

•The fsrC: sensor protein (histidine-kinase sensor). The fsrA gene is the response regulator protein.

•Fsr system assists and aids in the temporal disposition of proteins and polysaccharides into the extracellular polymeric matrix

•Autoinducer peptides (AIPs) reach a high-density quorum. This leads to signal activation and the release of genes including *gelE.* 

Enterococcus faecalis Gelatinase

•Gelatinase can degrade collagen in the basement membrane(intestinal tissue). Hydrolyzes peptides including Hgb, gelatin, caesin, and collagen. 

•Activates host PAR-2(protease-activated receptor-2 and MMP-9(matrix metalloproteinase 9) which leads to increase in epithelial permeability.

•Takes advantage of the host and can passively(leukocyte infiltration) and actively open portal on epithelial barrier. 

•Gelatinase-producing strains contributes to the virulence of endocarditis.

•Gelatinase production is also important in biofilm formation- promotes the aggregation of cells in microbes.

Enterococcus faecalis **IMMUNE EVASION**

•Can escape surveillance by avoiding opsonization

•Degrade compliment or by masking opsonin binding sites

•Suppresses immune system activation, lysis immune cells and survives intracellularly 

Enterococcus faecalis **ANTIBIOTICS**

•Antibiotic-resistance: acquired and intrinsic resistance mechanisms

•Difficult to treat due to increasing antibiotic resistance

•Preferred treatment is to use ampicillin, however other can be used if this does not work.

•Vancomycin-resistant strains(VREs) are treated with daptomycin or linezolid.

•Normal synthesis of the peptidoglycan has (D-Ala-D-Ala) dipeptide termini.

•Enterococci with acquired vancomycin resistance changes this into a D-Ala-D-Lactate.

Enterococcus faecalis Global analysis of multidrug resistant

serotypes

*Acinetobacter Baumannii* Background

•Gram-negative coccobacillus

•The *Acinetobacter* genus is comprised largely of soil microbes

•*A. baumannii* is an emerging pathogen colloquially deemed “Iraqibacter”

•Intracellular

*Acinetobacter Baumannii* Diseases

•Ventilator-associated pneumonia is most common

•Urinary tract infection

•Meningitis

•Necrotizing fasciitis

•Flu-like symptoms

*Acinetobacter Baumannii* Transmission

•Hospital acquired infection/ Nosocomial

•Long survival time on environmental surfaces

•6 days on dry filter paper

•25 days on cotton

•Person to person

*Acinetobacter Baumannii* Antibiotic Resistance

•Beta-Lactams

•Quinolones

•Growing resistance of Aminoglycosides

•Carbapenem resistant *A. baumannii* tops the list of the “Urgent Threats” category in the CDC 2019  Antibiotic Resistance Threats Report

•In 2017, 8,500 infections and 700 fatalities associated with Carbapenem resistant *A. baumannii*

*Acinetobacter Baumannii* Antibiotic Resistance Cont.

•Professor at UC San Diego treated with bacteriophage after acquiring *A. baumannii* infection in Egypt (2017)

•Unresponsive to antibiotic treatment

•First modern usage of phage therapy in North America

*Acinetobacter Baumannii* Outer Membrane Protein A

•**OmpA** is an important virulence factor with diverse functions

•Following adhesion, helps initiate entry via **zipper mechanism**

•Localization to **mitochondria**

Rickettsia rickettsii Introduction

•Gram-negative

•Coccobacillus

•Obligate intracellular pathogen

•Causative agent of Rocky Mountain spotted fever (RMSF)

*Rickettsia rickettsii* Overview

•Type of Rickettsial bacteria

•All Rickettsiae are **vector-borne pathogens**

•Naturally found in ticks

•American dog tick, Rocky Mountain dog tick, & brown dog ticks

**•Transmitted via tick bite**

Rickettsia rickettsii Rocky Mountain spotted fever

•Only disease caused by *R. rickettsii*

**•Targets Endothelial cells**

•Symptoms include:

•Fever

•Headache

•Upset stomach

•**RASH**

•**2-4 days after infection**

Rickettsia rickettsii Location 1

First emerged in Idaho in 1896

Rickettsia rickettsii Location 2

First emerged in Idaho in 1896

Rickettsia rickettsii Disease Overview/Treatment

•20-25% mortality rate

•Children most susceptible to death

•Early treatment is crucial

•Doxycycline is the most effective antibiotic used for treatment of RMSF

•Most effective within first 5 days of illness

**•Rash typically doesn't develop until day 2-4**

•Clinicians hesitant to prescribe doxycycline to children under 8 due to teeth staining

•Increased fatality rates

Rickettsia rickettsii Incidence & case fatality rates

Doxycycline introduced in 1940, leading to decline in case fatality rates

Rickettsia rickettsii Virulence Factors 2

•Type IV Secretion System

•Phospholipase A2 & Actin based motility

Rickettsia rickettsii T4SS

•Direct transfer of DNA into host cell

•"Tube" like appendage

Rickettsia rickettsii Phospholipase A2 & Actin-based motility

**•Type II Exotoxin**

**•Bacteria escape from host vacuole**

•Actin tail forms and allows for cell to cell spread

Rickettsia rickettsii Antibiotic Resistance

•No evidence of resistance... YET

•Beta-lactam antibiotics are ineffective

•Tetracycline drugs are effective

•Doxycycline is most effective

•Quinolones may be used in situations where Doxycycline cannot be used, but is variable in effectiveness

Rickettsia rickettsii Prevention steps

•**Avoid**

•Avoid places that ticks are commonly found

•**Protect**

•Wear long clothing when hiking

•**Spray**

•Spray your body/clothes with insect repellent

**•Don't Stray**

•Stay on trails, avoid tall grasses

**•Check**

•Check for ticks after being outside

**•Disclose**

•Disclose any potential exposure to your doctor if you fall ill after being outdoors

Vibrio cholerae Cholera Geographic Distribution

* Americas
* Africa
* Middle East
* Asia

Vibrio Cholera Common Symptoms

* 2-3 days for symptoms to appear after ingesting *V. cholerae*
* **Watery diarrhea**
* **Rice-water stools**
* Leads to severe dehydration
* Nausea and vomiting
* Dehydration

Vibrio Cholera Severe Symptoms

* Vomiting
* **Reduced urine (can lead to kidney failure)**
* **Intense Thrist**
* Severe diarrhea (Profusely watery; “Rice-water stools”)
* Dehydration (rapid heart rate, loss of skin elasticity, dry mucous membranes, low BP)