Lecture 4: Bacterial Infections Part 1 Flashcards
What are the 3 main G+ Cocci that cause infection?
Staphylcoccus
Streptococcus
Enterococcus
What is the most pathogenic staphylococcus?
S. aureus
Is S. aureus coagulase positive or negative? What does that tell us?
Coagulase +
Produces an enzyme that has the ability to clot blood.
What species of Staph are Coagulase negative?
S. epidermis
S. saprophyticus
S. lugdunesis
Where is staph usually found?
On the skin and anterior nares of healthy individuals.
What is the most common way staph infects someone?
Direct tissue invasion:
SSTI
Osteomyelitis
Septic arthritis
Pneumonia
Endocarditis
What is the indirect way staph infects someone/causes disease?
Exotoxin production:
Staph food poisoning
Toxic shock syndrome
Scalded skin syndrome
What is the common clinical presentation of a staph infection?
Erythema + purulent drainage of an abscess.
MRSA will look more severe.
What kind of infections typically attract staph?
Open wound
Open burn
What is the first step in treating a staph infection on skin?
Draining the abscess.
What would prompt us to culture post abscess drainage and what kind of culture?
Blood cultures if there are also systemic signs of infection like a fever.
If the patient is at low risk for MRSA, what tx would I give?
Keflex
Dicloxacillin
If the patient is at high risk for MRSA, what tx would I give?
Clindamycin
Doxy/Mino
Bactrim
What is safe to give in kids if they are at high risk for MRSA?
Bactrim
If the patient is being admitted for MRSA, what tx would I give?
Vanco IV
What percentage of osteomyelitis cases are caused by S. aureus?
60%!!!
How is osteomyelitis confirmed?
XRAY
What is the most confirmatory scan for osteomyelitis?
Bone Scan
What is the first step once osteomyelitis is confirmed?
Culturing the bacteria!!
What is the initial tx for osteomyelitis?
Empiric ABX:
Vanco + 3/4th gen cephalosporin (ex: ceftriaxone)
What are the specialized treatments for osteomyelitis?
Once a C&S is done, prolonged therapy for 4-6 weeks may be required:
MSSA: Nafcillin IV/oxacillin/cefazolin
MRSA: Vanco IV
Surgery may be required.
What are the primary ways Toxic Shock Syndrome occurs?
Tampon use
Nasopharynx packing
Diret inoculation via wound or abscess.
What causes toxic shock syndrome specifically?
A focal concentration of toxin-producing S. aureus.
How does toxic shock syndrome typically present?
Sudden onset high fever
Hypotension
Myalgia
Diffuse erythematous rash, specifically on palms and soles of feet. Usually will desquamate as well.
Why does toxic shock syndrome need to be treated asap?
Hepatic damage
Thrombocytopenia
Confusion
Leading to…
Renal impairment
Syncope
SHOCK
What is desquamation often indicative of?
Strep or staph infection
How is toxic shock syndrome treated?
IP admission with supportive measures.
Debridement and decontamination of local sites.
Empiric ABX.
What is the empiric ABX treatment for toxic shock syndrome?
VANCO + CLINDA + 1 of the following:
Pip/tazo
Cefepime
Imipenem/Meropenem
Note:
The 1 of the following is to cover pseudomonas!
The Clinda is to add additional G-, anaerobic , and group A strep coverage.
The vanco is the primary MRSA coverage.
What demographic is most susceptible to Scalded Skin Syndrome?
Infants & young children.
What causes scalded skin syndrome and how is it transmitted?
S. aureus toxins
Transmitted via birth canal or adult hands.
How does scalded skin syndrome present?
Widespread bullae with sloughing.
Desquamation.
Can lead to electrolyte abnormalities and sepsis.
How is scalded skin syndrome confirmed?
Clinical diagnosis.
Culture of bullae fluid
OR
Skin biopsy and culture confirmation.
What is the tx protocol for scalded skin syndrome?
Supportive care (treating it like actual burns)
ABX:
MSSA will be nafcillin or oxacillin.
MRSA will be Vanco IV.
What is staph food poisoning and what is the common clinical scenario in which it occurs?
Contamination of food by S. aureus carriers.
Improperly cooked food or room temp food can allow it to reproduce and produce toxins.
How does staph food poisoning present?
N/V/D, abd cramps 2-8 hours post digestion.
How do you treat staph food poisoning?
Self-limiting, resolves in 12 hours.
Where are coagulase negative staph infections from most commonly?
Hospital acquired.
Where do coagulase negative staph infections typically reside?
Postoperative incisions
Prosthetic devices
Indwelling catheters
What is the concern with coagulase negative staph infections?
It is resistant to most beta-lactams, so it needs to be treated with Vanco IV.
If it infects a prosthetic, the device needs to be removed.
What are the most common causes of pharyngitis?
Strep throat
Peritonsillar abscess
Scarlet fever
All of which are caused by GABHS
What are 3 common skin infections?
Impetigo
Erysipelas
Cellulitis
What systemic complications can occur from GABHS?
Rheumatic fever
Acute glomerulonephritis (2 weeks post infection)
What demographic is most susceptible to GABHS pharyngitis?
5-15 y/o.
<2 y/o are extremely rare due to lack of direct inoculation.
What is the most common cause of viral pharyngitis?
Adenovirus.
How does pharyngitis present?
Tonsillar hypertrophy with erythema and/or exudate
Beefy red uvula
Palatal petechiae
Tender anterior cervical lymphadenopathy
What is the most common clinical presentation of strep throat?
Beefy red uvula
Palatal petechiae
How is a diagnosis of strep throat made?
Clinical presentation.
THEN
Rapid strep.
Positive = treat
Negative = negative unless you are highly suspicious, then you can do a throat culture.
What is the treatment protocol for strep throat?
Benzathine PCN G IM
OR
Penicillin VK
OR
Amoxicillin.
What is the treatment protocol for strep if allergic to PCN?
Keflex
How does scarlet fever present?
Sandpaper rash, which blanches and fades with a fine desquamation.
Flushed face with circumoral pallor.
Strawberry tongue
What causes scarlet fever?
Exotoxin producing GABHS
How does impetigo present?
Focal, vesicular, pustular lesions with HONEY-CRUSTED appearance and STUCK ON appearance.
What are the most common causes of impetigo?
GABHS
S. aureus
What is the treatment for protocol for normal impetigo?
Topical mupirocin/bactroban if localized.
Systemic:
Keflex
Dicloxacillin
Omnicef/cefdinir can be used instead of keflex for less frequent dosing.
What is the treatment protocol for suspected MRSA impetigo?
TMP-SMZ (bactrim)
Doxy
Clinda
What sport commonly has impetigo as a result?
Wrestling.
What is erysipelas and its susceptible demographic?
Adult only.
Superficial and painful cellulitis with dermal facial involvement.
What can cause erysipelas?
GABHS
S. aureus
How is uncomplicated erysipelas treated OP?
Penicillin VK
Amoxicillin
Dicloxacillin
Keflex
Clinda/erythro
How is complicated erysipelas treated IP?
Vanco if MRSA suspected.
cefazolin/Ancef
Ceftriaxone/Rocephin
Clinda
How is cellulitis treated?
Empiric coverage of GABHS and S. aureus.
What demographic is most susceptible to necrotizing fasciitis?
IV drug users
What organisms can cause necrotizing fasciitis?
GABHS
Clostridium perfringens
This prompts a culture since tx is different.
What can toxic shock syndrome be caused by?
S. aureus
GABHS
Which strep is a Group B?
Strep agalactiae
What demographic is most susceptible to S agalactiae?
Newborns born vaginally.
How is Group B strep treated and screened for?
Prenatal screening, as it can cause neonatal sepsis.
Tx is intrapartum prophylaxis:
PCN G or ampicillin Q4h until delivery.
Ancef
Clinda/vanco
What is another term for alpha-hemolytic?
Incomplete hemolytic
What are the two types of alpha-hemolytic strep?
S. pneumo
S. viridans
What diseases is S. pneumo known for causing?
OM
Sinusitis
CAP (most common cause of CAP)
Meningitis
Endocarditis
When is S. pneumo most prevalent?
Winter and early spring.
What are the 3 MC of OM?
S. pneumo (#1)
M. cat
H flu
Oh My SMH
What demographic is most susceptible to OM?
2-14 y/o
How does OM present?
Otalgia (pulling at ear)
Hearing loss
Poor balance/coordination
Fever
N/V
Diarrhea
What are the main risk factors for OM?
Smoker in household
Family Hx (Horizontal eustachian tubes)
Bottle feeding (laying flat)
What are some significant PE findings for OM?
Erythematous, bulging TM
Absence/displacement of light reflex (aka cone of light)
Poor mobility
Otorrhea w/ TM rupture
How is OM diagnosed?
Clinically.
Can use tympanogram if available.
What is the tx protocol for OM?
Analgesics/antipyretics
ABX:
Amoxicillin.
If not improved after 2 weeks:
Omnicef or augmentin. Will cover atypical H. flu
What is a tympanogram used for?
TM movement since valsalva is hard for kids to do.
Why are ABX used in OM if it can self-resolve in 70% of cases?
Shortens recovery time
Reduces complications
What is the most common cause of acute sinusitis?
Adenovirus.
What are the common bacterial causes of acute sinusitis?
S. aureus
S. pneumo
M. cat
H. flu
AKA OM causes + S. aureus
What are the risk factors for acute sinusitis?
Allergic rhinitis
Structural abnormalities
Nasal polyps
How does acute sinusitis typically present?
Symptoms:
Purulent rhinorrhea/PND
Sinus pressure/HA
Nasal pressure
Signs:
Erythematous/swollen turbinates and mucosa
Maxillary/front sinus pressure
Purulent rhinorrhea
How is acute sinusitis diagnosed?
Clinically.
CT is PRN.
What is more indicative of severity, the snot color or length of rhinorrhea?
Length.
Green snot is caused by dead eosinophils and WBCs. not always indicative of severity.
What is the tx protocol for acute sinusitis?
Augmentin.
Requires tx for 14-21 days since it is a cavity.
Doxy is alternative.
What is the most common cause of CAP?
S. pneumo (2/3 of all isolates)
What are the S/S of pneumococcal pneumonia?
High fever, chills
Early onset rigors
Rust colored sputum!!
SOB
Pleuritic CP!!!
Bronchial breath sounds vs crackles in affected lobe.
How is pneumococcal pneumonia diagnosed?
CXR.
Sputum in IP with comorbidities, otherwise not needed for healthy OP.
What is the tx protocol for standard OP pneumococcal pneumonia?
PSI or curb 65 score
Empiric ABX:
Amoxicillin
Doxy
Zithromax in areas with <25% resistance.
What is the tx protocol for COPD/comorbidity or recent abx tx for OP pneumococcal pneumonia?
Levofloxacin
OR
Combination of…
Augmentin OR cephalosporin + zmax or doxy
What qualifies as a comorbidity?
COPD/DM/Lung disease/Heavy smoker
What is the tx protocol for IP pneumococcal pneumonia?
Levofloxacin
OR
Zmax + beta-lactam like amoxicillin or ceftriaxone.
It is essentially the same as complicated OP pneumococcal pneumonia.
What is CURB 65?
5 question pneumonia scale.
Confusion
BUN > 19
RR >= 30
SBP < 90 or DBP <=60
Age >= 65
2 = IP admission.
4-5 = ICU admission.
What is PSI?
Much more extensive index for calculating pneumonia severity.
REQUIRES ABG and CXR.
Which gender is more susceptible to pneumonia?
Males are slightly more at risk.
How is pneumococcal pneumonia prevented?
Pneumovax for >65 OR immunocompromised/very sick people > 2y/o.
19-64 is asthma/smoking/SNF resident.
Prevnar is for kiddos with chronic conditions OR adults that never got prevnar 13.
How is meningitis cause approximated? List the common causative organisms.
By age.
<3 months: Group B strep.
<3 mo - 10 y/o: S. pneumo
10 y/o - 19 y/o: N. meningitditis
S. aureus = penetrating head trauma
H. flu (rare since we have Hib but more prevalent outside of US)
Adults:
S. pneumo
S. aureus
N. meningitiditis
Elderly
S. Pneumo
S. aureus
Listeria monocytogenes.
Note:
If immunocomp, consider pseudomonas, listeria, and G-
How is the causative organism in meningitis often confirmed?
CSF via LP. They all look pretty different under the microscope.
What are the two main enterococci organisms?
E. faecalis
E. faecium
Where are the enterococci from?
Normal intestinal flora.
What do enterococci commonly cause?
UTI
Bacteremia
Endocarditis
Intra-abdominal infections
Wound infections
What is the tx protocol for enterococci?
Endocarditis:
Amp and gent
SSTI/UTI:
Mild or complicated is amp or vanco
Resistant:
VRE is treated with linezolid or dapto
What are the three G+ rods?
Bacillus
Listeria
Corynebacterium
What are the two types of bacilli?
B. anthracis
B. cereus