Lecture 4: Bacterial Infections Part 1 (Incomplete) 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:
Skin and soft tissue infections
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.
There is a patient with a staphylococcal skin infection. They are being treated outpatient. If the patient is at low risk for MRSA, what tx would I give?
Cephalexin - Keflex
Dicloxacillin
There is a patient with a staphylococcal skin infection. They are being treated outpatient. If the patient is at high risk for MRSA, what tx would I give?
Clindamycin
Doxycycline/Minocycline
sulfamethoxazole/trimethoprim (Bactrim)
What is safe to give in kids if they are at high risk for MRSA?
Bactrim
a patient has a staphylococcal skin infection. If the patient is being admitted for MRSA, what tx would I give?
What could be some other Treatment options if this first line med was not available
Vanco IV
Other options: clindamycin, cefazolin, naf/oxacillin, linezolid (this one is super expensive)
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?
broad spectrum 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 may be required:
MSSA: Nafcillin IV/oxacillin/cefazoline
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?
Admission to hospital
supportive measures (antipyretics, IV fluids, monitoring of hepatic and renal function)
debride/decontaminate local sources of infection
empiric antibiotics
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 causes of 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? (physical findings)
Tonsillar hypertrophy with erythema and/or exudate
Beefy red uvula
Palatal petechiae
Tender anterior cervical lymphadenopathy
may have sandpaper rash
What are the presenting signs of strep throat (what will the patient complain of?)
Abrupt onset of fever
malaise (general dscomfort/ill feeling)
nausea
sore throat
odynophagia (Painful swallowing)
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
Pencillin VK oral
OR
Amoxicillin oral
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 lymphatic involvement that frequently involves the face.
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? what must we discriminate between
GABHS
Must decipher whether it is necrotizing fasciitis or Clostridium perfringens. this is done via culture.
What can toxic shock syndrome be caused by?
S. aureus
GABHS
Which strep is a Group B?
Strep agalactiae
When 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
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 viral cause of acute sinusitis?
Adenovirus.
What are the common bacterial causes of acute sinusitis?
S. aureus
S. pneumo
M. cat
H. flu
What are the risk factors for acute sinusitis?
Allergic rhinitis
Structural abnormalities
Nasal polyps
How does acute sinusitis typically present?
Symptoms:
Purulent rhinrrhea/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
What is B. anthracis?
An encapsulated, toxin/spore producing bacteria.
It is the cause of anthrax poisoning and is a CDC cat A.
What are the three types of anthrax poisoning?
Cutaenous (MC)
Ingestion
Inhalation (most fatal)
How does cutaneous anthrax poisoning present?
PAINLESS black eschar.
Regional adenopathy
Fever, malaise, HA
All of this should present within 2 weeks of infection.
How does ingested anthrax occur?
Inadequately cooked meat that is infected.
How does GI anthrax poisoning present?
Lesions and bleeding in GI tract, AKA…
GI bleeding
Bloody diarrhea
Oral mucosa ulcerations
Bowel obstruction/perf
Initial presentation:
Fever
N/V
Bloody diarrhea
How does inhaled anthrax poisoning present?
Insidious onset of flu-like symptoms.
Progresses to CP, severe respiratory distress, and acidemia.
Severe hypoxemia and shock will occur.
Can also progress further to mediastinitis, pleural effusion, septicemia, and meningitis.
How is anthrax poisoning diagnosed?
Culture/biopsy
Gram stain
Nasal swab for inhalation suspicion
CXR if pulmonary symptoms
LP if systemic
What is the prophylactic tx for anthrax?
CIPRO ASAP
What is the tx protocol for anthrax poisoning?
Cipro:
Cutaneous, 7-10 days.
Inhalation, 60 days
Alternative is doxy.
TX MUST BE CONFIRMED BY C&S.
What are the two types of illness B. cereus can cause?
Diarrheal
Emetic: aka vomiting
Where does B. cereus commonly come from?
Food left out at room temp for too long.
What is the tx protocol for B. cereus?
Supportive care, aka resting and fluids.
It is self-limiting.
What is the onset of B. cereus?
1-10 hours of exposure.
What causes listeriosis?
Listeria monocytogenes (G+ Rod)
What demographic is most susceptible to listeriosis?
Neonates
Elderly
Immunocompromised
When is somoene at the greatest risk for listeriosis and what are the consequences?
Pregnancy.
It can cause sponatenous abortion or neonatal meningitis.
How is listeriosis transmitted?
Ingestion of contaminated foods:
Dairy
Raw veggies
Meat
How does listeriosis commonly present?
Bacteremia with high fever and multi-organ involvement
Meningitis
Dermatitis
Oculoglandular symptoms:
Retinitis
Lymph node enlargement.
How is listeriosis diagnosed?
Blood cultures
CSF
How is listeriosis treated?
IP is amp and gent
OP is amoxcillin (generally continuation of IP tx)
What is the primary disease causing corynebacterium?
Corynebactrium diphtheriae
What are the two types of diphtheria?
Pharyngeal diphtheria: gray membrane covers tonsils and pharynx.
Nasal infection: mainly just discharge.
How does pharyngeal diphtheria commonly present?
Gray membrane covering tonsils and pharnyx.
Fever, mild sore throat, and malaise followed by toxemia and prostration (super lethargy)
Can spread to heart, CNS, and kidneys.
How is diphtheria diagnosed?
Clinically.
Confirmed via culture.
How is corynebacterium diphtheria treated?
Diphtheria equine antitoxin from the CDC.
ABX:
PCN or erythro
Contact:
Erythro
How is diphtheria prevented?
Immunization. Tdap and DTap.
Note:
Susceptible people exposed should get a booster + PCN/erythro.
What are the 3 G- cocci?
Acinetobacter
Moraxella
Neisseria
How do acinetobacter infections occur?
Opportunistic, commonly nosocomial and critically ill/immunocomped.
What is unique about acinetobacter reservoirs?
It can stay on a dry surface for an entire month. (AKA medical equipment)
What are the most common infection sites for acinetobacter?
Respiratory is MC.
Esp. tracheostomy sites
Suppurative infection that can lead to bacteremia.
What infections does M. cat cause?
Acute OM
Acute and chronic sinusitis
COPD exacerbations
What is the treatment for acute OM?
Amoxicillin.
Augmentin or omnicef if persistent.
What is the tx for acute/chronic sinusitis?
Augmentin, second is doxy.
What are the two types of neisseria bacteria?
N. meningitiditis
N. Gonorrhoeae
What are the characteristics of meningococcal meningitis?
Human reservoirs (40% of adults are carriers)
Close contact required (aka college dorms)
Outbreaks most common in spring and winter.
Immunization available.
How does meningococcal meningitis present?
Fever, HA, stiff neck
N/V, photophobia, lethargy
AMS
Maculopapular rash, petechiae
Positive kernig’s and brudzinski
High mortality if progresses to meningococcemia.
How is meningococcal meningitis diagnosed?
Gram stain
LP with CSF analysis
Blood culture
What is the tx protocol for meningococcal meningitis?
PCN G - if C&S shows it is a susceptible strain.
Rocephin to cover all other organisms
ABX therapy must continue for at least 5 days of pt being afrebile.
Close contacts must be given prophylaxis.
Note:
Rocephin will cover atypicals, group B strep, S. pneumo, and H flu.
What is given for meningococcal meningitis prophylaxis?
Vaccine is primary
ABX includes:
Rifampin (all age. CI in preggo, jaundice, and drug interactions)
Cipro (non-pregnant adults only)
Rocephin (all age. preferred in preggos, but IM only)
Zithromax (used if high cipro resistance in area)
Link:
https://www.ncbi.nlm.nih.gov/books/NBK537338/
How does meningococcal vaccination work?
Meningococcal vaccine ACWY strains.
+
Meningococcal vaccine B strain
Vaccinate at 11-12.
Booster at 16.
What diseases can N. gonorrheae cause?
Cervicitis, Urethritis
PID
Prostatitis
Disseminated disease
Skin rashes
Septic arthritis
Conjuctivitis (esp in newborns)
How does a gonorrheal disease present?
Yellow-green purulent discharge
Erythematous cervix
Note:
Can be asymptomatic as well.
What bacteria can cause a yellow-green discharge?
H flu
Gonorrheae
Adenovirus
If there is excess discharge from an eye, what should I do?
Culture it.
How is gonorrhea diagnosed?
Gream stain + culture
What is the tx protocol for gonorrhea?
Rocephin (single dose)
What is the most common type of pseudomonas?
P. aeruginosa
G- rod
What is P. aeruginosa cause?
Opportunistic infections.
In healthy, it only causes OE, UTIs, and adermatitis.
In immunocomped pts, it can cause UTIs, pneumonia, bacteremia, and sepsis.
What counts as immunocomped relative to P. aeruginosa?
Burn pts
Cystic fibrosis pts
Ventilator acquired pneumonia.
What color is the discharge of P. aeruginosa?
Green.
What is pseudomonas the #1 causative organism in?
OE
Corneal ulcers in contact lens wearers due to bacterial keratinitis.
ICU-related pneumonia
Osteochondritis due to tennis shoe puncture.
What is pseudomonas the #2 causative organism in?
G- organism in nosocomial pneumonia
What is pseudomonas the #3 causative organism in?
Hospital-acquired UTIs
What is a common infection/manifestation of pseudomonas that is water-related?
Hot tub folliculitis.
What is the first common symptom of a pseudomonas infection?
Fever
What is the tx protocol for OP pseudomonas?
Cipro (oral)
Levofloxacin (oral)
Tobramycin (inhaled but its for 9 months and is post IP admission)
Note:
This is CId in children, but if you have CF, no other option.
What is the tx protocol for IP pseudomonas?
Pip/tazo
Ceftazidime
Cefepime
Meropenem
aztreonam
Note:
All IV. Need hosp admission if positive for pseudomonas on culture?
What are the 4 G- rods that cause respiratory tract illnesses?
B. pertussis
H. flu
Legionella
Klebsiella
What disease does B. pertussis cause?
Whooping cough
What is the most susceptible demographic to B. pertussis?
Unvaccinated children.
What are the 3 clinical stages of pertussis?
Catarrhal: similar to allergies or simple cold, insidious onset.
Paroxysmal: Forceful, worsening coughing fits. Whoop occurs when gasping for air.
Convalescent: Diminishing symptoms, lingering cough
Note: The coughing fits can cause children to aspirate and die.
How is whooping cough diagnosed?
Clinical presentation + NP culture.
What is the tx protocol for pertussis?
Supportive care.
ABX:
Zithromax, alt is bactrim if allergy.
If started early in catarrhal, it can stop the disease progression.
How is pertussis prevented?
Children: DTap
Booster: Tdap
Note:
ap standards for acellular pertussis
What diseases can H flu cause?
Sinusitis
OM
Bronchitis
Epiglottitis (MC)
Pneumonia
Cellulitis
Meningitis
Endocarditis
“SOB Even Platypusses Can Make Eggs”
What is H flu often implicated in?
COPD exacerbations resulting in purulent bronchitis.
What is the tx protocol for H flu?
Depends on site, but it is generally augmentin or omnicef.
What is the causative organism for legionnaire’s?
Legionella pneumophilia. Also a common cause of CAP.
What demographic is most susceptible to legionnaire’s?
Immunocomped
Smokers
Chronic lung disease (Esp those on CPAP)
What transmission causes outbreaks of legionnaire’s?
Aerosolization by water. Commonly if it is in a water tower or AC unit.
How does legionnaire’s present?
Scant sputum production
Pleuritic CP
High fever
Toxic appearance
How is legionnaire’s diagnosed?
CXR with focal patchy infiltrates or consolidation
Antigen detection:
PCR of lower respiratory tract secretions
Urine antigen
Respiratory tract fluid culture
NOTE:
SPUTUM GRAM STAIN WILL TYPICALLY SHOW NO ORGANISMS
What is the tx protocol for Legionnaire’s?
Macrolide (azithromycin, clarithomycin)
Fluoroquinolone (Levofloxacin)
10-14 days/ 21 days for immunocomped
What demographics are most susceptible to klebsiella infections?
Alcoholics (esp. those who aspirate)
Diabetics
HIV
How does a klebsiella pneumonieae infection commonly present?
Severe pneumonia symptoms like SOB and pleuritic CP.
Red currant/jelly-like sputum
Can progress to a lung abscess.
How is klebsiella diagnosed?
CXR
Sputum culture
What is the tx protocol for klebsiella?
C&S REQUIRED
Empiric abx:
Respiratory fluoroquinolones (levo and moxi and gemi)
Carbapenem
What G- rods cause GI illnesses?
E. coli
Campylobacter
Salmonella
Shigella
Vibrio
What is the general tx protocol for a diarrheal illness?
Cipro
Secondary is zithromax
How does E. coli diarrhea/traveler’s diarrhea commonly present?
Abrupt during or post trip to developing country.
Increased frequency, volume, and weight of stools.
Commonly 4-5 water stools a day.
Tenesmus
Abd cramps, all the usual N/V, bloating, fever
What is the main concern in traveler’s diarrhea?
Dehydration
What are the OTC/non-abx tx for traveler’s diarrhea?
Peptobismol
Antimotility/anti-diarrheals
What is the ABX tx for traveler’s diarrhea?
3-5 days of cipro if severe symptoms or 3+ stools/8h
What is the concern with antimotility agents?
Bowel obstruction.
Should stop after 48 hrs if s/s worsen.
Who cannot take peptobismol?
Children
Preggo
ASA allergy
Who should not take antimotility agents?
Infants
Fever or blood diarrhea (could delay clearance of bacteria)
