Lecture 5: Bacterial Infections Part 2 Flashcards
What are the 3 main G+ anaerobes?
Actinomyces
Peptostreptococcus
Propionibacterium
How do G+ anaerobes generally present?
Abscess formation with tissue necrosis.
Suppurative/purulent
FOUL ODOR of pus or infected tissue.
Site of infection is near somewhere anaerobes like.
Often polymicrobial!
Note:
G- anaerobes present similarly.
Which G+ anaerobe is most likely to be found on a prosthetic?
Propionibacterium
Which G+ anaerobe is most likely to cause aspiration pneumonia?
Actinomyces
Which G+ anaerobe is most likely to cause an oral infection?
Peptostreptococcus
How does aspiration pneumonia present on CXR if caused by a G+ anaerobe?
Infiltrates w/ or w/o cavitation
Lucency within an infiltrate suggests necrotizing tissue.
Air fluid levels within a circumscribed infiltrate = lung abscess
How do I check for an intra-abdominal abscess?
Abd/Pelvic CT
How do we diagnose a G+ anaerobe infection?
Clinical suspicion + Gram stain + C&S
Note:
C&S for an anaerobe can take 1+ week.
What is the tx protocol for a G+ anaerobe infection dependent on?
Site of infection.
What is the tx protocol for an oral/throat/neck G+ anaerobe?
Clindamycin
Augmentin
Unasyn (amp/sul)
What is the tx protocol for a GI/pelvic abscess dt G+ anaerobe?
Oral: Moxi
Mod/severe :
Ertapenem or Rocephin + metronidazole (covers B. fragilis and G-) all IV!!
Severe:
Imipenem (IV)
What is the tx protocol for a lung abscess dt G+ anaerobe?
Beta-lactam + inhibitor:
Unasyn OR imipenem OR meropenem OR clindamycin
What is the tx protocol for aspiration pneumonia?
OP
IP
OP: augmentin or doxy
IP: Unasyn
OR
Metro + amoxicllin or pen G
What is the prophylaxis tx for dental procedures?
PCN if joint implant.
Amoxicillin works for both joint implant or endocarditis prophylaxis.
What is the prophylaxis for colorectal surgery?
Metronidazole + 2nd/3rd gen cephalosporin OR cipro
Carbapenems
What are the 5 disease causing clostridiums?
C. perfringens
C. sepicum
C. tetani
C. botulinum
C. diff
What clostridiums cause gas gangrene?
C. perfringens
C. sepicum
What is the most common species of clostridium?
C. perfringens
Where is C. perfringens most commonly found?
soil
What are the S/S of a clostridium SSTI?
Pain, edema, erythema, TISSUE CREPITUS, foul smelling.
How is a clostridial SSTI diagnosed?
Clinical suspicion
Gram stain
Culture
Note:
Clostridia produce extremely fast, can culture in ~6 hours.
Need to culture bc strep, staph, and enterococci can cause similar symptoms.
What is the tx protocol for a clostridial SSTI?
Drainage and debridement
Pip/tazo + clindamycin (covers strep and clostridia)
Can change to PCN + clinda if no strep.
Hyperbaric tx
Note:
Pip/tazo also covers pseudomonas
What is the pathophys of C. perfringens gastroenteritis?
Enterotoxin production from C. perfringens.
How does C. perfringens gastroenteritis present?
Mild.
Watery diarrhea.
Emesis and fever are rare.
What is the tx protocol for C. perfringens gastroenteritis?
None.
Self-limiting
How does tetanus occur?
Spores from C. tetani enter body from wound/burn/IV drug use.
Attaches to peripheral nerve ending, cause muscle stimulation.
Leads to tonic spasticity and muscle rigidity.
CANNOT BE NEUTRALIZED ONCE BOUND
What is the incubation period of tetanus?
5-30 days.
How does tetanus commonly present?
Jaw stiffness
Difficulty swallowing
Stiff neck, arms, and/or legs
HA
Tonic muscle spasms
Trismus
Resp failure dt laryngeal/diaphragmatic spasms.
How is tetanus diagnosed?
Clinical suspicion
Cultures (not sensitive?)
What is the tx protocol for tetanus?
Supportive care
Wound debridement
Tetanus immune globulin (HTIG) IM within 24 hrs.
Full series of tetanus vaccine
PCN or metronidazole
Vaccination is best.
What are the common sources of C. botulinum?
Home-canned foods (MC)
Commercial foods
Direct injection/wound
What is the only non-natural form of botulinum infection?
Inhalation of toxin.
How many subtypes of C. botulinum are there?
8
How does botulism present in regards to the nervous system?
Dry mouth
Slurred speech
Dysphagia
Blurred vision
Drooping eyelids
Eventually respiratory failure due to diaphragmatic paralysis
How does botulism present initially before neurological symptoms?
N/V/abd cramps
18-36 hours post ingestion.
How is botulism different from tetanus if they both cause respiratory failure?
Botulism paralyzes the diaphragm.
Tetanus overstimulates the diaphragm to where it becomes stiff.
How is botulism diagnosed?
Cultures:
Stool for ingested
Wound for injection
Who can perform a toxin assay and what is it?
Identifies specific toxin made by C. botulinum.
Only performed at special labs, such as the health department or CDC.
What is the tx protocol for C. Botulinum?
Hospitalization + supportive care.
Requires NG tube and/or ET tube
Antitoxin through the CDC.
Wound botulism requires PCN G or metronidazole.
What is C. Diff colitis also known as?
Pseudomembranous colitis or antibiotic associated colitis
What is the MC of disease due to C. Diff?
Overgrowth of organism in the colon due to excessive ABX use.
How does C. Diff antibiotic associated colitis/pseudomembranous colitis present?
Diarrhea, frequent stool, either watery or bloody.
Abd cramping, tenderness, and bloating.
N/V is RARE.
Presents 5-10 days post abx initiation, but can take up to 2 months.
How is pseudomembranous colitis diagnosed?
Stool sample for toxin
Fecal leukocytes
Sigmoidoscopy if suspicious w/ - culture
Other imaging to check for ileus or distended colon
What is the tx protocol for mild-moderate pseudomembranous colitis?
Fidaxomicin or Vanco (oral)
What is the tx protocol for severe pseudomembranous colitis?
Vanco (oral or enema in rare cases)
Fidaxomicin + Metronidazole
What is the tx protocol for recurrent or refractory pseudomembranous colitis?
Recurrent will be same as mild-moderate.
Refractory will be a fecal transplant.
What are the 4 G- anaerobes?
Bacteroides
Fusobacterium
Porphyromonas
Prevotella
What kind of infection is B. fragilis most commonly known for?
Intra-abdominal infections (most virulent)
Where are prevotella and fusobacterium found?
Normal gut and bowel flora.
How do G- anaerobes typically present?
Abscess formation with tissue necrosis
Suppurative/Purulent
Foul odor
Site of infection is near a common anaerobe site
Polymicrobial
AKA identical to a G+ anaerobe.
How is a G- anaerobe diagnosed?
Same as G+ anaerobe. Culture the abscess.
Gram stain
C&S may take 1 week.
What do anaerobic infections generally all culminate in?
Bacteremia, but usually not sepsis.
What is the tx protcol for a G- anaerobe infection?
Drainage and debridement.
ABX depending on site of infection.
What is the recommended abx for an oral/throat/neck G- anaerobe infection?
Clinda or metro
What is the recommended abx for a G negative GI/pelvic abscess
pip/taz
Carbapenems
Metro + cefepime
What is the MC for bacterial vaginosis?
Gardnerella
How does bacterial vaginosis usually present?
Often asymptomatic.
Signs incude:
Thin, off-white to grayish vaginal discharge
Fishy smell from vagina
Elevated pH of vaginal discharge
Clue cells on microscopy
Positive whiff test
What is a whiff test?
Vaginal discharge + KOH.
KOH will alkalize amines made by anaerobes, which will result in a fishy odor.
What are clue cells?
Vaginal cells with a bunch of bacteria attached to them.
What is the tx protocol for bacterial vaginosis?
Metro (oral or vaginal)
Clinda (oral or vaginal)
Tinidazole (oral)
What are the 3 atypical causes of pneumonia?
Mycoplasma
Legionella
Chlamydia
What are significant characteristics of Mycoplasma?
Small bacteria w/o a cell wall.
Human pathogens.
M. pneumo is most associated with acute infection (pneumonia)
What is the pathogenesis of mycoplasma?
Filamentous organism that attaches to epithelial membranes, esp. in the respiratory tract.
Activates immune response by injuring epithelium.
What is the epidemiology of mycoplasma?
Respiratory droplet transmission with an incubation period of 2-3 weeks.
MC during fall, summer, young adults.
How does M. pneumo typically present?
Gradual onset
Mild form
Scant sputum production
Often has pharyngitis or AOM.
Bullous myringitis
Often called walking pneumonia
How is M. pneumo diagnosed?
Chest auscultation will be clear
Patchy infiltrates on CXR, negative for consolidation.
Usually, its just a clinical diagnosis or an NP swab.
What is the tx protocol for M. pneumo?
Azithromycin is the empiric abx of choice.
What are the characteristics of Chlamydia?
Obligate intracelullar bacteria without a cell wall.
3 pathogens are:
trachomatis
psittaci
pneumo
What is the second MCC of atypical pneumonia?
Chlamydia pneumo
What is the tx protocol for C. pneumo?
Same as M. pneumo in terms of presentation and tx.
Azithromycin.
How does psittacosis present?
Atypical pneumonia that is sicker than other.
How is psittacosis transmitted?
Bird contact with 7-15 day incubation period.
What is the tx protocol for Psittacosis?
Tetracycline
Erythromycin
What are the S/S of C. trachomatis?
Female: cervicitis, urethritis, PID
Male: Urethritis, epididymitis, prostatitis
Both: conjuctivitis, lymphogranuloma venereum
How does Chlamydia present?
ASymptomatic
Signs:
Females will have mucopurulent discharge, red, inflamed, friable cervix, and PID + chandelier’s sign.
Males will have mucoid/watery urethral discharge, dysuria, and epididymitis
How is chlamydia diagnosed?
Culture.
Gram stain is useless.
Often screened for as well.
What DDx should be considered with possible chlamydia?
Dysuria
Bacterial vaginosis
Trichomonas
Candidiasis
Gonorrhea
HSV
What is the tx protocol for urogenital chlamydia?
Zithromax 1g.
Rocephin shot in case for gonorrhea
What complications can occur due to chlamydia?
PROM (premature rupture of membranes) in pregnancy.
Infertility due to PID
Newborn transmission
Perihepatitis (Fitz Hugh-Curtis syndrome)
What 3 bacteria are spirochetes?
Treponema pallidum (Syphilis)
Borrelia (Lyme)
Leptospira (Leptospirosis)
What are the stages of syphilis?
Primary
Secondary
Tertiary
Neurosyphilis (Late)
Latent
What stages of syphilis are contagious and non-contagious?
Primary, seconday, and latent are contagious.
Tertiary and later is not.
What stage of syphilis is generally asymptomatic?
Latent syphilis, aka within 1st yr of primary infection.
How does primary syphilis present?
Chancres
Nontender regional LAN
Spontaneous healing
3-4 weeks post contact
How is primary syphilis diagnosed?
Culture of ulcer via dark field microscopy to look for spirochetes.
Serologic tests: (FIRST LINE)
RPR (rapid plasma reagin) & VDRL (venereal disease research lab test)
These are generally used for secondary stage diagnosis and are NON ANTIBODY
Antibody:
TPPA (treponema pallidum particle agglutination test)
FTA-ABS (Fluorescent treponemal antibody absorption)
Often used to confirm diagnosis.
How is primary syphilis treated?
1 shot of benzathine pencillin G (Bicillin-LA)
What is the main difference between primary and secondary syphilis?
Systemic symptoms due to dissemination of bacteria.
How does secondary syphilis present?
Generalized maculopapular rash
Mucous membrane patches and ulcers
Condyloma lata
Meningitis
Iritis
Hepatitis
Arthritis
Fever
Generalized LAN
What is the tx protocol for secondary syphilis?
Same as primary.
1 shot Bicillin
What is the hallmark sign of tertiary/late syphilis?
GUMMAS
Infiltrative tumors in the skin, bones, and internal organs (liver)
When is neurosyphilis most common?
Late syphilis. but it can occur at ANY STAGE
What is the disease course of neurosyphilis?
CSF infection with no symptoms.
Meningeal symptoms occur as meningovascular syphilis occurs.
Tabes dorsalis (chronic progressive degen of posterior columns of spinal cord)
Inability to walk in the dark, inability to control bladder, paresthesias, and a wide-based gait.
General paresis as cerebral cortex gets infected.
How is neurosyphilis diagnosed?
Same + LP
How is neurosyphilis treated?
Still pcn
What are the main risk factors for neurosyphilis?
HIV
Non-HIV: male or 45+ yo
What is the tx protcol in any stage of syphilis?
Benzathine PCN
What bacteria causes lyme disease?
Borrelia burgdorferi
What is the mode of transmission for lyme disease?
Ixodes tick (deer tick)
What are some characteristics of lyme disease?
Most common tick-borne illness in the US>
Most common in spring and summer
Most common in NE and North central US
How does the 1st stage of lyme disease present?
Early, localized infection with a target rash in 80-90% of pts within a week.
FLS
Even without tx, it can resolve in 3-4 weeks.
How does the 2nd stage of lyme disease present?
Bacteremia
Secondary skin lesions and rash
Worsening of FLS
Rare cardiac involvement (4-10%), such as arrhythmias or heart block.
Neurologic manifestations (10-15%), such as aseptic meningitis, facial palsy.
How does the 3rd stage of lyme disease present?
Months to years post infection
MSK pain (60%)
Neurologic
Skin
Generally fine if untreated.
What is the criteria of a lyme disease daignosis?
Person exposed to tick bite must have:
Erythema mirgans OR one late manifestation
+
Lab confirmation
What are the lab tests for lyme disease?
ELISA test first-line.
Western blot confirmation.
What is the tx protocol for lyme disease?
Doxycycline.
Pregnant women can use amoxicillin.
Doxy is ok in children if under 21 days.
How is leptospirosis transmitted?
Leptospira in the urine of infected rats.
How does leptospirosis present?
Minor to fatal liver/kidney disease
How is leptospirosis diagnosed?
Serologic testing
What is the tx protocol for leptospirosis?
Doxycycline
How is rocky mountain spotted fever transmitted?
Ticks carrying rickettsia rickettsii
Dermacentor ticks (wood and dog ticks)
Where is rocky mountain spotted fever most commonly found?
NC
TN
OK
AK
MO
What is the most fatal rickettsia disease?
Rocky mountain spotted fever, with a 73% mortality if untreated.
How does rocky mountain spotted fever present?
2-14 days post bite.
Starts with mild FLS, but progresses to a characteristic rash.
Rash starts as faint macules, goes to papules, then to petechiae.
Always begins on wrists and ankles.
How is rocky mountain spotted fever diagnosed?
Clinical + serologic testing
What is the tx protocol for RMSF?
DOXY
Cannot use amoxicillin!!!!!!!!!!
How are all rickettsial diseases treated?
DOXY!!!!!!
What is the clinical definition of diarrhea?
Increased stool frequency (>3 BMs/day)
OR
Liquidity of feces
What time frame is acute diarrhea?
<= 14 days
What time frame is persistent diarrhea?
> 14 days, <30 days
What time frame is chronic diarrhea?
> 30 days
What DDx are common for acute diarrhea?
Infectious etiology
Medications
Acute exacerbations of a chronic disease
What DDx are common for chronic diarrhea?
Osmotic
Secretory
Inflammatory
Meds
Malabsorption syndromes
Motility disorders
Chronic infections
Factitious
What are the bacterial etiologies possible for diarrhea?
S. aureus
B. cereus
E. coli (hemorrhagic or toxigenic)
C. diff
C. jejuni
Salmonella
Shigella
Vibrio
Listeria
What are the viral etiologies possible for diarrhea?
Norovirus
Rotavirus
Hep A
Adenovirus
CMV
What are the protozoal etiologies for diarrhea?
Giardia lamblia
Entamoeba histolytica
Cryptosporidium
Cyclospora
Isospora
What is the main clue in terms of diarrhea diagnosis?
Bloody = inflammatory
Non-bloody = non-inflammatory
What significant lab finding will be present in inflammatory diarrhea?
Positive fecal leukocytes
What does bloody stool suggest about etiology?
Most likely bacterial, as the only other causes are CMV or entamoeba histolytica.
What are the bacterial etiologies for inflammatory diarrhea?
C. jejuni
Salmonella
Shigella
E. coli (hemorrhagic)
C. diff
What are the bacterial etiologies for non-inflammatory diarrhea?
B. cereus
S. aureus
E. coli (Toxigenic)
V. cholera
Norovirus
Rotavirus
Giardia Lamblia
Cryptosporidium
Cyclospora
What are the common associated signs with inflammatory diarrhea?
Fever and abdominal tenderness.
What generally causes N/V in infectious diarrhea?
S. aureus
B. cereus
Norovirus
Rotavirus
Note:
All non-inflammatory etiologies
What kind of diarrhea usually causes volume depletion?
V. cholera causing non-inflammatory diarrhea.
What kind of etiologies do HIV pts have if they have diarrhea?
CMV
Cryptosporidium
Isospora
What is the second clue regarding diarrhea etiology?
Exposure history, such as what they ate, traveled to, abx use…
What is the third clue regarding diarrhea etiology?
Incubation period.
Which bacteria have the fastest incubation generally?
S. aureus
B. cereus
What bacteria generally take about 1 day to incubate for diarrhea?
E. coli (both kinds)
Vibrio
How long do mucosal invasion bacteria take to incubate?
1-3 days.
C. jejuni
Shigella
Salmonella
How long do viruses generally take to incubate to cause diarrhea?
1-2 days
How long do protozoans generally take to incubate to cause diarrhea?
1-2 weeks
What would prompt use to do a diagnostic workup for diarrhea?
Bloody/mucus stool
Severe dehydration
>2 weeks duration
What is the workup protocol for infectious diarrhea?
Fecal leukocyte
Stool culture (can check salmonella, shigella, and jejuni)
Stool for O & P (Protozoans)
Stool for C. diff
Viruses
Sample stool culture: Stool for SSYC, O&P, WBCs, C. diff, and viruses.
SSYC = salmonella, shigella, yersinia, campylobacter
Yersinia is a type of ecoli
How is diarrhea treated?
Fluids
Antidiarrheals (Loperamide, diphenoxylate, bismuth/pepto)
ABX if inflammatory or extended non-inflammatory.
What is the empiric abx tx for diarrhea?
Cipro, levofloxacin, etc…
Need cultures still.
How is the tx protocol for diarrhea modified for pregnant women and children?
Pregnant women, children, and inflammatory diarrhea should NOT TAKE PEPTO/BISMUTH.
Children should not take meds generally for diarrhea. Probiotics and fluids are preferred.
