First Pass Miss Exam 3 Flashcards
What is the major virulence factor of EPEC?
Ability to efface the microvilli and sit on actin pedestal, then type 3 secretion system
-> watery diarrhea in infants / children
What is one final bacterium that can release a heat-labile enterotoxin after ingestion?
Clostridium perfringens - much like B. cereus diarrheal form, produced in GI tract. From undercooked food
(alpha toxin, disrupts actin)
What are the four non-inflammatory diarrhea causing parasites in immunocompromised?
- Cryptosporidium
- Microsporidia
- Cyclospora -> long diarrhea
- Isospora
Micro, Iso, Cyclo
-> MIC
What does Hemolytic uremic syndrome cause? Why?
Triad:
Anemia
Thrombocytopenia
Acute renal failure
Due to microthrombi forming on damaged endothelium of renal glomeruli
Seen in Shigella and EHEC, basically there is damage to the glomerulus from Shiga-like toxins which causes platelets to aggregate, and platelet clots end up lysing RBCs as they squeeze by.
How does Shigella cause bacillary dysentery? Do they all produce Shigatoxin?
Uses local inflammation produced by PMNs to induce more epithelial damage and allowing more invasion by bacteria, although it typically does not cause sepsis.
Only Shigella dysenteriae produces Shigatoxin, which is a cytotoxin killing more intestinal epithelium (like EHEC).
What is the mechanism of Shiga-toxins?
Binds the 60S ribosomal subunit to cause translational arrest. AB toxin as well, binds the Ganglioside GM3 to get in
What is the mechanism of diphtheria toxin and what uses it?
Diphtheria and similar toxin include:
P. aeruginosa (Exotoxin A)
C. difficile (Exotoxin B, stops protein synthesis and actin polymerization)
Diphtheria toxins binds EF-2 and stops cellular protein synthesis
What will be seen in the stool in Shigella?
Large numbers of PMNs + mucoid
How can you distinguish EIEC vs Salmonella vs Shigella?
Shigella - lac -
EIEC - lac +
Salmonella - lac - and makes black colonies on Hektoen
How are Salmonella bacteremia and enteric fever told apart?
Bacteremia - rarely a positive stool culture. Rapid, spiking fever. Develops following gastroenteritis
Typhoid - positive culture only later in disease. Also has an INSIDIOUS onset rather than acute. That is, a slowly rising fever rather than a rapid, spiking fever. Blood diarrhea will occur later.
How is campylobacter identified and cultured?
Microaerophilic and capnophilic, grows at campfire temperatures (42 C)
Gram negative curved oxidase positive rod (like Vibrio)
What is the major difference between Vibrio parahaemolyticus and Vibro cholerae?
Although both are transmitted in seafood, only the former is halophilic and causes bloody diarrhea
Other than pet feces, what is one major reservoir for Yersinia enterocolitica?
Transfusion-related septicemia -> can grow in blood that is refrigerated.
Causes mesenteric lymphadenitis
In what way is E. histolytica similar in adherence to UPEC’s P-pilus
Both bind sugar receptors and are thus sugar-sensitive in the lab
E histolytica = galactose
E. coli = mannose
How is H. pylori identified in the lab?
Oxidase positive, campylobacterlike organism, gram negative and curved. Urease positive.
What types of colitis do C. difficile and Shigella cause?
C. difficile - pseudomembranous
Shigella - ulcerative
What is a common causative agent of intraperitoneal abscess? How is it identified?
Bacteroides fragilis, a gram-negative encapsulated anaerobic bacillus.
Identified via foul-smelling discharge and broad antibiotic resistance (i.e. aminoglycosides because they are oxygen-dependent)
These abscesses are typically polymicrobial (with facultative anaerobes)
What are common causes of pancreatic and hepatic abscesses?
Pancreatic - peptic ulcers
Hepatic - biliary tract disease
What causes splenic abscess?
Whatever is seeding a bacterial infection elsewhere in the body
i.e. intraperitoneal = bacteroides
right-sided endocarditis = S. aureus
What is diverticulitis?
when herniation of mucosa and submucosa ruptures, leads to peritonitis
What is the most diagnostic thing that shows the presence of a recent HBV infection? What is the critical period which we are covering for?
Presence of IgM antibodies to Hepatitis B core antigen (HBcAg)
Will persist even during the window period when HepB surface antigen (HBsAg) is not seen in the blood, and anti-HBsAg are not of protective, detectable titers
What is the mechanism of formation of mRNA in HBV viral replication cycle within hepatocytes?
- Enters the cell, is uncoating, and the partially dsDNA is converted into cccDNA (covalently closed circular form DNA) by host enzymes.
- Minus strand DNA is transcribed into full length plus-strand RNA by host DNA polymerase 2
What is the function of the P protein in HBV?
Uses the full length viral mRNA to Reverse-transcribe to full length (-) sense DNA. Then uses full length (-) DNA to transcribe a partial + strand.
It is a DNA/RNA-dependent DNA polymerase
What is delta antigen?
The only protein encoded by the - sense ssRNA virus Hepatitis D -> functions in RNA encapsidation
What histological finding is characteristic of acute hepatitis?
Councilman bodies - ballooning hepatocytes + dark staining necrotic / apoptotic hepatocytes
Hep A often causes this
What is asterixis?
Hand tremor which can accompany the lethargy and stupor associated with fulminant hepatitis (liver failure)
In terms of labs, what is the difference between Chronic Hepatitis B and Carrier Hep B?
In chronic hep B, liver enzyme tests will be abnormal, but they are normal in carrier hep. HBeAg may also be present in chronic.
For both conditions, HBsAg will be detected in blood, with no HBsAg for >6 months
What is the mainstay of treatment for SBP? How long?
3rd generation cephalosporins, i.e. ceftriaxone
Short course: 5-7 days
Remember you are just trying to hit facultative anaerobes here, anaerobic infection is unlikely
How do we treat community acquired vs nosocomial or critically ill CA intra-abdominal infections? How long?
CA: treat E. coli empirically based on location with a cephalosporin + metronidazole for B fragilis
Nosocomial/Critically ill: Expand coverage to cover Pseudomonas, i.e. Cefepime /metronidazole or Piperacillin/tazobactam
Treat 4-7 days, or until WBC drops, fever drops, and GI function returns
What is critical for stopping intra-abdominal infections?
Source control - need to drain abscesses / check for resolution via MRI
Most common causes of daycare associated gastroenteritis?
- Rotavirus
- Shigella
- Giardia
- Cryptosporidium
What diarrheal diseases do we always treat with antibiotics?
- Shigella
- ETEC
- Campylobacter
- C. difficile
What diarrheal diseases do we avoid anti-motility treatment in?
Blood diarrhea, EHEC, C. difficile
-> all toxin-mediated (need to poop the toxins out)
Do we treat Salmonella with antibiotics?
Not routinely, unless severe disease
What are the two recommended treatments for Salmonella / Shigella? How long in normal vs immunocompromised / relapsing patients?
Either Ciprofloxacin or Amoxicillin / Ampicillin (HELPS)
Salmonella normal: 5-7 days
Relapsing / compromised: 14 days
Generally, takes a few less days to treat Shigella
How long is E. coli treated?
3 days of Cipro or cephalosporins
What is the treatment for Aeromonas?
3 days of Cipro
What is the number 1 treatment for Vibrio, and what do you do if you can’t use that agent?
Doxycycline 300 mg x 1 (triple the normal dose)
If child under 8, use TMP/SMX x3 days, or 1 dose FQ
Why do we avoid fluoroquinolones in children for treatment of E. coli and what do we give instead?
Cartilage damage -> give Bactrim or cephalosporins
What is the duration of therapy for C. difficile?
10-14 days on first instance
What are the side effects of IFN-alpha?
Flu-like symptoms on administration
Long-term: Bone marrow suppression, severe depression of mood
What is the primary adhesion virulence factor of N. gonorrhoeae and how does it attach and evade host immune response?
Pili - binds human CD46 membrane receptor
- RNA level = Slipped strand mispairing - Change the pilus length and create pilus plus and pilus minus (do not survive) phenotypes
- DNA level = Antigenic variation, PilE = expression, must recombine with pilS (several loci) to express different amino acid sequence in pilus protein
What causes the majority of damage in gonorrhea?
Immune response to lipo-oligosaccharide (Neisserial LPS which gets sialyted to evade neutrophil attachment)
How can gonorrhea be detected in men vs women in the lab?
Symptomatic men = gram stains. Does not work for symptomatic women (need PCR).
Typically, just culture urethral discharge (men) or cervical swabs (women) on Thayer-Martin
Diplococci within PMN = diagnostic for men
What is tertiary syphilis marked by?
Gummas - Granulomatous lesions of skin, bone, and joints due to host immune response. (noninfectious)
Neurosyphilis - Argyll-Robertson pupils (constricts on accommodation but does not react to light), tabes dorsalis, dementia, optic atrophy, seizures
Cardiovascular syphilis - Aortic aneurysm
For severe cases of congenital syphilis, what are some of the pathopneumonic exam findings?
- Hutchinson’s teeth - notched teeth
- Saddle nose - bend in nose
- Hard palate defect
- Short maxilla
- Protruding mandible
- Rhagades - linear scars on edge of mouth
- CN8 deafness
What is the function of gp120?
Part of viral envelope, binds to CD4 and CCR5 or CXCR4
What are the four HIV accessory proteins?
Nef = immune EEEEvasion by downregulating cd4 and mhc class 1 Vif = Viron infectivity factor - Counteracts cytIIIdine deaminases that degrade viral mRNA Vpu = Virus bUUUUdding Vpr = translational aRRRest
What are Tat and Rev?
Tat = transcriptional activator -> upregulate viral mRNA synthesis
Rev = facilitates exit of viral mRNA from nucleus without splicing
What drug might be better than oral vancomycin for the treatment of C. difficile diarrhea?
Fidaxomicin
What is common in early onset neurosyphilis?
Meningitis
Tabes dorsalis + argyll-robertson pupil is more common in late onset
What two labs are typically elevated in vaginal trichomoniasis?
Vaginal pH and PMNs
What STDs will increase transmission of HIV?
Inflammatory - will result in increase of CD4+ cells near the genitals - transmission is actually more likely to occur to higher CD4 counts
Ulcerative - leads to exposed mucus membranes (i.e. HPV, HSV, Syphilis)
What three things can make you an elite controller?
- APOBEC3 - protein which interferes with reverse transcriptase
- CCR5 mutant
- CCR5-ligand is upregulated and competitive
What is the longterm risk of elite controllers?
Chronic immune activation can produce premature vascular disease (atherosclerosis) as well as non-AIDS cancers
Other than a loss of cell-mediated immunity, what are two other degradations of the immune system which can occur in HIV?
- Disordered antibody production and overproduction of non-specific antibodies (heterophile antibodies like EBV)
- Bone marrow failure in late AIDS leading to severe NEUTROPENIA
What are the three main types of Pili on UPEC and what is their mannose-sensitivity (unable to work when a plate it covered in it)
- P-pili - mannose insensitive - binds globobiose via PapG
- Type 1 Pili - mannose sensitive (binds mannose via FimH)
- Type S fimbriae - mannose insensitive - bind sialic acid
What two toxins are made by UPEC and what is their function?
- Hemolysin - causes kidney damage in pyelonephritis, used for iron acquisition
- Cnf1 - Cytotoxic necrotizing factor 1 -> kills human bladder epithelium by apoptosis
What is a struvite stone?
Kidney stone - magnesium ammonium phosphate
How is S. saprophyticus identified in the lab?
Grows on CNA agar (Gram positive), is catalase + (it’s Staph), catalase negative (not aureus), and novobiocin-resistant
What pili does K. pneumoniae have?
Type 1 - same as E. coli
Type 3 - mannose insensitive
Told apart from E. coli by being non-hemolytic
How is Proteus mirabilis told apart from E. coli / Klebsiella?
It is lac negative
Two major virulence factors of proteus?
- MR/P - mannose-resistant, proteus-like for pyelonephritis
2. Swarming motility to make it up ureter
What is PMF?
Proteus mirabilis fimbrae - like E. coli Type 1 Fimbriae but is not a hemagglutinin
What is Asa1? Give 2 other Enterococcus virulence factors
Aggregation substance, a virulence factor of Enterococcus which fascilitates conjugal plasmid exchange for antibiotic resistance, and is also involved in adherence via integrins
- Cytolysin - for freeing up iron
- Sex pheromones - for mating and exchanging drug resistance factors, also attracting neutrophils
What is the purpose of fimbrial adhesins for E. coli?
Internalization via Dr blood group antigens to epithelial cells to evade immune response.
What is recurrence vs relapse vs reinfection in UTI’s?
Recurrence = another UTI (about 25% will have another UTI within 1 year)
Relapse = recurrence with same micro-organism (usually <2 weeks)
Reinfection = recurrence with different micro-organism
(usually >2 weeks)
What are the cases in which asymptomatic bacteriuria is treated?
- Pregnancy (bad outcomes for child)
- Prior to invasive instrumentation of urinary tract for a procedure (need to do a pre-culture)
Questioned by Pogue: - Renal transplant patient (during first 6 months post transplant)
- Neonates
What makes the junctions of the blood brain barrier vs blood-CSF barrier?
BBB - tightly joined endothelial cells surrounded by glial processes (i.e. astrocytes)
BCSFB - endothelial cells with fenestrations and tightly joined choroid plexus epithelium
What are the risk factors for meningitis caused by S. pneumoniae?
immunosuppression (i.e. HIV or recent influenza), distant foci of infection (i.e. chronic otitis media), or low levels of circulating antibodies to capsule
What produces a ring-enhancing lesion on CT?
Fibrotic capsule of polymicrobial abscesses, most often caused by Streptococcus species or anaerobes
Also Toxoplasma or Cryptococccus
What are P1-P3 and what is their general function in picornaviruses??
CPR - all encoded by a single mRNA which has polypeptides cleaved
P1: C: Capsid proteins
P2: P: Processing proteins - includes 2A and 3C
P3: R: Replication of genome
What receptor does polio use?
Pvr = polio virus receptor
What are 3D and VPg?
Picornavirus proteins which must work together
3D = RNA-dependent RNA polymerase VPg = viral protein G, binds the 5' UTR, provides polyU primer for RNA synthesis
IRES = Internal Ribosome Entry Site - binds ribosome in 5’ UTR, not present in Flavivirus except Hepacivirus
What are the three major structural proteins for Flavivirus replication?
- C - capsid
- E - envelope
- PrM - protease for maturation
What is antibody-dependent enhancement?
Antibody-dependent enhancement (especially dengue-virus)
Since flaviviruses mutate so quickly, previously protective antibodies bind but do not neutralize the new virions. These antibodies facilitate opsonization which allow viruses to more efficiently enter macrophages + enhance replication
What is the most important flavivirus non-structural protein?
NS1 - soluble hemagglutinin which could become a vaccine target
What is the thing to remember about Chikungunya virus?
“Bent out of shape” - arthritis and join symptoms - transmitted by Mosquito
What to remember about EEE?
Small hemorrhages in brain + neuronal damage, very rare, otherwise similar to West Nile Virus
Other than flu-like symptoms, what are the common early symptoms of Rabies?
Late?
Increased muscle tone and hydrophobia
Late: Confusion, agitation, cerebral dysfunction, hallucinations, hypersalivation, insomnia
What is seen histologically in Rabies?
Cytoplasmic eosinophilic inclusions called Negri bodies (iNtEGRIty)
What is the primary virulence factor of Viridans Streptococci?
Glucans (dextrans in sketchy) which permit attachment to teeth, caries.
S. mutans is associated with dental caries
What three diseases do oral anerobes cause?
- Chronic marginal gingivitis
- Peridontitis - progression, between supporting tissue and teeth
- Acute necrotizing ulcerative gingivitis - trench mouth
can also form abscesses
What allows Actinomyces to colonize and what is the progression of the infection?
Some trauma, often a dental operation, that penetrates the epithelial barrier. It is slowly progressing, leading to pus and bacteria which flow in sinus tracts which drain the pus directly onto the skin
In severe infection, aspiration may lead to thoracic actinomycosis
What are the the physiological effects of increased cAMP in Pertussis? What is the severity of disease?
- Increased histamine sensitization
- Promotion of lymphocytosis in bloodstream by disabling lymphokine receptors which bring them out of the bloodstream. (sketchy Gi with overflowing popcorn)
- Insulin secretion
- Diminished oxidative killing via macrophages
This is also caused by invasive adenylate cyclase which increases PMN count and reduces killing
Fulminant disease in infants and young children (edema + brain hemorrhages), both adults / infants clear in 100 days
What is the pathogenesis of pertussis?
Filamentous hemagglutinin lets Bordetella adhere to bronchiolar epithelium. Toxins kill the cilia and interfere with phagocytosis. Systemic effects are felt due to circulating toxin (increased cAMP). Local inflammation to bacterial in bronchi leads to cough.
What is the morphology of pertussis?
Same as H. influenza -> gram negative coccobacillus
What are the systemic manifestations of diphtheria?
Can cause myocarditis, arrythmias, and attack the CNS
Is smallpox a centrifugal rash? Varicella?
Both are considered centrifugal
Smallpox - starts on face and spreads from proximal extremities and trunk to distal extremities, also considered centrifugal. There are more extremity lesions in smallpox
Varicella - starts on trunk and spreads outward, like the centrifugal force. There are more trunk lesions in varicella
What are the two diseases caused by Legionella? What are the clinical characteristics?
- Legionnaire’s Disease - severe lobar pnuemonia causing hyponatremia, diarrhea, headaches, confusion, and high fever
- Pontiac fever - Shorter incubation, self limiting, malaise which is less severe than the pneumonia (less virulent or dead strains)
What are the mechanisms by which Legionella enters the macrophage?
- Has surface protein for C3 binding and complement-mediated phagocytosis
- “Coiling phagocytosis” - induces alveolar macrophage uptake in the absence of opsonization via phagocytosis
What is significant about Acetinobacter and what is its morphology?
It is multiple-drug resistant and nosocomial, with a high incidence in U.S. Gulf War soldiers. Causes pneumonia and blood/wound infections in immunocompromised
Morphology: gram negative coccobacillus (similar to H. influenzae or B. pertussis)
What do Legionella, TB, Histoplasma, and Chlamydia all have in common?
They grow intracellularly inside macrophages
What can predispose people to pneumonia via Aspergillus?
Asthma, chronic bronchitis, tuberculosis. immunosuppression
-> neutrophils are the primary defense
What T / B cell combinations indicate a poor vs good response to Coccidioides?
Immunity is primarily T-cell mediated
Good: Strong T cell response with little antibody
Bad: Increased non-protective B cell response (complement fixation does not work)
What is done to get a PCP sample?
Bronchoalveolar lavage for a sputum sample via hypertonic saline, especially in AIDS patients since they normally won’t produce sputum.
Can also biopsy
What are the clinical symptoms of pneumocystosis? How do patients die?
Mild or low grade fever
Typical signs of pneumonia absent - NONPRODUCTIVE COUGH
Progressive dyspnea and tachypnea with cyanosis due to hypoxia.
Patients die by asphyxiation
Also is a trophozoite detected by Giemsa stain (although still a fungus)
What is vasogenic edema?
Edema caused by increased permeability of blood brain barrier, leads to increased ICP, especially due to exit of proteins from the blood into the CSF leading to increased oncotic pressure
Basically, edema caused by “vaso” or vessels opening
What is interstitial edema?
Increased resistance to CSF outflow due to inflammation of the subarachnoid space leads to increased ICP and breakage of blood-CSF barrier, but will NOT cause a protein increase
Basically, edema caused by excess CSF
At what age do we again start worrying about Listeria and E. coli as meningitis causes again?
Age 50
What is one really specific and important finding indicating meningitis in neonates / infants?
Bulging fontanelle
What is most likely to cause meningitis post head trauma / surgery?
S. aureus and S. epidermitis, maybe some aerobes like E. coli and Pseudomonas
Only an issue in CSF leak / basilar skull fracture: H. influenzae and Group A Strept
What is the most common cause of viral meningitis and who gets it?
Typically associated with enteroviruses (Polio and Cocksackievirus), most common in infants / young children in late summer and early fall
What are important predisposing factors to meningitis?
OPS of MOPS, although direct seeding has not been shown,
Endocarditis, recent head trauma / CSF leak, immunosuppression or splenic dysfunction, alcoholism, complement deficiency
What is one shared side effect of integrase inhibitors? One thing they all need to do in terms of a drug interaction necessity?
Binds divalent cations - give separately
All need to have doubled dose if given with rifampin
What is the side effect of concern with colbicistat and raltegravir?
Both cause CPK elevations, colbicistat due to inhibition of excretion and raltegravir due to rhabdomylosis
What is the cutoff GFR for giving tenofovir?
> 30 GFR is needed, because it’s nephrotoxic
What is the only integrase given with a booster?
Elvitegravir -> only one which is CYP3A4 metabolized
What is the best integrase inhibitor and a drug interaction we worry about?
Dolutegravir - once daily dosing
Doubles the effectiveness of metformin in diabetics -> hypoglycemic crisis
What are the two most common 2-NRTI backbones?
- Abacavir / lamivudine
2. Tenofovir / emtricitabine
What are the HIV major drugs which are CYP3A4 metabolized?
Ritonavir, Darunavir (All PIs)
Elvitegravir
Maraviroc
Pyramethamine for T. gondii is also CYP3A4
Pentamidine = CYP2C19
What is the PCP treatment of choice?
High dose TMP/SMX for 21 days, with option of corticosteroids to reduce inflammation in moderate/severe
What is the MAC treatment?
Two or more anti-mycobacterial drugs to prevent resistance.
First line: Clarithromycin + Ethambutol + sometimes rifabutin
What is the prophylaxis for PCP and T. gondii? MAC
Both are TMP/SMX or dapsone
MAC is once weekly azithromycin or clarithromycin
What is the treatment for PCP?
TMP / SMX x 21 days, +/- corticosteroids for moderate to severe inflammation
What are the first line treatments for community-acquired pyelonephritis, given orally? Duration of therapy?
FQ (i.e. Cipro)
TMP/SMX
3rd generation Cephalosporin
Generally 7-14 days of therapy is fine, leaning towards 7
What is the treatment for first episode of HSV-2?
Valacyclovir BID x7-10 days
What organism should be considered for non-gonoccal urethritis if doxycycline was given?
Mycoplasma genitalium
A second, less likely cause of non-gonococcal urethritis.
Treat with moxifloxacin (assuming they had doxy due to azithromycin allergy)
What are two uncomplicated gonococcal infections and what is the treatment?
Cervicitis, urethritis
Treatment: Ceftriaxone 250 mg IM x 1
+
Azithromycin 1g PO x 1 dose (always treat for chlamydia)
What are the treatments for bacterial and fungal vaginosis? Trichomonas vaginalis?
Bacterial: Gardnerella - Metronidazole x 7 days
Fungal: Fluconazole x 1 dose
Trichomonas - Metronidazole x7 days, or just one dose of 2g metronidazole
What is the treatment of epididymitis?
Ceftriaxone IM + doxycycline
Substitute levofloxacin for doxy if enteric organisms are a concern (cover pseudomonas)
What is the empiric regimen for PID?
Cefoxitin to cover gonorrhea
+
Doxycycline to cover chlamydia
BOTH GIVEN IV until there is a response
What are the drugs of choice for healthcare associated UTI?
Cefepime or ceftazidime Zosyn Cipro / Levo Carbapenems minus ertapenem Aminoglycosides
What does congenital varicella cause?
Mental retardation, cerebral atrophy, and non-CNS abnormalities (limb hypoplasia, blindness, cutaneous dermatomal scarring)
What proportion of kids have clinical signs of CMV at birth if infected, and what are they?
10%: Intrauterine growth retardation, hepatosplenomegaly, microcephaly, blueberry muffin rash, ventriculomegaly
Majority will develop longterm sequelae including mental retardation, seizures, sensorineural hearing loss, and death
What causes pathology in PML, a condition caused by JC virus?
Polyomavirus = circular dsDNA
PML - Progressive Multifocal Leukoencephalopathy
Demyelination of deep cortical white matter via replication in oligodendrocytes, with minimal inflammatory processes going on
What does BK virus cause in immunocompetent vs immunocompromised hosts?
Immunocompetent: Mild upper respiratory disease (same as JC virus)
Immunocompromised:
- Polyomavirus nephropathy, especially in renal transplant patients.
- Hemorrhagic cystitis, in bone marrow transplant patients.
Why do older people often get pneumonia?
Diminished ciliary clearance, abnormal elastic recoil of lungs, and diminished T and B cell response
What is the morphology of Moraxella catarrhalis?
Gram negative diplococci, causes pneumonia in COPD patients
What urine tests are run for pneumonia?
- Pneumococcal antigen
2. Legionella, serotype 1
What microbes are frequently implicated in nosocomial pneumonias, and do we worry about Candida?
Gram negative aerobes (Pseudomonas, Acinetobacter)
MRSA
Candida is often cultured, but does NOT cause disease and should not be treated
What are the X-ray features of aspergillosis? Risk factors?
Nodular lesions with “halo sign” that often progresses to cavities
Neutropenia, prolonged steroid use, and chronic granulomatous disease are risk factors
What lab is usually elevated in PCP pneumonia?
Serum beta-glucan
What are two lab signs that point to pneumonia?
- Elevated white cell count with left shift
2. High inflammatory markers (procalcitonin, C-reactive protein)
What is one specific finding that happens in about 5% of Mycoplasma pneumoniae?
Bullous myringitis -> inflammation of the tympanic membrane
What is a typical empiric treatment regimen for neutropenic patients?
Must cover P. aeruginosa
Piperacillin/tazobactam or cefepime or imipenem
PLUS
Aminoglycoside like tobramycin
What diseases cause defects in Cell-mediated immunity?
Hodgkin’s lymphoma, non-Hodgkin’s lymphoma, Chronic Lymphatic Leukemia, hairy cell leukemia.
What are four major immune defects associated with susceptibility to encapsulated organisms?
- Multiple myeloma
- Chronic lymphatic leukemia
- Waldenstrom’s macroglobulinemia
- Sickle cell disease
What cancers and lymphomas is EBV associated with?
Burkitt’s lymphoma (Africans, bar kid, swelling cheeks), Nasopharyngeal carcinoma (asians), Hodgkin’s Lymphoma (Owl sitting in Reeds), Lymphomas / Lymphoproliferative tumors in AIDS
What is Acute Respiratory Disease (ARD)?
Respiratory infection caused by Adenovirus commonly found in military recruits, transmission facilitate by stress and crowding.
Can cause mild URI to pneumonia
Only military has a vaccine
What epidemic eye infection does Adenovirus cause and how is it spread?
Epidemic keratoconjunctivitis, spread by eyedroppers of healthcare workers
What are two super uncommon adenovirus infections?
Urethritis and cystitis (think of statue of david peeing out blood into swimming pool transmission of pharyngoconjunctival fever)
What are the symptoms of EBV infectious mono-nucleosis? How long does it last?
Common in adolescents and adults
Fatigue, fever, sore throat (pharyngitis, copious)
Specific: Lymphadenopathy (cervical, could be generalized), splenomegaly (due to T cell proliferation), lymphocytosis, and heterophile antibodies
Lasts 2-4 weeks acutely, with fatigue lasting longer
What is the second phase of Parvovirus infection?
Deposition of immune complexes leads to erythematous rash + arthritis symptoms
What is the first stage of Parvovirus B19 infection / where does it replicate / shed?
Nonspecific flu-like symptoms and suppression of reticulocytes (RBCs)
Replicates in bone marrow and sheds in Upper Respiratory Tract (probably URT transmission)
Parvoviruses are inactivated by protective IgM response
What is the RNA complex called in Influenza, and what protein is involved in packaging nascent ones?
-sense RNA called Ribonucleoprotein (RNP)
M1 protein is a matrix protein involved in packaging new RNP’s and helping them bud out of the cell
What is the function of the NS1 protein in Influenza?
blocks the interferon-induced RNaseL pathway
What cleaves HA0 and what does it become?
Human protein trypsin, only present in lungs
Becomes HA1 - receptor for sialic acid and HA2 - transmembrane protein
What is Measles Virus also called, and what are its prodomal symptoms?
Rubeola virus
Remember the 4 C's of the prodrome: Cough Coryza Conjunctivitis Coplik's spots
What is the cell tropism of adenovirus?
Epithelial cells, including GI epithelium, URT, and conjunctiva of eyes (explains the wide range of illnesses it causes)
What does Parvovirus replicate?
In the bone marrow, but starts in the upper respiratory tract
What are the most common manifestations of mumps? Atypical?
Painful swelling of parotid glands (unilateral or bilateral), ear pain
Atypical:
Orchitis -> more severe, can cause infertility if bilateral
Also meningitis
What do paramyxoviruses typically cause in adults?
Pneumonia and laryngitis (similar to croup)
What is the empiric coverage we use for meningitis in patients <1 month?
Ampicillin + gentamicin or cefotaxime (3rd generation not ceftriaxone)
Gentamicin is okay because patient has no BBB
What must be added onto the antibiotic regimen for adults >50 and why?
ampicillin, for listeria coverage
So regimen is:
ampicillin + vancomycin + ceftriaxone
What is the empiric coverage for meningitis in patients 1-23 months of age and why?
Vancomycin + 3rd generation cephalosporin
Use vancomycin for possibility of mildly elevated MICs of Streptococcus pneumoniae which would not allow killing by cephalosporin in CSF
Usually coag-negative staph (from skin)
Recommended broad therapy: Vancomycin + cefepime or ceftazidime
Usually coag-negative staph (from skin)
Recommended broad therapy: Vancomycin + cefepime or ceftazidime
What is the most common causative pathogen in CSF shunt infections, and what is the recommended empiric treatment?
Usually coag-negative staph (from skin)
Recommended broad therapy: Vancomycin + cefepime or ceftazidime
Who gets prophylaxis for meningitis caused by N. meningitis and H. influenzae and what is it?
N. meningitis - anyone exposed to oral secretions and household contacts - Ciprofloxacin 500 mg or rifampin
H. influenzae - everyone in a household with unvaccinated children (might spread to them) - Rifampin
What is the first-line treatment for COPD exacerbation?
Doxycycline, with second-line amoxicillin/clavulanic acid, x3-7 days
What is the therapy for sinusitis?
Same as outpatient COPD: amox/clav or Doxycycline
What is given to healthy CA-pneumonia and high risk CA-pneumonia in outpatient therapy?
Previously healthy: azithromycin or doxycycline
High risk: beta-lactam + azithromycin or doxycycline
For inpatient non-ICU CAP, what is the treatment?
Option 1: Azithromycin + 3rd gen cephalosporin
Option 2: Doxycycline + 3rd gen cephalosporin
Option 3: Respiratory fluoroquinolone
What is the treatment of choice for outpatient aspiration pneumonia?
Amoxicillin/clavulanic acid (good gram negative / anaerobe coverage)
What dictates the duration of therapy for community-acquired pneumonia?
Minimum of 5 days, must be afebrile for 48-72 hours, and no more than one “sign of instability”
- Fever, leukocytosis, tachycardia, tachypnea
What is the empiric therapy for HAP/HCAP/VAP?
1. Antipseudomonal beta-lactam \+ 2. Antipseudomonal FQ or aminoglycoside \+ 3. MRSA coverage: Vancomycin or linezolid
x7 days, assuming clinical response
What are the drugs of choice for Stenotrophomonas as well as Listeria when patient is allergic to penicillin?
TMP/SMX
What is the mechanism of Borrelia recurrentis antigen switching?
VMP - Variable major protein, a cell surface serotype
What is the second stage of Lyme disease? Third stage?
Second: Bacteria spread to CNS and joints: Bilateral bell’s palsy and heart block (conduction defects). Possible early arthritis
Third: Encephalitis and polyarthritis likely, even in absence of organism
Where does Rickettsia live?
Lives in vascular endothelium of lung, spleen, brain, and skin as an obligate intracellular organism (internalized via phospholipase)
In what way is Bartonella infection of immunocompromised patients similar to Rickettsia?
Affects blood vessels.
While Rickettsia is the only one which is intracellular in the endothelium of lung, liver, brain, and skin,
Bartonella causes Bacillary angiomatosis which is a vascular infection as well. It can also cause hemorrhagic disease of spleen and liver
Other than the Type 3 secretion system used to disrupt macrophages and PMNs, what other two virulence factors does Yersinia pestis have?
- Invasins - inducing actin rearrangement and uptake of bacteria into nonprofessional phagocytes
- Plasminogen activator - plasminogen will dissolve fibrin clots and prevent chemotaxis of PMNs
What is the growth pattern of Francisella?
Intracellular, enters via skin lesion (i.e. tic bite), then travels to lymph nodes in macrophages before disseminating
What does Bartonella usually cause?
Axillary lymphadenitis
What is the incubation of smallpox vs chickenpox? Rash length?
Smallpox - 1-2 weeks
Chickenpox - 2-3 weeks
And smallpox lesions will last twice as long
What are the four types of smallpox?
Common:
- Major
- Minor
Rare:
- Flat-type - flat, soft, focal skin lesions
- Hemorrhagic-type - mucosal hemorrhage and death before lesion formation
What is the hallmark feature of ebola infections?
Massive hemorrhagic destruction of the liver. Also damage to spleen and kidney
What illness does hantavirus cause?
Hantavirus pulmonary syndrome (HPS), along regular malaise symptoms including nausea or vomiting
HPS - respiratory distress syndrome which causes respiratory failure and pulmonary edema
