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A microbe that may or may not be a member of the
indigenous microbiota, but it regularly causes
disease in apparently normal individuals.
PATHOGEN
A particular strain of S. aureus has a defect in the
plasmid encoding for its exfoliative toxin. Which
important disease entity will this strain be UNABLE to
cause?
Toxic epidermal necrolysis
The microbe, in its pulmonary disease spectrum,
causing hemorrhagic mediastinitis with invariable
mortality if untreated, elaborates this
metalloprotease that acts on host signaling
molecules.
LETHAL FACTOR
This endogenous probiotic suppresses the virulence
of Shiga-like toxins produced by verotoxigenic E. coli
by producing acetate-based compounds.
Bifidobacterium spp.
The gram-positive Firmicutes phylum including
genera such as Streptococcus, Veillonella, and
Clostridium appear to dominate which segment of
the GIT?
Small intestine
Other bacterial phyla such as Bacteroidetes and
Proteobacteria (gamma-proteobacteria including
E. coli) were found in greater abundance in the distal
ileum → colon
Activates macrophages; upregulates MHC class I
and II; sustains activated T cells; promotes antigen-
presenting cell differentiation, promotes Th1 activity
IFN-γ
Antibody/antibodies which fix/fixes complement
system via C1q
IgM and IgG
Primary immunodeficiency that involves defects in T-
cell CD40/CD40L in the immunoglobulin activation
pathway?
What diseases would be patients at risk for?
Hyper IgM syndrome
PCP, Hep C, recurrent ear and sinopulmonary
infections bronchiectasis, chronic
cryptosporidiosis, cholangiopathy, CMV, parvovirus,
neutropenia
As a consequence of the deficiency in CD40 ligand,
the T-lymphocytes in patients with X-linked Hyper IgM
(XHIGM) are unable to instruct B-lymphocytes to
switch their production of immunoglobulins from IgM
to IgG, IgA and IgE. CD40 ligand is also important for
other functions carried out by T-lymphocytes, so
patients with X-linked hyper IgM syndrome (XHIM)
have defective cellular immunity and are also
susceptible to all kinds of infections, particularly
opportunistic infections and to some types of
cancer.
Anogenital and oropharyngeal cancers are
associated with which microbe?
Human papillomavirus
What organisms are grown in the ff culture medium
of choice?
Novy-MacNeal-Nicolle (NNN) medium
Trypanosomes such as Leishmania
Polyribosylribitol phosphate is the main virulent
component of the capsule of which organism and
what is its main action?
H. influenzae B (Hib)
Anti-phagocytic action
This antibiotic/s, when given to pregnant women, are
shown to cause sensorineural hearing loss in the fetus
or infant.
Aminoglycosides
(Pregnancy Category D)
In a resource-limited setting, the use of
chloramphenicol and rifampin, owing to their lipid
CNS infections e.g. meningitis
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solubility, is advocated in the treatment of which
type of infections?
Preferred treatment for gonorrhea among
penicillin/cephalosporin-allergic individuals.
Spectinomycin
An HIV+ man with CD4+ of 92 with tactile hallucinations treated
with Pyrimethamine+Sulfadiazine showed no clinical
improvement. Therapeutic lumbar taps were done to reduce
ICP. Very high opening pressure was noted. If this is a
cryptoccocoma, what rapid test can be done on the CSF to
confirm?
CALLAS
Cryptococcal Antigen Latex Agglutination
System
This gram-positive cocci synthesize as cell-wall precursors D-
alanine-D-lactate instead of the usual D-alanine-D-alanine
effectively conferring them resistance to Vancomycin, making
them particularly hard to treat.
E. faecium
Clinical syndrome of: arthralgias, pneumonia, pulmonary
nodules, erythema multiforme, and erythema nodosum.
What is the infective particle?
Arthroconidia
Coccidioidomycosis; “desert rheumatism”
*take note of the dermatologic signs
accompanying the joint and pulmonary
manifestations common in fungal
infections
Two important virulence factors (similar function) that have to
be present in E. coli to cause pyelonephritis or complicated UTI.
P Pili / Fimbriae (Pyelonephritis-associated Pili
or PAP)
Adhesins
The presentation of adhesive molecules
(adhesins) by UPEC is the most important
determinant of pathogenicity. UPEC adhesins
can contribute to virulence in different ways:
(i) directly triggering host and bacterial cell
signaling pathways, (ii) facilitating the
delivery of other bacterial products to host
tissues, and (iii) promoting bacterial invasion.
P fimbriae are the second common virulence
factor of UPEC, which plays an important role
in the pathogenesis of ascending UTIs and
pyelonephritis in humans
A physically (and often temporally) structured aggregate of
microorganisms, often containing multiple taxa, and often
adhered to each other and/or to a defined substrate.
BIOFILM
If this child contracted the condition shown antenatally, which
THREE viruses may have infected the mother during
pregnancy?
1. Rubella
2. Varicella
3. Herpes simplex
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A man associated with farm and slaughterhouse work;
consumption of unpasteurized milk; and contact with possibly
blighted sheep, goats, or cattle…
Presenting with: atypical pneumonia, hepatitis,
hepatomegaly, relative bradycardia, and/or splenomegaly
which may progress to infective endocarditis.
Q fever secondary to Coxiella burnetii
A 46-year-old man with CKD V secondary to Chronic
IgA has had a failure of his AV fistula due to
thrombosis. An IJ catheter was placed so he can
resume his dialysis treatments. However, 1 week post
IJ Cath placement, he complains of fever and chills.
Vancomycin was started, the IJ cath was replaced
with the previous one’s tip sent for culture. No
bacterial growth on aerobic culture but hyphal
elements were noted. Fluconazole is started on an
outpatient IV treatment but no clinical improvement
was noted after 3 days.
What antibiotics would you give him instead?
Give Echinocandins instead. An azole-resistant
Candida might be the culprit:
C. auris
C. glabrata
C. krusei
A man living in a crowded community (e.g.
congested tenements) presenting with high fevers
that relapse and remit, accompanied by rigors,
delirium, arthralgia, myalgia and
hepatosplenomegaly. Platelet abnormalities are also
noted on CBC.
What is the vector?
Human body louse
Causing relapsing fever (Borrelia recurrentis)
A 40-year-old construction worker presenting with bi-
temporal and frontal headache, with fever, calf and
lumbar muscle tenderness, conjunctival suffusion
which progressed to hepatic and renal failure. He
eventually died from hemorrhagic pneumonitis.
Likely causative agent?
Leptospira interrogans
Raxibacumab is a pre and post-exposure prophylaxis
agent as well as a treatment adjunct for which deadly
microbe?
B. anthracis
A patient was admitted after returning from a hunting
trip and was subsequently diagnosed with TULAREMIA.
What is the treatment of choice?
Gentamicin/Streptomycin
Mass casualties (bioterrorism) Fluoroquinolones or
Tetracycline/Doxycycline
What organism/s are grown in the ff culture medium
of choice?
Charcoal cefoperazone deoxycholate agar (CCDA)
Campylobacter spp.
A particular strain of VRSA (vancomycin-resistant) has
been shown to exhibit point mutations in the gene
encoding for the 23S rRNA of the 50S ribosomal
subunit. What would be the best antibiotic to treat
infections caused by this strain?
DAPTOMYCIN
The case described the mechanism of resistance to
LINEZOLID. If the mutation involves teichoic acids,
Daptomycin resistance is likely.
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A particular strain of VRSA (vancomycin-resistant) has
been shown to exhibit point mutations in the gene
encoding for the 23S rRNA of the 50S ribosomal
subunit. What would be the best antibiotic to treat
infections caused by this strain?
These two common agents of HAP/VAP are multi-drug
resistant by virtue of “MDR efflux pumps” which confer
them resistance to many groups of antibiotics all at
once.
Pseudomonas aeruginosa
Stenotrophomonas maltophilia also has an
impervious outer membrane which beta-lactams
cannot penetrate
This anti-TB drug was proposed to cause the
accumulation of an acid substrate within the TB bacilli
eventually inhibiting fatty acid synthase, as well as
inhibit trans-translation by binding key ribosomal
proteins in the pathogen.
Give the name of this drug as well as its most fatal
toxicity.
Pyrazinamide
Hepatotoxicity
Arthralgias → most common
NSAIDs would suffice if symptomatic
Hyperuricemia is not addressed unless symptomatic
In an outbreak last 2016 in Iraq and nearby Middle East
countries, this infection became a resounding public
health concern once again. Otherwise called
“Baghdad Boil”, this lesion is caused by what
organism?
(Give one of the possible specific species)
Cutaneous leishmaniasis
L. major or L. tropica
Mucocutaneous (usually in the South/Latin America)
L. braziliensis
Visceral → L. donovani, L. infantum
Dirofilaria immitis is a filarial pathogen whose primary
host are usually canines but sometimes infects humans
causing disease with variable severity. Inflammatory
reactions to the dying pathogens forming granulomas
in the process.
The most common location of these granulomas is
the: _______________
PULMONARY ARTERY
The organism is otherwise known as the “dog
heartworm” because its habitat in its host is the
pulmonary artery and the right side of the heart (but
this occurs rarely in humans). Granulomas form
causing cough at times, but most people incur the
infection remain asymptomatic. Sometimes, the filiaria
manage to escape into the systemic circulation
leading to granuloma formation in variable locations:
subcutaneous tissue, conjunctiva, brain etc.
Rifaximin is indicated for recurrent infection of which
microbe and prophylaxis for infection of which other
organism?
Treatment for RECURRENT C. difficile infection
Prophylaxis for ETEC causing traveler’s diarrhea
Also used for hepatic encephalopathy
CKD V patient develops CR-BSI. Started treatment
and presents like this.
Diagnosis?
RED MAN/NECK SYNDROME (due to Vancomycin)
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