Microbiology-Systems Flashcards
What is the main normal skin flora?
S. epi
What is the main normal nare flora?
S. epi and colonized by S. aureus
What is the main normal oropharynx flora?
Viridans strep
What is the main normal dental plaque flora?
S. mutans
What is the main normal colon flora?
B. fragilis over E. Coli
What is the main normal vaginal flora?
Lactobacillus, colonized by E. coli and GBS
NOTE: Neonates delivered by C-section have no flora but are rapidly colonized after birth
______ and ______ cause food poisoning that starts quickly and ends quickly
S. aureus and B. cereus
The classic cause of food poisoning from fried rice is _______
B. cereus
The classic cause of food poisoning from improperly canned food and raw honey is _______
C. botulinum
The classic cause of food poisoning from maonnaise and custards is _______
S. aureus
What needs to be on the DDx for dysentery?
Campylobacter (comma or s-shaped and growth at 42C)
E histolytica (protozoan; liver abscesses)
EHEC (can cause HUS) and EIEC
Salmonella and Shigella
Y. enterocolitis (day care outbreaks and pseudoappendocitis)
What needs to be on the DDx for watery diarrhea?
C. difficile
C. perfringens (also causes gas gangrene)
ETEC (heat labile and heat stabile toxins)
Protozoa (Giardia and Crytposporidium)
V. cholerae (rice water diarrhea)
Virusus (Rotavirus, norovirus, adenovirus)
What are the most common causes of pneumonia in children less than 4 weeks old?
GBS and E. Coli
What are the most common causes of pneumonia in children 4 weeks-18 yo?
Viruses (RSV)
Mycoplasma
C. trachomatis (infants- 3 yo)
C. pneumoniae (school aged)
S. pneumoniae
What are the most common causes of pneumonia in adults 40-65 yo?
S. pneumo
H. influenzae
Anaerobes, Viruses, Mycoplasma
What are the most common causes of pneumonia in adults 65+ yo?
S. pneumo
Influenza virus
Anaerobes
H. influenzae
gram negative rods
Common causes of pneumoniae in Alcoholics and IVDU?
S. pneumoniae, Klebsiella, and S. aureus
Common causes of pneumoniae in aspiration cases?
Anaerobes (e.g. Peptostreptococcus, Fusobacteriu Prevotella, Bacteroides)
Common causes of atypical pneumoniae?
Mycoplasma, Legionella, Chlamydia
Common causes of pneumoniae in cystic fibrosis pts?
Pseudomonas, S. aureus, S pneumo.
Common causes of pneumoniae in Nosocomial (hospital acquired) cases?
S. aureus, Pseudomonas
Common causes of pneumoniae in immunocompromised pts?
S. aurues, P. jirovecii with HIV
Common causes of pneumoniae in 2ndary postvirally?
S. aureus, H. influenza, S. pneumo
What are the most common causes of meningitis in neonates (0-6 months old)?
GBS
E. Coli
Listeria
What are the most common causes of meningitis in 6 mo-6 yr?
S. pneumo
N. meningitidis
H. influenza type B
Enteroviruses
What are the most common causes of meningitis in 6-60 yo?
S. pneumo
N. meningitis (no. 1 in teens)
Enterovirsuses
HSV
What are the most common causes of meningitis in 60+ yo?
S. pneumo
Listeria
Gram neg rods
How should meningitis be tx generally?
Vanco and ceftriaxone and add ampicillin if Listeria is suspected
What are the major viral causes of meningitis?
Enteroviruses (esp Coxsackievirus),
HSV-2 (HSV-1 = temporal lobe encephalitis),
HIV
West Nile virus,
VZV
Meningitis in HIV pt, think ______
Cryptococcus
What are the CSF findings of bacterial meningitis?
elevated opening pressure
neutrophils dominant
elevated protein
decreased glucose
What are the CSF findings of viral meningitis?
normal/slightly elevated opening pressure
lymphocytes
normal/slightly elevated protein
normal glucose
Brain abscesses are most commonly caused by what?
Strep viridans and S. aureus, or if a dental infection or extraction precedes abscess formation, consider oral anerobes
More hints about brain abscesses
Multiple abscesses suggest bactermia
single lesions are commonly from contiguous sources such as otitis media and mastoiditis (found in the temporal lobe and cerebellum)
With sinusitis or dental as the source, the frontal lobe is commonly affected
Brain abscesses in AIDs pts suggests _______
Toxoplasma
Osteomyelitis in a pt without risk factors is most likely due to what?
S. aureus (most common overall)
Osteomyelitis in a pt who is sexually active is most likely due to what?
Neisseria gonorhoeae (rare) - septi arthritis more common
Osteomyelitis in a pt with SCD is most likely due to what?
Salmonella and S. aureus
Osteomyelitis in a pt with a rposthetic joint replacement is most likely due to what?
S, aureus or S. epi
Osteomyelitis in a pt with vertebral involvement is most likely due to what?
S. aureus, Mycobacterium tuberculosis (Pott Disease)
Osteomyelitis in a pt with a Hx of cat/dog bites is most likely due to what?
Pasteurella multocida
Osteomyelitis in a pt with a Hx of IVDU is most likely due to what?
Pseudomonas, Candida, or S. aureus
How should osteomyelitis be diagnosed?
MRI is best for detecting acute infections and detailing anatomic involvement. Radiographs are insensitive early but can be useful with chronic osteomyelitis
How does cystitis present?
dysuria. frequency, uregncy, suprapubic pain, and WBCs (but not WBC casts) in urine.Primarily due to ascension of microbes from the urethra to the bladder.
Mlaes with congenital defects and vesicoureteral reflux more liekly
Elderly, those with enlarged prostate
Describe the findings of pyelonephritis
fever, chills, flank pain, CVAT, heamturia, and WBC casts
What are the major UTI bugs?
E. Coli
S. Sapro
Klebsiella pneumoniae
Serratia marcescens (often nosocomial and drug resistant)
Clues to diagnosing bacterial vaginosis
-No inflammation, thin white discharge with fishy odor
Clue cells and pH 4.5+
Tx with metronidazole
Clues to diagnosing Tirchomoniasis
Strawberry cervix
frothy, grey-green foul smelling discharge
pH 4.5+
Tx with Metronidazole and tx partners
What are TORCH infections?
Microbes that may be passed vertically- transmission is transplacental in most cases, or via delivery (esp. HSV-2).
Nonspecific signs common to many TORCH disease include HSM, jaundice, thrombocytopenia, and growth retardation
What are the TORCH infections?
Toxoplasma
Rubella
CMV
HIV
HSV 2
Syphillis
How is Toxoplasma transmitted?
Cat feces or ingestion or undercooked meat
What are the maternal and neonatal manifestations of Toxoplasma?
Maternal: Usually asymptomatic or LAD
Neonatal: Chorioretinitis, hydrocephalus, and intrancranical calcifications +/- blueberry muffin rash
Toxo- Chorioretinitis
How is Rubella transmitted?
Respiratory droplets
What are the maternal manifestations of Rubella?
Rash, LAD, and arthritis
What are the neonatal manifestations of Rubella?
PDA (pulmonary artery hypoplasia), cataracts, and deafness +/- blueberry muffin rash
How is CMV transmitted?
sexual or transplants
How does CMV present in the mom and neonate?
Maternal: asymptomatic or mono-like course
Neonate: Hearing loss, seizures, petechial rash, periventricular calcifications
How does neonatal syphillis present?
can result in stillbirth, hydrops fetalis
if child survives, presents with facial abnormalities including notched teeth, saddle nose, short maxilla, saber shins, and deafness
What are the main causes of childhood rash?
Coxsackivirus type A (hand-foot-mouth disease)
HHV-6 (Roseola; exanthem subitum)
Measles virus
Parvovirus B19 (Erythema infectiosum; 5th disease)
Rubella S. pyogenes (Scarlet fever)
VZV
Hand-Foot-Mouth Disease
Presents with oval-shaped vesicles on palms and soles and ulcers near the oral mucosa
Roseola
Asymptomatic rose-colored macules appear on body after several days of high fever; can present with seizures
Measles
Beginning at the head and moving down; rash is preceded by cough, coryza, conjunctivitis, and Koplik spots
Fifth Disease
Slapped chee rash on face (can cause hydrops fetalis in pregnant women)
Rubella
Scarlet fever
Sandpaper like rash with fever and sore throat
VZV rash
Begins on the trunk and spreads to the face and extremities with different lesions of different ages
What is this?
Condylama acuminatum (HPV 6,11)
What causes Lymphogranuloma venereum?
C. trachomatis L1-L3
What are the top causes of PID?
C. trachomatis (subacute, often not diagnosed)
N. gonorrhoeae (acute)
What nosocomial infection is most common in a pt. with altered mental status, old age, or aspiration?
Polymicrobial, gram negs, and often anaerobe
What nosocomial infection is most common in a pt. with decubitus ulcers, surgical wounds, and drains?
S. aureus
What nosocomial infection is most common in a pt. with IV catheters?
S. aurues, S. epi, and Enterobacter
What bug should you think of in a pt with CGD?
Catalase positive, including S. aureus
What bug should you think of in a pt with a cat or dog bite?
Pasteurella multocida
What bug should you think of in a pt with current jelly sputum?
Klebsiella
What bug should you think of in a pt with a fungal infection in a diabetic or immunocompromised?
Mucor or Rhizpus spp.
What bug should you think of in a pt with organ transplant?
CMV
What bug should you think of in a pt with a surgical wound?
S. aureus
