Microbiology Flashcards
All DNA viruses are double stranded except
Parvovirus (single stranded)
All DNA viruses replicates in the nucleus except
Poxvirus (Cytoplasm)
All DNA viruses are has icosahedral capsid except
Poxvirus (complex)
All DNA viruses has linear genome except
Papillomavirus
Polyomavirus
Hepadnavirus
(circular)
A mnemonic for DNA viruses
PARdon PAPa As HE Has POX DNA
(naked)
PARvovirdea
PAPovavirdea
Adenovirdea
(enveloped)
HErpesvirdea
Hepadnavirdea
POXvirdea
Treatment of Genital Herpes
Doesn’t have any. if you have it, you have it for life.
Symptomatic relief regimen:
Acyclovir 400 mg TID for 5 days (4-3-5)
HSV incubation period
2-7 days
Target or Bull’s eye lesion is specific for
Erythema Multiform (HSV1-2)
Steven Johnson Syndrome
Is Eryhtema Multiform Major (HSV1-2)
-Fever
-Extensive Oral Lesions
-Desquamating lesions
Histological feature of CMV
Owl’s eye
Most commonly available serologic test for measuring antibodies to CMV.
ELISA
Varicella Zoster Virus Incubation Period
1-3 Weeks (7-21 days)
CMV incubation period
3-12 Weeks
Congenital defects associated with CMV
IUGR
Microcephaly
Hepatosplenomegaly
Sensory neural hearing loss
Most common cause of sensory neural hearing loss
CMV
Materno fetal transmission rate of CMV
40%
CMV causes a disease called
Mononucleusis Syndrome
Most common cause of Infectious mononucleosis
Ebstein-Barr Virus
HIV primarily infects which cells?
CD4 cells
Dendritic cells
Macrophage
Perinatal Transmission rates of HIV
with treatment <1%
Without treatment =15%
Perinatal Transmission rates of HIV
with treatment <1%
Without treatment =15%
Risk factors of HIV Perinatal transmission
High maternal viral load
Low CD4 count
Prolonged rupture membrane
Chorioamnionitis
Co morbidity (HCV, malaria)
Breastfeeding
Preterm birth
What disease does rubella cause?
German Measles
Feto- maternal Transmission Rate of Rubella virus
1st trimester = 90%
2nd trimester = 30%
Risk of transmission is decreased after 16 weeks
Obligate Aerobes
Pseudomonas
Mycobacterium
Nocardia
Facultative Anerobes
E. Coli
Staphylcoccus
Enterococcus
Obligate Anerobes
Colistridia
Bacteroids
Prevotella
Which one of the following bacteria produces an exotoxin causing ‘toxic shock syndrome’ associated with tampon usage
Staph aureus
Features of Strept. Pneumonia
- alpha hemolytic strept.
- G+ve diplococci
- Optochin sensitive
- Bile soluble
- Quellung reaction (spelled capsules)
Clinical features of Strept. Pneumonia
MOPS
Meningitis
Otitis media
Pneumonia
Sepsis (in sickle cell disease/ splenic patients)
DOC in treating Strept. Pneumonia
Penicillin
then ceftriaxione and Macrolides
Features of Staph aureus
- G+ve cocci
- Catalase +ve
- Urease -ve
- Coagulase +ve
- Ferments mannitol
Clinical features of Staph aureus
Skin infections
Osteomylitis –> septic arthritis
Endocarditis
Toxic shock syn. (with tampon usage)
Food poisoning
Staph scalded skin syndrome SSSS
Toxin by Staph aureus causes Toxic shock syndrome
TSST-1 Enterotoxin F (superantigen)
Toxin by Staph aureus causes Staph Scalded Skin Syn.
Exfoliate toxin A & B (superantigen)
Most common cause of UTI
E.coli
Most common cause of UTI in sexually active women
Staph. Saprophyticus
Group F streptcocci
Strept. anginosus
Group D streptococci
Enterococci
Strept. Bovis
Most pathogenic beta hemolytic strept
Strept pyogens GAS
GAS is commensal in
Nasopharynx
Features of GAS
Has M protein and Hyaluronic acid capsule
Bactricin Sensitive
Catalase negative
produce different endotoxins & extoxins
Symptoms of GAS
Pyogenic:
- Pharyngitis
-impetigo
-erysipales
-cellulitis
Immungenic:
-Rhemuatic fever
-Glomerulonephritis
Toxogenix:
-toxic shock-like syn.
- Scarlet fever (strawberry tongue
GAS produce three important inflammatory enzymes
- Hyalorunidase-> degrades hyaluronic acid -> Skin infection
- Streptokinase (fibrinolysin)
- DNAse-> degrades DNA in exudates and necrotic tissue
GAS produce important toxins
- Erythrogenic toxin A (pyrogenic toxin A)
- Streptolysin O
- Streptolysin S
- Exotoxin B
Scarlet Fever
- Fever
- Flushed Cheeks
- Endometritis
-Strawberry tongue
Cause of Necrotizing fasciitis type 2
GAS
M Protein virulence factor:
- Fimbrial protein
-Involve in capsule formation - Anti phagocytic
-Involve in destroying c3 convertas and prevents opsonization by c3b - Responsible for organ adhesion and invasion
What type of hypersensitivity is Rheumatic fever
Type II
What type of hypersensitivity is Glomerulonephritis
Type III
Which is the single most appropriate treatment of Chlamydia vaginal infection in pregnancy
Erythromycin 500 mg BID/14 days
Early onset neonatal infection of GBS
before 7 weeks - presented by neonatal sepsis
Late onset neonatal infection of GBS
7 weeks to 3 months - presented by meningitis (capsular serotype III) most common
GBS clinical features in neonates
Neonatal Sepsis
Meningitis
Pneumonia
GBS clinical features in adults
Endocarditis
Arthritis
Pneumonia
Osteomyelitis
Postpartum endometritis
Main predisposing factor of GBS transfer to neonates
Prolonged Rupture of membranes in women who are colonized with the organism
Main predisposing factor of GBS in Adults
Diabetes Mellitus
risk factors for neonatal GBS
- Preterm Delivery (<37 w)
- Prolonged ROM (>18 before time of delivery)
- Prolonged Labour
-Choriamnionitis
Antibiotic Regimen to treat GBS
- Benzylpenicilin G 3 gm IV then 1.5 gm IV/4 hrs until delivery
- Clindamycin 800 mg IV/ 4hrs until delivery
- Erythromycin 500 mg IV/ 6hrs until delivery
Most Enterococci species to cause infection
E. faecalis 85-90%
How is Enterococci are hardy organisms
They are commensals of normal flora of the colon.
They can grow in hypertonic (6.5%) saline or in bile
They are not killed by Penicillin G
Important Risk factors of Enterococci infection
Nosocomaila Infection:
Indwelling urinary Catheter
Urinary tract instrumentation
Important Risk factors of Enterococci infection
Nosocomaila Infection:
Indwelling urinary Catheter
Urinary tract instrumentation
Treatment of Enterococci infection
synergetic combination of penicillin G and amino glycoside (gentamycin)
N. Meningitides has three important virulence factors:
- Polysaccharride capsule. It is antiphagocytic in nature.
- The endotoxin of N. Meningitidis is a lipopolysaccharide (LPS). It induces septic shock by causing release of cytokines.
- IgA protease. It cleaves the IgA antibodies present in respiratory mucosa.
Method of transmission of N. Meningitides
The organisms are transmitted by airborne droplets
most common cause of meningitis in persons between the ages of 2 and 18 years.
N. Meningitidis
What is waterhouse friderichsen syndrome
Is a group of symptoms caused when the adrenal glands fail to function normally. This occurs as a result of bleeding into the glands. Caused by Meningococci
Different methods for laboratory diagnosis of N. Meningitidis are
-Gram staining: G-ve bean shaped diplococci
-Culture: grows on blood and chocolate agars
-Oxidase test: Oxidase +ve
-Fermentation tests: ferment maltose & mannitol
-Latex agglutination test: detects capsular polysaccharide in the spinal fluid.
features of meningitis caused by N. Meningitidis
- headache
- fever
- neck stiffness
- photophobia
- phonophobia
N. Gonorrhoeae causes
- gonorrhea
- neonatal conjunctivitis (ophthalmia neonatorum)
- pelvic inflammatory disease (PID).
Most important virulence factor of N. gonorrhea
Pili
Piliated gonococci are usually virulent, whereas non piliated strains are avirulent.
Different methods for laboratory diagnosis of N. Gonorrhea are
-Gram staining: G-ve bean shaped diplococci
-Culture: grows on Thayar-Martin Agar or Mueller-Hinton agar (chocolate Agar)
-Oxidase test: Oxidase +ve
-Fermentation tests: ferment mannitol {not maltose}
Clinical picture of gonorrhea in males
- Urethritis
- Prostatitis
- Epidedimitis
PID Clinical Picture
- Fever
- Lower Abdominal Pain
- Abnormal menstrual bleeding
- Cervical motion tenderness
Comiication of PID
- Infertility
- Scarring Ectopic pregnancy
- Peritonitis
- Violin string adhesions
- Fitz-Hugh-Kurtis synd.
difference between conjunctivitis of gonorrhea and chlamydia
Both Purulent
If infection before 4 days of delivery: gonorrhea
If infection after 5 days of delivery: chlamydia
Treatment of Gonorrhea
Ceftriaxone + Azithromycin
What sexually transmited disease (STD) is caused by Haemophilus ducreyi?
Chancroid
Syphilis caused by which organism
Treponema Pallidum
Mode of transmission of Syphilis
- Acquired (direct contact)
- MSM 35%
- Oral 15% - Vertical from mother to fetus
(transplacental passage only occurs when placenta fully developed at 14 weeks)
1ry stage of Syphilis
1-3 weeks after infection
Chancer (painless ulcer)
Regional lymphadenopathy
2ry stage of Syphilis
6-12 w after infection (4-10 w after chancer appears)
Maculopapular rash
Chondyloma Lata
Neurosyphilis features
from 15-30 years of infection
- Ascending aorta (aortitis, aortic aneurysm)
-Endartritis (info. of vasa vasorum
Features of early onset congenital syphilis
within 2 years
- IUFD
- Rhagades (linear cracks at the angle of the mouth)
-Hemorrhagic Rhinitis (Bloody snuffles)
Features of late onset congenital syphilis
After 2 years
- saber shins
- saddle nose
- hutshingson’s disease
-Mulberry molars
Syphilis Antigens
- Group specific antigen (all treponema)
- Species specific antigen (specific to T. palladium)
- Cardiolipin (lipoprotein present in spirochetes)
Antibodies appear 4-8 weeks after infection
Sexual history in primary syphilis
History of partners for the last 3 months
Sexual history in early 2ry and late latent syphilis
History of partners for the last 2 years
VDRL to assess syphilis serological activity
> 1:8 –> Positive
1:16 –> Active disease
<1:6 –> doesn’t exclude active disease particularly if symptoms are present
VDRL to assess response to treatment of syphilis
After treatment with penicillin –> Repeat VDRL after 4 weeks –> 4 folds decrease means treated
Donovan bodies’ are associated with?
Granuloma inguinale
What is the incubation period for Rubella?
12-23 days
Chlamydia trachomatis causes
- urogenital infection
- trachoma
- conjunctivitis
- pneumonia
- Lympogranuloma venerium
What kind of Organism is chlamydia
Obligate intracellular parasites
Chlamydia trachomatis serovars
L1, L2, L3
What virus family does HIV belong to?
Retroviridae
What kind of organism is Toxoplasma Gondii?
intracellular protozoan
What is the most common type of nosocomial infection in uk hospitals?
UTI
Which group of viruses cause molluscum contagiosum ?
Pox virus
congenital infections is most characteristically associated with fetal hydrops?
Parvovirus-B19
What is the causative organism of Toxoplasmosis?
Toxoplasma Gondii
which infection is most commonly associated with an increased risk of ectopic pregnancy?
Chlamydia trachomatis
What is the primary causative organism in Bacterial Vaginosis?
Gardnerella vaginalis
Which kind of organism is Neisseria Gonorrhoeae?
Gram Negative Cocci
What stage of syphilis infection is gumma?
tertiary stage
What is the causative organism of gas gangrene?
Clostridia perfringens
Which species of candida is the most common cause of genital candida infection in pregnancy?
Candida albicans
Which group of beta haemolytic streptococci isassociated with chorioamnioitis?
GBS
What is the approximate risk of HIV transmission during a single episode of vaginal unprotected sexual intercourse with a known HIV positive person?
0.05%
REGARDING URINARY TRACT INFECTIONS, WHICH MICRO-ORGANISM IS MOST LIKELY TO BE ASSOCIATED WITH BLADDER CATHETERISATION?
PSEUDOMONAS AERUGINOSA
- Which of the following cell types lyses cells that have been infected with viruses?
CD8+T CELLS
Causative organism of granuloma inguinale
Klebssiella Granulomatous
Structure of mycoplasma genitalium
Flask shaped
Which HPV causes genital warts
HPV 6 & 11
When is the highest risk of maternal-fetal transmission of Toxoplasma gondii
24-26 weeks
Percentage of women develop antibodies to human papilloma virus following infection
50-60%
Routine antenatal screen is usually for
- HIV
- HBV
- Syphilis
Tubal Infertility rate after 1 episode of PID
12%
Tubal Infertility rate after 3 episode of PID
50%
Mortality rate in patients with Septic shock
60%
Prevalence of HIV in the UK obstetric population
2 per 1000 live births
GBS Antibiotic Prophylaxis in elective CS
No AB prophylaxis needed in planned CD with no labor and intact membranes
Mortality rate of treated disseminated neonatal herpes
30%
Percentage of CMV infected infants are symptomatic
10%
Leading cause of surgical site infections
Staphylococcus aureus
What percentage of HPV infections will be cleared by the host within one year
70%
What percentage of HPV infections will be cleared by the host within 2 year
90%
Which group of beta hemolytic streptococci is associated with liver abscess formation
Group F: S. anginosus
Fetal case mortality rate associated with listeria infection during pregnancy
20-30%
What percentage of trichomoniasis cases would you expect to a strawberry cervix
2%
HPV Vaccine Gardasil is of what type
Recombinant vaccine of virus-like particles
The risk of FVS to babies born to mother who have chickenpox in first 20 weeks of gestations
1-12 weeks = 0.4%
13-20 weeks= 2%
Features of fetal varicella syndrome
- hypoplasia of one limb
- cicatricial lesions with a dermatomal distribution
- CNS abnormalities
- Eye abnormalities
What percentage of trichomoniasis cases is asymptomatic
50%
What percentage of trichomoniasis cases has yellow frothy discharge
20%
[total patients with vaginal discharge 70%]
What epithelium cell type lines in the endometrium
Columnar
Congenital rubella syndrome
- Cataract
- Bluberry muffin rash
- PDA
- deafness
1st line TTT of Listeria
Amoxicillin or Penicillin
What is the first line treatment of trichomoniasis
Metronidazole 400 mg TDS 7 days
(HIV +ve 500 mg BD)
Most common causative organism of Fitz Hugh Curtis syndrome
Chlamydia trachomatis
TTT of toxoplasmosis
W/O fetal infection: Spiramycin
W/ Fetal infection: primethamine, sulfadiazine and folinic acid
Incidence of listeriosis in pregnancy
1 per 10,000
What are the two major onco proteins associated with high risk HPV
E6 and E7
Most common cause of sepsis in puerperium
Genital tract infections (endometritis)
Most common causative organism of puerperal sepsis
GAS
Which type of cells are clue cells
Epithelial cells
Lancefield grouping of streptococci is based on the presence of
Carbohydrate antigen on cell wall
What do these signs refer to:
- green vaginal discharge
- erythematous cervix
- perinuclear halo by microscope
Trichomonas vaginalis
Organism subunit vaccine
Pertissis
Hepatitis B
Influenza
Neisseria meningitides
Which organism colonize copper IUD
Actinomyces species
