Microbiology- a clinical approach by Anthony
Strelkauskas et al. 2010
Chapter 23: Infections of the genitourinary system
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The urogenital tract is directly exposed to the
outer environment and many pathogens use this
portal of entry.
As a health care professional you will see many
infections here.
Major complications of STDs are infertility and
ectopic pregnancies.
STDs can infect the fetus and the newborn.
Some organism can move
retrograde causing an
ascending UTI using pili
and adhesins
Obstructions in urinary system associated with increased incidence of infections
Blue: male
Orange: female
Prostate enlargement
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Urine is essentially sterile.
When passing through urethral opening urine becomes
contaminated with normal microbiota and some epithelial
cells.
◦ Refrigerate urine after collection!
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Presence of one type of microbe at > 105 CFU/mL
indicates UTI.
Presence inflammatory cells and erythrocytes indicates
UTI.
UTIs are typically caused by bacteria, less often yeasts.
UTIs are more common in women due to the ureter
anatomy, closeness of the anus and contaminating fecal
normal microbiota.
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UTIs are serious problems in hospitals.
Usually associated with indwelling catheters
Bacteria or yeast ascend the outside of the
catheter and reach the bladder.
Complicated by high antibiotic resistance
among nosocomial strains.
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Urethritis – in the urethra
Cystitis – in the bladder
Pyelonephritis – in the kidneys
Prostatitis – in the prostate
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Urethritis and cystitis
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Pyelonephritis
◦ Dysuria with painful,
frequent and urgent
urination
◦ Low back pain, abdominal
pain, and tenderness over
bladder
◦ Urine will be cloudy.
◦ Pain in the flanks
◦ Fever above 38.3˚C
◦ Severe cases can cause
septic shock.
◦ Usually no damage to kidney
function
◦ Can further ascend and
develop into sepsis: iv
antibiotics.
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Prostatitis
◦ Pain in the lower back,
perirectal area, and
testicles
◦ Can be high fever, chills,
and symptoms similar to
bacterial cystitis
◦ Inflammatory swelling can
lead to obstruction of the
urethra.
◦ Retention of urine can
cause abscess formation,
epididymitis, and seminal
vesiculitis.
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Detection of nitrate and
leukocytes in urine
◦ > 10 leukocytes/mL urine
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Bacteria urine culture
with > 105 CFU (colony
forming unit)/mL in clean
catch urine
Diseased kidney
Normal kidney
Kidney stones
Nosocomial
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Trimethoprim: uncomplicated outpatient UTI
Cephalexin
Amoxycillin: Enterococcus infection
Ciprofloxacin, gentamicin, : complicated UTI
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Primarily Candida infections
Descending UTI with yeasts more often in
diabetic patients
Indwelling catheters
Therapy mainly removal of catheter and azoles
◦ Fluconazole
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Major infections in the reproductive system
are sexually transmitted.
◦ Sexual promiscuity more likely to contract STD
◦ Concurrent STDs increase risk for HIV infection
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Many infected individuals do not seek medical
help, because asymptomatic
Infertility and ectopic pregnancies are major
complications of even asymptomatic STDs.
The term sexually transmitted infections
(STI) includes infections that are transmitted
via intercourse but manifest elsewhere.
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Urethritis
Vaginitis
Cervicitis
Lymphadenitis
Pelvic Inflammatory Disease (PID)
Prostatitis, epididymis
Pharyngitis
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STDs have been around for hundreds of years.
◦ Affect all populations and social strata
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Most common pathogens:
◦ Chlamydia trachomatis
◦ Neisseria gonorrhoeae
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Also occurring
◦ Papilloma virus, herpes simplex, and HIV virus
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Less frequent but still around
◦ Treponema pallidum
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Sexually transmitted infections (STI) transmitted
via intercourse but the disease manifests
elsewhere
◦ HIV, Hepatitis B
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Ulcers (Haemphilus dycrei, Treponema pallidum,
Herpes simplex)
Vesicles (Herpes simplex )
Warts (Human papillomavirus)
Discharge (Neisseria gonrrohoeae, Chlamydia
trachomatis)
Unpleasant smell (fishy in bacterial vaginosis
and foul smelling in trichonomiasis)
Pruritus (Candida infections)
Pain
Fever (PID)
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Presents as dysuria and/or urethral discharge.
Caused by Neisseria gonorrhoeae and Chlamydia
trachomatis
pus
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watery
Diagnosis typically based on molecular genetic
methods (nucleic acid amplification tests)
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Bacterial is the most
common type of vaginitis.
◦ Associated with overgrowth of
vaginal anaerobic flora
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Can be homogeneous
yellowish discharge
◦ Stays adhered to vaginal wall
◦ Clue cells found in discharge
covered with bacteria.
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Also caused by Trichomonas
vaginalis
◦ Abundant foul smelling frothy
discharge
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Etiology can vary.
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May involve mucopurulent vaginal discharge.
◦ Usually caused by Neisseria gonorrhoeae and
Chlamydia trachomatis
◦ Inflammation of the cervix
◦ Leukocytes found in discharge.
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Inflammation of lymph
nodes.
Seen in several sexually
transmitted infections
◦ Especially in lymphogranuloma
venereum
◦ Caused by a certain serotypes
of Chlamydia trachomatis
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Usually begins as a small
genital ulcer that is
frequently unnoticed.
First evidence is usually a
tender swollen lymph node
in groin.
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Usually presents with
abdominal pain.
Neisseria
gonorrhoeae
Chlamydia
trachomatis
Scarring can block
uterine tubes
Chronic abdominal
pain
Infertility and
ectopic pregnancies
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Three of the most common bacterial sexually
transmitted infections causing disease in the
genital tract:
CDC 2010
data
Chlamydia
Gonorrhea
Syphilis
Cases reported
1,307,893
309,341
13774
Rates per 100,000
426.0
100.8
4,5
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Originally called non-gonococcal urethritis (NGU)
Caused by Chlamydia – a unique form of bacteria
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Obligate intracellular
Chlamydia trachomatis most common species
One of the smallest genomes of all the prokaryotes
Life cycle- elementary body (EB) and reticulate body
(RB)
EB
RB
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Unique replication
cycle involving two
forms
◦ Small, hardy, infectious
form
 Elementary body (EB)
◦ Larger, more fragile,
replicative form
 Reticulate body (RB)
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Full cycle takes about
48 - 72h
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Initiates its own uptake
Prevents fusion of lysosomes with endosome
Blocks inflammatory responses of the cell
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Diagnosis
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Treatment
◦ Nuclei acid amplification assay for detection
◦ doxycycline (7 days), azithromycin (single dose), and
some fluoroquinolones.
 Treat partner too.
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No vaccines available
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Gram-negative diplococcus
Fastidious
◦ Requires transport medium, avoid
cooling
Numerous pili which are
essential pathogenicity factors
◦ High antigenic variability
◦ No vaccine
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Typically causes urethritis and
cervicitis
Adheres with pili to epithelial
cells, transcytoses, and sets an
subepithelial infection
Attracts large numbers of
neutrophils
Pili
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Neisseria has a variety of mechanisms to evade
neutrophil killing
◦ Blocks the deposition of C3 and shuts down complement
◦ Surface proteins bind to antibodies and inhibit their
bacteriocidal response.
◦ Produces excess catalase and neutralizes phagocytic oxidative
killing
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May spread to nearby genital tissue
May spread systemically and cause joint infections
(knee)
Can cause PID
Mothers can infect newborns during birth
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Often asymptomatic (~ 50%)
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◦ Newborn conjunctivitis
◦ Transmission rate ~ 20 – 50%
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Diagnosis
◦ Nucleic acid amplification assay and culture on
chocolate agar for diagnosis
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Treatment
◦ Many patients are co-infected with Chlamydia
trachomatis, hence dual therapy.
◦ To prevent that patients stop treatment early
because of clinical improvement give single doses
◦ Cephalosporine (ceftriaxone, i.m. ) PLUS
azithromycin (orally)
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Earliest recorded sexually transmitted
infection.
◦ First described in 1600s
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“The great imitator”
Caused by Treponema pallidum
 Slim spirochete
 Slow rotating motility
 Cannot be grown on
bacterial media
 Can be grown in
mammalian cell cultures
 Exclusive human pathogen
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Key virulence factors
◦ Can penetrate tissue
easily
◦ Evade immune response by
binging off complement
factors and
immunoglobulins
Several clinically
defined stages:
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Primary
Secondary
Latent
Tertiary
Congenital
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Painless hard ulcer called chancre
Rubbery painless lymph node swelling
Appears 1 -3 weeks after infection
Highly infectious
◦ Can be hidden
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Self healing within several weeks
◦ Treponema have already spread
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Also known as disseminated
syphilis
Develops 2-8 weeks after the
chancre disappears.
Characterized by:
◦ Generalized lymphadenopathy
◦ Symmetric mucocutaneous
maculopapular rash
 On the face, trunk, and extremities
including the palms of the hands
and soles of feet
 Infectious
◦ Mucosal changes
 Comdylomata lata
◦ Also fever, malaise, and
lymphadenitis.
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Self healing
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Can last for years
◦ No clinical signs or symptoms but infection is
continuing.
◦ Serological tests are positive
Latency can be interrupted by less severe
bouts of secondary syphilis.
◦ Sexual transmission only possible during relapses.
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Transmission from mother to fetus is possible
throughout latent period.
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Occurs in about 1/3 of
untreated patients.
Takes years to develop.
◦ Can be 5 years after the initial
infection
◦ Usually 15-20 years
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Characterized by
appearance of Gummas
◦ Localized granulomatous lesions
in skin, bones, joints, and
internal organs
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Clinical findings depend on
where the infection
spreads.
◦ Cardiovascular system –
cardiovascular syphilis
◦ Nervous system – neurosyphilis
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Passed from mother to fetus during any stage
but more frequently during primary and
secondary syphilis
Can have devastating consequences
◦ Miscarriage and still birth
◦ Neonatal death and infant disorders such as
deafness, neurologic impairment, and bone
deformities
◦ Anemia, thrombocytopenia, and liver failure
Hutchinson’s teeth
Perforated palate
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Diagnosis
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Treatment
◦ Darkfield micoscopy
◦ Extensive serological testing with multiple assays
primarily looking for antibodies
◦ Penicillin
 Single dose in early stages
 Later on several doses
◦ Patients allergic to penicillin are treated with
tetracycline, azithromycin, or cephalosporin.
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Most important viral infection is HIV.
Two other prominent viruses:
◦ Herpes simplex type 2
◦ Human papillomavirus
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Two distinct epidemiological and antigenic types of
herpes simplex virus.
◦ HSV-1 – above-the-waist
 Causes cold sores
◦ HSV-2 – below-the-waist
 Causes genital herpes
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Transmission is through direct contact with
infected secretions.
Antibodies against HSV-1 found in large portion of
the population.
Antibodies against HSV-2 are rarely seen before
puberty.
Both viruses are able to undergo latent stage
hiding in neurons
When exacerbate painful liquid filled vesicles that
turn into ulcerations
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HSV-2
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Painful burning recurrent multiple ulcerations
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◦ Double stranded DNA, icosahedral enveloped virus
◦ Triggered by UV, fever, stress.
◦ 4 – 5 episodes per year
Liquid is infectious, contains many viruses
Latency in sacral ganglion
Primary infection often undetected
◦ 90% of HSV2-antibody positive patients cannot
recollect an acute infection
“Unlike love herpes is forever”
48
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Infections in newborn infants results from
transmission during delivery.
Most cases associated with maternal primary
infection at or near the time of delivery.
◦ Intense viral exposure to infant.
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Very serious infection
◦ Mortality rate of approximately 60%
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Most effective and most commonly used is the
nucleoside analog acyclovir.
◦ Decreases the duration of a primary infection
◦ Can also suppress recurrent infections
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Foscarnet is effective for resistant HSV
virions.
Can be prevented by avoiding contact with
infected individuals expressing lesions
◦ Important to remember virus still being shed in
asymptomatic individuals
◦ Can also be transmitted via saliva
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Double stranded DNA, icosahedral nonenveloped virus
Cause papillomas (benign tumors) or warts
Wide genetic diversity among human
papillomaviruses.
◦ Indicated by using numbers to identify different
genotypes.
◦ More than 70 genotypes of HPB have been
identified.
◦ Some are associated with specific lesions.
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HPVs identified cause genital hyperplastic
epithelial lesions.
◦ Cervical, vulvar, and penile warts
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HPVs are also associated with premalignant
and malignant cervical cancer.
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In particular HPV 16
causes cervical
cancer and cancer of
the penis
DNA test to detect
cancer-causing
strains
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Only treatments are surgical, cytotoxic drugs,
and cryotherapy.
◦ Recurrence is common after cessation of treatment.
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A vaccine has recently become available.
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Most prominent fungal infection is vaginal
candidiasis caused by Candida albicans
Infections are normally endogenous.
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Infections are usually opportunistic
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◦ Except in direct mucosal contact e.g. sexual
intercourse.
◦ Increased after antibiotic therapy, in pregnancy and
diabetes
Main symptoms are itching and a thick white
cheesy discharge.
Therapy topical antifungal creme
◦ Clotrimazole, miconazole, nystatin
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Hyphae excrete proteases and phospholipases.
◦ Digest epithelial cells.
◦ Facilitate tissue invasion.
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Trichomonas vaginalis
Protozoan
Found in semen or urine of
male carriers
Vaginal infection causes
irritation and profuse
discharge (foul smelling,
frothy)
Diagnosis: “strawberry
cervix”, microscopic
identification of protozoan
Therapy: metronidazole
PMN
Epithelial cell
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The presence of pathogens or inflammatory cells in urine
is an indication of a urinary tract infection.
Urinary tract infections that occur in hospitals are
usually related to indwelling catheters.
Infections of the urethra are called urethritis;
infections of the bladder are called cystitis; and
infections of the kidneys are referred to as
pyelonephritis.
Urinary tract infections are seen in women more than
men because of the difference in the lengths of the
urethra.
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The majority of bacterial infections seen in the
reproductive system are STDs.
STDs can be caused by bacteria, viruses, fungi, and
protozoan parasites.
The most common STDs are non-gonococcal urethritis,
which is caused by Chlamydia trachomatis and gonorrhea,
caused by Neisseria gonorrhoeae.
There are several viral STIs, including those caused by
HIV and herpes simplex virus type 2.
Humans are the only reservoir for herpes simplex virus
type 2, and many people infected with this virus are
asymptomatic.
The most common form of genital fungal infection is
candidiasis.
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10:45am – 1:15pm
Lecture, Chapter End Self Study Questions
100 Multiple Choice Questions: 2 points each x
100 = 200 points
~65%: Chapters 14-26
~35%: Chapters 1-13
Please bring Scantron and No. 2 pencil