Transcript Bacterial Infections of Wounds

Review from last lecture
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Skin Infections:
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Contrasting Staph aureus with Strep pyogenes
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Folliculitis, boils and carbuncles
Rocky mountain spotted fever (R. rickettsii)
Lyme disease (B. burgdorferi)
Anthrax (Bacillus anthracis)
Bacterial infections of Wounds:
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Tetanus (C. tetani)
Gangrene (C. perfringens)
Burn infections (P. auerginosa)
Actinomycosis (A. israelii)
Sexually-transmitted Diseases
Denise Kirschner,PhD
Dept of Micro/Immuno
MICRO 532 Nov 29, 2001
Outline
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Epidemiological principles of STDs
UTI/Bladder infections
Infections of mucosal surfaces
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Neisseria gonorrhea and Chlamydia trachomatis
Ulcerative Infections
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Syphilis (T. pallidium) and Chancroid (H. ducreyi)
General uro-genital tract information
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More female infections that males
Urine is sterile
Above bladder entrance-sterile, below lots of
IM: Lactobacillus, Staphylococcus, Cornybacterium,
Haemophilus, Streptococcus, Bacteriodes
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Urinary tract infections (UTI):
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More than 100,000 bacteria/ml indicated
Bladder infection
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Catherization is the major cause of infection (usually IM)
Intercourse (for women)
Sexually-transmitted Diseases
Mucosal infections
• gonorrhea
• chlamydia
Ulcerative infections
• herpes simplex
• syphilis
• chancroid
• LGV
Proliferative infections
• papillomavirus
Systemic infections
• HIV
• hepatitis B
Epidemiologic Principles of STDs
Occurrence of STDs in the U.S.
Disease
Incidence Prevalence
-Chlamydia
4,000,000
-Gonorrhea
1,400,000
Papillomavirus
800,000 45,000,000
Herpes simplex
300,000 30,000,000
Syphilis (primary) 50,000
(all stages) 100,000
100,000
HIV
70,000
1,500,000
Chancroid
~4,000
?
Trends in common STDs
500
400
chlamydia
gonorrhea
syphilis
chancroid
300
200
60
40
100
20
0
1950
1960
1970
1980
Year
1990 1995
1980
1990 1995
Note: 60% of all N. gonorrhea infection are ages 15-24
Determinants of STD Morbidity
Rate of transmission
 Sexual behavior (rate of
new partner acquisition)
 Duration of infectivity
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Factors That Affect the Transmission of STDs:
• Age
• Gender
• Genetic susceptibility
• Sexual practices
• Contraceptive and
"hygienic" practices
• Circumcision
Determinants of the
Duration of Infectivity in STDs
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Etiologic agent
tendency to asymptomatic
carriage
 antimicrobial resistance
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Access and utilization of the
health care system
Compliance with therapy
Contact tracing
Theoretical Structure of an STD Core Group
PPNG in Colorado Springs,
Dec. 1989 - Dec. 1991
- not gang-related
- gang-related
C
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D J F M A M J J A S O N D J F M A M J J A S O N D
PPNG Outbreak,
Colorado Spgs., 1989-91
56 cases in a 2-year period
Traced to a network of 578 persons
• 410 (218 males and 192 females) were affiliated with a
street gang that moved to the area in May 1988.
Mean age: females (19.7 yrs); males (21.5 yrs)
Prominent behaviors among females: multiple
partners, heavy crack use, drugs for sex
CO-INFECTIONS
Relevance of STD Co-infections
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May identify a core group member
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STDs increase transmission of HIV
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ulcerative and mucosal infections only
Effect of HIV on expression of STDs
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i.e., a "sentinel event"
accelerates HPV-associated tumors
facilitates spread of gonococcus
alters the natural course of syphilis
Presumptive therapy
80-90% of college men with 1 STD have
others (50% with Chlamydia)
Infections of mucosal
surfaces
Infections caused by
gonococci and chlamydiae
urethritis
 cervicitis
 epididymitis
 proctitis
 pharyngitis
 eye infection
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Epidemiologic characteristics of
chlamydial and gonococcal infections
GONOCOCCUS
PATIENT AGE
teenagers > young adults
CHLAMYDIA
teenagers > young adults
SEXUAL HISTORY usually acquired from a
recent contact
may have been acquired
in the remote past
ASX INFECTION
(male)
~ 50% of infected sexual
partners
~ 5% of infected males
( higher in some areas)
ASX INFECTION
(female)
ASX=asymptomatic
50 - 80% of
infected females
~ 50% of infected sexual
partners
Microbiology of gonorrhea
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Strict human pathogen
Gram-negative diplococcus
Adherent- pilus (antigenic variation)
IgA protease (cleaves IgA)
Oxidase-positive
Fastidious growth
Modified Thayer-Martin media (VCN)
Virulence determinants of
Neisseria gonorrhoeae
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pilus colonization factor--> antigenic variation
opa proteins-------------------> phase variation
lipooligosaccharide--------->antigenic variation
IgA1 protease
transferrin/lactoferrin binding proteins
intracellular environment?
Treatment of gonococcal
infections
PPNG
 Tetracycline resistance
 Quinolone resistance
Single-dose treatment options for
uncomplicated disease:
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1944 10^5 units of penicillin
 1970 10^7 units
 Resistance (R plasmids)
 PPNG strain
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Microbiology of
Chlamydia trachomatis
Obligate intracellular bacteria
 Not G+/G- (lacks part of LPS)
 Complex, 2-stage life cycle
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Elementary body (spore like)
 Reticulated body (vegetative like)
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Treatment: antibiotics:
tetracyclines (not penicillin-why?)
Chlamydial infections
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urethritis (NGU)
epididymitis
proctitis
mucopurulent cervicitis
pelvic inflammatory disease
trachoma (serotypes A-C)
LGV (L1, L2, L3)
50-60% of women with
infertility have serologic
evidence of chlamydia or
gonococcus, but no history of
symptoms!
Ulcerative infections
Frequency of genital ulcer
infections
HSV>>syphilis>>chancroid
Distinguishing features of
genital ulcers
anatomical location
 multiplicity
 pain
 induration
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Microbiology of syphilis
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Treponema pallidum
spirochete -- labile spiral
bacterium with axial filaments
man is the only recognized
host
non-cultivable
Gram-negative like
T. pallidum darkfield examination
% reactive cases
iary
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Manifestations of 1° Syphilis
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Chancre (may be unnoticed)
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painless, but tender
indurated
highly contagious
rapid dissemination
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motility of the organism?
Congenital
MANIFESTATIONS OF SECONDARY SYPHILIS
Rash
Lesions
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mucous patches
Fever
Natural history of secondary
syphilis
1/3
Secondary
infection
1/3
1/3
spontaneous
resolution
infected without
clinical disease
tertiary syphilis:
Neurosyphilis
DTH
Organisms rare
Syphilis- principles of
treatment
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T. pallidum is exquisitely sensitive to
penicillin
Dosing and penicillin formulation
used depends on the stage of the
disease
Microbiology of chancroid
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Haemophilus ducreyi
Gram-negative coccobacilli
fastidious and labile
Diagnosis is usually clinical, by
exclusion of other agents of
genital ulcers
Epidemiology and treatment of
chancroid
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CDC reported a 10-fold increase in
incidence from 1978 - 1987
10% of patients are co-infected with
either HSV or T. pallidum
Males >> females
Occurs in sustained, urban outbreaks
Associated with female commercial sex
workers and “sex-for-drugs” trade
TREATMENT: sensitive to ceftriaxone or
azithromycin in single dose