Session 10: Genitourinary infections Flashcards
(27 cards)
Urine
- kidney: removes waste from blood ( filtration)
- valves control backwards flow of urine from bladder (storage) to ureters
- urine: lower pH, has antimicrobial properties, sterile
- flushing of urine is physical
- analysis of cell content, osmolarity, protein, glucose content, “casts” important for diagnosis of complicated infection
UTI
- most common site of bacterial infection
- most common in females
- majority of infections are acute and uncomplicated (cystitis, urethritis)
- most common type of nosocomial infection ( catheter)
- severe infection affect kidney function (pyelonephritis)
common cause of UTIs
- outpatients: E. Coli 80%, S. aureus, CNS, Enterococci, Streptococcus Group. B
- inpatients: E. Coli 40%, other enteric bacteria (25%), gram positive, proteus mirabilis, candida species
symptoms
lower UTI:
- painful urination (dysuria)
- urgency and frequency of micturation
- catheter related infections are asymptomatic
- cloudy urine WBC (pyuria) and bacteria ( bacteriuria)
Upper UTI: Kidney
- fever, some same symptoms
- may have lower back pain
cystitis and pyelonephritis
infection of urinary bladder and kidney
Asymptomatic UTIs:
- presence of significant #s of bacteria ( bacteriuria) in absence of symptoms
- can cause complications, such as scarring in young children and pregnant women
problems with catheter usage
significant bacteriuria: if urine held in bladder for less than 4 hours, there is an infection with S. Saphrophyticus
-contaminated urine means species are growing
UTI in children
- Reflux found in 30-50% of children with asymptomatic bacteria
- high risk for renal scarring
- difficult to get good specimen, especially from infants, often require SUPRA-PUBIC ASPIRATION for adequate sample
E. Coli
- gram negative bacilli, motile, can and not have a capsule
- has O (somatic), H ( flagella), K (capsule), F (fimbrial) antigens
- adhesion is by P fimbriae
- susceptible to a variety of antibiotics
Staphylococcus Saphrophyticus
- gram positive cocci, coagulase negative
- novobiocin resistant
- infections in young healthy women
Streptococcus agalactiae (Group B)
- gram positive cocci in chains
- beta hemolytic on blood agar, very small zones
- important if patient is pregnant
- neonatal meningitis, sepsis, respiratory failure
- think B=BABIES
Enterococcus faecalis/faecium
- gram positive cocci, short chains or pairs
- may produce alpha, beta, or no (gamma) hemolysis on BAP
- common in UTI
- bile and salt resistant
- VRE=PROBLEM
proper collection of UTI specimens- important due to quantitative nature of cultures
-Mid-stream sample (MSU) in sterile container
-incubate in bladder 4 hours best, note other
babies: bag urine often contaminated
SUPRAPUBIC Aspiration recommended
-catheterized patients: withdraw from tube with syringe
-urine esterase: measured by dip-stick, pos means presence of WBC (infection)
STD/STI
- no vaccine available
- produce negligible symptoms initially
- symptoms may persist and reoccur
- may allow for reinfection because agents are poor antigenic
- fastidious, spread from mucous membrane to another
PID: Pelvic inflammatory disease
- extensive infection in female
- cervix, uterus, Fallopian tubes, ovaries
- spread to peritoneal cavity and cause liver damage ( hepatitis)
- over 50% of women with PID asymptomatic but have sequalae
Symptoms:
- lower abdominal pain, radiating to back
- discharge from vagina
- C. trachomatis and N. gonorrhoeae most common causative agents
- MORE CHLAMYDIA THAN Gonorrhea in canada
Gonorrhea
-Gram negative diplococci
pathogenesis:
- mucous membrane of vagina, cervix, urethra, rectum, throat
- pilli attaches to human mucosal epithelium, inactive complete and inactivate T cells
- spread up reproductive tract
- bacterial cell walls contain LPS ( virulence factor)
- produce IgA protease
- Opa proteins on cell surface vary and prevent immune recognition by antibodies
- damage to tissues results from the inflammation that the gonococcus elicits ( no exotoxin)
- infection usually localized but some strains which are resistant to bactericidal effects of serum, can spread systemically.
Symptoms: incubation period 2-7 days
- male: urethral discharge (pus) and dysuria
- female: vaginal discharge
Systemic disease in both males and females
- results in endocarditis, meningitis, monoarticular arthritis with tendonitis and skin lesions
- pharyngeal gonorrhoea: sore throat
- rectal gonorrhoea: itching, painful inflammation
laboratory diagnosis:
- finding of gram negative diplococci in WBC urethral discharge (men)
- culture, DNA probes, PCR
- antibiotic susceptibility tests as there is increase resistance to many antibiotics
treatment: no vaccines available! partner tracing and treatment important
Chlamydia trachomatis
- most common bacterial STD
- Gram negative (LPS in cell wall)
- unique development cycle with infectious form (RB), obligate intracellular parasites
3 species of chlamydia infect humans:
- C. trachomatis serotypes A to C cause trachoma, serotypes D-K cause genital infections, serotypes L1,2,3 cause LGV
- C. psittaci: zoonosis from birds, respiratory infection
- C. pneumoniae: respiratory infection, associated with cardiovascular disease
pathogenesis of C. trachomatis
-elementary bodies enter mucosal membrane
-bind host cell receptors, internalized in a vacuole
-chlamydia vacuole is not fused with host lysosome
-site of infection determines disease
-disease effects due to inflammation
serotypes D-K infects only columnar and transitional epithelial cells, including neonates eyes ( inclusion conjunctivitis)
-LGV are invasive and cause systemic disease
Genital infection with C. trachomatis D-K
- endemic
- highest frequency in 15-25 year olds
- 50% asymptomatic in women
- PID: asymptomatic in women, results in ectopic pregnancy, scarring of Fallopian tubes, infertility, peritonitis
- causes NGU (non-gonococcal urethritis in men)
Laboratory diagnosis:
- culture, DNA probes, PCR (urine and secretions)
- serology not helpful in uncomplicated genital infections
treatment:
- tetracycline or macrolides
- partner tracing
- NO VACCINE
LGV (Lymphogranuloma venereum)
- C. trachomatis (L1,L2,L3)
- characterized by supperative inguinal adenitis
- most common in tropics
- lesions formed on genitals, infects nearby lymph glands
- untreated results in tissue damage, fibrosis, elephantiasis
Lab diagnosis:
- culture, DNA probes, PCR (urine and secretions)
- serology not helpful in uncomplicated genital infections
treatment:
-tetracycline or macrolides, partner tracing, NO VACCINE
syphillis
- spirochaete, gram negative helix ( not visible in gram stain)
- can’t be cultured in vitro
- low prevalence
- risk population are drug users and homosexuals
- closely related to other treponema species causing tropical diseases (T. pertenue: yaws and T. carateum: pinta)
3 stages of disease for syphilis
incubation period is 3 weeks
primary: initial sign is chancre (painless), highly infectious (HARD chancre). bacteria enters blood and lymph
secondary: occurs weeks after the chancre disappears. Characterized by rash on skin and mucous membranes, very infectious
latent: may last months to years
tertiary stage: 50% of patients, chronic stage
pathogenesis of syphilis
- portal of entry is breaks in skin or mucous membranes
- local lesion leads to inflammation, recruitment of macrophages
- poorly antigenic due to lipid layer, only dead “treponema” can activate immune system and induce antibody formation
Diagnosis: serology and wet mount direct microscopy
Complications: aortic aneurysm, CNS damage (paresis), blindness,
seizures, dementia, congenital syphilis
Treatment: penicillin: drug of choice (no resistance), no immunity, no vaccine
