Chapter 24

Question 1

Bacterial Urinary Tract Infections (92)

Answer 1

Signs & Symptoms
Frequent, urgent, painful urination, urine may be cloudy w/foul odor

Pathogens & Virulence factors
Enteric Bacteria are the most common cause; ESCHERICHIA COLI cause mos cases; Virulence factors include flagella and attachment fimbriae

Pathogenesis & Epidemiology
Often results when fecal bacteria is self-inoculated into urethra; more common in females

Diagnosis, treatment, and prevention
Diagnosis is based on urinalysis; many cases resolve without treatment; some treated w/antimicrobial drugs; prevented by limiting contamination by fecal microbes

Question 2

Leptospirosis (93) Bacterial

Answer 2

Zoonotic disease seen primarily in animals

Signs & Symptoms
Abrupt fever, myalgia, muscle stiffness, and headache, rarely fatal

Pathogen
LEPTOSPIRA INTERROGANS; normally lives in many wild & domestic animals; virulent strains make adhesions, are motile, and can evade complement activity

Pathogenesis
Transmitted by contact w/urine of infected animal or urine-contaminated water; spirochete travels via the bloodstream through the body

Epidemiology
Occurs throughout world but rate in the US

Diagnosis, treatment, prevention
Diagnosis is based on antibody test; treated with antimicrobial drugs; prevented by avoiding contaminated water

Question 3

Staphylococcal Toxic Shock Syndrome (94)

Answer 3

Signs & Symptoms
Sudden-onset fever, chills, vomiting, diarrhea, low blood pressure, confusion, and severe red rash; Individuals go into shock if untreated

Pathogen & Virulence factors
Caused by S. Aureus; These strains produce TOXIC SHOCK SYNDROME TOXIN; cause excessive cytokine production by T cells

Pathogenesis & Epidemiology
Absorption of toxin into blood triggers toxic shock syndrome; most cases occur in menstruating females

Diagnosis, treatment, prevention
Diagnosis is based on signs & symptoms; considered medical emergency; requires removal of foreign material and antimicrobial drugs; avoiding tampons or using less absorbent tampons reduces risk

Question 4

Bacterial Vaginosis (95)

Answer 4

Signs & Symptoms
White vaginal discharge w/a “fishy” odor

Pathogen and Virulence Factors
Caused by various anaerobic bacteria

Pathogenesis and Epidemiology
Associated w/multiple sexual partners and vaginal douching

Diagnosis, treatment, and prevention
Diagnosis is based on signs and symptoms; treated w/oral or vaginal metronidazole

Question 5

Vaginal Candidiasis (96)

Answer 5

Signs & Symptoms
Severe Vaginal itching & burning

Pathogen & Virulence factors
CANDIDA ALBICANS; normal microbiota of skin and mucous membranes

Pathogenesis & Epidemiology
Candida overgrows if vaginal pH becomes alkaline or normal microbial populations are reduced; can become systemic in immunocompromised people

Diagnosis, treatment, and prevention
Identification of Candida in presence of symptoms is diagnostic; treated w/azole or fuconazole; avoiding excessive use of antibacterial drugs can prevent candidiasis

Question 6

Gonorrhea (97) Bacterial

Answer 6

Signs & Symptoms
Men experience painful urination and a purulent discharge; women are asymptomatic but pelvic inflammatory disease may develop

Pathogen & Virulence factors
NEISSERIA GONORRHOEAE; virulence factors include fimbrae, capsule, and endotoxin

Pathogenesis
Bacteria attach to epithelial cells of the mucous membranes; infections outside the reproductive tract also occur; babies delivered vaginally by infected mothers can become infected

Epidemiology
Gonorrhea occurs only in humans; cases in US declining; risk increases with frequency of sexual encounters

Diagnosis, treatment, prevention
Genetic probes are used to diagnose asymptomatic infection; treated with broad spectrum cephalosporin, strains resistant to many antimicrobials, prevented with safe sex

Question 7

Syphilis (98)

Answer 7

Signs & Symptoms
4 Phases: Primary syphilis, Secondary syphilis, Latent syphilis, Tertiary syphilis

Pathogen & Virulence Factors
TREPONEMA PALLIDUM CAUSES SYPHILIS; lives only in humans; Virulence factors have been difficult to identify

Pathogenesis
Transmitted mostly via sexual contact; Sometimes transmitted from mother to child; Most individuals do not develop tertiary syphilis

Epidemiology
Syphilis occurs worldwide; endemic among sex workers, men who have sex with men, and users of illegal drugs

Diagnosis, treatment, prevention
Antibody test is used to diagnose primary, secondary, and congenital syphilis; Tertiary syphilis is difficult to diagnose; Penicillin G is used to treat all but tertiary syphillis; prevented with safe sex practices

Question 8

Chlamydial Infections (99)

Answer 8

Signs & Symptoms
Women are usually asymptomatic; men have painful urination and pus discharge from penis; causes numerous diseases

Pathogens and Virulence Factors
CHLAMYDIA TRACHOMATIS; all strains but one are pathogens of humans; grow only within vesicles inside host cells; development cycle

Pathogenesis
Microbes enter body through scrapes or cus; infect conjuctiva or cells lining mucous membranes; spread to lymphatic system causes proctitis; adolescent infection increases cervical cancer risk

Epidemiology
Most common reportable STD in the US; eye infections endemic in poor, crowded areas

Diagnosis, treatment, prevention
Detection of chlamydial DNA by PCR is diagnostic; treated with antimicrobial drugs; prevented by abstinence or mutual monogamy

Question 9

Chancroid (100)

Answer 9

Signs & Symptoms
Soft Chancres in women, pain upon urination

Pathogen and Virulence factors
HAEMOPHILUS DUCREYI; PRODUCES A TOXIN THAT KILLS EPITHELIAL CELLS

Pathogenesis
Most cases in the US are due to foreign travel

Diagnosis, treatment, prevention
Diagnosis based on presence of lesion and buboes; treated with antimicrobial drugs; prevented by abstinence or mutual monogamy

Question 10

Trichomoniasis (101) (protozoan)

Answer 10

Signs & Symptoms
Females have vaginal discharge and irritation; males are typically asymptomatic

Pathogen and Virulence Factors
TRICHOMONAS VAGINALIS

Pathogenesis and Epidemiology
Transmitted primarily via sexual intercourse; most common curable STD in women; Increase risk of infection by HIV; various virulence factors contribute to disease

Diagnosis, treatment, prevention
Diagnosed by presence of Trichomonas in clinical samples; treated with a single dose of oral metronidazole; Prevented by avoiding sexual intercourse with infected persons

Question 11

Genital Herpes

Answer 11

Signs & Symptoms
Small blisters on or around the genitals or rectum

Pathogen and Virulence factors
HUMAN HERPES VIRUS 2 causes most cases
HHV 1 causes remainder of cases
Virus becomes latent in nerve cells

Pathogenesis
Herpesvirus kills epithelial cells at the infection site; blisters may form at sites far from initial infection; babies can become infected during birth

Epidemiology
Genital herpes quadruples the risk of HIV infection

Diagnosis, treatment, prevention
Diagnosis is made by presence of warts; variety of methods available to remove warts; Vaccine is available against HPV strain associated with cervical cancer