Microbiology Chapter 27

What are the most frequent healthcare-associated infections?

Urinary Tract Infections (UTIs)

What are the parts of the urinary system?

Kidneys, ureters, bladder, urethra

Bacterial Cystitis (Bladder Infection) Symptoms

Sometimes asymptomatic, typically sudden, burning pain during urination, urgent need to urinate, frequent release of small amounts of urine. Urine cloudy from leukocytes, may be pale red from blood. Bad odor, area above pubic bone may be painful.

What infection sometimes arises from bacterial cystitis?

Pyelonephritis (inflammation of kidney tissue): fever, chills, vomiting, back pain

Causative agents of Bacterial Cystitis

Majority of cases from specific uropathogenic strains of Escherichia coli.

Pathogenesis of Bacterial Cystitis

Pathogens move up the urethra to the bladder. Uropathogenic E. coli have pili that attach to receptors on bladder epithelial cells

Epidemiology of Bacterial Cystitis

Anything that inhibits urine flow increases the risk

Factors that predispose women to bacterial cystitis

Shorter urethra, birth control devices, sexual intercourse

Treatment and Prevention of Bacterial Cystitis

Few days of antibiotics, most successful with trimethoprim-sulfamethoxazole. Pyelonephritis typically requires hospitalization, IV antibiotics.

Prevention - drink enough water, urinate following intercourse, wipe front to back, low antibiotic doses

Bacterial Vaginosis Symptoms

Thin, grayish-white, slightly bubbly vaginal discharge with very fishy smell
It could spread to fallopian tubes or uterus, causing pelvic inflammatory disease (PID), could lead to sterility

Causative Agent of Bacterial Vaginosis

Cause(s) unknown, but typically the dominant Lactobacillus presence is declined when BV is present

Pathogenesis of BV

thought to start with development of Gardnerella biofilm, which helps the development of a polymicrobial community. Characteristic changes in vagina, such as loss of acidity of secretions.

Epidemiology of BV

Not well known since the causative agent is unknown. Most common among sexually active women and sometimes sexually abused children. Pregnant women are at an increased risk.

Women who douche, have multiple sex partners, have sex with other women, have a new sex partner, or use an IUD are at increased risks.

Treatment and Prevention of BV

Most cases respond well. to antibiotics (metronidazole or clindamycin). Rumored that yogurt restores vaginal lactobacilli

Symptoms of Staphylococcal Toxic Shock Syndrome (STSS)

Sudden development of fever, headache, muscle aches, bloodshot eyes, vomiting, diarrhea, sunburn-like rash, confusion. Skin peels after a week, blood pressure could drop, in worse cases, multi-organ failure, coma, even death

Causative agent of STSS

Staphylococcus aureus strains that produce toxic shock syndrome toxin-1 (TSST-1) or similar exotoxins

Pathogenesis of STSS

During menstruation when tampons are used, bacteria grows in the tampon, and released toxins act as superantigens, causing activation of T-cells, which causes a huge release of cytokines

Epidemiology of STSS

Can occur after infection of any number of body sites with a Staphylococcus,
Not spread person to person

Treatment and Prevention of STSS

Requires hospitalization, antibacterials, IV fluids, other measures taken to prevent shock. Recovery in 2-3 weeks, could be fatal within hours.
Prevention - appropriate use of tampon: wash hands, use lower absorbency, change every six hours, use a pad when sleeping.

Women who have had STSS cannot use tampons again, very increased risk of reinfection

Symptoms of Sexually Transmitted Infections (STIs)

Many are asymptomatic, unknowingly transmitted, symptoms could include vaginal/urethral discharges, urination pain, genital sores, rashes, vaginal bleeding, abdominal pain.

Some ascend the female tract and cause pelvic inflammatory disease (PID)

Epidemiology of STIs

Transmitted through body fluids, all sexual contact creates risk, fetuses and newborns are at risk by mother

Symptoms of Chlamydia

Mostly asymptomatic, symptoms appear 7-14 days after exposure.
Men - thin, gray-white discharge from the urethra, sometimes painful testes, urination pain, fever
Women - increased discharge, painful urination, vaginal bleeding, abdominal pain, sexual intercourse pain, could lead to PID

What do newborns infected with Chlamydia sometimes have at birth?

Eye inflammation

Pathogenesis of Chlamydia

persists for months by avoiding host defenses.
Men - usually involves urethra, spreads to epididymis, causes acute pain, swelling could cause infertility
Women - involves cervix, could cause PID

Epidemiology of Chlamydia

Most common notifiable bacterial infectious disease
Number of reported cases has been risingT

Treatment and Prevention of Chlamydia

single dose of azithromycin, sexual partners are also treated. Neonatal conjunctivitis/pneumonia treated with oral erythromycin.
Prevention - abstinence, monogamy, correct condom use, and sexually active people are advised to get tested

Gonorrhea Symptoms

Incubation 2-5 days, typically asymptomatic

Men - urination pain, pus-discharge
Women - urination pain, vaginal discharge, PID, sometimes scarring

If Gonorrhea is untreated in women…

Infections can spread to fallopian tubes, cause PID, sometimes infertility, disseminated gonococcal infection (DGI), which causes fever/rash/arthritis

If Gonorrhea is untreated in men…

inflammation can produce scar tissue that obstructs the urethra, slows urination, could produce prostatic abscesses and orchitis, infertility

Causative Agent of Gonorrhea

Neisseria gonorrhoeae, Gram-negative diplococcus, pili for attachment, outer membrane has highly branched oligosaccharide structure

Epidemiology of Gonorrhea

Only infects humans, resistant to many medications, decline in cases since increased condom use, susceptible to UV lights.

Treatment/Prevention of Gonorrhea

Resistant to antibacterial medications, but typically the combination therapy of ceftriaxone injection and azithromycin works.
Prevention - abstinence, condoms, no vaccine.

Symptoms of Syphilis (Primary)

Painless, red ulcer that appears at site of infection within three weeks. Often unnoticed if hidden in vagina or rectum. Local lymph nodes enlarge.

Symptoms of Syphilis (Secondary)

2-10 weeks later, systemically spread. Rash on palms/soles, white patches of mucous membranes, runny nose, watery eyes, aches/pains, sore throat, fever, malaise, weight loss, headache.
Sometimes hepatitis or renal disease.
MOST INFECTIOUS AT THIS STAGE.

Symptoms of Syphilis (Latent)

No outward signs, antibodies are present

Symptoms of Syphilis (Tertiary)

Latent period that can last years
Gummatous syphilis - localized tissue damage from prolonged inflammation. Gummas are chronic granulomas, which can occur anywhere in the body.
Cardiovascular syphilis - aneurysms in ascending aorta

Symptoms of Syphilis (Congenital)

T. pallidum can easily cross the placenta in pregnant women

Damage to fetus usually not until fourth month
Spontaneous abortion, stillbirth, and neonatal death are common

Causative agent of syphilis

Treponema pallidum, highly motile spirochete, the outer membranes lack LPS (lipopolysaccharides).

Epidemiology of Syphilis

Transmitted sexually, can occur via kissing if person has secondary syphilis, most common in mid to late twenties

Treatment and Prevention of Syphilis

Primary, secondary, and latent are treated with ONE intramuscular injection of penicillin

Tertiary is treated with weekly IM injections of penicillin for 3 weeks
Congenital is prevented by treating mother before she reaches fourth month

What do some strains of HPV cause?

Papillomas (warty growths) on external and internal genitalia

What is HPV short for?

Human papillomavirus

Symptoms of HPV

Most infections are cleared without signs or symptoms
Warts can appear roughly 3 months after infection on head or shaft of penis

Causative agent of HPV

Human papillomaviruses, non-enveloped, double stranded DNA viruses of Papillomaviridae

Epidemiology of HPV

Spread through intercourse or oral sex, asymptomatic individuals are still infectious
HPV causes more than half of mouth and throat cancers

Treatment and Prevention of HPV

Warts often regress, but they can also be removed by laser treatment, freezing, surgery, etc.
Prevention - abstinence, monogamy, proper condom use, annual pap smear for women
Gardasil 9 vaccine