Infectious Diseases: Clinical Correlations

Published on 18/02/2015 by admin

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Last modified 18/02/2015

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Infectious Diseases

Clinical Correlations

I Sexually Transmitted Diseases (STDs)

1. Usually spread during asymptomatic period when partners are unaware of problem

2. Chlamydia trachomatis and human papillomavirus (HPV) infections are the most common STDs worldwide.

• C. trachomatis is often masked by coinfection with Neisseria gonorrhoeae.

B Table 30-1 summarizes diseases spread primarily by sexual contact.

TABLE 30-1

Sexually Transmitted Diseases

AIDS, acquired immunodeficiency syndrome.

When treating for N. gonorrhoeae, also treat for C. trachomatis.

II Urinary Tract Infections (UTIs) (Table 30-2)

TABLE 30-2

Bacteria Causing Urinary Tract Infections

Organism	Distinguishing Features	Notes
Escherichia coli	Gram negative, no capsule, red-black colonies on EMB agar	Most common cause of UTIs (50% to 80%)
Staphylococcus saprophyticus	Gram positive, coagulase negative, resistant to novobiocin	Second most common cause of UTIs in young women (10% to 30%)
Proteus mirabilis	Gram negative, urease positive, swarming growth on agar	Associated with struvite urinary stones
Klebsiella pneumoniae	Gram negative, nonmotile, prominent capsule, large mucoid colonies	Usually in catheterized patients
Enterobacter species	Gram negative, motile, capsule, moist colonies, often drug resistant	Usually in immunocompromised patients
Pseudomonas aeruginosa	Gram negative, oxidase positive, fruity odor, blue-green pigment	Usually in patients with kidney stones, chronic prostatitis, or a catheter
Enterococcus faecalis	Gram positive, variable hemolysis, salt tolerant (6.5% NaCl)	Usually in immunocompromised or catheterized patients

UTI, urinary tract infection.

• Most common causes of nosocomial UTIs are Escherichia coli, Enterococcus species, and Pseudomonas aeruginosa.

A Cystitis (lower UTI)

1. Most commonly caused by E. coli.

2. Higher incidence in women

3. Dysuria, frequency, urgency, suprapubic pain

4. Not accompanied by bacteremia

E. coli is the most common UTI.

B Pyelonephritis (upper UTI): flank pain, fever, chills, dysuria

1. Results from ascension of bacteria from infected bladder

2. May be accompanied by bacteremia

C Genitourinary tract pathogens that are not sexually transmitted

• Candida albicans (vulvovaginitis), Staphylococcus aureus (toxic shock syndrome), and various organisms that infect the urinary tract.

III Infectious Diarrheas (Tables 30-3 and 30-4)

TABLE 30-3

Major Infectious Agents of Diarrhea

cAMP, cyclic adenosine monophosphate; cGMP, cyclic guanosine monophosphate; I, inflammatory; I-I, inflammatory, invasive; NI, noninflammatory.

TABLE 30-4

Food Sources of Bacterial Infections

Food	Bacteria
Poultry	Salmonella enteritidis, Campylobacter species
Raw eggs	Salmonella enteritidis
Dairy products	Listeria monocytogenes, Brucella species, Mycobacterium bovis
Shellfish	Vibrio species
Reheated rice	Bacillus cereus
Undercooked beef	Escherichia coli O157:H7, B. cereus, Brucella species, C. perfringens
Picnic foods (mayonnaise, custard, salted meats)	S. aureus toxin mediated

A Distinguishing features of three types

1. Noninflammatory diarrhea is watery

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