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.
B Table 30-1 summarizes diseases spread primarily by sexual contact.
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 |
• Most common causes of nosocomial UTIs are Escherichia coli, Enterococcus species, and Pseudomonas aeruginosa.
1. Most commonly caused by E. coli.
3. Dysuria, frequency, urgency, suprapubic pain
4. Not accompanied by bacteremia
B Pyelonephritis (upper UTI): flank pain, fever, chills, dysuria
C Genitourinary tract pathogens that are not sexually transmitted
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 |
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