week 8: overview of human infectious diseases

body site helps guide…

• expected clinical cues

• specimen or test selection

• transmission precautions

infection may…

• remain localized

• involve multiple sites

• spread systemically

dermatitis: meaning + possible clinical cues

• inflammation of skin

• redness, itching, rash

conjunctivitis: meaning + possible clinical cues

• inflammation of conjunctiva

• redness, drainage, irritation

pharyngitis: meaning + possible clinical cues

• inflammation of pharynx

• sore throat

gastritis: meaning + possible clinical cues

• inflammation of stomach

• epigastric pain, nausea, vomiting

inflammation

body’s response to infection, injury, irritation, or immune reaction

infection

invasion and multiplication of pathogens in body

conjunctivitis: example of infectious cause + example of noninfectious cause

• ic: viral or bacterial infection

• nic: allergy

hepatitis: example of infectious cause + example of noninfectious cause

• hepatitis b virus

• autoimmune hepatitis

skin

• major physical barrier

• breaks in skin can become portals of entry

• lesions describe what nurses see + document

macule

flat area of color change

papule

raised solid lesion

vesicle

fluid-filled lesion

pustule

pus-filled lesions

follicular skin infections:

• folliculitis

• furuncle

• carbuncle

folliculitis

• inflammation of hair follicle

• often infectious

furuncle

• boil

• deeper infection involving a hair follicle

carbuncle

cluster of interconnected furuncles

impertigo

superficial skin infection w/ honey-colored crusts

cellulitis

infection of deeper skin + subcutaneous tissue

surgical site infection is an example of:

a hospital-associated infection

axillary candidiasis & submammary candidiasis are examples of:

fungal skin infections (candidiasis) - yeast

ringworm on back, arm, and scalp are examples of:

fungal skin infections (tinea)

eye inflammation:

• conjunctivitis: conjunctival inflammation

• keratitis: corneal inflammation

• retinitis: retinal inflammation

• possible clinical cues: redness, pain, drainage, vision changes

ear inflammation:

• otitis externa: external ear canal inflammation

• otitis media: middle ear inflammation

• possible clinical cues: pain, fever, drainage, hearing changes

upper respiratory tract inflammation:

• sinusitis: sinus inflammation

• pharyngitis: pharyngeal inflammation

• laryngitis: laryngeal inflammation

• cues: congestion, facial pressure, sore throat, hoarseness

pharyngitis

• most caused by viruses

• streptococcus pyogenes (group A strep) is important bacterial cause

• testing: when group A strep suspected, throat swab for rapid antigen detection test or throat culture can confirm diagnosis

• clear viral symptoms: cough, runny nose, hoarseness, generally indicate strep testing is unnecessary

• symptoms alone not confirm group A strep

lower respiratory tract inflammation:

• bronchitis: bronchial inflammation

• pneumonia: infection involving lung tissue/alveoli

• cues: cough, sputum, dyspnea, adventitious breath sounds

bronchitis

• bronchial inflammation

• acute: usually viral infection

• chronic: associated w/ COPD

• possible cues: cough + sputum

pneumonia

• infection involving lung tissue/alveoli

• may impair gas exchange + compromise oxygenation

• may be bacterial, viral, or fungal

• possible cues: cough, fever, dyspnea, tachypnea, hypoxemia, adventitious breath sounds

oral region

• oral cavity contains diverse indigenous microbiota

• indigenous microbes contribute to disease when local conditions change

• dental caries: commonly associated w/ streptococcus mutans

• gingivitis, periodontitis

gingivitis

inflammation limited to gums

periodontitis

inflammation w/ dmg to tissues + bone that support teeth

GI tract

• inflammation and/or infection can occur in GI tract

• stomach = gastritis

• small intestine = enteritis

• colon = colitis

• stomach + intestines = gastroenteritis

• liver (accessory digestive organ) = hepatitis

diarrhea may result from:

• food or medications

• viral, bacterial, protozoal, or helminth infections

• diarrhea alone doesn’t identify cause; history, assessment, and testing when indicated help determine cause

  • collect fresh, unformed stool sample when testing

  • depend on cause, test may include stool polymerase chain reaction (PCR), culture, toxin testing, parasite testing

genitourinary (GU) system is:

• urinary system: kidneys, ureters, bladder, urethra

• genital/reproductive system: male + female reproductive structures

• infection terms often reflect anatomic site involved

upper urinary tract inflammation:

• pyelonephritis: kidney/renal pelvis infection

• possible cues: fever, flank pain, urinary symptom

• upper UTI symptoms can signal more serious infection + require prompt attention

lower urinary tract inflammation:

• cystitis: bladder inflammation/infection

• urethritis: urethral inflammation

• possible cues: dysuria, frequency, urgency, suprapubic discomfort

male genital/reproductive system inflammation:

• prostate inflammation

  • pelvic/perineal pain + urinary symptoms, fever + chills

• epididymitis: epididymal inflammation

  • possible cues: scrotal pain, swelling

female genital/reproductive system inflammation:

• vaginitis/vulvovaginitis: vaginal/vulvar inflammation

  • possible cues: discharge, itching, irritation

• pelvic inflammatory disease (PID): infection/inflammation of upper reproductive tract

  • possible cues: pelvic/abdominal pain, ferver, discharge

most common cause of cystitis and pyelonephritis

e. coli

most common cause of urethritis

chlamydia trachomatis

common causes of vaginal symptoms include:

• candidiasis (often candida albicans, a yeast)

• trichomoniasis (trichomonas vaginalis, a protozoan)

• bacterial vaginosis (vaginal microbiota imbalance)

when considering GU microbiology causes:

• symptoms + organisms may overlap

• diagnosis requires history, exam, and appropriate testing

cardiovascular inflammation:

• endocarditis: endocardium inflammation

• myocarditis: myocardium inflammation

• pericarditis: pericardium inflammation

• blood normally sterile

lymphatic inflammation:

• lymphadenitis: lymph node inflammation

• lymphangitis: lymphatic vessel inflammation

• lymphadenopathy: enlarged/abnormal lymph nodes

bacteremia

• bacteria present in bloodstream

• may or may not cause illness

• bacteremia not equal sepsis

sepsis

• current clinical term: life-threatening organ dysfunction caused by dysregulated response to infection

• clinical syndrome, not require positive blood culture

central nervous system:

• includes brain + spinal cord

• meninges surround + protect CNS

• CNS no indigenous microbiota

• CNS infections are high priority since neurologic changes can progress quickly

CNS inflammation:

• meningitis: meninges

• encaphalitis: brain

• myelitis: spinal cord

• meningoencephalitis: meninges + brain

• encephalomyelitis: brain + spinal cord

meningitis: structure inflamed + cues

• meninges surrounding brain + spinal cord

• fever, severe headache, neck stiffness, light sensitivity

encephalitis

• brain tissue

• fever or headache w/ changes in thinking or behavior, reduced alertness, seizure

meningitis & encephalitis, both conditions cause:

• fever, headache, confusion, seizures

• symptoms not confirm the diagnosis or cause

• nursing priority: suspected meningitis or encephalitis requires urgent assessment + escalation

microbiota & disease risk:

• oral microbiota can contribute to dental/periodental disease

• disruption of vaginal microbiota allow overgrowth

• antibiotics can disrupt GI microbiota

• body site + host context determine whether microbial presence is protective, harmless, or concerning

• microbiota usually part of normal host ecology, disruption increase disease risk

opportunistic infections

• become more likely when host defenses, barriers, or protective microbiota are disrupted

• examples include:

  • candida overgrowth after antibiotics

  • pneumocystis pneumonia in patients w/ impaired immunity

emerging vs. remerging infections:

• emerging: newly recognized or increasing in incidence/geographic range

• reemerging: known infection that returns or increases after previously declining

infectious-disease patterns change over time as:

microbes, hosts, environments, and public-health conditions change

candida auris: organism, reported cases, host vulnerability, population spread, colonization, and precautions

• o: yeast that cause serious infections + often resistant to antifungal medications

• rc: increased from 186 in 2024 to 253 in 2025

• hv: severe underlying illness + invasive devices increase infection risk

• ps: contaminated hands, surfaces, and shared equipment spread C. auris among patients

• c: patients carry organism w/o illness + still transmit it

• p: standards plus contact precautions

candida auris: purpose, who, specimen, population response

• p: identify patients carrying c. auris w/o symptoms

• w: screen selected ptnts based on healthcare exposure, contact w/ known causes + facility policy

• s: collect one combined skin swab from both armpits + both groin areas for lab testing

• pr: newly identified case may prompt screening or other ptnts on unit

• positive screening swab identifies colonizations , does not iteself establish invasive infection

measles, ex of reemerging:

• eliminated in US in 2000s, but causes + outbreaks continue to occur

• as of 10/15/26, CDC reported 4410 confirmed causes

• prev eliminated infection can reemerge when susceptible population allow transmission to occur