Respiratory Tract Infections

Respiratory Tract Infections

Major Types and Major Etiologies

Upper Respiratory Tract Infections (URI):

Common cold (Children) Parainfluenzavirus & Coronaviruses

(Adult) Rhinoviruses > others

Winter>Summer person-person spread (esp hand contact)

No fever or mild fever (mainly in kids)

Pharyngitis

< 3 yr and adults Viruses (Rhino-, Adeno-, Coronaviruses)

Children 5-15 yr youngadults Strep pyogenes (Group A) less int adults

Mycoplasma pneumoniae

EBV

5-15 yr children, usually not adults Enteroviruses (community outbreaks)

Non-immunized Corynebacterium diphtheriae

All Influenzaviruses A, B, C

Laryngitis

Hoarseness with concurrent URI (can include Moraxella catarrhalis/.TB)

Sinusitis

Often mixed including anaerobes and sometimes fungi

Otitis media (in children almost always)

Strep pneumoniae, non-typable Haemophilus influenzae, Moraxella catarrhalis

Tracheobronchitis

Viral

Adult – adeno, parainfluenza, influenza

Children RSV

Bacterial

Bordetella pertussis, Mycoplasma, Chlamydia

In COPD different causes – more like pneumonia

Nontypable H. influenzae, Strep pneumoniae (not easily cleared)

Croup

Stridor and “seal’s bark”. Children < 3 yr, parainfluenzaviruses

Respiratory Tract Infections

Major Types and Major Etiologies

Lower Respiratory Tract Infections (URI):

Pneumonia (inflammatory disease involving lung parenchyma)

Typical (rapid onset of chills, fever, dyspnea, pus in sputum)

Strep pneumoniae (common post-viral)

Klebsiella pneumoniae

Haemophilus influenzae

Moraxella catarrhalis

Staph aureus (common post-viral)

Atypical (gradual onset)

Mycoplasma,

Chlamydia,

Legionella

Viral pneumonia

Not so common in adults (except bad influenza)

but seen in children (esp RSV and influenza)

ARDS

VZV

Adenovirus

Hantavirus (deer mouse contact)

TB (depends on exposure risks on the whole: though worse in AIDS)

Immunosuppressed

Many etiologies including CMV, Fungi, Actinomycetes (Nocardia)

Causes of pneumonia

Newborn (0-6 wks) Strep Group B + E. coli

Children (6 wk-18 yr) Viruses (RSV)

Mycoplasma and Chlamydia

Strep pneumoniae

Adults (18-40 yr) Mycoplasma and Chlamydia

Strep pneumoniae

Adults (45-65 yr) Strep pneumoniae

Haemophilus influenzae

Viruses

Anaerobes

Old adults (>65 yr) Strep pneumoniae

Viruses

Anaerobes

Haemophilus influenzae

Gram-negative rods

(Entereobacteriaceae and Pseudomonas)

Nosocomial Gram-negative rods

(e.g. Klebsiella pneumoniae + Pseudomonas)

Staphyloccus aureus

Drug-resistant bacteria

Immunocompromised Gram-neg rods

Strep pneumoniae

Fungi (Crypto, Pneumocystis, Aspergillus)

Actinomycetes (Nocardia)

Viruses

Alcoholics (Anaerobes, Strep pneumo, Klebsiella)

Gross aspiration (Anaerobes)

Neutropenia (Aspergilllus)

i.v. drugs (Staph aureus)

Travel history with/without immunosuppression (Histo, Blasto Cocci) but look at

morphology

Urogenital tract infections

Urinary tract infections (UTIs)

Mainly E. coli ( also Proteus and Klebsiella)

Gram pos cocci mainly Staph saprophyticus (also Enterococcus)

Increase in women and during pregnancy

Obstructive (urinary stasis) and catheters –

mixed infections E coli, Proteus

Skin microbes seen in catheterized (Candida Staph epi)

STDs (Exudative, Inflammatory lesions)

Urethrits, cervicitis gonorrhea

Chlamydia (non-gonococcal urethritsis/cervicitis)

Mycoplasma genitalium

Vaginitis Trichomonisasis

Candidiasis

STDs (Non exudative)

Syphilis painless ulcer

Herpes (HSV-2> HSV-1) painful, vesicles

Chancroid (Haemophilus ducreyi)

Lymphogranulona venereum (Chlamydia trachomatis)

Genital warts (papillomaviruses)

STDs (Infections)

HIV?AIDS

Pelvic inflammatory disease (mixed microbes often including Neisseria gonorrhoeae,

Chlamydia trachomatis, anaerobes)

HBV

Cancer

Cancer or cervical neoplasia due to HPV

Kaposi’s sarcoma (human herpesvirus 8)

Gastrointestinal and Liver infections

Chronic gastritis (ulcer)

Stomach/abdominal pain: improves after mea, no diarrhea Helicobacter pylori

Food poisoning (preformed toxins with rapid onset))

Nausea and vomiting (+/- diarrhea) Bacillus cereus

Staph aureus

Weakness (longer 12-24 h incubation) Botulism

Acute infectious gastroenteritis

Secretory diarrhea (watery with few fecal leukocytes)

E. coli (ETEC, EPEC, EAEC)

Vibrio. cholerae

Norovirus (Norwalk)

Rotavirus

Giardia

Cryptosporidium

Dysentery (signs of true invasion)

Colonic pain, Diarrhea, Bloody feces often containing many white cells

Campylobacter

Salmonella

Shigella

Yersinia enterocolitica

EIEC Enteroinvasive E coli

Entamoeba histolytica

Strongyloides (larvae in feces, autoinfective)

Clostridium difficile (often post-antibiotic, pseudomembrane)

High temp killing of spores is necessary

Hemorrhagic colitis

Colonic pain, Diarrhea, seriously bloody feces but few white cells, HUS

EHEC (E. coli O157:H7 and a few other serotypes)

Salmonella

Shigella

Gastrointestinal infections (cont.)

Enteric fever - Salmonella typhi (typhoid fever)

Salmonella paratyphi (paratyphoid fever)

Infection via small intestine but systemic illness (Bacteria found in bone marrow)

Chronic Yersinia enterocolitica (terminal ileitis/pseudoappendicitis in ~1/4 patients) can persist months. Most times patients have simple enterocolitis with 1-2 weeks of pain

Chronic diarrhea in AIDS : wateru diarrhea from small intestine

Cryptosporium

Microsporidium species (protozoan parasites – allied to fungi)

Cyclospora

CMV

Mycobacterium avium complex

Hepatitis:

Jaundice (remember icteric sclera), fatigue, often abdominal pain, loss of appetite

Blood HB, HCV, HDV (delta agent) - cause chronic infections

Gut HAV, HEV acute infections that resolve

Parasites (Schistosoma, hydatid cyst (Echinococcus)

Liver abscess (Amebiasis, TB lesion might be ahydatid cyst if history suggests)

Nervous System

Bacterial Meningitis

Newborn (0- 3 months) Strep Group B +

E. coli

Listeria monocytogenes

Infants Children (3 months-18 yr) Strep pneumoniae

Neisseria meningitides

Haemophilus influenzae type b (not immunized)

Adults (18-50 yr) Strep pneumoniae

Neisseria meningitidis

Older Adults (> 50 yr) Strep pneumoniae

Listeria

Gram neg rods (Klebsiella, Pseudomonas)

Head trauma (any age)

Staph aureus

Strep pneumoniae

Anaerobes

Immunosuppressed (additional) Listeria

Gram-negative rods

(Klebsiella and Pseudomonas)

AIDS Cryptococcus

Note Toxoplasma causes ring-enhancing lesion in CNS, not a meningitis

Skin and Wound and Soft tissue

Impetigo (vesicles with purulent contents)

Staph aureus and Strep (Group A)

Staph may cause large blisters (bullae)

Erysipelas (dermis and lymphatics inflamed) Lesions show sharp borders.

Strep (group A)

Cellulitis (all skin layers – fever leukocytosis)

Group A strep and Staph aureus are most common causes

Severe progression may lead to gangrene

Necrotizing fasciitis (Group A strep: certain M serotypes are much more common)

Flesh eating: post chicken pox, post surgery / trauma in majority suggests skin breaks enhance access to deeper tissues.

Viruses

Measles and rubella (maculopapular rash). Rash starts on face and moves down

. Measles: Koplik spots on buccal mucosa.

Chickenpox vesicles - several crops of lesions crusting at different times

Smallpox lesions tend to be all present at same stage of maturity

Rashes

Rickettsia such as Rocky Mountain spotted fever. Significant rash (almost always)

Ehrlichiosis. Rash may be absent

Lyme disease (bull’s eye and target: spreading rash)

Sporotrichosis Lymphocutaneous spreading lesions

Ringworm (sepatate hyphae +/- arthrospores in skin) often itchy

Candida (yeasts and filaments) often itchy

Tinea versicolor (clusters of yeast and some filaments: depigmented patches) –

no symptoms usually

Scabies (Female mite and eggs within tunnels in epidermis) itchy

Lice (eggs attached to hair) itchy

Pinworm (eggs on anal skin- Scotch tape test) itchy