N236: Bacterial Infections of Humans

Acne Vulgaris

Pathogen: Propionibacterium acnes

S+S: Clogging of skin pores with sebum and dead cells --> formation of papules and pustules on face, forehead, chest, upper back and shoulders

Cystic acne

Uncommon, severe form of acne with painful pustules

Gas gangrene (clostridial myonecrosis)

Pathogen: Clostridium perfringens

S+S: Rapid destruction of muscle and soft tissues by necrotizing exotoxins

Reservoir: Soil

Treatment: Amputation

Palpable crepitus

Crackling sensation or popping sound during palpation due to the presence of gas in the subcutaneous tissue

Hansen's Disease (Leprosy)

Pathogen: Mycobacterium leprae

S+S:

skin: Flat, discolored patches on skin, ulcers on the feet, nodules on the face, loss of eyebrows/eyelashes,

mucous membranes: stuffy nose, epistaxis,

peripheral nerves: numbness, paralysis

limbs: shortening of fingers and toes

Reservoir: Armadillos

Transmission: Long term inhalation of respiratory secretions; touching/handling infected armadillos

Anthrax

Bacillus anthracis

S+S: Cutaneous anthrax --> depressed black lesions (eschars) on the skin of the head, neck, forearms, and hands as a result of damage by exotoxins

Reservoirs: Animals (wool)

Anthrax used to be called...

Woolsorters' disease

Other forms of anthrax

Inhalation --> Flu-like symptoms, SOB, hemoptysis, death

GI --> Nausea, vomiting, abdominal pain, loss of appetite, followed by diarrhea/dysentery, and death

Injection --> Redness and swelling at the site of injection, no eschars, multiple organ failure

Staphylococcal Skin Infections

Pathogen: Staphylococcus aureus

Infections: Folliculitis, hordeolum (sty), furuncle (boils), carbuncle

Scalded skin syndrome

Rare infection caused by certain toxin-producing strains of Staphylococcus aureus

S+S: Peeling of the epidermis --> looks like the skin has been burned over large parts of the body

higher risks to immunocompromised and children <5 years

treatment: burn units or ICUs

MRSA

Methicillin-resistant staphylococcus aureus

Scarlet fever

Pathogen: Streptococcus pyogenes

S+S: High fever, sore throat, bright red colored skin rash progressing from macular > papular, resolving within a week

Transmission: Inhalation of infected oropharyngeal secretions, contact with articles freshly soiled with infected oropharyngeal secretions

Necrotising fasciitis

Pathogen: Streptococcus pyogenes (“flesh-eating” strain)

S+S: Red, warm, blistered skin, swelling, severe pain

Transmission: Bacteria enter through skin cuts

treatment: requiring surgery removing dead, damaged tissue (debridement)

Gonococcal conjunctivitis

Pathogen: Neisseria gonorrhoeae

S+S: Inflammation of the conjunctiva, redness, purulent discharge; scarring if untreated

Transmission: Direct contact with an infected birth canal during delivery, finger-to-eye contact with infected genital secretions

Another name for Gonococcal conjunctivitis

Gonococcal Ophthalmia Neonatorum, occurs within 2 days after birth

Chlamydial Conjunctivitis

Pathogen: Chlamydia trachomatis

S+S: Inflammation of the conjunctiva, redness, purulent discharge; scarring if untreated

Transmission: Direct contact with an infected birth canal during delivery, finger-to-eye contact with infected genital secretions

Another name for Chlamydial Conjunctivitis

Chlamydial Ophthalmia Neonatorum, occurs within weeks after birth

Trachoma

Chlamydia trachomatis

Inflammation of the conjunctiva and cornea --> eyelid swelling, pain, photophobia, blindness

Transmission: Direct contact with infected ocular secretions, fomites, flies that have touched infected ocular secretions

Musca sorbens

Bazaar fly, eye seeking fly --> causes trachoma

Streptococcal Pharyngitis

Streptococcus pyogenes

S+S: Inflammation of the pharynx, throat pain, dysphagia, fever, headache, enlarged tonsils, enlarged cervical lymph nodes

Transmission: Inhalation of or contact with infected oropharyngeal secretions

Diagnosis of strep throat

Rapid strep test where they swab the back of ur throat and you literally fight for your life trying not to gag and throw up all over the nurse lmao

Diphtheria

Corynebacterium diphtheriae

S+S: Inflammation of the pharynx and larynx --> throat pain, dysphagia, fever, headache, enlarged tonsils, enlarged cervical lymph nodes, tough adherent grayish-white pseudomembrane in throat

Transmission: Inhalation of or contact with infected oropharyngeal secretions

Vaccine: DTaP or Tdap

Pseudomembrane

A layer of exudate resembling a membrane, made of dead cells and bacteria --> causes severe airway obstruction, death

DTap/Tdap

Vaccine that protects against diphtheria, tetanus, and pertussis

Pertussis (Whooping Cough)

Bordetella pertussis

SS+: Inflammation of the pharynx, larynx, trachea, bronchial tubes --> whooping cough

Prevention: DTap or Tdap vaccine

Prodromal stage of pertussis

Mild, cold-like symptoms

Paroxysmal stage of pertussis

Bouts of severe coughing (paroxysm) + "whooping" sound on inspiration

Convalescent stage of pertussis

Gradual cessation of the coughing

Typical Pneumonia

Pathogen: Streptococcus pneumoniae

S+S: Inflammation of the alveoli in one or both lungs --> Rapid onset of chest pain, dyspnea, high fever, productive cough

X-Ray: Looks equal to S+S severity - lobar involvement

Transmission: Inhalation of or contact with infected oropharyngeal secretions

Legionnaires' Disease (Pontiac fever)

Pathogen: Legionella pneumophila

S+S: Inflammation of the alveoli in one or both lungs --> Rapid onset of chest pain, dyspnea, high fever, productive cough

Transmission: Inhalation of contaminated mist and dust particles

Reservoirs: Hot water, humidifiers, shower heads

Atypical (walking) Pneumonia

Pathogen: Mycoplasma pneumoniae

S+S: Inflammation of the alveoli in one or both lungs --> Slow onset of dry cough and mild fever, NO chest pain/dyspnea

X-Ray: Look worse than symptoms - interstitial involvement

Transmission: Inhalation of/contact with infected oropharyngeal secretions

Psittacosis/Ornithosis/Parrot Fever

Pathogen: Chlamydophila psittaci

S+S: Inflammation of the alveoli in one or both lungs --> Slow onset of dry cough and mild fever, NO chest pain/dyspnea, Horder spots

Transmission: Inhalation of respiratory secretions of birds

Reservoirs: Birds

Pulmonary Tuberculosis (TB)

Pathogen: Mycobacterium tuberculosis

S+S: Inflammation of the alveoli

Transmission: Inhalation of infected respiratory/oropharyngeal secretions (coughing, sneezing)

How to test for TB?

Skin test or blood test --> if positive, sputum smear and x-ray to confirm

Latent TB infection

TB bacteria is present in the body, but there is no evidence that the bacterium is growing/causing disease --> TB skin/blood test is positive, but no other S+S, NOT contagious

TB disease

TB bacteria is causing disease --> fever, weight loss, cough, dyspnea, hemoptysis, positive TB test/abnormal x-ray, CONTAGIOUS

https://www.sciencehistory.org/distillations/podcast/vampire-panic

prevention of pulmonary tuberculosis

preventing exposure when traveling abroad, trating LTBI, Bacille Calmette-Guerin BCG vaccine - single dose is recommended soon after birth in countries w/ high burden of TB disease

Necrotizing Ulcerative Gingivitis/Trench Mouth

Pathogen: 2 or more species of anaerobic bacteria

S+S: Painful bleeding of the gingivae, fever, swollen cervical lymph nodes, extreme halitosis

Prevention: Maintain good oral hygiene (not contagious)

Chronic Bacterial Gastritis

Pathogen: Helicobacter pylori

S+S: Chronic inflammation of the gastric mucosa --> early satiety, indigestion, nausea, vomiting, ulcer formation, pyrosis when the stomach is empty, epigastric pain

Transmission: Saliva, fecal-oral route

Typhoid Fever

Salmonella typhi, Salmonella paratyphi

S+S: Fever, malaise, severe headache, dry cough, loss of appetite, rose spots

Transmission: Fecal-oral route, ingestion of contaminated food or water, vectors (houseflies)

Rose spots

Red macular rash on the chest/abdomen caused by typhoid infection

Campylobacter Enteritis

Pathogen: Campylobacter jejuni

S+S: Acute inflammation of the small intestine --> nausea, vomiting, abdominal pain, fever, diarrhea --> lasts 2-5 days

Reservoirs: Pigs, cattle, chicken

Transmission: ingestion of infected chicken, beef, pork, or food prepared on contaminated cutting boards

Cholera

Pathogen: Vibrio cholerae

S+S: Profuse watery diarrhea, vomiting, rapid dehydration --> death in 50% of untreated cases

Reservoirs: Shellfish

Transmission: Fecal-oral route, ingestion of contaminated food or water, vectors (houseflies)

Salmonellosis

Pathogen: Salmonella enterica

S+S: Abdominal pain, nausea, vomiting, diarrhea

Reservoirs: Pigs, chicken, cattle

Transmission: Fecal-oral route, ingestion of infected chicken, beef, pork, incompletely cooked eggs

Shigellosis

Pathogen: Shigella dysenteriae

S+S: Abdominal pain, nausea, vomiting, fever, dysentery

Transmission: Fecal-oral route, ingestion of contaminated food or water

Clostridium difficile Colitis

Pathogen: Clostridium difficile

S+S: Inflammation of the colon --> bloody diarrhea 1-2 weeks after starting oral antibiotic therapy

Transmission: Fecal-oral route (spores persist on surfaces for weeks)

EHEC Enterocolitis

Pathogen: Enterohemorrhagic Escherichia coli (common strain is O157:H7)

S+S Nausea, vomiting, abdominal cramps, dysentery

Reservoirs: Humans, cattle

Transmission: Fecal-oral route, ingestion of infected beef, contaminated fruits, green leafy vegetables, or fluids

Hemolytic Uremic Syndrome (HUS)

Complication of EHEC Enterocolitis, destruction of RBCs and platelets by shiga toxin --> acute kidney failure

ETEC Enterocolitis

Pathogen: Enterotoxigenic Escherichia coli

LT strain produces a heat labile toxin

ST strain produces a heat stable toxin

S+S: Nausea, vomiting, abdominal cramps, diarrhea

Reservoirs: Humans, cattle

Transmission: Fecal-oral route, ingestion of infected beef, contaminated fruits, green leafy vegetables, or fluids

Urinary Tract Infections

Pathogen: Neisseria gonorrhoeae, Chlamydia trachomatis, Pseudomonas aeruginosa, Escheria coli

S+S: upper UTI’s - fever, chills, lumbar pain; lower UTI’s - fever, pelvic, pelvic discomfort, a persistent urge to urinate, a burning sensation during urination, hematuria, redness around the opening of the urethra

Transmission: Urinary catheterization, person to person by sexual contact

Gonorrhea

Pathogen: Neisseria gonorrhoeae

S+S: Urethral --> dysuria, purulent discharge from penis or vagina within one week after infection, pain

Rectal --> anal itching, purulent discharge/bleeding from rectum

Oropharyngeal --> sore throat, dysphagia, swollen cervical lymph nodes

Transmission: Person to person by sexual contact

Chlamydia

Pathogen: Chlamydia trachomatis

S+S: Urethral --> dysuria, purulent discharge from the penis or vagina within 2 weeks after infection, pain

Rectal --> Anal itching, purulent discharge/bleeding from the rectum

Oropharyngeal --> Sore throat, dysphagia, swollen cervical lymph nodes

Transmission: Person to person by sexual contact

Syphilis

Pathogen: Treponema pallidum

S+S: Vary depending upon the stage

Transmission: Person-to-person by sexual contact

Primary Syphilis

Hardened, painless chancre develops 3 weeks after exposure

Secondary Syphilis

Chancre curls inward and a rash develops about 4 to 6 weeks after exposure; rash resolves within weeks to 12 months

Latent Syphilis

No symptoms; may last for weeks to years; sometimes continues throughout life

Tertiary Syphilis

CNS, cardiovascular, and other symptoms (sometimes death) occur 5 to 20 years after exposure, gummas

Gummas

Soft, rubbery tumors seen in tertiary syphilis

Congenital syphilis

S+S: Failure to gain weight, loss of hearing, loss of vision, skeletal abnormalities, scarring of the skin around the genitals, teeth abnormalities

Transmission: Mother to baby via placenta

Hutchinson teeth

Peg-shaped teeth; seen in congenital syphilis

Chancroid

Pathogen: Haemophilus ducreyi

S+S: Small, painful papules appear within 1 week of infection --> break down into shallow, painful ulcers w/ elevated erythematous edges, enlarged inguinal lymph nodes

Transmission: Person-to-person by sexual contact

Lymphogranuloma Venereum

Pathogen: Chlamydia trachomatis

S+S: Small, painless, ulcer on the genitals --> chronic inflammation of the lymphatic vessels and lymph nodes --> buboes

Transmission: Person-to-person by sexual contact

Buboes

A swollen, inflamed lymph node in the armpit or groin

Bacterial Vaginosis

Pathogen: Several anaerobic bacteria

S+S: Inflammation of the vagina --> grayish-white discharge --> itchin' and burnin', stanky and fishy

Transmission: unknown, sexual contact??

Risk factors: Douching, multiple sex partners

Infective Endocarditis

Pathogen: Staphylococcus aureus, Streptococcus pyogenes

S+S: "Vegetations" on the endocardium, fever, heart murmurs, myalgia, Osler's nodes, Janeway's lesions

Transmission: Entry of bacteria into the bloodstream following tooth brushing, oral surgery, phlebotomy, IV, injections

Osler's nodes

Painful erythematous nodules on fingers and toes

Janeway's lesions

Painless erythematous nodules on palms and soles of feet

Rocky Mountain Spotted Fever

Pathogen: Rickettsia rickettsii

S+S: Infected capillaries --> Fever, headache, nausea, vomiting, loss of appetite, abdominal pain, Red, non-itchy rash on wrists and ankles --> then spreads to the rest of the body

Reservoirs: Dogs, deer, rodents

Transmission: American dog tick bite

Ehrlichiosis

Pathogen: Ehrlichia bacteria

S+S: Infected leukocytes --> fever, headache, nausea, vomiting, loss of appetite, abdominal pain, myalgia, rash

Reservoirs: Dogs, deer, rodents

Transmission: Lone star tick bite

Bubonic Plague (Black Death)

Pathogen:Yersinia pestis

S+S: Fever, headache, weakness, chills --> infected lymph nodes --> buboes

Reservoirs: Infected rodents (rats, mice, squirrels)

Transmission: Infected flea bite

Septicemic Plague

Pathogen: Yersinia pestis

S+S: Fever, headache, weakness, chills --> infected bloodstream --> blackening/necrosis of fingers and toes

Reservoirs: Infected rodents (rats, mice, squirrels)

Transmission: Infected flea bite

Pneumonic Plague

Pathogen: Yersinia pestis

S+S: Fever, headache, weakness, chills --> infected alveoli --> dyspnea, hemoptysis

Reservoirs: Infected rodents (rats, mice, squirrels)

Transmission: Inhalation of infected respiratory secretions

Lyme Disease

Pathogen: Borrelia burgdorferi

S+S: Fever, headache, chills, myalgia, arthralgia, fatigue, bull's-eye rash (erythema migrans)

Reservoirs: Infected deer and rodents

Transmission: Bite of infected deer tick

Bacterial (purulent) Meningitis

Pathogen: Haemophilus influenzae, Neisseria meningitidis, Streptococcus pneumoniae

S+S: Fever, headache, nuchal rigidity

Transmission: Respiratory or oropharyngeal secretions

Listeriosis

Pathogen: Listeria monocytogenes

S+S: Mild illness to meningoencephalitis --> fever, headache, nuchal rigidity

Reservoirs: Soil and water

Transmission: Contaminated foods

Botulism

Pathogen: Clostridium botulinum

S+S: Ptosis, diplopia, dysphagia, muscle paralysis

Transmission: Can be from infected food, wounds, or environmental

Botulinum

A neurotoxin produced by bacteria --> prevents the release of Acetylcholine at the neuromuscular junction --> depressed motor response

Used in BOTOX !!

Tetanus (lockjaw)

Pathogen: Clostridium tetani

S+S: Spasms of the masseter, neck and respiratory muscles, opisthotonus

Reservoirs: Soil contaminated with animal or human feces

Transmission: Bacteria enter an open wound from soil

Tetanospasmin

Bacteria secrete a toxin --> toxin inhibits the release of gamma-aminobutyric acid (GABA) in the motor neurons --> muscles cannot relax --> involuntary muscular contractions

Opisthotonus

Abnormal posture seen in severe tetanus --> the back becomes extremely arched due to muscle spasms

Sensitivity

Probability of testing positive when you have a disease

P (T+ / D+)

Specificity

Probability of testing negative when you do not have a disease

P (T- / D-)

Positive predictive value

Probability of having a disease if you test positive

P (D+ / T+)

Negative predictive value

Probability of not having a disease if you test negative

P (D- / T-)

pyelonephritis

upper UTI involving inflammation of one or both kidneys

ureteritis

upper UTI involving inflammation of one or both ureters

cystitis

lower UTI inflammation of the urinary bladder

urethritis

inflammation of the urethra

ascending UTI (more common)

bacteria migrating up the urethra to the urinary bladder, then the ureters, and finally the kidneys

descending UTI (less common)

bacteria from an infection elsewhere in the body can spread to the kidneys via the bloodstream

prevention of UTI

maintaining adequate fluid intake, wiping from front-to-back after defecation, emptying the bladder after sex, avoiding delaying urination

complications of gonorrhea

septic arthritis - spread via bloodstream to one or more joints

pelvic inflammatory disease - spread to uterus and fallopian tubes

epididymitis - spread to the epididymides

risk factor for bacterial vaginosis

multiple sex partners, condomless sex, low levels of lactobacilli in the vagina,

douching - rinsing out vagina with water or other cleansing agents, which can upset the natural balance of resident bacteria and alter its acidic environment