Infectious Diseases Quiz

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Questions and Answers

What symptoms are primarily associated with urinary tract infections in females?

Fever and chills

Cough and wheezing

Dysuria and urgent urination (correct)

Chest pain and difficulty breathing

What is the primary demographic affected by urinary tract infections?

Children under 10

Men over the age of 50

Elderly individuals

Women (correct)

Which characteristic distinguishes pertussis toxin?

It only affects children

It is harmless to the ciliated cells

It causes respiratory droplet spread

It is a type of AB toxin producing systemic symptoms (correct)

During which stage of whooping cough does a cough with a 'whoop' sound occur?

Paroxysmal stage Signup and view all the answers

What is the primary impact of pertussis toxins on the respiratory system?

They stop the mucou ciliary escolator Signup and view all the answers

What diagnostic indicator is commonly used to identify urinary tract infections?

Elevated WBC count in urine Signup and view all the answers

What is a common symptom of pleuritis?

Sharp chest pain during breathing Signup and view all the answers

What role do hemagglutinin spikes play in the structure of the influenza virus?

They clump red blood cells and recognize and attach to host cells. Signup and view all the answers

Which statement correctly describes the epidemiology of Influenza A and B viruses?

Influenza A is associated with more severe and widespread disease compared to Influenza B. Signup and view all the answers

What are the characteristics of the influenza virus's genetic material?

It has 8 RNA segments that encode various viral proteins. Signup and view all the answers

Which symptom is commonly associated with influenza infection?

Extreme fatigue and body aches. Signup and view all the answers

What is the primary function of neuraminidase spikes in the influenza virus?

They assist in the release of new viral particles from the host cell. Signup and view all the answers

What type of bacteria is Legionella pneumophila?

Gram-negative bacilli Signup and view all the answers

Which of the following is NOT associated with Legionnaires' Disease?

Direct person-to-person transmission Signup and view all the answers

What media is primarily used to diagnose Legionella pneumonia?

Charcoal yeast extract media Signup and view all the answers

How many Mycobacterium tuberculosis cells are needed for infection?

10 Signup and view all the answers

What is a characteristic of active tuberculosis?

Formation of tubercles Signup and view all the answers

What occurs during the reactivation phase of tuberculosis?

Increased inflammation and spread Signup and view all the answers

Which type of tuberculosis infects other organs besides the lungs?

Extrapulmonary or Miliary TB Signup and view all the answers

What is the characteristic feature of a tubercle?

Core of bacilli within macrophages Signup and view all the answers

Which condition is characterized by caseating necrosis?

Potentially active tuberculosis Signup and view all the answers

Which of the following is true about Mycobacterium tuberculosis?

Intracellular pathogen Signup and view all the answers

What is a characteristic symptom of Pertussis?

Cough with whooping sound Signup and view all the answers

What is the primary treatment for Pertussis?

Erythromycin Signup and view all the answers

What is the main cause of primary pneumonia as described in the content?

Streptococcus pneumoniae Signup and view all the answers

Which of the following describes a common diagnostic method for Pertussis?

Rapid serological testing Signup and view all the answers

What feature is associated with the pneumonia caused by Streptococcus pneumoniae?

Lobar consolidation Signup and view all the answers

What is the expected consequence if bacteria invade the pleura during pneumonia?

Pleurisy Signup and view all the answers

What type of vaccine is the DTaP for Pertussis?

Acellular Signup and view all the answers

What happens to immunity after Pertussis vaccination over time?

Immunity wanes after 5-10 years Signup and view all the answers

Which symptom is NOT associated with primary pneumonia caused by Streptococcus pneumoniae?

Severe dry cough Signup and view all the answers

What is a key characteristic of Streptococcus pneumoniae?

Gram-positive diplococci Signup and view all the answers

Which factor contributes to the virulence of Streptococcus pneumoniae?

Capsule Signup and view all the answers

What is the treatment of choice for Streptococcus pneumoniae infections?

Penicillin Signup and view all the answers

Which vaccine is specifically recommended for children to prevent pneumococcal infections?

PCV 13 Signup and view all the answers

What is a common symptom of Mycoplasma pneumoniae infections?

Low-grade fever Signup and view all the answers

Which of the following describes the growth conditions for Mycoplasma pneumoniae?

Doesn’t grow on regular media Signup and view all the answers

What is a significant challenge with treating infections caused by Streptococcus pneumoniae?

Increased regional antibiotic resistance Signup and view all the answers

Which organism is known as an obligate intracellular parasite?

Chlamydophila pneumoniae Signup and view all the answers

What percentage of pneumonia cases in young adults is attributed to Mycoplasma pneumoniae?

20% to 25% Signup and view all the answers

What distinguishes atypical pneumonia caused by Mycoplasma pneumoniae from other types of pneumonia?

Infiltration in interstitial tissues Signup and view all the answers

Study Notes

Diseases of the Urinary and Reproductive Systems (Genitourinary Tract)

The genitourinary tract is comprised of two distinct systems: the urinary tract and the genital system (also known as the reproductive system).
The urinary tract removes metabolic wastes from the blood through the kidneys, regulates bodily processes, and transports urine out of the body.
The genital system functions mainly in reproduction.

The Urinary System

The urinary tract consists of the kidneys, ureters, bladder, and urethra.
Kidneys filter metabolic waste from blood.
Ureters transport urine from kidneys to the bladder.
The bladder stores urine.
The urethra carries urine to the external environment.
Pathogens can enter the urinary tract in some cases.

Urinary Tract Defenses

Urine flushing action helps to remove pathogens.
Desquamation, the sloughing of epithelial cells, helps remove microbes.
Normal flora (helpful bacteria) in the urethra inhibits pathogenic bacteria growth.
Antibacterial proteins like lysozyme, lactoferrin, and secretory IgA combat infection.

General Terms for Urinary Tract Infections (UTIs)

Pyelonephritis: Kidney infection, can cause sepsis.
Cystitis: Urinary bladder infection.
Urethritis: Urethra inflammation.

Diagnosis

Quantitative urine culture on blood and MacConkey agar.
Quantification of urine by a calibrated pipette.
Counting colonies to obtain CFU/mL.

Urine Specimen Types

CCMS (Clean Catch, Mid-stream): Common method for specimen collection.
Suprapubic aspirate: Urine sample collected directly from the bladder.
Catheterized specimen: Direct collection of urine via catheter.

Screening Urine Specimens for Bacteria

Dipstick method: Simple tests detecting leukocyte esterase and nitrates.
Leukocyte esterase indicates presence of neutrophils-infection.
Nitrites indicate presence of bacteria.

Urethritis due to Coliforms

E. coli is a common gram-negative rod; often causing UTIs.
Other coliforms (like Klebsiella, Enterobacter, Citrobacter) can also cause UTIs

Urethritis Disease

Inflammatory response
Painful urination, cloudy/pink (bloody) urine.
Can lead to cystitis and nephritis (ascending infection).

Epidemiology of E. coli UTI

The most common cause of UTIs is E. coli.
Most UTIs are community-acquired.
Nosocomial infections account for a significant number of UTIs (hospital setting).
Catheterization is also a significant factor (hospital setting).

Diagnosis of E. coli UTI

Standard urine culture.
Gram negative.
Lactose-fermenter

Treatment of E. coli UTI

Antibiotic resistance is common, so susceptibility testing is important.
Treatment with appropriate antibiotics.

Urethritis due to Enterococci

Enterococcus species are opportunistic pathogens frequently causing UTIs.
The second most common cause of UTIs.
10% of all UTIs, 16% nosocomial UTIs, are often Enterococcal infections.

Diagnosis of UTI due to Enterococci

Culture on blood and MacConkey agar.
Gamma-hemolytic and catalase positive.
Lancefield Group D.
Enterococci do not produce nitrate reductase.

Other Species causing Urethritis

Klebisella sp.
Staphylococcus aureus
Other Staphylococcus sp
Proteus sp
Enterobacter sp
Pseudomonas sp

Cystitis

95% of cases are E. coli infections in females.
Symptoms include painful urgent urination (dysuria).
Common in women due to anatomical factors (short urethra, proximity to anus, sexual intercourse).
Poor hygiene is a significant factor.

Treatment of Cystitis

Trimethoprim/sulfamethoxazole (TMP/SMX), quinolones, and ampicillin.

Pyelonephritis

E. coli infection (75%).
Symptoms include fever, back pain, and potentially impaired kidney function.
Scar tissue can lead to permanent kidney damage.
Can spread to the blood.

Diagnosis of Pyelonephritis

A supra-pubic aspirate can be collected from the bladder.

Treatment of Pyelonephritis

Administration of antibiotics.
2/3-generation cephalosporins are often used.

Leptospirosis

Leptospira interrogans.
Spirochete bacteria; usually found in animal urine.
An obligatory aerobe- needs oxygen to survive & replicate
Zoonotic infection (spread from animals to humans).

Leptospirosis Disease

Typically asymptomatic
Phase 1 (Leptospiremic): Sudden high fever, headache, muscle aches, and chills.
Phase 2 (Immune or Weil's Disease): kidney, liver, and other organ damage.
Mortality (5-15%)

Epidemiology of Leptospirosis

Animal urine in soil & water.
Enters through a wound or abrasion- such as a cut or scrape on the skin.
Risk to those who deal with or are in close contact with animals or water (e.g., farmers, those who swim or work around contaminated water).

Diagnosis of Leptospirosis

Isolating pathogen from blood and CSF (cerebrospinal fluid)

Prevention of Leptospirosis

Vaccination may be offered to people at high risk for exposure.
Avoid water with animal contact.
Clean wounds promptly and thoroughly.

Reproductive System Barriers

Ciliated epithelial cells
Mucus Membranes
Mucus + IgA
Vaginal pH (low in women)
Normal flora (many in women; mostly skin flora in men)

Diseases of the Genital Tract (STDs)

Infectious agents increase fluid discharge in the male and female reproductive tract.
Transmission of pathogens through genital fluids.
Genital ulcer diseases may result in lesions.
Infections can increase chance of HIV exposure due to open lesions.

Gonorrheal Urethritis

Neisseria gonorrhoeae (gonococcus) is a gram-negative diplococci (in pairs) pyogenic (pus-forming) coccus.
Diagnostic indicator: Gonococci in pairs with neutrophils.

Gonococcal Disease

Sexually transmitted disease (STD).
Purulent (pus) discharge
Symptoms in females can include abnormal bleeding & pain.
Many women are asymptomatic.
Male symptoms: painful urination and discharge (pus).
Untreated, leads to Pelvic Inflammatory Disease (PID) in women.

Pelvic Inflammatory Disease (PID)

Infection of the pelvic organs (uterus, fallopian tubes, and ovaries) frequently linked to STDs.
The infection can cause damage, including scarring preventing eggs from traveling and contributing to ectopic pregnancies.

Pharyngeal/Anal Gonorrhea, or Gonococcal Sepsis

Pharyngeal (throat) or anal infections are extremely rare.
Associated with systemic infections like arthritis, endocarditis, and meningitis.

Gonorrhea Virulence Factors

Phase Variation: bacteria can turn genes coding for fimbrial proteins on & off according to the bacterium's circumstance.

Gonorrhea Diagnosis

Gram stain: Gram-negative intracellular diplococci.
Culture- fastidious bacterial strains require 5% CO2 incubation, Modified Thayer Martin agar plus antibiotics to inhibit normal flora.
Other tests:
DNA probe, or ELISA

Gonorrhea Treatment

Floroquinolones (1 dose) or Ciprofloxacin/Ofloxacin.

Chlamydia trachomatis

Obligate intracellular bacteria; complex life cycle.
Has two forms: Elementary Body (EB)- infectious; Reticulate Body (RB)- noninfectious but metabolically active

Chlamydial Disease

Urethritis (NOW most common bacterial STD in the U.S., now most common)
Frequent coinfection.
Asymptomatic (75%) in men & women
often a clear discharge rather than purulent.
No pus (neutrophil influx)
Little pain or irritation.
Pelvic Inflammatory Disease (PID) frequently in women
Epididymitis frequently in men.

Chlamydia Epidemiology

Sexual contact.
Asymptomatic carriers spread infection.
Infections cause increased HIV incidence.
Recruitment of CD4 lymphs.
Increased HIV targets.

Chlamydia Diagnosis

DFA (Direct Fluorescent Antibody), Direct ELISA
PCR (Polymerase Chain Reaction).
If positive, screen for gonorrhea.

Chlamydia Treatment

Doxycycline, Cefoxitin.

Ophthalmia neonatorum

Eye infection in newborns.
Transmission during birth via infected birth canal frequently with gonorrhea or chlamydia.

Syphilis

Treponema pallidum (spirochete) – gram-negative; cannot be cultured
Elicits little immune response.

Primary Syphilis

Chancre (lesion)
Fluid from the sore is infectious.
Females often unaware (chancre inside cervix).
Organisms replicate and disseminate to other organs via blood.

Secondary Syphilis

Skin rash- infectious.
Hair loss, malaise, mild fever.
Heals in weeks or months.

Latent Syphilis

Symptoms latent (absent) for years.
Bacteria continue to spread to various body systems.

Tertiary Syphilis

Can begin following years or decades of a latent period.
Gummas, a granuloma-like lesion, form on skin and organs, causing severe organ damage.
Cardiovascular complications are possible.
Neurological complications.
Death outcome

Congenital Syphilis

Placental transfer can occur during pregnancy.
Untreated infections can be very severe or deadly.
May affect newborn’s development and organ function.

Epidemiology of Syphilis

Sexual contact.
Low transmission rates in some populations.
Incidence has increased in other populations.

Syphilis Diagnosis

Screening tests:
Rapid Plasma Reagin (RPR) test.
Venereal Disease Research Laboratory (VDRL).
Antigen latex test
Confirmatory tests:
FTA-abs (fluorescent treponemal antibody-absorbed).

Syphilis Treatment

Penicillin (Benzylpenicillin)- commonly administered long-acting penicillin injection, Doxycycline, or Tetracycline.

Soft Chancre

Haemophilus ducreyi (small gram-negative rods; facultative anaerobe)
Symptoms: Develop into papules, become pustules, ulcerate into larger lesions
Lymphadenitis (buboes).

Soft Chancre Epidemiology

Important in Asia, Africa, and Latin America; less common in the U.S.
Chancres facilitate HIV transmission.

Diagnosis of Soft Chancre

Culture on chocolate agar (fastidious).
PCR for H. ducreyi, Treponema pallidum (syphilis) - or HSV1/2

Soft Chancre Treatment

Erythromycin is used in the US due to resistance differences.
Treatment determined by susceptibility testing

Bacterial Vaginosis (BV)

Gardnerella vaginalis (an anaerobe; small pleomorphic gram-negative bacilli; common normal vaginal flora).

G. vaginalis Disease

Malodorous discharge ("fishy odor"), itching.
No vaginal epithelium inflammation
Superinfection occurs due to pH changes or balance of normal flora disruption.
Low birth weights in infants born to mothers with BV during pregnancy.

G. vaginalis Diagnosis

Clue cells (diagnostic)
Anaerobic culture

G. vaginalis Treatment

Re-establish low vaginal pH (higher pH kills Lactobacillus)
Metronidazole.

Human Immunodeficiency Virus (HIV)

Retrovirus, Reverse transcriptase (RNA-DNA-Protein).
Similar to Simian Immunodeficiency Virus (SIV) mutated from a zoonotic virus.
Primarily an STD.
HIV-1 and HIV-2 have been identified

Genital Herpes

Herpes Simplex Virus (HSV) is usually subclinical and doesn't present with lesions during the primary infection.
All subsequent outbreaks = genital lesions.
Vesicular lesions
Macrophages and lymphocytes are the main host cells
Burning sensation
latent infection- recurrences
Virus over time in dorsal root ganglia.
Chronic herpes may develop Encephalitis in some individuals
Mortality rate 70% without treatment: but Acyclovir is good treatment.
Neonatal herpes- crosses placental barrier and causes problems.

Herpes Epidemiology-

Direct sexual contact
42 million infected in the U.S.
20% of genral population seropsoitive
500,000 new cases per year

Herpes Diagnosis

Seeing lesions
Serology
PCR
Virus culture

Herpes Treatment

• Acyclovir •Famiciclovir, Valcyclovir

Genital Warts (HPV)

Human Papillomavirus (HPV) is over 100 serotypes
A few strains are linked to cancers (Cervical, penile, anal, oropharyngeal cancer).
HPV is the most common viral STI in the U.S.

HPV Disease

Warts = Hyperplasia (finger-like projections).
Prickle cells are infected & transformed.
Majority of infections self-limiting
Malignant cancers occur in some infected individuals. (Malignancy is infrequent).
Cervical cancer is common: caused by HPV types 16 and 18.

HPV Epidemiology

Sexually transmitted disease.
1 million new cases per year
70% Cervical cancer cases associated with HPV 16 and/or 18.
Other high risk types (31, 33, 35, 39, 45, 51, 52, 56, 58, 59 and 68).
Intermediate risk (HPV 31, 33, 35).
Low risk (HPV 6, 11 - most genital warts, 42, 43, 44)

HPV Diagnosis

Serological typing.
Pap smear
Looking for nucleic acid of cancer-causing HPV.

HPV Treatment

Imiquimod (Aldara) induces interferon
Vaccination against cancer-causing strains and genital warts. • HPV types 6, 11, 16 and 18

Candidiasis (Yeast Infection)

Candida albicans (a yeast, a dimorphic fungus).
Thick, white, and cheesy discharge.
Vulvovaginal candidiasis (VVC) or oral candidiasis (thrush).
Frequently observed during pregnancy
Often an opportunistic infection secondary to antimicrobial use.

Candidiasis Epidemiology

Occurring in up to 75% of women.
Contributed to by oral contraceptives and pregnancy, due to elevated glycogen levels in vaginal secretions.

Candidiasis Diagnosis

Microscopic identification of yeast
Germ tube tests.

Candidiasis Treatment

Miconazole, clotrimazole (OTC).
Prescription oral medication- Flucanozole.

Trichomoniasis

Trichomonas vaginalis (anaerobic, flagellated protozoon).

Trichomoniasis Disease

Itching (dysuria)
Profuse green/yellow discharge.
Foul-smelling, frothy discharge

Trichomoniasis Epidemiology

50% of infected cases are asymptomatic (in men).
Need direct sexual contact.

Trichomoniasis Diagnosis

Microscopic analysis (routine urine analysis); dysuria = frequent urination with painful sensation during passing urine.
Undulating membrane, jerky motility.
Direct ELISA.
DNA probes

Trichomoniasis Treatment

Metronidazole.

Diseases of the Digestive Tract

Structures of the mouth.
Normal flora of the mouth.
Bacterial infections of the mouth.
Gram stain results.
Diseases.
Epidemiology.
Virulence factors.
Key characteristics.

Dental Caries (Cavities)

Key culprits: Streptococcus mutans, Streptococcus sobrinus, Scardovia wiggsiae
Nursing bottle caries; early in childhood

Oral Micro-bial Community

Saliva leaves protein on teeth to which normal flora (NF) adhere.
NF make sticky polymers (like glucans or fructans).
Secondary colonizers ferment sucrose resulting in acid production (leaches calcium from tooth enamel).
Introduction of sugars can result in dentin breakdown.

Treatment of Caries

Brushing and flossing.
Alternative carbohydrates.
Natural defenses: saliva-lysozyme, crevicular fluid, flushing, and phagocytic cells.
Good dental hygiene practice.

Periodontal Disease

Inflammation and degeneration of structures that support teeth (gums and bone).
Gingivitis (gum infection) occurs frequently, due to swelling, redness, and bleeding.
Usually caused by anaerobes.

Acute Necrotizing Ulcerative Gingivitis (ANUG)

Tissue damage due to an inflammatory response.
Synergistic infection.
Treponema vincentii, Prevotella intermedia, and Fusobacterium species (anaerobes).
Causes rapid advancement into periodontal tissues.
Symptoms: severe pain, bleeding, pseudomembrane formation and necrosis.
Treatment: Debridement, oxidizing agents, and metronidazole for anaerobes.

Digestive Tract Defenses

Mucus, secretory IgA, peristalsis, saliva (high acid), bile
GALT, tonsils, adenoids, lymphoid tissue in esophagus, Peyer's patches, M cells, appendix, microbial antagonism.

The Digestive System

• Stomach, small intestine(Duodenum, Jejunum, Ileum), Normal Flora of the stomach and small intestines (Few microorganisms, High acid, Rapid food movements, Essentially no normal flora), Large intestine (Colon; 100 million organisms/ gram feces; 40% fecal mass, Multiple species, Almost all anaerobes) • Identifying stool pathogens is very difficult due to multiple species being mixed within the sample

Most common isolates in stool normal flora

• Facultative Gram-negative rods • E. coli, Proteus, Citrobacter, Enterobacter, Klebsiella • Gram-positive cocci • Enterococci (No growth on MacConkey.)

Selective and Differential Media in Stool Cultures

Hecktoen- Enteric agar, MacConkey agar, Campylobacter agar , MacConkey sorbitol • Pathogens are non-lactose fermenters (can distinguish Salmonella from Shigellea.) • Normal flora are lactose fermenters. • Certain pathogens need special incubation conditions.

Terms to describe GI tract infections

Diarrhea, dysentery, gastroenteritis, enterocolitis

Bacterial Diseases of the Digestive Tract

Food intoxication (toxins cause symptoms. QUICK ONSET, typically 3-6 hours.)
Food infection (organisms cause symptoms, usually 24-48 hours.)

Staphylococcal Food Poisoning

Staphylococcus aureus; Enterotoxin-producing strains; Phage genes code for toxin; Superantigen.
Symptoms are associated with a strong immune response.
Usually self-limiting 24 hours

Foods at risk for Staph Food Poisoning

Cream-filled products, dairy, salads (esp. with mayo), ham, meat, and meat products
Bacteria can survive on food handler hands, nose, and skin; stable to heat/boiling

Staph Toxemia Diseases

Toxemia
Onset is quick: 3-6 hours
Nausea and vomiting
Emetic toxin- vomiting agent
Diarrhea, chills
Self-limiting: 24 hours

Staph Enterotoxin Virulence Factors

5 distinct enterotoxins commonly identified.
SEA, SEB, SEC, SED, SEE are frequently seen

Staph Intoxication Diagnosis

No detectible organism in food or stool, so the Staph enterotoxin must be tested
Stool culture (if organism).
Beta-hemolytic Golden Colored
Catalase +, Coagulase +

Staph Food Poisoning Treatment

Remove food
Treat the carrier
Often antibiotics are not helpful
Prevention: Proper food handling and refrigeration, control of infected food handlers.

AAD (Antibiotic-Associated Diarrhea)

Clostridium difficile (an anaerobe, gram-positive spore-former).
Opportunistic pathogen that is usually in low numbers in the gut, but can proliferate in the bowel following antibacterial treatment (superinfection).

AAD Disease

Disrupts normal gut flora causing pseudomembranous colitis
Nearly 100% due to C. difficile
Symptoms include severe diarrhea, bowel obstruction, and rarely death.
Often nosocomial (hospital setting).

AAD Virulence Factors

Toxin A – diarrhea
Toxin B – cytotoxin, destroys cells
Substance that inhibits bowel motility.

AAD Diagnosis

Anaerobic Culture
ELISA for Toxin A & B

AAD Treatment

Antibiotics (metronizadole) for anaerobes.

Bacillus cereus Food Poisoning

Bacillus cereus (gram-positive rod spore-former).
Caused by two different toxins, linked to meat and vegetables; linked to rice
Quick onset (typically within 6 hours), self-limiting.
May cause either diarrhea or nausea & vomiting.

Clostridium perfringens Food Poisoning

Clostridium perfringens (gram-positive rod spore-former).
Enterotoxin (associated with sporulation); Quick onset (self-limiting, 2-3 days).
Spores contaminate meat.
Problems only due to canning industry defects; toxin is polypeptide.
Spores often survive food processing, resulting in toxin production during subsequent growth within the food if the food is undercooked.

Vibrio cholerae Food Poisoning

Vibrio cholerae (gram-negative, curved rod).
Cholera toxin.
Causes severe watery diarrhea (1 liter/hour) and vomiting, but fatality rate has lessened with medical interventions.
Requires higher bacterial inoculum (1x10^8 bacteria.)
Can colonize crustaceans and seafood

Cholera Epidemiology

Commonly seen in Southern U.S. and requires a high inoculum.
Often found in brackish water.
Commonly found in food at restaurants (like sushi).

Cholera Toxin Virulence Factor

A-B subunit toxin
A subunit is the enzymatic active portion that ADP-ribosylates the host’s cellular protein, then changes intestinal cells into water-secreting cells: causing extreme water loss.
B subunit binds to the target cells.

Cholera Diagnosis

Characteristics of rice water stools.
Culture. (Detection of bacterial strains in the culture.)

Cholera Treatment

Fluid replacement therapy (oral rehydration).
Antibiotics (tetracycline)

Shigella Species

Shigella dysenteriae (gram-negative rod), uncommon in the US; international disease.
Severe bloody diarrhea. Rapid onset, and self-limiting course (3-5 days)
Toxins: heat-labile exotoxin, enterotoxin, endotoxin (LPS).

Salmonella Infection

Salmonella Enterica serotype (not Typhi) is a gram-negative rod, intracellular, and has 2000 serovars linked to animal infections.
Common symptoms include fever, abdominal cramps, and diarrhea.
Onset can occur 12-36 hours before symptoms, lasting 3-5 days
Bacteremia (occasional septicemia): bacteria entering the blood. May be shed for 6 months.

Salmonella Enterica Epidemiology

Contamination in various raw meats and eggs.
Inadequate heating during processing can allow bacteria to survive.

Salmonella Enterica Virulence Factors

Intracellular life
Attachment to cells.
Serotypes infect specific animals.

Salmonella Enterica Diagnosis

Culture using non-lactose-fermenting media (NLF) requiring MacConkey & Hektoen-Enteric agar.
Serotyping (by O antigen).
Susceptibility testing.

Pathogenic strains of Escherichia coli

Lactose fermenters; magenta-pink on lactose-MacConkey agar, orange-salmon on Hektoen-Enteric agar.
Includes strains EPEC, EIEC, EHEC, & ETEC.

Enteropathogenic E. coli (EPEC)

Infantile diarrhea—mild chronic disease
No toxins; intimately associated with the gut epithelium

Enteroinvasive strains (EIEC)

Contaminated food/water, in poor hygiene areas
Severely invades intestinal tissue; blood and mucus in the stool
Increased symptom severity (e.g. more severe than EPEC).

Enterohemorrhagic strains (EHEC)

Serious outbreaks frequently associated with shigella-like disease.
Produces Shiga toxin, a non-invasive toxin
O157:H7 strain.
Destroys epithelial lining (intimin).
Delivers Shiga toxin.
Hemolytic Uremic Syndrome (HUS; acute kidney failure)

How to Identify EHEC

Looks like normal flora E. coli.
Use special MacConkey sorbitol plate.
O157:H7 = Sorbitol Non-fermenter.

Hemolytic Uremic Syndrome

Inflammation of the colon (often preceding hemorrhagic colitis)
Kidney damage; destroys kidney function.

Enterotoxigenic E. coli (ETEC)

Cholera-like diseases, particularly common in travelers
Non-invasive cholera toxin.

Campylobacter Gastroenteritis

Campylobacter jejuni (curved gram-negative rods)
Microaerophilic (requires low oxygen concentrations for respiration).
Optimal temperature = 42°C.

Campylobacter Disease

Inflammatory bowel disease (e.g., gastroenteritis).
Abdominal pain, diarrhea, and dysentery.
Fever; Recovery in 1 week; can last months.

Campylobacter Epidemiology

Most common bacterial cause of gastroenteritis in people (U.S.).
2 million cases yearly
Animals & humans, specifically poultry and cattle
Via feces in milk or environment

Guillain-Barre Syndrome

20-40% incidence rate; temporary acute paralysis
Surface molecule of bacteria resembles nerve tissue lipid causing an autoimmune attack.
Possible death.

Campylobacter Diagnosis

Blood agar plus antibiotics to inhibit normal flora, incubate at 42°C.
Look for growth.
Part of routine stool culture.

Yersiniosis

Yersinia enterocolitica (gram-negative intracellular bacteria; grows at 4°C).
Diarrhea, fever, and headache are common.
Frequently misdiagnosed as appendicitis.

Helicobacter pylori

Curved gram-negative rod; potent urease enzyme.
Bacteria attach to stomach lining causing inflammation.
Chronic inflammatory disease (ulcers), some links to stomach cancer.

Helicobacter pylori Epidemiology

Common infection (30-50% of world population).
Can contribute to gastric & duodenal ulcers (15-20%).
Individuals with Type O blood type are more susceptible to its effects.
Emotional stress may also contribute to infection

Helicobacter pylori Treatment

Antibiotics
Bismuth (Pepto-Bismol) to halt ulceration; ulcers need to heal afterward.

Helicobacter pylori Diagnosis

Endoscopy (stomach biopsy-staining)

Listeria monocytogenes

Foodborne transmission (commonly in ground beef; chicken & turkey carcasses, lunch meat, hot dogs, and unpasteurized dairy).
Grows well in refrigerators.
Infection of the fetus.
Organism crosses the placenta causing a congenital infection of the fetus involving meningitis

Viral Causes of Digestive Diseases

• Mumps, • Rotavirus, • Norovirus, • Hepatitis A, • Hepatitis B, • Hepatitis C, • Hepatitis D (co-infections with HBV), Hepatitis E (HEV), Hepatitis F (HFV), Hepatitis G (HGV).

Parasitic Causes of Digestive Diseases

Common helminths (worms), such as Ascaris lumbricoides, Necator americanus (hookworm), Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), Diphyllobothrium latum (fish tapeworm/fish worm).
Symptoms can sometimes be subtle- few physical symptoms.
Sometimes eggs or parasite segments are found in stool, blood tests may show elevated eosinophils (a type of white blood cell).
Treatment can involve anti-helminthic drugs.

Respiratory Tract Review

• Barriers to infection • Normal flora of the lower respiratory tract • Bacterial causes of lower respiratory tract infections • Gram stain result • Epidemiology • Virulence factors • Viral causes of LRT disease and descriptions • Fungal causes of LRT disease

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Description

Test your knowledge of urinary tract infections, whooping cough, and influenza. This quiz covers symptoms, epidemiology, and characteristics of various infectious agents. Perfect for students studying microbiology or health sciences!