Unit 3 Microbes

AIDS and HIV

HIV: enveloped retrovirus, infects helper T cells, unique viral enzymes, GP-120 protein

Reverse transcripts RNA —> DNA

Intergrase: Viral DNA permanently integrated into host genome

-Results in AIDS (Acquired Immodefincey Syndrome) (depletion of Helper T-cells from HIV

Soft tissue infection (MRSA): S.aureus

Common cause of skin lesions in non hospitalized people

S. Aureus: gram positive cocci, nonmotile, highly virulent but also part of normal biota, highly resistant, salt tolerant, can survive extreme pH, high temps, and antimicrobials

-Virulence factors: coagulase, DNase, Lipase, can digest connective tissue and blood clots

-Diagnosis: PCR, blood agar/MSA, catalase, coagulase

-Signs/symptoms: redness, swelling, pain, pus formation (very contagious through surface contaminants)

Impetigo (S.pyogenes and S.aureus)

A highly contagious skin infection caused by bacteria, often seen in children. Symptoms include red sores, blisters, and honey-colored crusts.

-Caused by S.aureus and S.pyogenes

Signs: peeling skin, crusty/flaking, lesions around face mouth and nose. It can spread through direct contact or contaminated objects.

Maculopapular rash

Maculopapular: rashes with skin eruptions of flat to slightly raised colored bumps (measles, rubella, fifth disease, roseola)

Tineas (ringworm)

A fungal skin infection caused by dermatophytes, characterized by ring-shaped, red, itchy patches on the skin or scalp or other parts of the body

(dermatophytes: colonize skin and digest keratin)

Conjunctivitis (bacterial and viral)

Infection by microbes into the conjunctiva (eye)

-normal eye defenses: tears, lids/lashes, lysozyme

Signs: milky discharge around the eye, redness, irritation, and swelling

Common causes: (bacterial) S.epidermis, S.pyogenes, S.pnemoniae

(viral) Adenoviruses

Keratitis (HSV-1)

A viral infection of the cornea caused by the herpes simplex virus type 1, leading to symptoms such as eye pain, redness, and possible vision loss.

-leading cause of blindness by herpes

Septicemia (sepsis)

A serious bloodstream infection caused by bacteria or their toxins, leading to systemic inflammatory response and potentially septic shock.

Causative agents: MRSA, Gram + and - bacteria, gram - release endotoxin (toxic shock)

-Can be traced to IV lines and surgery

20-50% mortality rate

Signs: fever, chills, low BP (most dangerous symptom)

Treated with broad spectrum antibiotics

Endocarditis

Inflammation of the endocardium

Subacute and acute

Signs: fever, fatigue, joint pain, edema of lower body, abnormal heartbeat, anemia and petechiae

Acute: occurs suddenly, transmits from direct entry or lots of bacteria, caused by S.aureus, S.pyogenes, S.pneumoniae

Subacute: occurs from low pathogenicity bacteria in minor cuts (oral) entering from previously damaged or malformed heart valves, caused by Alpha-hemolytic streptococci

Treatment: surgery, antibiotics (long around 6 weeks)

Malaria (plasmodium)

A life-threatening disease transmitted by Anopheles mosquitoes, caused by the Plasmodium parasites.

Symptoms include fever, chills, and flu-like illness, and it can lead to severe complications if untreated.

10-16 day incubation

Plague (Yersinia pestis)

A highly infectious disease caused by the Yersinia pestis bacterium, primarily transmitted through fleas from rodents.

Symptoms include fever, weakness, and swollen lymph nodes (buboes), and it can lead to septicemia and pneumonia if untreated.

Yersinia pesitis: small, gram negative rods, member of enterbacteriaceae family, lots of virulence factors, infectious dose is 3-50 cells with a 15-100% mortality rate

Pharyngitis

An inflammation of the throat, often due to viral or bacterial infections, characterized by sore throat, fever, and difficulty swallowing (sore throat)

Signs: pain and inflammation of throat, reddened mucosa, swollen tonsils

40-60% caused by viruses

Bacteria make up severe cases: S.pyogenes and F.necrophrum

Diagnosis: rapid strep test, blood agar

Treated with penicillian and cephalexin

Pneumonia

A respiratory condition characterized by inflammation of the air sacs in one or both lungs, typically caused by infections from viruses, bacteria, or fungi.

Symptoms include cough, fever, chills, and difficulty breathing.

Healthcare-acquired pneumonia is most commonly associated with mechanical ventilation (MRSA and gram negative bacteria)

Influenza

A contagious respiratory illness caused by influenza viruses, leading to symptoms like fever, cough, body aches, and fatigue. It can result in severe illness and complications, especially in vulnerable populations.

Signs: begins in upper respiratory tract, headaches, chills, dry cough, fever, aches, stuffy nose and sore throat

-Causes secondary infections (can lead to pnemonia)

Tuberculosis

An infectious disease caused by the bacterium Mycobacterium tuberculosis, primarily affecting the lungs and characterized by chronic cough, fever, night sweats, and weight loss. It is transmitted through airborne particles and can result in serious health complications if left untreated.

Acute diarrhea

Episode of diarrhea caused by microorganisms that lasts less thank 2 weeks

Signs: fever, abdominal pain, cramping, nausea, vomiting, dehydration

1/3 cases in USA are caused by foodborne illness

Food poisoning

A type of foodborne illness caused by consuming contaminated food or beverages, leading to symptoms such as nausea, vomiting, diarrhea, and abdominal pain, often resolving within a few days.

Common causes: S.aureus, B.cereus, C.perfringenes

Hepatitis

An inflammatory condition of the liver often caused by viral infections, alcohol consumption, or toxins.

Symptoms may include jaundice, fatigue, abdominal pain, and liver dysfunction.

Causes: Hepatitis A,B,C,D,E viruses

Lyme disease

A tick-borne illness caused by the bacterium Borrelia burgdorferi, resulting in symptoms such as fever, headache, fatigue, and a characteristic skin rash.

Signs: “bulls-eye rash” (only in 10-20% of cases)

First stage: stiff neck, fever, headache

Second: cardiac and neurological symptoms

Third: arthritis and chronic neurological disabilities

Borrelia Burgforferi: large, gram negative spirochete, can evade immune system, transmitted by ticks of genus lxodes

Cholera

A highly infectious disease caused by ingesting water or food contaminated with the bacterium Vibrio cholerae, leading to severe diarrhea and dehydration. It can result in death if not treated promptly.

Strepotococcus pyogenes

Gram positive cocci

Beta-hemolytic

Common cause of impetigo in newborns

Measles virus

A highly contagious virus that causes measles, characterized by a red rash, fever, and respiratory symptoms. It can lead to serious complications, especially in young children.

-One of most contagious diseases

-Transmitted by respiratory droplets

Signs: sore throat, dry cough, headache, conjuntivitis, fever, oral lesions and really bad cases can lead to brain damage

Influenza virus

Influenza A, B, C

Enveloped virus

Glycoproteins (HXNX) which can result in variations of the virus

Antigenic drift: gradual changes in virus antigens over time, reduces host memory

Antigenic shift: major genetic change, can lead to pandemics.

Mycobacterium tuberculosis

Acid fast, bacillus shaped

Mycolic acids

Strict anaerobe

Very slow growing

Waxy cell wall, resistant to drying and disinfectants, slow growth aids in antibiotic resistance

Clostridiodes difficile (C.diff)

A gram-positive, spore-forming bacterium that causes antibiotic-associated diarrhea and colitis. It often emerges after the use of antibiotics and can produce toxins leading to inflammation of the colon.

-opportunistic pathogen

Rotavirus

Double stranded RNA virus

Fecal-oral transmission

Usually mild, but dangerous in newborns

Norovirus

Second most common cause of hospitalization from food borne illness

Fecal-oral transmission

Common cause of illness on cruise ships

Chronic diarrhea

Persistent diarrhea lasting more than four weeks, often due to infections, chronic diseases, or digestive disorders.

Cause can be both infectious and noninfectious

IBS and ulcerative colitis

Common causes: E.coli (EAEC), Giardia, Cyclospora

Enteroagressive E.coli

One of most common causes of chronic diarrhea

Can adhere to human cells and produce toxins that disrupt intestinal function

Stimulates secretion of high amounts of mucus

Hepatitis A and E

ssRNA, non enveloped viruses

Fecal oral transmission

Poor personal hygiene and public health measures

Prevention: vaccine and good hygiene (no treatment avaliable)

Hepatitis B and D

Both are enveloped viruses that can cause liver disease.

Hepatitis B is transmitted through blood and bodily fluids

Hepatitis D requires the presence of Hepatitis B for infection

Can be serious/life threatening (chronic liver disease)

Prevention: HBV vaccine

Hepatitis C

enveloped RNA virus

“silent epidemic”

Symptoms take years to develop

HCV is common cause of liver failure

Transmission similar to HBV

No vaccine avaliable