Title | Microbiology - Osmosis micrbio notes |
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Course | General Microbiology |
Institution | Boston University |
Pages | 174 |
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Osmosis micrbio notes...
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NOTES PARAMYXOVIRUSES MICROBE OVERVIEW ▪ Paramyxoviruses: negative-sense singlestranded RNA virus family ▪ Natural hosts: humans, vertebrates, birds ▪ Replication: occurs in cytoplasm; exits by budding ▪ Transmission: air borne particles
▪ Viral structure: enveloped, linear genomes, spherical/pleomorphic ▪ Pathogenic paramyxoviruses: human parainfluenza virus (HPIV), measles, mumps, respiratory syncytial virus (RSV)
HUMAN PARAINFLUENZA VIRUSES (HPIV) osms.it/human-parainfluenza-viruses PATHOLOGY & CAUSES ▪ Croup (laryngotracheobronchitis): infection usually caused by HPIV ▪ Four distinct HPIV serotypes ▫ HPIV-1: croup ▫ HPIV-2: croup; upper, lower respiratory tract illnesses ▫ HPIV-3: bronchiolitis, pneumonia ▫ HPIV-4: infrequently detected ▪ Common respiratory distress cause (children) ▪ Viral infection → infiltration of histiocytes, lymphocytes, other white blood cells → airway inflammation, edema → upperairway obstruction → ↑ breathing work, barky cough, inspiratory stridor (turbulent, noisy airflow), vocal hoarseness
RISK FACTORS ▪ Age ▫ Six months to three years
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▪ Biologically-male to biologically-female ratio of 1.4:1 ▪ Previous intubation ▪ Hyperactive airways ▪ Congenital airway narrowing ▪ Late autumn (peak case onset)
COMPLICATIONS ▪ Respiratory failure ▪ Bacterial superinfection ▫ Pneumonia, bacterial tracheitis
SIGNS & SYMPTOMS ▪ Prodrome ▫ Upper respiratory tract infection symptoms (coryza, cough, mild fever) ▪ Acute onset: “barking” cough ▪ Inspiratory stridor; biphasic stridor (severe obstruction sign) ▪ Hoarseness
Chapter 87 Paramy ▪ Respiratory distress, ↑ breathing work (e.g. suprasternal, intercostal, subcostal retractions) ▪ Agitation ▪ Symptoms worse at night ▪ Asynchronous chest movement ▪ Severe: fatigue, hypoxia, hypercarbia
TREATMENT MEDICATIONS ▪ Corticosteroids; dexamethasone for antiinflammatory effects ▪ Nebulized epinephrine in moderate, severe croup; temporary airway obstruction relief
OTHER INTERVENTIONS
DIAGNOSIS
▪ Provide comfort, avoid child’s further distress
OTHER DIAGNOSTICS Westley score ▪ Severity classification ▪ Calculated on five factors ▫ Level of consciousness, cyanosis, stridor, air entry, retractions ▫ Score between 0–17 classifies case as mild, moderate, severe croup; impending respiratory failure
MEASLES VIRUS osms.it/measles PATHOLOGY & CAUSES ▪ A paramyxovirus that causes measles, a highly infectious illness ▫ Fever, cough, coryza, conjunctivitis, followed by exanthem ▪ Transmitted via person-to person contact, droplets → infects upper respiratory tract epithelial cells Clinical stages (four) ▪ Incubation ▫ 6–21 days ▫ Virus infects respiratory mucosa/ conjunctiva → local replication → lymphatic tissue spread → disseminates via blood circulation → first virema (infection of endothelial, epithelial, monocyte, macrophage cells) ▫ Usually asymptomatic ▪ Prodrome ▫ 2–4 days
▫ Onset of fever, malaise, anorexia, conjunctivitis, coryza, cough ▪ Exanthem ▫ Onset 2–4 days after fever ▫ Erythematous, maculopapular, blanching rash ▫ Begins on face → trunk → extremities ▪ Recovery ▫ Cough persists 1–2 weeks ▫ Immunity thought to be lifelong
RISK FACTORS ▪ ▪ ▪ ▪ ▪
Measles virus exposure Travel to measles-endemic areas No prior measles immunization Failed measles vaccine response Immunocompromised individuals: AIDS, lymphoma/other malignancy, T cellsuppressive medication
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COMPLICATIONS ▪ Secondary infection ▪ Diarrhea (most common) ▪ Pneumonia (most common children’s death cause) ▪ Otitis media (younger individuals) ▪ Encephalitis, acute disseminated encephalomyelitis, subacute sclerosing panencephalitis ▪ Subacute sclerosing panencephalitis
▪ Atypical measles ▫ Measles virus infection in individuals immunized with killed virus vaccine ▫ Higher, prolonged fever ▫ Dry cough, pleuritic chest pain may present
DIAGNOSIS ▪ Individual presenting with febrile rash, cough, coryza, conjunctivitis
SIGNS & SYMPTOMS LAB RESULTS ▪ Prodrome ▫ Fever onset, malaise, anorexia, conjunctivitis, coryza, cough ▪ Koplik’s spots on buccal mucosa (1–2 days before rash onset) ▫ Red spots on erythematous buccal mucosa ▫ Measles pathognomonic ▪ Maculopapular, blanching, erythematous rash (approx. 14 days after initial infection) ▫ Head → trunk → extremities ▪ Persistent cough after resolution ▪ Modified measles ▫ Measles infection in individual with existing measles immunity ▫ Milder symptoms
▪ Measles detection; one of following ▫ Enzyme-linked immunosorbent assay (ELISA): positive measles-specific IgM serology (most common) ▫ Measles IgG antibody: ↑ (between acute, convalescent titers) ▫ Reverse transcription polymerase chain reaction (PCR): measles virus RNA detection ▫ In culture: Measles virus isolation
TREATMENT MEDICATIONS ▪ Antipyretics, bacterial superinfection treatment
OTHER INTERVENTIONS
Figure 87.1 Koplik spots on the oral mucosa of an individual infected with the measles virus.
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▪ Respiratory support, fluids ▪ Vitamin A supplementation ▫ Vitamin A deficiency plays role in delayed recovery, complications ▪ Prevention ▫ No specific antiviral therapy ▫ MMR (measles, mumps, rubella) vaccine ▫ Infection control (airborne transmission precautions for four days after rash onset)
Chapter 87 Paramy
Figure 87.2 The histological appearance of the lungs of an individual with measles pneumonia. There are numerous giant cells, the nuclei of which display inclusions.
MUMPS VIRUS osms.it/mumps PATHOLOGY & CAUSES ▪ Causes mumps; largely preventable by vaccination ▫ Fever, headache, malaise, myalgia, anorexia; followed by parotitis ▪ Transmission ▫ Highly contagious ▫ Transmission via respiratory droplets, direct contact, contaminated fomites ▫ Viral shedding begins before symptoms onset ▪ Incubation period: 14–18 days ▪ Outbreaks: schools, military posts, camps, healthcare settings, workplaces ▪ Replication: occurs in upper respiratory tract epithelium → spread via lymphatics → viremia ▪ Lifelong post-infection immunity
COMPLICATIONS ▪ Orchitis/oophoritis, meningitis, encephalitis, pancreatitis, myocardial involvement, arthritis, deafness
SIGNS & SYMPTOMS ▪ Prodrome ▫ Fever, malaise, headache, myalgias, anorexia ▪ Parotitis ▫ Swelling, inflammation, tenderness of parotid gland(s) ▫ May obscure mandible angle ▫ Unilateral/bilateral ▫ Usually 48 hours after prodrome onset ▫ Commonly children 2–9 years old ▫ Stensen duct orifice: may be erythematous, enlarged ▪ Mastitis
RISK FACTORS ▪ Unvaccinated status, international travel, vaccine failure, immunosuppressed individuals, healthcare workers, closecontact
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DIAGNOSIS ▪ Diagnosis suspected in individuals with parotitis/other salivary gland swelling, orchitis/oophoritis with prodrome, mumps virus exposure
LAB RESULTS ▪ In parotitis setting, diagnosis established by detection of ▫ Mump virus RNA: reverse-transcription PCR (buccal/oral swab) ▫ Serum mumps IgM (may not be detectable until 5 days after symptom onset) ▪ Full blood count ▫ Leukocytosis may be seen ▪ Lumbar puncture indicated in suspected meningitis/encephalitis
TREATMENT ▪ No specific antiviral therapy
MEDICATIONS ▪ Analgesics, antipyretics, non-steroidal inflammatory agents (orchitis/oophoritis)
OTHER INTERVENTIONS ▪ Prevention ▫ Measles, mumps, rubella (MMR) vaccine ▫ Infection control (isolation with droplet precaution until parotid swelling resolved)
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Figure 87.3 Mumps virus causes parotitis, which presents as swelling at the angle of the jaw, widening the facial outline.
Chapter 87 Paramy
RESPIRATORY SYNCYTIAL VIRUS (RSV) osms.it/respiratory-syncytial-virus PATHOLOGY & CAUSES
SIGNS & SYMPTOMS
▪ Most common cause of bronchiolitis: viral infection of the lower respiratory tract, blockage of small airways (bronchioles) ▫ May also be caused by rhinovirus, influenza virus ▪ Terminal bronchiolar epithelial cell viral infection → lung epithelial cell damage/ destruction → small bronchi/bronchioles inflammation → edema, mucus production, inflammation → small airways/atelectasis obstruction ▪ Commonly: children < two years old ▪ Often preceded by upper respiratory tract infection symptoms; rhinorrhea, headache, mild fever
▪ Prodrome ▫ Upper respiratory tract infection (rhinitis, fever) ▪ Cough; tachypnea; expiratory wheeze; ↑ breathing work (nasal flaring, grunting, retractions); crackles heard on auscultation; cyanosis
DIAGNOSIS DIAGNOSTIC IMAGING Chest X-ray ▪ If differential diagnosis includes pneumonia
RISK FACTORS
OTHER DIAGNOSTICS
▪ Infants < 12 weeks old, November–May, prematurity, bronchopulmonary dysplasia/ other chronic lung disease history, tobacco smoke exposure, daycare attendance, impaired airway clearance/function (e.g. cystic fibrosis), congenital heart disease, immunodeficiency
Pulse oximetry ▪ ↓ oxygen saturation
COMPLICATIONS ▪ Bacterial pneumonia, apnea, respiratory failure, dehydration, aspiration pneumonia, asthma
TREATMENT MEDICATIONS ▪ Oral corticosteroids: prior wheeze history
OTHER INTERVENTIONS ▪ Supplemental oxygen, hydration, mechanical ventilation ▫ Respiratory symptoms peak on days 3–5, begin to resolve
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NOTES TOGAVIRUSES MICROBE OVERVIEW ▪ Pathogenic viruses in Togaviridae family ▪ Capsid symmetry: icosahedral ▪ RNA structure: linear, positive polarity
EASTERN EQUINE ENCEPHALITIS VIRUS (EEEV) osms.it/eastern-equine-encephalitis PATHOLOGY & CAUSES ▪ Highly pathogenic; causes central nervous system illness in humans, horses (equines) ▪ Genus: Alphavirus ▪ Spherical, approx. 69nm diameter (including glycoprotein spikes) ▪ Enveloped, single-stranded, positive-sense RNA genome ▪ Glycoproteins associated with neurovirulence, cellular apoptosis ▪ Potential bioterrorism agent use (aerosol route) ▪ Range ▫ Atlantic, Gulf-coast states in eastern USA ▪ Four lineages ▫ Group I: endemic in North America, Caribbean (causes most human disease) ▫ Groups IIA, IIB, III: primarily cause equine illness in Central, South America ▪ Viral life-cycle: wild birds, Culiseta melanura mosquito (enzootic vector) ▫ C. melanura rarely bites humans ▫ Human transmission requires other mosquito species (e.g. Aedes,
Coquillettidia, Culex) to bridge between infected birds, humans ▫ Infected mosquito bite → 4–10 day incubation period → prodromal period → neurological symptom development occurs rarely
RISK FACTORS ▪ Rural residence; living in/visiting woodland habitats, swampy areas ▪ Outdoor occupation/recreational activity
COMPLICATIONS ▪ Encephalitis; cerebral edema; coma; residual brain damage (mild–severe, esp. young children); death (some)
SIGNS & SYMPTOMS ▪ May be asymptomatic ▪ Prodromal period: high fever, headache, nausea, vomiting ▪ Neurologic presentation: cranial nerve palsy, seizure, stupor → coma ▪ Infants: fever, bulging fontanel, generalized flaccid/spastic paralysis
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DIAGNOSIS DIAGNOSTIC IMAGING
TREATMENT ▪ No specific treatment
MRI ▪ Focal lesions in basal ganglia, thalamus, brainstem
LAB RESULTS ▪ Leukocytosis; left shift ▪ Hyponatremia ▪ Serology ▫ IgM antibody presence ▪ Cerebrospinal fluid (CSF) examination ▪ Lymphocytic pleocytosis, ↑ neutrophils; ↑ protein; IgM antibodies (assay); virus isolation
MEDICATIONS ▪ Supportive: anticonvulsants, corticosteroids (↓ inflammation)
OTHER INTERVENTIONS ▪ Supportive: IV fluid, respiratory support, monitor intracranial pressure ▪ Prevention ▫ Insect repellent (DEET, picaridin, IR3535, oil of lemon eucalyptus) ▫ Protective clothing ▫ Vector control
OTHER DIAGNOSTICS Electroencephalography (EEG) ▪ Generalized slowing; disorganized pattern
RUBELLA VIRUS osms.it/rubella-virus PATHOLOGY & CAUSES ▪ Highly communicable virus → German measles ▪ Enveloped, positive-sense, single-stranded RNA virus ▪ Family: Togaviridae ▪ Genus: Rubivirus ▪ Three structural proteins ▫ C: capsid protein surrounding virion RNA ▫ E1, E2: glycosylated proteins forming transmembrane antigenic sites ▪ Humans are the only natural hosts ▪ Transmission: droplet inhalation/direct contact with infectious nasopharyngeal secretion ▪ Viral contact → 12–23 day incubation → nasopharyngeal cell, regional lymph
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node viral replication → viremia → maculopapular rash eruption → rash resolution (approx. two days) ▫ Contagious via virus shedding before, after rash appears ▫ ↑ contagiousness during rash eruption ▪ Spreads transplacentally
RISK FACTORS ▪ Unvaccinated ▪ Travel (especially abroad) ▪ Contact with febrile rash individuals
COMPLICATIONS ▪ Thrombocytopenic purpura ▪ Encephalitis (rare) ▪ If infected during pregnancy: congenital rubella syndrome (CRS)
Chapter 101 To ▫ ↑ risk of miscarriage, fetal death, stillbirth ▫ CRS: A ToRCHeS (see mnemonic) infection; ↑ first trimester risk; extramedullary hematopoiesis (“blueberry muffin” rash), cataract, heart defect, hearing impairment, intellectual disability
MNEMONIC: ToRCHeS Perinatal infections passed from mother to child Toxoplasmosis, toxoplasma gondii Other infections Rubella Cytomegalovirus Herpes Simplex virus-2/ neonatal herpes simplex
SIGNS & SYMPTOMS
▫ Reverse transcription-PCR (rubella virus RNA performed on amniotic fluid)
OTHER DIAGNOSTICS ▪ Clinical diagnosis ▪ High suspicion index ▫ Febrile rash, unvaccinated status
TREATMENT ▪ No specific antiviral therapy
OTHER INTERVENTIONS ▪ Infection control measures ▫ Prompt isolation for seven days after rash development ▪ Vaccine: live-attenuated measles-mumpsrubella (MMR)/measles-mumps-rubellavaricella (MMRV) ▫ First dose: 12–15 months old ▫ Second dose: 4–6 years old
▪ Maculopapular rash ▫ Pink/light red macules: coalesce to form evenly-colored desquamating rash ▫ Initially: face → generalized rash within 24 hours ▫ Duration: three days ▪ Lymphadenopathy; primarily posterior auricular/suboccipital lymph ▪ Low-grade fever ▪ Mild nonexudative conjunctivitis ▪ Forchheimer spots on soft palate ▪ Arthralgias ▪ Orchitis ▪ Asymptomatic (half of cases)
DIAGNOSIS LAB RESULTS ▪ Polymerase chain reaction (PCR) testing/ molecular typing ▫ Throat, nasal, urine specimens ▪ Serologic testing ▫ Enzyme immunoassay (EIA) detects rubella-specific IgM antibodies ▪ Pregnancy
Figure 101.1 A child with rubella showing a characteristic maculopapular, erythematous rash.
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WESTERN EQUINE ENCEPHALITIS VIRUS (WEE) osms.it/western-equine-encephalitis PATHOLOGY & CAUSES ▪ Causes central nervous system illness in humans, horses (equines) ▪ Genus Alphavirus ▪ Spherical, approx. 69nm diameter (including glycoprotein spikes) ▪ Enveloped, single-stranded, positive-sense RNA genome ▪ Contain glycoproteins associated with neurovirulence, cellular apoptosis ▪ Range: most commonly US states, Canadian provinces west of Mississippi River ▪ Virus life-cycle: wild birds, other vertebrates, Culex tarsalis mosquito (enzootic vector) ▫ Culex tarsalis (another human vector) ▪ Potential bioterrorism agent use (aerosol route) ▪ Infected mosquito bite → 2–10 day incubation period → sudden onset of severe headache, fever/chills, dizziness, chills, myalgias, malaise, tremor, irritability, photophobia, neck stiffness → rapid neurological manifestation development → recovery ▫ Most adults: no residual neurological effects ▫ Infants, children: ↑ long-term neurologic sequelae risk
RISK FACTORS ▪ Most cases June–September ▪ Bimodal age pattern: < one year; ↑ risk in elderly ▪ Biologically-female ▪ Rural residence ▪ Outdoor occupation/recreational activity
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COMPLICATIONS ▪ Encephalitis, coma, respiratory failure, death ▪ Infants: intellectual disability, cerebellar damage, spastic paralysis, developmental delay
SIGNS & SYMPTOMS ▪ Neurological manifestations ▫ Generalized weakness; somnolence; hand, tongue, lip tremor; cranial nerve palsy; motor weakness; ↓ deep tendon reflexes ▪ Infants: poor feeding, fussiness, fever, vomiting, tense/bulging fontanelle
DIAGNOSIS LAB RESULTS ▪ Serology ▫ Enzyme-linked immunosorbent assay (ELISA): IgM antibodies ▫ Hemagglutination-inhibition, neutralizing antibody presence ▪ CSF ▫ ELISA: IgM antibodies ▫ Lymphocytic pleocytosis ▫ ↑ protein
TREATMENT ▪ No specific treatment
MEDICATIONS ▪ Supportive: anticonvulsants, corticosteroids
Chapter 101 To
OTHER INTERVENTIONS Prevention ▪ Insect repellent (DEET, picaridin, IR3535, oil of lemon eucalyptus) ▪ Protective clothing ▪ Vector control
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NOTES TRICHOMONA MICROBE OVERVIEW ▪ Trichomonas vaginalis: pear-shaped (pyriform), flagellated protozoa; infects genitourinary tract ▪ Causative agent of trichomoniasis (trich), common sexually transmitted disease (STD) Morphology ▪ Size ▫ 9 x 7 micrometers ▪ Motile via four flagella, undulating membrane
▪ Rigid axostyle runs through cell from anterior to posterior end ▪ Contains hydrogenosomes (unique energyproducing organelles) Replication/Multiplication ▪ Humans only host ▫ Does not survive well in external environments ▫ Multiplies when vaginal pH basic ▫ Incubation period: 5–28 days ▫ No cyst stage
TRICHOMONAS VAGINALIS osms.it/trichomonas-vaginalis PATHOLOGY & CAUSES ▪ Resides in lower genital tract of individuals who are biologically female; urethra, prostate of individuals who are biologically male → trophozoite stage (infective stage) → transmitted sexually → infects squamous epithelium of lower genital tract → replicates by longitudinal binary fission → inflammatory response
RISK FACTORS ▪ Sexual activity with infected partner ▪ Multiple sexual partners ▪ More common in individuals who are biologically female
COMPLICATIONS ▪ ↑ risk of contracting HIV due to genital inflammation
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▪ Pregnancy ▫ ↑ risk of premature rupture of membranes, preterm delivery, low birth weight ▪ Urethritis, cystitis
SIGNS & SYMPTOMS ▪ May be asymptomatic ▪ Individuals who are biologically female ▫ Watery, foul-smelling vaginal discharge; burning; pruritus; dysuria, urinary frequency; lower abdominal pain; dyspareunia; vulvar, vaginal erythema ▪ Individuals who are biologically male ▫ Urethral discharge; pruritus; burning after urination/ ejaculation
Chapter 103 Tri
DIAGNOSIS LAB RESULTS Microbe identification ▪ Saline microscopy (wet mount of genital secretions) ▫ Characteristic organism ▫ ↑ polymorphonuclear leukocytes ▪ ↑ vaginal pH (> 4.5) ▪ T. vaginalis assay ▫ Detects species-specific ribonucleic acid (RNA); vaginal swab/urine specimen ▪ Nucleic acid amplification testing (NAAT) ▪ Trichomonas rapid test
TREATMENT MEDICATIONS ▪ Systemic 5-nitroimidazole drugs (e.g. metronidazole, tinidazole) ▫ Treat both partners
OTHER INTERVENTIONS ▪ Rate of transmission decreased with consistent use of condoms, spermicidal agents (e.g. nonoxynol-9)
OTHER DIAGNOSTICS ▪ Speculum exam ▫ Punctate hemorrhages cervix (strawberry cervix)
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NOTES TRYPANOSOMA GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Genus of flagellated parasitic protozoa Morphology ▪ Elongated body ▪ Flagellum: forms undulated membrane along body ▪ Kinetoplast: functions as mitochondrion Transmission ▪ Through vectors ▪ Incubation period: 1–2 weeks
DIAGNOSIS ▪ ▪ ▪ ▪
Direct microscopy Serologi...