Title: Study Aid
1Study Aid
- Microbiology Dr. Felton Part 1
2Viruses Assoc. W/ Common Cold
- More than 90 of URT infxns caused by viruses.
- 1) Rhinovirus
- 2) Coronavirus
- 3) Parainfluenza virus
- 4) Influenza virus
- 5) Respiratory Syncitial virus (RSV)
- 6) Adenovirus
3Rhinovirus
- 30 of colds in adults
- Small RNA viruses related to poliovirus
- Members of picornavirus
- Grow optimally at 33 degrees
- Virus multiplies in cytoplasm of host
- No Envelope
4Coronavirus
- ssRNA
- Round or petal shaped projections around capsid
resembling a crown - Lipid envelope
5Respiratory syncitial virus
- RNA
- Envelope
- 2 Antigenic types
- Infects infants children more often than it
does adults - Occasionally causes bronchopneumonia, bronchitis
- Belongs to paramyxovirus group
6Myxoviruses
- Orthomyxoviruses
- Influenza virus
- All 3 antigenic types cause influenza
- Mild illness that resembles colds can also result
7Myxoviruses
- Paramyxoviruses
- Parainfluenza virus
- 4 Antigenic types
- ssRNA
- Enveloped
- Major cause of viral laryngitis pharyngitis in
adults - PaRaMyxovirus Parainfluenza
RSV Mumps, Measles -
8Adenovirus
9Transmission of viruses that cause common colds
- Main source? young children
- Spread? mostly in home school
- Modes? Infectious secretions on skin
- Large particles of respiratory secretions
- Infectious droplet nuclei suspended in air
10Clinical characteristics of common cold
- Incubation period 48-72 hrs
- Sx. Run 5-7 days
- Complications are rare
11Diagnosis of common cold
- Pt. Self dx. Usually correct
- No way of differentiating etiology of cold
12Treatment of common cold
13Sinusitis
- Inflammation of one or more of paranasal sinuses
- Frontal
- Ethmoidal
- Sphenoidal
- Maxillary
14Sinusitis
- Acute sinusitis most often follows rhinitis
(viral) - Most common bacterial Strep Pneumoniae,
Haemophilus Influenza - Anaerobes, S. Aureus, S. Pyogenes also cause it
- Chronic sinusitis commonly assoc. with Anaerobic
bacteria - Infxn. Of Maxillary sinuses may follow dental
extractions
15Pathogenesis of sinusitis
- Obstruction impedes drainage
- Mucus converted into mucopus by bacterial
multiplication in sinus cavities - Pus also irritates underlying mucosa ? further
edema aggravating obstruction
16Epidemiology of sinusitis
- 0.5 of URT infxns. are complicated by acute
sinusitis - Sinusitis most prevalent in fall, winter, spring
- Summer ? swimming
- More common in adults than children
17Clinical Manifestations of sinusitis
- Pressure over a sinus? acute sinusitis
- Facial pain purulent nasal discharge most
constant - Photophobia tearing may be present
18Diagnosis of sinusitis
- Can be made w/o radiographic exam w/ history of
URT infxn or allergic rhinitis - Pain and tenderness over sinus
- Purulent discharge in the corresponding meatus
- Specific etiology only w/ culture of exudate, or
of a rinse by sinus puncture aspiration - Cultures from nasal pus or rinsing of nose
unreliable
19Treatment of sinusitis
- In most pt. Acute sinusitis responds well to
antimicrobial therapy
20Pharyngitis
- Mostly viral
- Caused by both viral bacterial
- Bacterial (15-30) Mostly Strep.
Pyogenes - Viral Impt. To differentiate btwn. Viral Bac.
- Strep. Pyogenes can cause Rheumatic Fever, Acute
Glomerulonephritis - Viral Rhinovirus
Coronavirus Adenovirus Herpes
simplex - Adenovirus and Herpes simplex are less common but
more serious
21Epidemiology of pharyngitis
- Mostly winter months
- Some with annual periods of peak prevalence?
Rhinovirus - Reservoir in humans
22Clinical Presentation Pharyngitis w/ common cold
- Mild to moderate pharyngitis discomfort
frequently present, but not primary complaint - Pharynx maybe normal or mild erythema or edema
- Rhinorrhea post-nasal discharge usually present
- NO pharyngeal pain!
- NO dysphagia!
- Subsides 3-4 days
23Pharyngitis w/ Influenza
- Sore throat major complaint
- Coryza (catarrhal inflamm.) sx. May be present
- Temp. elevation common
- NO Edema!
- NO Erythema!
- NO pharyngeal exudate!
- NO painful cervical adenopathy!
- Subsides 3-4 days
24Pharyngoconjunctival Fever
- Commonly caused by adenoviruses
- More severe than pharyngitis assoc. with common
cold - Temp. elevation 5-6 days
- Sore throat
- Conjunctivitis (adenoviral) 1/3 cases.
Follicular, bilateral - Cough, hoarseness, substernal pain occurs in
acute resp. disease in military recruits
25Adenovirus
- DNA
- Causes 3 types of resp. disease
- 1) Acute Febrile (self-limited)
- 2) Pharyngoconjunctival
- 3) Pertussis-like syndrome, indistinguishable
from infx. W/ Bordetella Pertussis (whooping
cough) - Major etiologic agent of acute resp. disease and
pharyngitis
26Acute Herpetic Pharyngits
- Primary infxn.w/ herpes simplex
- Presence of inflamm. exudate may mimic
full-blown Strep. Pharyngitis - Vesicles shallow ulcers of the palate are
characteristic of herpetic infxn. - Vesciles ulcers are present on the labial
buccal mucosa when there is an associated
gingivostomatitis
27HSV
- DNA
- Latent infxns.
- Recurrent fever blisters
- Lipid containing capsids inactivated by Ether!
28Herpangina
- Uncommon type of pharyngitis
- Coxsackieviruses
- Small vesicles on soft palate, uvula, ant.
Tonsillar pillars - Children severe, febrile illness w/ marked sore
throat dysphagia
29Coxsackieviruses
- Member of picornaviruses
- Causes
- Aseptic Meningitis
- Myocarditis
- URT infxns.
- Picornaviruses (PERCH)
- Poliovirus
- Echovirus
- Rhinovirus
- Coxsackievirus
- Hepatitis A
30Infectious Mono.
- EB virus (Herpesvirus family)
- dsDNA
- Fever
- Cervical adenopathy
- Splenomegaly, ½ cases
31Streptococcal Pharyngitis
- Pharyngeal pain
- Dysphagia
- 39.4 degrees or greater temp.
- Fiery red pharyngeal membrane, thick exudate
covers the post. Pharynx and tonsillar area - Tender, enlarged cervical nodes
- Strep. Pyogenes? Erythematous rash of scarlet
fever
32Anaerobic Pharyngitis
- Purulent exudate coats the membrane
- Foul odor of breath
- Abscess
- Pharyngeal pain severe
- Dysphagia
- Low grade fever
- Usually limited to one side
- When bilateral, partial obstruction of pharynx
occurs
33Gonococcal Pharyngitis
34Diphtheria
- NO pharyngeal discomfort!
- Low grade temp. elevation
35Mycoplasma Pneumonia
- Mild
- No distinguishing clinical features
- Characteristically causes
- Bronchitis
- Atypical Pneumonia
36Diagnosis of Pharyngitis
- Main goal Separate strep. Pharyngitis from
others. - Exudate may suggest Strep. Pharyngitis, Vincents
Angina, Pharyngoconjunctival fever, herpes
simplex, infectious mono - Small vesicles or ulcers suggests herepes simplex
infection or herpangina
37Diagnosis of Pharyngitis
- Neisseria Gonorrheae? Thayer Martin Agar
- Vincents Angina? Crystal Violet stained smear
- Diphtheria? Loefflers medium
- Infectious Mono? Specific serological tests
38Laryngitis, Epiglottitis, Laryngotracheobronchitis
- Acute inflammatory diseases of the upper airway
- Common hazard? obstruction of airway
- Grave in the very young
39Etiology
- Bacteria viruses
- Individually or combination
40Haemophilus Influenza
- Small, pleomorphic, Gram neg. rod
- Non-motile, non-sporulating, capsualted
- Aerobic or facultative
- Requires iron prtoporphyrin compound (X factor),
pyridine nucleotide (V factor) - Virulence assoc. with capsulation
- Six antigenic types (a ? f)
- Type b formerly acctd. for almost all serious
infections in humans - Intro of vaccine reduced frequency in young
children
41Haemophilus Influenza
- HaEMOPhilus
- Epiglottitis Felton relavent
- Meningitis
- Otitis Media
- Pneumonia Felton relavent
42Corynebacterium Diphtheria
- Larynx and pharynx classical sites for
localization of diphtheria infections
43Bordetella Pertussis
- Whooping cough special kind of bronchitis
primarily in un-immunized children - Small, ovoid, non-motile, non-sporeforming
- Gram Negative rod
- Fastidious requirement for growth
- Freshly isolated in phase I, virulent,
encapsulated, piliated, produces several toxins - Only phase I bacilli are suitable for prep. Of
vaccines
44Strep. Pneumonia
- Major cause of bac. Pneumonia in adults and
children - Frequently recovered from sputum of pts. W/
chronic bronchitis
45Parainfluenza Viruses
- Paramyxoviruses w/ binding sites for erythrocytes
- RNA core, Ether sensitive envelope
- Multiply in cytoplasm
- 4 types 1,2,3,4
- Types 1,2,3? Croup
- Types 1,3? Bronchitis, bronchopneumonia
- Types 1,3,4? Common cold, pharyngitis
46Influenza Viruses
- Typically cause lower resp. tract infxns both in
adults and children
47Respiratory syncitial virus
- Can cause croup
- Usually causes bronchiolitis or bronchopneumonia
in infants
48Acute Laryngitis
- Typically assoc. with common cold and influenzal
syndrome - Barking cough, hoarseness characteristic
complaints - Airway obstruction due to infxn of larynx and
tracheobronchial tree more common in young
children than in adults
49Diagnosis of acute laryngitis
- Clinical characteristics of illness
- Confirmed with exam of larynx
50Treatment of acute laryngitis
- Resting voice until hoarseness and aphonia have
subsided - Inhalation of moistened air (relief)
- No evidence of antimicrobial agents being useful!
51Epiglottitis
- Rapidly progressive cellulitis of epiglottis
adjacent structures - Frequency decreased dramatically since intro of
vaccine against Haemophilus influenza type b
52Clinical Manifestations of epiglottitis
- Typical pt. 2-4 y.o.
- 6-12 hr. history of fever dysphagia
- Sore throat most prominent sx in older children
and adults
53Diagnosis of epiglottitis
- Edematous cherry red epiglottis
- Lab leukocytosis, positive cultures of blood and
epiglottis evidence of pneumonia on CXR - Hib isolated in most pt.
- Hib occurs in up to 100 children w/ epiglottitis
54Treatment of epiglottitis
- Maintenance of adequate airway
- Control of infxn
- Blood epiglottis should be cultured, pt. should
begin IV antibiotic therapy against Hib
55Immunity to epiglottitis
- Episode of Hib epiglottitis usually results in
high levels of serum Ab to capsular polysacch. - 2nd cases of epiglottits extremely rare!
- Vaccine against Hib available!
56Croup
- Age specific viral infxn of upper lower resp.
tract. - Inflammation in subglottis area
- Dyspnea on inspiration
- Characteristic stridulous notes of croup
57Etiology of croup
- Variety of viral agents
- Occasionally Mycoplasma pneumonia
- Parainfluenza Type 1 - most common
- Parainfluenza Type 3 - 2nd most common
- Influenza A ? broader range of children with a
higher frequency of hospitalization tracheotomy.
58Epidemiology of croup
- Occurs mostly in children btwn. Ages 3 months 3
years - Peak 2nd yr of life
- More common among boys than girls
59Clinical Manifestations of croup
- Hoarseness, deepening, non-productive,
brassy-tone cough - Most children fever
- Resp. rate elevated
- Hallmark fluctuating course
60Diagnosis of croup
- Characteristic clinical picture
- Id of viral agent isolation in tissue culture
by one of the newer techniques
61Acute Bronchitis
- Inflammatory condition of tracheobronchial tree
- Usually assoc. w/ generalized resp. infxn.
- Most commonly - winter
62Etiology of acute bronchitis
- Common during influenza epidemics
- Rhinoviruses important cause
- Military recruits Adenovirus major cause
- Measles virus severe form of disease
- Mycoplasma pneumonia B. Pertussis nonviral
causes of severe acute bronchitis
63Clinical Manifestations of acute bronchitis
- Cough begins early, prominent as illness
progresses - Frequency duration of cough prolonged in cig.
Smokers - Adults Influenza virus, Adenovirus, M.
Pneumonia temp. elevation
64Diagnosis of acute bronchitis
- A diagnosis of exclusion
- Complete history info on exposure to toxic
substances and cigarette use
65Treatment of acute bronchitis
66Chronic Bronchitis
- Cough chronic, excessive secretion of mucus is
present in the tracheobronchial tree not due to
asthma or TB. - It is a clinical diagnosis!
- Coughed sputum 3 consecutive months for more
than 2 successive years
67Etiology of chronic bronchitis
- Causes not elucidated completely
- 3 factors important
- Cigarette smoking
- Infxn
- Inhalation of dust or fumes
68Epidemiology of chronic bronchitis
- 10-25 adults
- More common in men
- More common 40 y.o.
- Recurrent resp. infxns and persistent chronic
bronchitis might signal presence of
immunodeficiency
69Clinical Manifestations of chronic bronchitis
- Incessant cough
- Emphysema often present
- Pt. Tend to be obese!
70Relationship of chronic bronchitis to Bac. Infxn.
- Bac. Infxn does not appear to initiate disease.
- Bac. Significant in penetrating disease
- Pathogenic bac. Cultured in 82 pts.
- Chronic colonization of airways sputum w/
unencapsulated strains of H. Influenza or w/
pneumococci occurs in at least ½ of affected pts. - 25-50 acute exacerbations related to viral agents
71Bronchiolitis
- Acute lower resp. illness
- Viral
- Occur w/in 1st 2yrs of life
72Etiology of bronchiolitis
- Viruses
- Occasionally M. Pneumonia
- 87 of isolates
- RSV, Parainfluenza 13
- Adenoviruses
- Rhinoviruses
- M. Pneumonia
- In hospitalized cases, RSV even higher
73Epidemiology of bronchiolitis
- Definite seasonal pattern
- Mirrors pattern of RSV
- Peak attack rate 2-10 mths age
- Significant levels of hospital admission of
infants within 1st year of life esp. due to RSV
74Clinical Manifestations of bronchiolitis
- Coryza, cough herald onset
- Mild fever common
- Dehydration common from paroxysms of coughing,
may trigger vomiting - Acute course 3-7 days
75Diagnosis of bronchiolitis
- Clinical and epidemiologic findings
- Specific dx. - Viral isolation from a nasal wash
76Therapy of bronchiolitis
- Oxygen admin
- Supportive care
- Aerosolized ribavirin severe bronchiolitis due
to RSV - NO vaccine available!
77Influenza
- Acute, febrile disease
- Fever, malaise, headache, myalgia
- Uncomplicated case self limited
- Affected individuals recover completely within
a week
78Etiology of Influenza
- 3 Serotypes A, B, C
- Influenza A Pandemic Influenza
- Influenza B Localized epidemics
- Influenza C Sporadic Mild
- Pandemic An epidemic so widely spread that vast
numbers of people in different countries are
affected.
79Morphologic Characteristics of Influenza
- Enveloped virus
- Irregular shape
- Segmented genome w/ 8 pieces RNA
- 8 RNA? 8 mRNA? 8 proteins (structure)
- Surface projections or spikes
- Glycoproteins ?hemagglutinins (H) or
neuraminidases (N) - - determine antigenic subtypes of influenza
virus
80Hemagglutinins (HA)
- HA spike site of attachment of virus to host
cells to initiate infxn - HA one of major antigens of virus
- HA contains common (to subtypes) strain
specific antigens - HA Most frequently involved in antigenic
variation - Specific Ab to HA prevent initiation of infxn or
hemagglutination
81Neuraminidase (NA)
- Other important antigen of virus
- Contains antigens common to each subtype and
variation within a subtype
82Epidemiology of Influenza
- Antigenic variation
- Ability to change surface antigens
- Frequent w/ Influenza A
- Less frequent w/ Influenza B
- Not assoc. w/ Influenza C
- Involves only HA NA
- HA most important
- Antigenic variation? Antigenic drift or Antigenic
shift
83Antigenic Drift
- Minor changes frequently occur within an
influenza subtype - Every year or every few years
- HA H1,H2,H3
- NA N1, N2
- Antigenic drift results from mutation(s)
affecting the RNA segment coding for either HA or
NA, more commonly HA
84Antigenic Shift
- Herald pandemic influenza
- NEW viruses popn. has no immunity
- Mxn Genetic reassortment of genome segments
betwn. different strains of virus
85Clinical Manifestation of Influenza
- Incubation period 1-3 days
- Begins abruptly, fever 39-40 degrees
- Chills common
- Headaches severe
- Conjunctiva congested
- Sense of extreme prostration w/ myalgia
- Cough scantily productive
86Clinical Manifestations of Influenza
- If no complications fever abates in 3-4 days,
recovery complete w/in a week - Infants sx. mild, resemble common cold or URT
infxn - Old people pts. W/ underlying chronic resp.,
cardiovasc., metabolic, renal disease, pregnant
women, course of influenza may worsen rapidly - Pneumonia complicating influenza - secondary bac.
Infxn caused by - S. aureus, H. Influenza, S. pneumonia, or S.
pyogenes
87Immunity to Influenza
- Secretory Ab develop in resp tract
- Predominantly IgA
- Interferon freq. Detected
- Time of appearance of interferon
- improvement of sx. decrease in virus titers
88Immunity to Influenza
- Neutralizing, HA-inhibition (HAI), complement Ab
develop in serum of pts. - Development of anti-NA Ab parallels that of HAI
Ab. - HAI Neutralizing Ab persist for months years
with gradual decline - HLA restricted cytotoxic T lymphocytes also play
a role in recovery from influenza virus infxn
89Complications of Influenza
- Myocarditis or severe myositis occasionally
occurs - Myoglobinuria encephalopathy
- Postinfluenza asthenia pts. take weeks to
return to full activity - Reyes Syndrome Often fatal encephalopathy,
mostly
90Prevention of Influenza
- Vaccination principal method
- New strains causing disease around the world are
grown w/ attenuated older vaccine strains in eggs - Recombinants that grow to high yield and carry
the new HA and NA antigens are selected for use
in vaccines
91Pneumonia
- Inflammatory disease of pulmonary parenchyma
(functional part of organ). - Abnormal density CXR
- 50 of LRT infxns are bacterial in origin
92Acute Pneumonia Etiology
- Common Bacterial
- Strep. Pneumonia
- S. Aureus
- H. Influenza
- Anaerobic bac.
- Enterobacteriaceae
- P.Aeruginosa
- Legionella
93Etiology of Acute Pneumonia
- Common Viral - Children
- RSV
- Parainfluenza 1,2,3
- Influenza A
94Etiology of Acute Pneumonia
- Common viral adults
- Influenza A
- Influenza B
- Adenovirus 4,7 (military recruits)
- Others Fungal, Rickettsial, Bacteria-like,
Parasitic
95Diagnosis of Acute Pneumonia
- Good history
- Look for defects in host resistance predispose
pt. to pneumonia possible exposure to specific
pathogens
96Diagnosis of Acute Pneumonia
- Gram stain exam and culture of sputum mainstay
of eval. - Mucopurulent sputum most commonly with
bacterial pneumonias - Large s of epithelial cells reflect
contamination - Neutrophils indicate acute inflammation
- Gram stain helpful in selection of initial
antimicrobial therapy - Some cases transtracheal aspiration may be
necessary to id pathogen
97Pneumonia Syndromes
- Acute community-acquired pneumonia
- Pt. In mid 50s
- Midwinter or early spring
- Most pt. One or more chronic underlying diseases
- Majority due to
- S. pneumonia
- Others Legionella pneumophila, H. Influenza, S.
Aureus
98Aspiration Pneumonia
- Setting states of altered consciousness, normal
gag swallowing reflexes not present - Anaerobic bac. mostly seen
- Anaerobic bac. In combo with aerobes or
facultatives 2nd most seen
99Atypical Pneumonia Syndrome
- Symptom complex representing disease caused most
commonly by Mycoplasma - Age 5, adolescent, young adult greatest risk
- Others
- Parainfluenza virus
- EB Virus
- RSV
- Adenovirus
100Chronic Pneumonia
- Pulmonary parenchymal infectious or
non-infectious agent, present for weeks to months - Abnormal CXR
- Chronic or progressive pulmonary sx
101Etiology Chronic Pneumonia
- Mixed aerobic-anaerobic bac.
- Mycobacteria
- Fungi
- Protozoa
- Worms
- Non-infectious
- Neoplasia
- Sarcoidosis
- Vasculitis
- Chemicals
- Radiation
- Recurrent pulmonary infarction
- Fibrosing alveolitis
102Epidemiology of chronic pneumonia
- Elderly at higher risk
- Pt. With Diabetes or COPD at higher risk
- Sex likely to play role in determining occupation
or avocation ultimately likelihood of exposure
to certain infectious agents - Race of pt. maybe important
- Certain occupations hobbies suspicion
- Travelled?
- Drinks?
- Personal habits
103Legionnaires Disease
- Form of pneumonia discrete outbreaks or as
sporadic cases - 1st recognized American Legion Convention in
Philadelphia July 1976 - Only caused by Legionella pneumophilia
- Pontiac Fever acute resp. illness caused by
legionella but without pneumonia
104Etiology of Legionnaires Disease
- Fastidious
- Filamentous
- Flagellated
- Gram negative rod
- Isolated from lung or pleural fluid
- Legionella grown on charcoal-yeast extract or
supplemented Mueller-Hinton medium - Can be isolated from inoculated embryonated eggs
- 9 serogroups exists most clinical isolate?
serogroup 1
105Epidemiology of Legionnaires Disease
- Widely distributed in soil water
- Contaminated water systems
- Disease acquired by inhalation of aerosols
contaminated with organisms - Person to peron x-mission not documented!
- Attack rate for Legionnaires disease higher in
elderly, chronic lung disease, malignancies,
renal failure, immunosuppression - Cause 5,000-10,000 cases of pneumonia annually
in the U.S.
106Diagnosis of Legionnaires Disease
- Isolated from sputum using charcoal-yeast extract
agar, transtracheal aspirates used for culture - Detection of L. pneumophilia antigens in urine
- Most often indirect immunofluorescence detect
anti-Legionella Ab in pt. Serum - 4 fold or greater rise in titer ? diagnostic
107Prevention of Legionnaires Disease
- Hyperchlorination of cooling towers and potable
water ineffective - superheat and flush tx. Of water distribution
systems currently used - No vaccine available!
108Hantavirus Pulmonary Syndrome
- 1st found to cause resp infxn in 1993
- Prior to that, only known human disease caused by
Hantavirus was Koren hemorrhagic fever - 1st few cases seen in Navajo Indian population
- Now, 100 cases seen
- New strain called Sin Nombre
- Infxn begins with febrile prodrome? pulmonary
edema? hypotension/shock - Fatality 50
- Virus carried by deer mouse, and other rodents,
excretes virus in saliva, urine, feces
109Lung Abscesses
- Lung abscessNecrotizing Pneumonia
- Early manifestation pneumonia
- In absence of therapy? lung abscess
110Etiology Lung Abscess
- Similar to aspiration pneumonia
- Mixed anaerobic bacteria seen in most cases
- Fusobacterium nucleatum
- Bacteroides melaningenicus
- Peptostreptococci
- Microaerophilic streptococci
111Clinical Features Lung Abscess
- Cough - almost all pt.
- When abscess drains into bronchial tree
copious, foul-smelling sputum - Chest pain common
- Fever majority of pts.
112Diagnosis Lung Abscess
113Empyema
- Purulent inflammatory exudate of pleural cavity
that maybe acute or chronic - Most commonly direct spread of bronchopulmonary
infxns - Also, complication of thoracic surgery
114Etiology Empyema
- Most common Staph Aureus
- Various Gram negatives
- P. aeruginosa
- Klebsiella pneumonia
- E. coli
115Diagnosis Empyema
- Requires aspiration of pleural fluid
- Gram stain of pleural fluid
116Treatment Empyema
- Surgical drainage of purulent exudate
- Plus, antibiotics