Transcript Final Case Study - Cal State LA

Case Study
Pathogenic Bacteriology
2009
Case 51
Anthony Obisesan
Tania Guevara
Edmund yeo
Case Summary
A 53 year-old man with non-insulin-dependent diabetes and hypertension presents
symptoms of fever, chills, and a cough with green sputum. Gram stain, blood
culture, biochemical test, chest x-ray were performed to identify the causative agent.
Streptococcus Pneumoniae was isolated and identified. This organism is by far the
most common cause of bacterial pneumonia, particularly in the elderly.
Key Information Pointing to Diagnosis
Degree of resistance to host:
Age: 53 year old
Gender: Male
Physical Health: Mellitus diabetes and Hypertension, 2 packs of cigarettes daily
for 40 years.
Symptoms: fatigue, fever, chills, dyspnea, left-sided pleuritic chest pain, and cough
with green sputum.
Gram Staining and blood culture to role out other organism
The Diagnosis for Case 51
•Based on the patient’s symptoms (green sputum) and
findings from physical examination (crackles in lung
fields) Pneumonia is suspected.
•Chest X-ray:
•Chest X-ray is typically used for diagnosis in
hospitals
•Right lower lobe, left lingular, and left lower
lobe infiltrates
One week into admission, there is
segmental infiltrate within right upper
lobe.
After 4 weeks in hospital, multiple
cavities with air-fluid level are seen in
right lung
Computed tomography of chest (lung
window) shows two large cavities with
air fluid level.
Diagnosis
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Blood Culture: Significant in ruling out other gram (+)
organism that cause pneumonia such as staph. aureus,
and strep. agalactiae an important cause of pneumonia
(especially in new borns).
Gram stain: Strep Pneumoniae present & Normal
Respiratory Flora
• High white blood cell count indicates the presence of an
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infection or inflammation.
staining: Gram (+)
Catalase (+)
Coagulase (-)
Staph Epidermidis Present, NF in upper respiratory tract.
Classification,Gram Stain Results, and
Microscopic Appearance of Streptococcus
Pneumoniae
• Classification: Streptococcus – a major cause of human infections.
They are untypable in the Lancefield classification which is based
on the antigenicity of a carbohydrate which is soluble in dilute acid
and called the C carbohydrate. They can, however, be subdivided
into more than 80 serological types on the basis of antigenic
differences in their capsular polysaccharide. For pneumococcal
pneumonia, 23 types are the cause of 90% of the case
Morphology and General Characteristics: a gram (+), aphahemolytic diplococcus, aerotolerant anaerobe.
Gram Stain Results: Gram positive diplococcus
Streptococcus pneumoniae Gram-stain of blood
broth culture. CDC
Diseases and Pathogenesis of Disease
Caused by Streptococcus Pneumoniae
Diseases: Lobar Pneumonia, meningitis, Otitis media, Septicemia, endocarditis and
so on.
In the elderly or in other individuals whose ciliary activity or respiratory
drainage is likely to be impaired the organism can reach its pathogenic site in
the lung and cause serious disease. Those most susceptible would be the
bedridden, heavy smokers, alcoholics, or individuals who had suffered a recent
respiratory viral infection or toxic damage to the mucociliary escalator..
Transmission: Person to person by direct inoculation from shared respiratory
equipment has been documented, other medical equipment might be cause to
infection, and transmission via HCW
Pathogenesis
Virulence Factors: The capsule of the pneumococci is its most
potent virulence factor.
•The antiphagocytic properties of the capsule allow the
pneumococci to grow in the lung. This results in an
inflammatory response in which fluid accumulates in the
lung.
Other virulence factors include: the cell wall; cholinebinding proteins; pneumococcal surface proteins A and C
(PspA and PspC); the LPXTG-anchored neuraminidase
proteins; hyaluronate lyase (Hyl); pneumococcal adhesion
and virulence A (PavA); enolase (Eno); pneumolysin;
autolysin A (LytA); and the metal-binding proteins
pneumococcal surface antigen A (PsaA), pneumococcal
iron acquisition A (PiaA) and pneumococcal iron uptake
A (PiuA).
Common Disease & Symptoms caused by
Streptococcus Pneumoniae
Septicemia
Fever
Hypotension
Acute
confusion
Chills
Dyspnea
Tachypnea
Headache
Tachycardia
Bacteremia
Pneumonia
Fever
Dyspnea
Lung
consolidation
Hemoptysis
chills
Chest pain
Cyanosis
malaise
Rust colored
sputum
Diagnosis/Isolation/Identification/ of
Streptococcus Pneumoniae
•Isolation: Isolation can be done on Columbia Blood Agar (CBA)
•Identification: Gram staining; Pneumococci are differentiated in
the laboratory from other alpha hemolytic streptococci by virtue of
their sensitivity to optichin. This is usually tested by means of an
impregnated disc, the P disk, placed on a lawn of the bacteria on a
blood agar plate, and sensitivity demonstrated by a zone of no
growth around the disc.
Test for Bile solubility also
Therapy, Prevention and Prognosis of
Patient Infected with Streptococcus
Pneumoniae
•Prevention: Vaccination is recommended for individuals over 10 years of age who are at risk; i.e.,
those with sickle cell disease, splenic malfunction, congestive heart failure, alcoholism, diabetes,
confinement in a nursing home.
•Sterilized hospital equipment and the use of personal safety equipment (gloves, gowns etc) by
healthcare worker will reduce transmission.
A recent disturbing finding is that about 25% of isolates of S. pneumoniae are now resistant to one
or more antibiotics. The penicillin resistance in this organism is usually not due to beta lactamase,
but rather to mutations in penicillin binding proteins. Sensitivity testing is necessary
Between 5 and 10 million people get pneumonia in the United States each year, and more than
1 million people are hospitalized due to the condition. As a result, pneumonia is the third
most frequent cause of hospitalizations (births are first, and heart disease is second). About
500,000 children are hospitalized for respiratory infections each year, and a third of them have
pneumonia. Although the majority of pneumonias respond well to treatment, the infection
kills 40,000 - 70,000 people each year.
Primary Research Article Contributing to
the Understanding of the Disease caused by
Streptococcus Pneumoniae
Kwan, S.K. et al, 2009, “Changes of serotype and genotype in Streptococcus pneumoniae
isolates from a Korean hospital in 2007”, Diagnostic Microbiology and Infectious Disease, vol
63: 271 - 278.
Experimental set up:
Capsular quellung method: To determine serotypes of Strep. pneumoniae (154
isolates) from sputum, blood, tracheal aspirate, nasal swab, and pus. 104 were
invasive
In vitro susceptibility testing was performed by broth microdilution (MIC). 8
antimicrobial agents were tested: penicillin, erythromycin, amoxixillin-clavulanate,
levofloxacin, ciprofloxacin, clarithromycin, clindamycin and trimethoprimsulfamethoxazole.
Multilocus sequence typing was performed to determine the genotypes of all isolates.
Erythromycin-resistant genes in isolates were determined by duplex PCR method.
Findings
New serotypes
found
Antimicrobial
Resistance in
isolates between
1998-2000 and
2007
Conclusion
Conclusion:
Helpful information on local vaccine serotype expansion
or replacement in Korea
Emergence of new serotypes with time
Resistance to antimicrobials
Changes in serotype and genotype in Streptococcus
pneumoniae is unfavorable to preventing pneumoniae
especially in hospital patients. With these changes,
resistant serotypes emerge and are a major threat to
human lives.
Take Home Message
Pneumonia is a common illness which occurs in all age groups, and is a leading cause of death among the elderly
and people who are chronically and terminally ill
Typical symptoms are fatigue, fever, chills, dyspnea, left-sided pleuritic chest pain, and cough with green sputum.
Pathogen is Streptococus pneumoniae, a gram (+), apha-hemolytic diplococcus, aerotolerant anaerobe
Diagnostics include test gram staining, optochin susceptibility & bile solubilty, blood culture, and X-ray
Therapy is based on vaccination, vaccination to prevent certain strains are available
Prognosis: with treatment, pneumonia can be cleared within two to four weeks. The eventual outcome of an
episode depends on how ill the person is when he or she is first diagnosed
•
Prevention is via vaccination for individuals over 10 years of age who are at risk; i.e., those with sickle cell disease,
splenic malfunction, congestive heart failure, alcoholism, diabetes, confinement in a nursing home.Sterilized
hospital equipment and the use of personal safety equipment (gloves, gowns etc) by healthcare worker will reduce
transmission
Transmission is via Person to person by direct inoculation from shared respiratory equipment has been
documented, other medical equipment might be cause to infection, and transmission via HCW
Threat is Changes in serotype and genotype in Streptococcus pneumoniae is unfavorable to preventing
pneumoniae especially in hospital patients. With these changes, resistant serotypes emerge and are a major
threat to human lives
References
Kwan, S.K. et al, 2009, “Changes of serotype and
genotype in Streptococcus pneumoniae isolates from a
Korean hospital in 2007”, Diagnostic Microbiology and
Infectious Disease, vol 63: 271 - 278.
http://www.cdc.gov/ncidod/biotech/strep/strepindex.
htm accessed on March 11, 2008
Point Spread
Case summary
5
Key Information pointing to Diagnosis
10
Diagnosis
5
Microbiology of Pathogen
10
Pathogenesis of the disease
10
Diagnostic tests
5
Therapy and Prognosis
5
Prevention
5
Epidemiology and threats
5
Primary research article (last 5 years)
20
Take home message
5
Are all questions addressed?
5
Appearance
5
Presentation skills (individual)
5
Total
100