Body Sites: Blood and Respiratory

1:10

The traditional blood-to-broth ratio used to reduce the bactericidal effects of serum in adults is what?

collecting the recommended volume of blood in a 24hr period

What variable is crucial in ensuring a high sensitivity of blood cultures?

there has bee a decrease or lapse in proper antiseptic blood culture collection technique

Rates of Staphylococcus epidermidis isolated in blood cultures for the past month on average 4x higher than pervious months. What is the best explanation for increase in isolates?

Granulicatella or Abitrophia (Nutritionally Variant Strep)

A MLS noted tiny white colonies on CHOC and no growth on BAP of a blood culture at 24hrs. The positive blood smear was reported out as gram-positive cocci in chains. What organisms are most consistent with this pattern of growth and gram-stain?

reject the specimen for culture & call the patient care team to request a new specimen

A sputum was received for culture, the direct smear was performed.

Based on the representative field shown, the MLS should do what?

S. pneumoniae and H. influenzae

Which organisms are most frequently isolated form middle ear culture of individual with otitis media?

Pneumocysis jirovecii

Which organism most commonly causes an opportunistic infection in patients with HIV/AIDS?

culture on buffered charcoal yeast extract agar

A bronchoscopy sample with request for culture Legionella is sent to the lab. What is the correct plating protocol?

Butyrate esterase

An elderly patient presents to the ER with difficulty breathing

Blood count: shows an elevated WBC count with increased segmented neutrophils

Sputum gram stain: reported to contain a large amount of WBCs and a large amount of gram-negative diplocci

Plate: white, shiny colony that scoots across the agar like a hockey puck

What test could be utilized to obtain an identity for the organism?

Microdase

A positive blood culture shows a very yellow colony on the BAP. The gram stain reveals gram-positive cocci in tetrads and clusters. Catalase is positive & Coagulase is negative (slide & tube).

What is the most appropriate next test for this organism?

true

True or False:

Very high WBC counts can lead to false-positive blood cultures

5-7 days

For how long should routine blood culture bottles be incubated on an automated blood culture instrument?

false

True or False:

Acute bronchitis is most commonly bacterial in origin

NAAT

What is the most common method of testing for Mycoplasma pneumonia, Bordetella pertussis and Chlamydia pneumoniae?

72 hours

How long should we incubate and examine routine lower respiratory cultures?

Streptococcus pyogenes

What is the most common cause of bacterial pharyngitis?

beta-lactam

A PCR respiratory panel was run on a NP specimen from a 17 year old female and was positive for Mycoplasma pneumoniae. Which class of antibiotic would NOT be effective to treat the infection?

**hint: Mycoplasma's do not have cell walls

Bronchoalveolar lavage (BAL)

A quantitative lower respiratory culture can be performed off of what type of specimen?

true

True or False:

Streptococcus pneumoniae is the most common cause of community acquired pneumonia in adults

BAP, CHOC, MAC

Which media would be most appropriate for a lower respiratory culture?

CO2

For lower respiratory cultures, where do we incubate BAP and CHOC?

ambient air

For lower respiratory cultures, where do we incubate MAC?

small, round, tan-brown colonies

Which is the best description of the colony morphology of Haemophilus influenzae on CHOC agar?

Optochin & Bile Solubility

What are the best 2 tests to differentiate Streptococcus pneumoniae and Viridans Streptococci?

improper antiseptic technique during collection led to contamination of the aerobic bottle from 1629

A patient arrived in the ER 4/20/26 and 2 blood cultures were collected: one set at 1629 & another set at 1632

Only the aerobic bottle from the set at 1629 flagged as positive by day 5 of incubation

The blood smear from the aerobic bottle showed diphtheroids.

What is the best interpretation of this result?

Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae

What are 3 common causes of Ventilator Associated Pneumonia?

gram-negative coccobacilli

What is the gram stain of Haemophilus influenzae?

Intravascular

Begins in the blood, continuous -- Primary Source

- Acute infective endocarditis

- Subacute endocarditis

- Intravenous catheters

Acute infective endocarditis

Subacute endocarditis

Intravenous cartheters

What are the 3 intravascular infections seen in Bacteremia?

Staph aureus, Strep pyogenes, Step pneumoniae

Intravascular Bacteremia

What organisms are responsible for Acute Infective Endocarditis?

- Rapid on set of disease with severe symptoms

viridans group Strep, HACEK group, CNS

Intravascular Bacteremia

What organisms are responsible for Subacute endocarditis?

- Slower progressing infection

Staph spp (attach well to catheters)

Enterococcus & Yeast

Intravascular Bacteremia

What organisms are responsible for Intravenous catheters?

- Directly entry into bloodstream

Extravascular

Enter blood from another source (typically lymphatic system) -- Secondary Source

- Pneumonia

- Urogenital tract (Kidneys)

- Intraabdominal

- Skin (agents that cause cellulitis, decubitus ulcers, burns)

Strep pneumo, Staph aureus, Pseudomonas, Klebsiella, Enterobacter

Extravascular Bacteremia

What organisms are responsible for Pneumonia?

E coli

Extravascular Bacteremia

What organisms are responsible for UTIs?

E coli, Klebsiella, Enterococcus

Extravascular Bacteremia

What organisms are responsible for Intraabdominal infections?

Septicemia

Constant & multiplying bacteria in the blood and harmful effect bacteria produce

Systemic Inflammatory Response Syndrome (SIRS)

The systemic response to an infectious or noninfectious trigger

Criteria for SIRS

Must include 2 of the following:

Temperature: >38C or <38C

Heart Rate: >90bpm

Respiratory Rate: >20 breath/min or pCO2 <32mmHg

WBC count: >12,000/uL or <4,000/uL

Sepsis

Infection with SIR

Hypotension

Systolic <90mmHg

Arterial <70mmHg or reduction of >40mmHg from baseline

Severe sepsis

Sepsis with organ dysfunction, hypoperfusion or hypotension

Septic shock

Sepsis with hypotension despite adequate treatment (IV fluids, vasopressors)

Lab Signs of Septicemia

C-reactive protein (CRP)

Procalcitonin

Lactic Acid (Lactate)

Monocyte Distribution Width

C-reactive protein (CRP)

Lab Signs of Septicemia

Synthesized in the liver -- marker of inflammation& tissue damage

Sensitive but not specific

Procalcitonin

Lab Signs of Septicemia

Often produced by cells in response to bacterial infection

Normally, gets converted to calcitonin so our levels are almost undetectable

During serious infection, a different pathway is followed leaving it being released into the blood

Lactic Acid (Lactate)

Lab Signs of Septicemia

Increased levels can indicate lack of O2 causing acid/base imbalance in the body

Increase often seen in sepsis

Fungemia

Nonbacterial Etiologic Agents of BSI

Fungi

- Candida spp

Parasitemia

Nonbacterial Etiologic Agents of BSI

Parasites

- Plasmodium, Trypanosoma, Babesia

Viremia

Nonbacterial Etiologic Agents of BSI

Viruses

- Epstein-Barr virus, cytomegalovirus, HIV

1. Cleanse skin with chlorhexidine & scrub for 1 min

2. Let skin sit for 1 min

3. Draw aerobic bottle, then draw anaerobic bottle

What are the steps for blood culture collections?

Nutrient broth

Anticoagulant (SPS)

Resin Beads

Blood culture bottles used are dependent on automated system being used but all contain what 3 things?

for growth

What is the purpose of the nutrient broth in blood culture bottles?

prevents coagulation & traps bacteria

What is the purpose of the anticoagulant (SPS) in blood culture bottles?

inactivate antimicrobials

What is the purpose of the resin beads in blood culture bottles?

8-10mL

For an adult blood culture, how much blood is collected?

1-5mL

For a pediatric blood culture, how much blood is collected?

automated

Blood culture bottles are most commonly incubated where?

5-7 days at 35-37C

How do we manually incubate blood cultures?

How long & at what temp?

gram-stain

Once growth is detected in a blood culture (positive), what do we do next?

true

True or False

A positive gram-stained smear from a blood bottle is a critical value

BAP, ABAP, CHOC

What media is set up based on gram stain result for a blood culture?

3%

Contamination rates in blood cultures should be kept below what percent?

improper antiseptic technique

Contamination of blood cultures is most commonly due to what?

Bacillus, Corynebacterium, Cutibacterium acnes, Micrococcus

What are 4 likely contaminants seen in 1 out of several blood culture bottles?

Likely Pathogen

Growth of same organisms in multiple blood culture sets

Growth of organisms not considered part of normal skin flora

Growth of blood culture organisms matches organism causing primary infection or is consistent with clinical presentation

Upper and Lower

Respiratory Cultures are separated based on what?

Upper Respiratory

Abundant normal flora

Consists of: Throat, Nasopharynx, Mouth, Sinuses/Ear

Lower Resipratory

Sterile Sites

Consists of: Trachea, Bronchi, Lungs

Respiratory Tract Host Defenses

Nasal hairs

Antibacterial substances in respiratory secretions (lysozyme)

Goblet cells & cilia of the columnar epithelial cells

Coughing, sneezing, swallowing

Alveolar machrophages

Upper Respiratory Tract Infection

Pharyngitis

Sinusitis

Otitis media

Laryngitis

Croup (laryngotracheobronchitis)

Epiglottis

Peritonsillar abscess

Stomatitis

Thrush

Periodontal infections

Parotitis

Pharyngitis

Upper Respiratory Tract Infections:

Inflammation of the back of the throat (pharynx)

Strep pyogenes (primary bacterial cause), Arcanobacterium, C. diptheriae

Sinusitis

Upper Respiratory Tract Infections:

Inflammation of the nasal sinus tissues

Strep pneumo, H. influenzae, M. catarrhalis, Staph aureus

Otitis Media

Upper Respiratory Tract Infections:

Inner Ear Infection

Strep pneumo, H. influenzae, M. catarrhalis

Laryngitis

Upper Respiratory Tract Infections:

Inflammation of the voice box (larynx)

Strep pyogenes, H. influenzae, Staph aureus

Croup (Larynogotracheobronchitis)

Upper Respiratory Tract Infections:

"Seal Bark" Cough

Epiglottis

Upper Respiratory Tract Infections:

Inflammation of epiglottis

H. influenzae

Peritonsillar abscess

Upper Respiratory Tract Infections:

A pus-filled infection near the tonsils

Anaerobes

Stomatitis

Upper Respiratory Tract Infections:

Inflammation of the oral mucosa

HSV

Thrush

Upper Respiratory Tract Infection

Fungal infection in the mouth and/or throat

Candida spp

Periodontal infections

Upper Respiratory Tract Infection

Bacterial infection that destroys the gums, ligaments, and bone supporting the teeth, often caused by plaque buildup

Polymicrobial, Anaerobes

Parotitis

Upper Respiratory Tract Infection

Inflammation of the parotid salivary gland

Mumps

Lower Respiratory Tract Infection

Acute bronchitis

Acute pneumonia

Chronic pneumonia

Cystic Fibrosis

Infections in pts with HIV

Lung abscess

Pleural infection

Acute Bronchitis

Lower Respiratory Tract Infection

Inflammation of bronchial tubes

Over 90% of time caused by viruses

If Bacterial: Mycoplasma pneumo, B. pertussis (whooping cough), & Chlamydia pneumo

Acute Pneumonia

Lower Respiratory Tract Infection

Routes of infection: aspiration, inhalation of airborne droplets, seeding of lung via blood from distant site infection, upper airway colonization/infection that extends to the lung

Children Acute Pneumonia

Lower Respiratory Tract Infections

- More than 80% of cases are viral (RSV, Influenza, Parainfluenza, Adenovirus)

Strep agalactiae, E coli, Listera

What 3 organisms cause Acute Pneumonia in NEONATES?

M. pneumo, C. pneumo, H. inflenzae, Step pneumo, Staph aureus

What 5 organisms cause Acute Pneumonia in CHILDREN?

Viruses, M. pneumo, C. pneumo

What 3 organisms cause Acute Pneumonia in YOUNG ADULTS?

Community Acquired Pneumonia (CAP)

Adult Acute Pneumonia

Strep pneumoniae, Viral, M. pneumoniae, C. pneumoniae, H. influenzae, Legionella

Hospital Acquired Pneumonia (HAP)

Adult Acute Pneumonia

Enterobacterales, Pseudomonas, Acinetobacter, Staph aureus (MRSA), Strep pneumoniae, H. influenzae, Legionella

Chronic Pneumonia

Lower Respiratory Tract Infections

Mycobacteria spp, Actinomyces, Nocardia, mixer aerobic & anaerobic bacteria, dimorphic fungi, Cryptococcus

Cystic Fibrosis

Lower Respiratory Tract Infections

Genetic Disorder

Staph aureus, H. influenzae, non-fermenter organisms

Infections in pts with HIV

Lower Respiratory Tract Infections

Thrush, Pneumocysits pneumonia, dimorphic fungi, Cryptococcus neoformans, tuberculosis

Lung abscess

Lower Respiratory Tract Infections

Pus-filled localized cavity

Specimen Collection of Lower Respiratory

Sputum

Suctioning - Lukens trap

Bronchoscopy

Mini-BAL

Thoracentesis

Biopsy

Sputum

Specimen Collection - Lower Respiratory

- May be expectorated or induced

Suctioning - Lukens trap

Specimen Collection - Lower Respiratory

- Endotracheal Tube (intubation) - shorter term airway management

- Tracheostomy Tube - longer term airway management

Bronchoscopy

Specimen Collection - Lower Respiratory

- Bronchial wash - specimen from larger airways

- Bronchoalveolar lavage (BAL) - specimen from smaller airways

- Bronchial brushing

Mini-BAL

Specimen Collection - Lower Respiratory

- Catheter instead of bronchoscope, smaller amount of saline used