Sepsis Workup

Dr. Hisham Abid Aldabbagh MSc. Internal Medicine

Kingdom of Saudi Arabia

Ministry of Health

Directorate of Health

Affairs in Gurayat

Gurayat General Hospital

Workup for sepsis may include the following

• Blood and urine studies, including appropriate cultures

• Diagnostic imaging of the chest and abdomen/pelvis

• Cardiac studies such as ECG and cardiac enzymes, as indicated

• Interventions such as paracentesis, thoracentesis, lumbar puncture, or aspiration of an abscess, as clinically indicated

•Measurement of biomarkers of sepsis such as procalcitonin levels

Laboratory Studies

Complete blood cell count

• A complete blood cell (CBC) count is usually not specific,

because of the numerous conditions that mimic sepsis and produce leukocytosis with variable degrees of a left shift. Leukopenia, anemia, and thrombocytopenia may be observed in sepsis.

Blood Culture • Blood cultures are used to detect the presence

of bacteria or fungi in the blood, to identify the type present, and to guide treatment.

• Also blood samples may be used to detect viruses

• Susceptibility testing—determines the drug (antimicrobial) that may be most effective in treating the infection

• Blood cultures are drawn more frequently in newborns and young children, who may have an infection but may not have the typical signs and symptoms of sepsis.

• Two or more blood cultures that are positive for the same bacteria or fungi means that the patient tested likely has a blood infection with that microorganism. The results typically identify the specific bacteria or fungi causing the infection.

• If one blood culture set is positive and one set is negative, it may mean that an infection or skin contaminant is present. You will consider the patient's clinical status and the type of bacteria or fungi found before making a diagnosis. Also, additional testing may be warranted in this case.

• Blood culture sets that are negative after several days (often reported as "no growth") mean that the probability that a patient has a blood infection caused by bacteria or fungi is low. If symptoms persist, however, such as a fever that does not go away, additional testing may be required.

• A few reasons that symptoms may not resolve even though blood culture results are negative may include:

• Some microorganisms are more difficult to grow in culture, and additional blood cultures using special nutrient media may be done to try to grow and identify the pathogen.

• Viruses cannot be detected using blood culture bottles designed to grow bacteria. If you suspects that a viral infection may be the cause of the patient's symptoms, then other laboratory tests would need to be performed. The tests that would be ordered depend upon the patient's clinical signs and the type of virus suspected to cause the infection.

• Rapid tests are available that can detect several different types of bacteria that are commonly known to cause infections of the blood. These tests are used in follow up to positive blood cultures to quickly identify the bacteria that are present. They can identify types such as methicillin-resistant Staphylcoccus aureus (MRSA), which is typically difficult to treat, and gram negative rods such as E. coli that live in the gastrointestinal tract. Rapid identification can facilitate treatment with appropriate antibiotics

Bacterial Cultures

• Bacterial culture isolates might suggest the underlying

disease process. Bacteroides fragilis suggests a colonic or pelvic source, whereas Klebsiella species or enterococci suggest a gallbladder or urinary tract source.

• If central intravenous (IV) line sepsis is suspected, remove the line and send the tip for semiquantitative bacterial culture. If culture of the catheter tip yields positive results and demonstrates 15 or more colonies and if the isolate from the tip matches the isolate from the blood culture, an infection associated with the central IV line is diagnosed.

• The rationale for nasal cultures is that nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) is often viewed as a potential marker of subsequent risk for severe MRSA infection. However, a meta-analysis found nasal colonization with MRSA to be a poor predictor for the subsequent occurrence of MRSA lower respiratory tract infections and MRSA bloodstream infections that require antimicrobial treatment.. Thus, caution should be exercised in interpreting nasal cultures in patients in the intensive care unit (ICU).

Urine Culture

• Results of a urine culture are often interpreted in conjunction with the results of a urinalysis and with regard to how the sample was collected and whether symptoms are present. Since some urine samples have the potential to be contaminated with normal flora from the skin, care must be taken with interpreting some culture results.

• If a culture is positive, susceptibility testing is typically performed to guide antimicrobial treatment

• A systematic review found that in adult ICU patients, catheter-associated urinary tract infection was associated with significantly higher mortality and a longer stay.

• Typically, the presence of a single type of bacteria growing at high colony counts is considered a positive urine culture. For clean catch samples that have been properly collected, cultures with greater than 100,000 colony forming units (CFU)/mL of one type of bacteria usually indicate infection.

• In some cases, however, there may not be a significantly high number of bacteria even though an infection is present. Sometimes lower numbers (1,000 up to 100,000 CFU/mL) may indicate infection, especially if symptoms are present. Likewise, for samples collected using a technique that minimizes contamination, such as a sample collected with a catheter, results of 1,000 to 100,000 CFU/mL may be considered significant.

• A culture that is reported as "no growth in 24 or 48 hours" usually indicates that there is no infection. If the symptoms persist, however, a urine culture may be repeated on another sample to look for the presence of bacteria at lower colony counts or other microorganisms that may cause these symptoms.

• If a culture shows growth of several different types of bacteria, then it is likely that the growth is due to contamination. This is especially true in voided urine samples if the organisms present include Lactobacillus and/or other common nonpathogenic vaginal bacteria in women.

• If the symptoms persist, you may request a repeat culture on a sample that is more carefully collected. However, if one type of bacteria is present in significantly higher colony counts than the others, for example, 100,000 CFUs/mL versus 1,000 CFUs/mL, then additional testing may be done to identify the predominant bacteria

Bacterial Wound Culture • Is ordered to determine whether a wound is infected, to identify the bacteria causing the infection, and to prepare a sample for susceptibility testing where required.

• Also be ordered on an individual who has undergone treatment for a wound infection, to determine whether the treatment was effective.

• It may also be ordered at intervals on a patient who has a chronic infection, to help guide further treatment.

• If a fungal infection is suspected, then a fungal culture of the wound specimen may be ordered along with the bacterial wound culture.

• If pathogenic bacteria are identified in the culture, then it is likely that they are the source of the infection. An infection is typically caused by a single type of bacteria, but wounds may have two or more pathogens (aerobes and/or anaerobes) that are contributing to the infection. If more than three organisms are present, they may not be identified as individual bacterial species and the report may refer to them as "mixed bacterial flora." This may indicate a mixture of normal flora and pathogens from a contaminated sample or from a dirty wound

• Very little growth may still be significant, especially when the wound infection is in an area of the body considered to be essentially sterile – such as the eye.

• If there are no bacteria recovered in the wound specimen, then there may not be a bacterial infection, or the pathogen was not successfully recovered with the sample and test.

•With burn wounds, quantitative culture results may be requested – the numbers of bacteria that grow are correlated to the number of bacteria in the infected wound. When burn tissue specimens have a specific bacterial count above a certain number, then removal of dead tissue (debridement) may be indicated.

Throat Culture / Strep Throat Test

• This test is ordered when a person has a sore throat and

other symptoms that suggest strep throat. There is a higher suspicion of strep when the affected person is a child and/or if the person has been in close contact with someone who has been diagnosed with strep throat.

• A rapid strep test, also known as a rapid antigen detection test (RADT), can detect group A strep antigens. Results are available in 10-20 minutes. If the results of the rapid test are positive, further testing is not needed and treatment can be started right away.

Bacterial Sputum Culture

• A bacterial sputum culture is ordered when you suspect that the patient has a bacterial infection of the lungs or airways, such as bacterial pneumonia or bronchitis

• Sometimes lower respiratory tract infections are caused by pathogens that cannot be detected with routine bacterial sputum cultures, so specialized tests may be done in addition to or instead of a routine culture to help identify the cause of infection. These additional tests include, for example, an AFB smear and culture to detect tuberculosis and non-tuberculous mycobacteria infections, a fungal culture, or a Legionella culture

• Sputum is not sterile, so when a person has an infection, there will typically be both normal flora and pathogenic bacteria present. If pathogenic bacteria are identified during a sputum culture, then antimicrobial susceptibility testing is usually performed so that the appropriate antibiotics can be prescribed

• Sometimes a sputum culture may be ordered after treatment of an infection, to verify its efficacy.

CSF Culture

• Obtain a cerebrospinal fluid (CSF) culture before initiating

antibiotic therapy if the child’s condition is stable but clinical evaluation cannot exclude central nervous system (CNS) infection.

•Many pathogens can be recovered from CSF cultures several hours after a dose of antibiotics; thus, a child whose condition is unstable should receive antibiotics and be stabilized before lumbar puncture.

• Once the child’s condition is stable, identification of CSF pleocytosis is helpful, even if prolonged antibiotic therapy may have rendered culture results negative.

• Culture of skin lesions, eye drainage, throat, vagina, rectum, cellulitic areas, nasal secretions, sputum, tracheal aspirates, and stool may be helpful in the appropriate clinical context.

• Viral cultures may have a role in certain contexts, although many viral infections are diagnosed via molecular methods or serologically.

Procalcitonin

• The procalcitonin test is relatively new, but its utilization is

increasing.

• The procalcitonin test has been approved by FDA for use in conjunction with other laboratory findings and clinical assessments to assist in the risk assessment of critically ill people for progression to systemic bacterial infection,or severe sepsis and septic shock.

• For diagnostic purposes, it is best used during the first day of presentation. It may be used later on to monitor the response to treatment.

• Procalcitonin may be ordered, along with other tests such as

CRP, blood culture, CBC, or CSF analysis to help detect or

rule out, distinguish between viral and bacterial meningitis,

or

detect/rule out bacterial pneumonia in those who are

seriously ill and in children with a fever of unknown origin.

• Low levels of procalcitonin in a seriously ill person represent a low risk of sepsis and progression to severe sepsis and/or septic shock but do not exclude it.

• Low concentrations may indicate a localized infection that has not yet become systemic or a systemic infection that is less than six hours old.

• It may also indicate that the patient's symptoms are likely due to another cause, such as transplant rejection, a viral infection, or trauma – post-surgery or otherwise.

• High levels indicate a high probability of sepsis, that is, a higher likelihood of a bacterial cause for the symptoms. They also suggest a higher risk of progression to severe sepsis and then to septic shock

•Moderate elevations may be due to a non-infectious condition or due to an early infection and, along with other findings, should be reviewed carefully.

• Decreasing procalcitonin levels in a person being treated for a severe bacterial infection indicate a response to therapy.

Chest Radiology Chest radiography is important to rule out pneumonia and diagnose other causes of pulmonary infiltrates, such as the following:

Pneumothorax Pulmonary drug reactions

Hydrothorax Pulmonary embolism

Fluid overload Pulmonary hemorrhage Congestive heart failure Primary or metastatic pulmonary

neoplasms

Acute myocardial infarction Lymphangitic spread of malignancies

Acute respiratory distress syndrome Large pleural effusions

Abdominal Ultrasonography

• Perform abdominal ultrasonography if biliary tract obstruction

is suspected on the basis of the clinical presentation. However, abdominal ultrasonography is suboptimal for the detection of abscesses or perforated hollow organs.

• Ultrasonograms in patients with cholecystitis may show a thickened gallbladder wall or biliary calculi but no dilatation of the common bile duct (CBD).

• Stones in the biliary tract are visible in patients with cholangitis, but the CBD is dilated

CT & MRI

• Use CT or MRI of the abdomen if a nonbiliary intra-abdominal source of infection is suspected on the basis of the history or physical examination findings. These 2 imaging modalities are superior to ultrasonography in demonstrating all lesions, except those related to the biliary tract

• Abdominal CT or MRI is also helpful in delineating intrarenal and extrarenal pathology. Gallium or indium scanning has no place in the initial workup of sepsis; patients with sepsis are acutely ill by definition, and rapid diagnostic tests (eg, CT or MRI of the abdomen and ultrasonography of the right upper quadrant) are time-critical, life-saving tools

Cardiac Studies

• If an acute MI is likely, perform (ECG) and obtain cardiac

enzyme levels. Remember that certain patients may present with a silent, asymptomatic MI, which should be included in the differential diagnosis of otherwise unexplained fever, leukocytosis, and hypotension. Silent MIs are common in elderly patients and in those who have recent undergone abdominal or pelvic surgical procedures. They are also common in individuals with alcoholism, diabetes, and uremic conditions

Invasive Interventions

• Thoracentesis/paracentesis

• Perform thoracentesis for diagnostic purposes in patients with substantial pleural effusion. Perform paracentesis in patients with gross ascites.

• Swan-Ganz catheterization

• Use data obtained via a Swan-Ganz catheter to manage the fluid status of the patient and to assess left ventricular dysfunction in patients with acute MI.

Sepsis Workup positive Cultures in GGH in the last 3 months

38 patients, 22 male, 16 female; ages: NB11, children 5, adults 12, elderly 10

No. Provisional diagnosis No. Provisional diagnosis

3 DM 6 ARDS

2 Diabetic foot 4 Wound

1 Septic shock 4 RTA

1 Appendicitis 4 UTI

1 ESRD 3 Pneumonia

1 URTI 3 Abscess 1 CVA 3 Sepsis?

Sepsis Workup positive Cultures in GGH in the last 3 months

Blood

15

Urine

13

Wound

10

Sputum

4

Throat

4

Central line

1

Acinetobacter 7 4 2 1 - 1

Klesiella pneumoniae 3 4 2 - 3 -

Staph.hominis 2 - - - - -

MRSA 1 - 4 2 - -

Strepto.epidermidis 1 - - - - -

Proteus mirablis 1 - - - - -

E.coli - 4 1 - -

Pseudomonas

aeruginosa

- 1 1 1 1 -

Professional message

Dear colleagues, please

• Fight Against Contamination

• Strict with Infection Control Procedures

• Look Well for the Source of Infection

•Work Together for successful Sepsis Workup

Thank you for Sharing in Sepsis Workup

I will be happy to share your action

Email: dr.hishamdabbagh@gmail.com