1. Antimicrobial Stewardship Training
Part 1: Review of Basic Principles and Selected Antimicrobials
By Keith Teelucksingh, PharmD
Infectious Disease Pharmacist, Kaiser Permanente Vallejo
With contributions by Linh Van, PharmD
Infectious Disease Pharmacist, Kaiser Permanente Oakland
Welcome to this two-hour continuing education program: Review of Basic Principles and Selected Antimicrobials, Part 1 of the Antimicrobial Stewardship Training.
This program has been accredited by the California Accreditation for Pharmacy Education, a division of the Pharmacy Foundation of California, and is brought to you by the Inpatient Pharmacy Directors Subcommittee on Education, Kaiser Permanente Northern California Region.
In order to obtain continuing education (CE) credit for this program, you are required to complete study of three modules: Microbiology Lab review, Antibiotic review and Allergy review, and to complete a 30-question post-test and program evaluation. A correct score of 70 percent is required for CE credit.
Please submit your completed post-test and evaluation to your inpatient director (IPD) or inpatient supervisor (IPS) who will score your test. Your IPD or IPS will then fax your graded post-test and evaluation form to Dan Dong for recordkeeping and issuance of your CE certificate. This will be ed to your Kaiser address within one week of submission. Please keep this certificate for your CE records.
This course is accepted by the California State Board of Pharmacy for 2.0 hours of credit. Provider #127: Accredited by CAPE Coursework expires: 1/1/2011

2. Antimicrobial Stewardship Training
An Antimicrobial Stewardship program is a “an overarching program to change and direct antimicrobial use at a heath care institution.”1
A series of training programs have been developed to enhance pharmacists’ knowledge and expertise in providing antimicrobial stewardship at Kaiser Permanente hospitals.
1 MacDougall C, Polk R. Antimicrobial Stewardship Programs in Health Care Systems. Clin. Microbiol. Rev. Vol. 18 Oct 2005, p

3. Antimicrobial Stewardship Training*
Part 1: Review of Basic Principles and Selected Antimicrobials
Provides core background information in three modules:
Microbiology Lab review
Antibiotic review
Allergy review
The Microbiology Lab review covers some basic clinical microbiology concepts and will familiarize the pharmacist with interpreting cultures from blood, urine, sputum and tissue.
The Antibiotic review will focus on the β-lactam class of antibiotics, aztreonam, vancomycin, clindamycin, metronidazole and the fluoroquinolones. Knowledge of these selected antibacterials and their appropriate clinical use are essential for assessing antimicrobial therapy commonly administered in hospitals today. Other pertinent antibiotic classes will be reviewed at later dates.
The Allergy review will focus on β-lactam allergy and the cross reactivity between the various classes of β-lactam antibiotics (penicillins, cephalosporins, carbapenems, etc).
A red asterik in the title indicates that there is text/narrative in the notes section.
See Notes

4. Module 1 (of 3): Microbiology Lab Review*
Goal
The goal of the Microbiology Lab Review module is to review and enhance pharmacists’ basic understanding of microbiology in the clinical setting.
The Microbiology Lab review covers some basic clinical microbiology concepts and will familiarize the pharmacist with interpreting cultures from blood, urine, sputum and tissue.
 See Notes

5. Objectives
Upon completion of this module, the participant will be able to:
Differentiate between gram-positive and gram-negative bacteria and name pertinent species from each group.
Be able to interpret blood, urine, tissue and sputum culture results.
Define contamination and colonization.
Explain the purpose of urinalysis.
Be able to name some species of Coagulase-negative Staphylococcus (CoNS) and explain the significance of isolating CoNS from blood cultures.

6. Definitions *
Infectious Disease: “an interaction with a microbe that causes damage to the host.”1
Pathogen: “any microorganism that has the capacity to cause disease.”1
Virulence: properties that enable a microorganism to establish itself on or within a host of a particular species and enhance its potential to cause disease.
When thinking about virulence, consider the differences between two bacteria within the same species: Staphylococcus aureus versus Staphylococcus epidermidis (these will be reviewed later in this presentation). Both have the capacity to cause infections, but due to virulence factors, infections with S. aureus are much more severe and can be life-threatening, whereas infections due to S. epidermidis generally are less severe.
1. Mandell, Bennett, & Dolin: Principles and Practice of Infectious Diseases, 6th Ed.
See Notes

7. Definitions * Microbiology results will be reported similar to this
Organism: Staphylococcus aureus
Drug
MIC
Result
Penicillin
>8 R
Ampicillin
Oxacillin
<=0.25 S
Clindamycin
<=1
Tetracycline
Trimeth/sulfa
<=0.5/9.5
Before we get into basic definitions, it is important to visualize how culture results will be reported out. For the most part, if bacteria are isolated in a culture, susceptibilities will be available once the culture is final (i.e. the culture has been incubated by the lab for the appropriate length of time).
See Notes

8. Definitions
Susceptible (S): implies that an infection due to the isolate may be appropriately treated with the dosage of antimicrobial agent recommended for that type of infection.
Only use an antibiotic that is reported as susceptible.
Intermediate (I): implies that an infection due to the isolate may be appropriately treated in body sites where the drugs are physiologically concentrated or when a high dosage of drug can be used (i.e., urinary tract).

9. Definitions
Resistant (R): isolates that are not inhibited by the usually achievable concentrations of the agent with normal dosage schedules and/or fall in the range where specific microbial resistance mechanisms are likely (e.g., β-lactamases).
Minimum inhibitory concentration (MIC): the lowest concentration of the antimicrobial agent that prevents visible growth after an incubation period.
Breakpoint: discriminatory antimicrobial concentration used in the interpretation of results of susceptibility testing to define isolates as susceptible, intermediate or resistant. That is, the MIC where a bacteria goes from S to either I or R.

10. Gram Stain * Provides for rapid identification of presumed pathogen
Gram Positive (+) versus Gram negative (-)
Gives idea of morphology or arrangement of bacteria
cocci vs. rod
cluster, pairs, chain
Aids in selecting appropriate empiric antibiotic choices
Bacteria often are classified by how they appear after application of Gram Stain, their morphology (rods or cocci) and their growth pattern (for example, whether they utilize oxygen: aerobe vs. anaerobe).
Bacterial species will primarily stain as either Gram + or Gram -. Certain species also will organize themselves in particular arrangements (Staphylococci tend to form clusters, Streptococci can appear as pairs or chains).
In addition to helping classify the bacteria, a Gram Stain can be performed on infected body fluids (like blood, urine) to give the clinician a preliminary idea of what types of infecting organisms might be present.
After the gram stain is performed, the infected fluid then is incubated for culture result. It is the result of this incubation that gives the definitive final culture result.
Can be performed on any body fluid
Only useful as preliminary guide – NOT definitive
See Notes 10

11. Gram Stain *
Application of series of dyes that affix to the peptidoglycan in bacterial cell wall:
Purple
Gram Positive
Pink
Gram Negative
Bacteria isolated and colored with Gram stain. Gram-positive cocci, Staphylococcus aureus, from a lab culture.
Peptidogycan is a component of the bacterial cell wall. These compounds are found in much higher concentration in cell walls of the Gram + organisms. That is why these bacteria stain most markedly (violet/indigo) with the Gram stain, since the dye has affinity for the peptidoglycan in their cell wall. Gram – bacteria appear pink because they do not have as much peptidoglycan in their cell wall and thus stain weakly.
Gram-negative bacilli with a capsule, Klebsiella pneumoniae, from a pneumonia lung abscess (magnified 1,000×).
See Notes 11

12. Bacterial Morphology *
Shapes
cocci = round
bacilli = rods
coccobacilli = ovoid
fusiform = pointed-end
Arrangements
single
pairs
clusters
chains
When classifying bacteria, another major consideration is the bacterial morphology.
Cocci are round-shaped, whereas bacilli are rod-shaped. There are some species of bacteria that are hard to identify on shape alone since they may appear as either cocci or bacilli (examples of coccobacilli include Acinetobacter spp., Haemophilus spp.)
See Notes

13. Microbiology: Common Pathogens *
Gram-Positive Cocci
Clusters
Staphylococcus spp.
Pairs or chains
Streptococcus spp. including S. pneumoniae, S. viridans
Enterococcus spp.
Other species:
Micrococcus spp.
Be aware that a bacterial species may arrange itself in several different ways. That is, in the case of Staphylococci, they tend to form clusters but also can appear as pairs or chains. Also, remember the Gram stain analysis is being done by a laboratory technician so there is room for interpretation on what they are seeing under the microscope.
Staphylococcus aureus
See Notes

14. Microbiology: Common Pathogens
Gram-Positive Bacilli (Rods)
Diphtheroids:
Corynebacterium spp.
Proprionibacterium acnes
Large, with spores:
Clostridium spp (anaerobic)
Bacillus spp
Branching, beaded, rods:
Nocardia spp.
Actinomyces spp.
Other
Listeria spp.
Lactobacillus spp. (vaginal flora)
Clostridium difficile

15. Common Bacteria and Classifications
Adapted from Jeff Kuper, Pharm.D., BCPS
See Notes 15

16. Microbiology: Common Pathogens
Gram-Negative Cocci
Diplococci
Pairs:
Neisseria meningitidis
Neisseria gonorrhea
Other
Acinetobacter spp. (technically a rod but can appear as cocci or bacilli)
Neisseria gonorrhoeae
Acinetobacter baumannii

17. Microbiology: Common Pathogens *
Gram-Negative Bacilli (Rods)
Lactose fermenters
Enterobacteriaceae (“enteric Gm -”)
Serratia spp.
Proteus spp.
Enterobacter spp.
Escherichia coli
Citrobacter spp.
Klebsiella spp.
Nonfermenters
Acinetobacter baumannii
Pseudomonas aeruginosa
Stenotrophomonas maltophilia
Most of the bacteria on this slide can be considered nosocomial pathogens with the possible exceptions of Proteus, E. coli and Klebsiella. However, be aware that these bacteria can develop powerful resistance mechanisms (for example ESBL – extended spectrum beta lactamase), which can in turn cause severe nosocomial infections (pneumonia, bacteremia).
Pseudomonas aeruginosa
See Notes

18. Microbiology: Common Pathogens
Anaerobes
Gm +
Clostridium spp. (rods/bacilli)
Peptostreptococcus (cocci)
Gm -
Bacteroides spp. (rods/bacilli)
e.g. B. fragilis
Prevotella spp. (rods/bacilli)
Clostridium difficile adhering to microvilli in the gut

19. Microbiology: Common Pathogens
Atypical bacteria
Mycoplasma pneumoniae
Legionella pneumophilia
Chlamydia pneumoniae
These bacteria are hard to culture on standard media, hence the name ‘atypical.’
Commonly implicated in infections like community-acquired pneumonia (CAP).
Legionella pneumophilia

20. *Program Learning* What type of bacteria is Bacteroides fragilis?
How does the group of Enterobacteriaciae appear on gram stain?
Name some atypical bacteria. What types of infections do atypical bacterial cause?

21. *Program Learning Answers*
What type of bacteria is Bacteroides fragilis? An anaerobic gram-negative rod.
How does the group of Enterobacteraciae appear on gram stain? Gram-negative and appear pink.
Name some atypical bacteria. What types of infections do atypical bacterial cause? Legionella pneumophilia, Chlamydia pneumoniae, Mycoplasma pneumoniae. These are mostly associated with community-acquired pneumonia.

22. Colonization *
The presence of bacteria on a body surface or mucous membrance without causing disease/infection.
Upper respiratory tract (URT) – Strep. viridans, Candida spp
Skin – S. epidermidis, Corynebacterium spp., S. aureus
GI tract – E. coli, K. pneumoniae, Candida spp., Bacteroides spp.
Urogential – Lactobacillus (vaginal flora)
S. epidermidis. CDC.
Now that we have reviewed the basic definitions, we can consider some other clinical microbiology concepts like colonization.
Some areas of the human body will have bacteria that are commensal. Only under certain circumstances (breakage of physical defense barrier, bacterial inoculum overwhelming host defense mechanism) do these bacteria become able to cause disease. When interpreting culture results, it is important to note the site of the culture and be aware of the common organisms that usually are found there.
These are just some examples of the normal microbiological flora that will be found at particular sites within the human body.
Note that on this slide there are some relatively benign bacteria we usually don’t think about causing severe infections (i.e. S. epidermidis) and some that can cause severe infections (i.e. E. coli, B. fragilis, S.aureus). The point is there are some colonizing microbes that, when the circumstances are favorable, can cause severe infections at their given site (Enterobacteriaciae in intra-abdominal infections). In contrast, there are some colonizing microbes that rarely will cause infection at their given site (i.e., URT infection due to S. viridans or Candida spp.)
See Notes

23. Colonization *
The presence of bacteria/organisms in a culture does not necessarily mean they are pathogenic.
It is up to the clinician to interpret the culture result and clinically correlate to the patient’s signs and symptoms.
Patients who have been exposed to health care environments or have specific disease states (structural lung disease or cystic fibrosis) may be colonized with bacteria that usually are considered pathogenic like MRSA in the nares or Pseudomonas in the sputum respectively. In addition, patients who recently have been exposed to antibiotics also may be colonized with more drug-resistant bacterial species.
The same concept as the previous slide applies—only under certain circumstances (breakage of physical defense barrier, bacterial inoculum overwhelming host defense mechanism) do these bacteria become able to cause disease.
See Notes

24. Colonization
The following are considered sterile sites and are not prone to colonization:
Blood
Brain
Muscle
CSF
Synovial fluid

25. Contamination
An organism that is introduced at some point during the culturing process not related to or causing an infectious process.
Examples: Improperly prepped skin prior to venipuncture, drawn from ‘dirty’ IV line, poor lab technique  contamination on Petri dish).
Example: skin flora (S. epidermidis) being isolated in blood cultures.

26. Blood Cultures *
Definitive means of identifying most likely pathogens.
Most pathogens will grow within first 12–24 hours of collection (Candida, anaerobes may take longer).
Incubated for five days by laboratory.
Should be taken PRIOR to initiation of antibiotics.
Growth may be inhibited by antibiotics.
While culture information is the definitive means of identifying the most probable pathogen(s), not all infectious diseases will yield positive blood cultures. There are some infectious diseases where the patient most likely will have positive blood cultures: endocarditis, IV line-related infections and urosepsis/pyelonephritis are some examples. There are other infectious diseases where it is less likely the patient will have positive blood cultures: pneumonia and cellulitis are some examples.
See Notes

27. Blood Cultures * Common contaminants:
Gm +cocci: Coagulase neg Staph (CoNS): S. epidermidis, S. hominis, S.capitis, S. warneri
Gm + rods: Corynebacterium spp., Micrococcus spp., Bacillus spp. (not anthracis)
When a blood culture starts growing an organism, or if something is identified with Gram stain, there will be a preliminary result in HealthConnect (i.e., ‘Gram positive cocci in clusters and chains isolated, Dr. Smith called with result’). Recall, however, this is a preliminary result and the definitive culture may reveal any of the Gram + bacteria (from Staphylococcus aureus to some form of coagulase-negative Staphylococci (CoNS) to Streptococci spp.)
The isolation of CoNS from blood cultures is common. Most of the time, these bugs are contaminants and can be disregarded without needing antimicrobial therapy. The next few slides are designed to aid interpreting blood cultures where CoNS is isolated.
See Notes

28. See Notes Adapted from Jeff Kuper, Pharm.D., BCPS
S.aureus, which is much more virulent than most, if not all, other Staphylococci spp., is quickly distinguished by the microbiology laboratory by running a coagulase test. S. aureus is always coagulase positive.
Adapted from Jeff Kuper, Pharm.D., BCPS
See Notes

29. Blood Cultures The following should NEVER be considered contaminants:
Staphylococcus aureus
Gram – rods/bacilli
Candida spp.

30. Blood Cultures *
So what’s the significance of isolating a Coagulase negative Staphylococcus spp. (CoNS) species from blood cultures?
To help determine whether a blood culture positive for CoNS should be considered a contaminant, the following questions should be asked about the culture and the patient specific variables.
See Notes

31. Blood Cultures: Significance of CoNS
Assess how many blood cultures are positive vs. how many were drawn.
There should be a low suspicion for true infection if only one blood culture from multiple sets drawn around the same time period are positive for CoNS
There should be a low suspicion if only one culture is positive and cultures were drawn from separate sites (e.g., one from IV line, one from peripheral site). See next slide for more information.

32. Blood Cultures: Significance of CoNS *
What disease state/infection being treated?
Patients with an indwelling central line, hemodialysis catheter may be more at risk of infection.
Patients with foreign material (especially cardiac), bone/joint infections may have positive blood cultures for CoNS.
CoNS can cause infections of indwelling central lines. Either multiple positive cultures drawn through a line or accompanying positive peripheral blood culture(s) help support this diagnosis. Multiple positive cultures drawn from a central line or catheter that continue to be positive most likely indicate the line is colonized and the patient runs the risk of becoming infected if the line is left in place (i.e., removal of the line/catheter is necessary for eradication of infection).
CoNS (like other Staphylococcal species) are good at forming biofilms, especially on prosthetic materials, and can definitely cause infection in their presence.
So what about a situation where a patient has an infection not typically associated with CoNS (for example, pneumonia) and has one out of two blood cultures growing a CoNS? Since CoNS are very unlikely to cause respiratory infections, a patient with pneumonia and a sole blood culture positive for CoNS probably does not need to be covered with antibiotics to cover CoNS (i.e., treat the pertinent disease state, not the culture results).
See Notes

33. Blood Cultures: Significance of CoNS *
What constitutional symptoms does the patient have?
Fever, leukocytosis
What type of patient?
Immunocompetent
Immunocompromised
Chemotherapy/meds
Disease state (advanced HIV)
Transplant
Neutropenic
While CoNS are less virulent than S. aureus, this does not mean they cannot cause significant infections. Immunocompetent patients typically have infections associated with prosthetic materials or IV lines. In contrast, patients who are immunocompromised may be at risk of having other types infections due to CoNS (skin and soft tissue, etc). In these cases, it is best to seek the aid of the infectious disease physician in interpretation of those culture results.
See Notes

34. Blood Cultures: Significance of CoNS
In general, a solitary peripheral blood culture positive for CoNS in an immunocompetent patient should be regarded as a contaminant if:
No other blood cultures drawn in a reasonable time frame are also growing CoNS.
The patient does not have prosthetic material present or does not have a central line/catheter.
If another source of infection is identified to account for the patient’s constitutional symptoms.
If patient has no signs or symptoms of infection.

35. Blood Cultures: Significance of CoNS
Just as in any clinical situation where the case is not straightforward or there are questions:
If ever in doubt, present case to ID physician.

36. Urine Culture *
Urine samples are held for 24 hours by microbiology lab.
Bacterial growth expressed as colony counts, i.e., >100,000 colony forming units (CFU).
Should always have a corresponding urinalysis (UA) performed for microscopy.
If >2 bacteria are isolated from a urine culture, the lab will not perform any further work-up on the specimen.
From the Northern California Online Laboratory handbook ( “When more than two organisms are recovered, the likelihood of contamination is high; thus, the significance of definitive identification of the organisms and susceptibility testing in this situation is severely limited. A repeat culture with proper specimen collection/patient preparation is often indicated."
See Notes

37. Urine Culture Why perform a UA?
The examination of fluid microscopy allows for some differentiation between infection vs. colonization vs. contamination.
Infected fluid should have WBC, neutrophils or other inflammatory markers.
Uninfected fluids generally are devoid of these markers.
Keep in mind that immunocompromised patients may not be able to mount a strong enough immune response to produce these markers.

38. Urine Culture: Interpreting the UA
How many WBCs in urine?
How many epithelial/squamous cells present?
The lower the number, the ‘cleaner’ the sample (i.e., you can probably trust culture result).
The higher the number increases risk of contamination with colonizing flora (i.e., sample taken too early in the urine stream)
What amount of leukocyte esterase present?
Given as trace, small, moderate and large.
Found in certain WBC, sign of inflammation.

39. Tissue Culture
Preliminary report available at 24 hours, incubated for 72 hours total.
Lab will quantify growth of organism: rare, light, moderate and heavy.
Tissue sample is plated onto agar plate.
Quantification of growth on plate gives some idea of the bacterial burden of a sample.

40. Tissue Culture These cultures can vary in quality:
Some may be superficial samples (i.e., more prone to contamination or colonization); others may be deep tissue samples or cultures from an operation (i.e., less likely to be contaminated or colonized).
The presence of cellulitis, pus, exposed bone can help distinguish true infection from contamination or colonization.
Read the MD note carefully and get some idea of what the area looks like, whether the MD thinks the area looks clinically infected or not.

41. Sputum Culture
Gram stain done initially by lab to assess quality of specimen.
If > 10 epithelial cells, sample is not worked up:
Sample not indicative of lower airway secretion.
May be prone to contamination.
Patients with pulmonary infection should have purulent sputum.
Presence of WBC on gram stain.

42. *Program Learning*
Name some organisms that are commonly found on the skin.
True or False: Coagulase positive Staphylococci growing from a blood culture should be considered a contaminant.
Which microbes may take longer to grow out in blood cultures?
True or False: It is common for CSF and synovial fluid to be colonized with bacteria.

43. *Program Learning Answers*
Name some organisms that are commonly found on the skin: S. epidermidis, S. aureus, Corynebacterium spp.
True or False: Coagulase positive Staphylococci growing from a blood culture should be considered a contaminant False: CoNS are usually contaminants. Staphylococcus aureus is coagulase + and should never be considered a contaminant when isolated from the blood.

44. *Program Learning Answers*
Which microbes may take longer to grow out in blood cultures? Anaerobes and Candida spp. take longer to grow out in blood cultures.
True or False: It is common for CSF and synovial fluid to be colonized with bacteria CSF and synovial fluid are considered sterile sites and are not commonly colonized.

45. References
Mandell, Bennett & Dolin. Principles and Practice of Infectious Disease. 7th ed. (accessed Oct. 14, 2009).
Kaiser Permanente Laboratory Manual – Information - Northern California. (accessed Oct. 14, 2009).
Mermel, L. et al. Clinical Practice Guidelines for the Diagnosis and Management of Intravascular catheter-related infection: 2009 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2009;49:1-45.
This concludes Module 1, the Microbiology Lab Review.
Please proceed to Modules 2 and 3.