The document discusses hospital antibiograms, which are periodic summaries of antimicrobial susceptibilities of bacterial isolates in a hospital. They are useful for clinicians to assess local susceptibility rates and monitor resistance trends over time. The document covers various topics related to antibiograms including how they are tested, interpreted, and documented. It emphasizes the importance of generating antibiograms using standardized methods and interpreting them carefully based on multiple factors.

1. HOSPITAL
ANTIBIOGRAMS
principles interpretation and
documentation
Dr.T.V.Rao MD
03-08-2016 Dr.T.V.Rao MD 1

2. Different methods to Test
Antibiotic Sensitivity patterns
03-08-2016 Dr.T.V.Rao MD 2

3. What is an
antibiogram
•An antibiogram is a
laboratory test used to
determine the
sensitivity pattern of a
given microorganism
to a range of
antibiotics.
03-08-2016 Dr.T.V.Rao MD 3

4. What is a Hospital
Antibiogram
•The hospital antibiogram is a periodic summary
of antimicrobial susceptibilities of local bacterial
isolates submitted to the hospital's clinical
microbiology laboratory. Antibiograms are often
used by clinicians to assess local susceptibility
rates, as an aid in selecting empiric antibiotic
therapy, and in monitoring resistance trends
over time within an institution
03-08-2016 Dr.T.V.Rao MD 4

5. Helps in identifying the Antibiotic
Resistance patterns
•Antibiograms can
also used to
compare
susceptibility rates
across institutions
and track
resistance trends03-08-2016 Dr.T.V.Rao MD 5

6. Why we need An Antibiogram
•Antimicrobial-resistant bacterial infections
are a challenging problem in the hospital
setting. Infections caused by resistant- and
multidrug-resistant (MDR) bacteria not
only increase morbidity and mortality, but
also increase overall healthcare costs,
primarily by prolonging hospital length of
stay.03-08-2016 Dr.T.V.Rao MD 6

7. Hospital Associated Infections can
be Monitored with Antibiograms
• In situations when
hospital-acquired
infections do occur, the
preponderance of MDR
bacteria as the causative
pathogen challenges
clinicians in selecting
appropriate therapy and
treatment regimens.
03-08-2016 Dr.T.V.Rao MD 7

8. We need better methods to monitor
Antibiotic Therapy
•Inappropriate
therapy can have
significant
clinical and
economic
consequences
03-08-2016 Dr.T.V.Rao MD 8

9. Wrong Antibiograms add to
MDR Strains
• Inappropriate
antimicrobial
selection also has
the potential to
increase the risk for
resistance
development.03-08-2016 Dr.T.V.Rao MD 9

10. Antibiograms are also
used to
•Check if the causative agent belongs to a
species capable of exhibiting resistance to
commonly used antibiotics.
•Study the epidemiology of resistance
•Evaluate the efficacy of a new antibiotics
03-08-2016 Dr.T.V.Rao MD 10

11. Hospital Antibiograms are essential
tools
• Hospital antibiograms can be an
essential tool to monitor local
epidemiology and emerging
resistance trends.
Antibiograms, if generated and
utilized appropriately, can
monitor resistance at
healthcare facilities by
reporting susceptibility rates of
common pathogens over a
period of time03-08-2016 Dr.T.V.Rao MD 11

12. Selecting an Appropriate Antibiotic
a Priority
•They can, therefore,
serve as an invaluable
guide in selecting
appropriate empiric
therapy and influence
institutional
antimicrobial use
policies
03-08-2016 Dr.T.V.Rao MD 12

13. Growing Importance of
Antibiograms
•Over the last twenty
years, new categories
of antibiotics have
entered the market
and numerous forms
of resistance have
appeared and
multiplied
03-08-2016 Dr.T.V.Rao MD 13

14. Antibiograms are also used to
• Check if the causative agent
belongs to a species capable
of exhibiting resistance to
commonly used antibiotics.
• Study the epidemiology of
resistance
• Evaluate the efficacy of a
new antibiotic
03-08-2016 Dr.T.V.Rao MD 14

15. Why should you develop and use
an antibiogram at your Hospital
facility?
• Antibiograms encourage responsible use of antibiotics
throughout facilities. Prescribing clinicians—physicians,
nurse practitioners, and physician assistants—can consult
these tools before initiating empiric antibiotic therapy, which
may improve outcomes among patients with infections.
• Antibiograms are a good way to detect changes in resistance
patterns for an entire facility or for locations within a facility.
• Antibiograms can be inexpensive to develop and maintain.
The results are easily accessible to health care providers.
03-08-2016 Dr.T.V.Rao MD 15

16. How to begin our Work with
Antibiograms
• Isolation, identification of the
pathological Microbe and
antibiogram of a pathogenic
agent are normally carried out
when a bacterial disease has
produced a problem
• We have specific and
General methods to identify
the pathogenic bacterial
isolate
03-08-2016 Dr.T.V.Rao MD 16

17. Mechanism in Testing the
Antibiograms
• The basic idea of
diffusion assays is as
follows: the tested
antibiotics are
impregnated in paper
discs which are placed on
plate of agar medium
inoculated with the
bacteria in question.
03-08-2016 Dr.T.V.Rao MD 17

18. Mechanism in Testing the
Antibiograms
• Following diffusion of the
compounds through the
agar, a "halo" or zone of
inhibition forms where a
concentration of the
specific diffused
antibiotic is sufficient to
inhibit that microbial
growth
03-08-2016 Dr.T.V.Rao MD 18

19. Interpreting an
antibiogram• The correct
interpretation of the
antibiogram will be of
interest to
Microbiologists and
laboratory technicians
alike. Standardized
methods are established
and can be found in the
WHO manuals.
03-08-2016 Dr.T.V.Rao MD 19

20. Still we have not
Understood Problems with
Antibiograms
• One of the most frequently
asked questions relates to in-
vitro (in the lab)/in-vivo (in
the field) relationships. Why is
it that satisfactory in vitro or
laboratory test results can
translate into poor clinical
efficacy In these situations,
thought should be given to:
clinical and laboratory
coordination
03-08-2016 Dr.T.V.Rao MD 20

21. To have a better Understanding of
Antibiograms
•a) Whether or not the diagnosis correct?
•b) Whether the problem is really caused by the isolated
bacteria?
•c) Whether the product was administered correctly, at the
right dose level, for the correct number of days?
•d) Whether the activity level of the drug coincides with
label specifications
03-08-2016 Dr.T.V.Rao MD 21

22. Factors influencing the
interpretation of an antibiogram
• Based on this reasoning, the
diffusion method is sometimes
mistakenly interpreted as a
quantitative method. The more
potent an antimicrobial
compound, the less
concentrated it need be, and
consequently at points further
from the disc with consequently
lower concentrations, microbial
growth will still be inhibited
03-08-2016 Dr.T.V.Rao MD 22

23. 03-08-2016 Dr.T.V.Rao MD 23

24. Basic Interpretation of
Zone Sizes
•Therefore, it is often
assumed that the
larger the diameter
of the zone of
inhibition, the more
potent the
antimicrobial
03-08-2016 Dr.T.V.Rao MD 24

25. Why Concentration of the Antibiotic
matters
• A number of factors however,
may interfere with this
interpretation. Firstly, the
concentration of the antibiotic in
the disc must be taken into
account. The higher the
concentration in the disc, the
more concentrated the
compound will be at a given
distance from the disc itself.
03-08-2016 Dr.T.V.Rao MD 25

26. Time too matters in optimal
Reading of Antibiograms
• Also, the length of time
allowed for the process to
occur can greatly influence
the diameter of the zone of
inhibition as the longer
diffusion is allowed to take
place the higher the
concentrations at any given
point in the gradient will be.
03-08-2016 Dr.T.V.Rao MD 26

27. Zone sizes are Interpreted with
consideration of many factors
• Related to this, the infusibility of
the antimicrobial compound
through the agar can greatly
impact on the observed zone of
inhibition, such that a very
potent inhibitor may produce a
relatively small "halo" simply
because it is unable to diffuse
adequately through the
medium. In addition, the extent
of the growth of the microbe
03-08-2016 Dr.T.V.Rao MD 27

28. Outcome of Antibiograms
depend on many factors
• In relation to the
degree of diffusion,
can influence the
resulting zone of
inhibition, such that
the timing of both
factors, microbial
growth and
diffusion, interplay.
03-08-2016 Dr.T.V.Rao MD 28

29. What are the Isolates to be Taken for
Reporting Antibiograms
•Only the first isolate from the patient is to
be included in the analysis. The analysis
should be done on the basis of patient
location and specimen type. The percentage
susceptibility of the most frequently
isolated bacteria should be presented in the
antibiogram, preferably in a tabular form
03-08-2016 Dr.T.V.Rao MD 29

30. Basis of Choosing
Antibiotic Discs
•The selection of the most appropriate antibiotics
to test is a decision best made by each clinical
laboratory in consultation with the field
veterinarian. To avoid unnecessary duplication,
only one antibiotic from each family should be
used. Agents of the same family have similar
clinical efficacy, show nearly the same spectrum
of activity and have similar cross-resistance and
cross-susceptibility.03-08-2016 Dr.T.V.Rao MD 30

31. How to prepare the inoculum for
Testing the Antibiograms
•At least three to five well-
isolated colonies of the
same morphological type
bacteria are selected from a
primary agar plate culture
and transferred into a tube
containing 4-5 ml of broth
medium.
03-08-2016 Dr.T.V.Rao MD 31

32. Preparing inoculum for
Testing Antibiograms• This is incubated at 35°C for
2-6 hours and then applied
with a sterile cotton swab on a
dried surface of a Mueller-
Hinton agar plate.
Alternatively the inoculums
can be prepared by making a
direct broth or saline
suspension of isolated colonies
selected from a primary agar
plate03-08-2016 Dr.T.V.Rao MD 32

33. Placement of Antibiotic Discs for Optimal
Antibiograms
• The predetermined battery of
anti-microbial disks is dispensed
onto the surface of the
inoculated agar plate. Each disk
must be pressed down to ensure
complete contact with the agar
surface. The disk must be
distributed evenly no closer than
24mm from Center to centre.
The plates are inverted and
placed in an incubator at 35°C.
03-08-2016 Dr.T.V.Rao MD 33

34. Reading the Zones of
Inhibition
• After 16-18 hours of
incubation, each plate is
examined. The resulting
zones of inhibition (halo) will
be uniformly circular and
there will be a confluent
lawn of growth. The
diameters of the zone of
complete inhibition are
measured, including the
diameter of the disk03-08-2016 Dr.T.V.Rao MD 34

35. Measuring Zone Sizes in
Antibiograms
• The measurement can be
done using a sliding calliper,
ruler or compass as
demonstrated in picture .
The zone margin should be
taken as the area showing
no obvious, visible growth
that can be detected by the
naked eye.
03-08-2016 Dr.T.V.Rao MD 35

36. Formulating the Concentration of
Antibiotic and relevance of zones
depend on
•Comparing zone diameters to
minimum inhibitory
concentrations (MICs) of a
large number of isolates,
including those with known
mechanisms of resistance
relevant to the particular
class of drug
03-08-2016 Dr.T.V.Rao MD 36

37. Pharmaco kinetics play a Major
Role
•Analysing the MICs
and correlated zone
sizes in relation to
the pharmaco-
kinetics of the drug
from normal dose
range schedules
03-08-2016 Dr.T.V.Rao MD 37

38. Choosing Antibiotics to the
effectiveness of isolated
pathogens
•Analysing whenever
possible the tentative
in vitro interpretive
criteria in relation to
studies of clinical
efficacy in the
treatment of specific
pathogens
03-08-2016 Dr.T.V.Rao MD 38

39. What is Susceptible
• This category implies that an
infection due to this
bacterium may be
appropriately treated with
the dosage of antibiotic
recommended for that type
of infection and infecting
species, unless otherwise
contraindicated
03-08-2016 Dr.T.V.Rao MD 39

40. Intermediate
• This category implies that an
infection due to this
bacteria, may be treated
when possible with higher
than normal dosage of this
antibiotic, or when the drug
is physiologically
concentrated in certain body
sites, like Quinolones in
urine03-08-2016 Dr.T.V.Rao MD 40

41. Resistant
•Resistant strain will
probably not respond to
any treatment, as they
are not inhibited by the
usually achievable
systemic concentrations
of the antibiotic when
normal dosage schedules
are used.
03-08-2016 Dr.T.V.Rao MD 41

42. How we express the
Results
• Because of these
complexities in the
diffusion method, it is
perhaps best to consider
the results of the
diffusion assay as
qualitative only,
expressed as: Sensitive,
Intermediate and
Resistant03-08-2016 Dr.T.V.Rao MD 42

43. Do not Process the specimens
Directly for Antibiotic Sensitivity
testing•The practice of
conducting susceptibility
tests directly with clinical
material should be
avoided except in clinical
emergencies when direct
gram staining suggests
the presence of a single
pathogen03-08-2016 Dr.T.V.Rao MD 43

44. Document Antibiograms with
WHONET
• Some hospitals have
adequate support from
the computer
department to be able to
extract data from their
reporting module. The
WHONET software can
be freely downloaded
and used for analysis.
03-08-2016 Dr.T.V.Rao MD 44

45. 03-08-2016 Dr.T.V.Rao MD 45

46. WHONET AND CLSI HELPS IN
ANALYSIS OF THE ANTIBIOGRAMS
Consensus guidelines have
been developed by the
Clinical and Laboratory
Standards Institute (CLSI) to
standardise methods used in
constructing antibiograms.
These guidelines can be
incorporated into the
WHONET software for
analysis
03-08-2016 Dr.T.V.Rao MD 46

47. 03-08-2016 Dr.T.V.Rao MD 47

48. How to modernized Hospital
Antibiograms
• The antibiogram must be
printed or put up in the
intranet for easy access to
all clinicians. Antibiotic
policy is one of the
mandatory requirements
for accreditation, and
making an antibiogram is
the first step before framing
the antibiotic policy.
03-08-2016 Dr.T.V.Rao MD 48

49. Critical Thinking on
Antibiograms
•Antibiograms only
capture the aggregate
proportion of
susceptible isolates for a
given organism-
antibiotic combination.
They do not provide the
prevalence resistance to
multiple antibiotics.
03-08-2016 Dr.T.V.Rao MD 49

50. Antibiograms helps for taking decisions on
Empiric Antibiotics
•Antibiograms provide
guidance for empiric
antibiotic use in patients,
but other factors including
patient characteristics and
prevalence of other risk
factors should be
incorporated when making
therapeutic decisions
03-08-2016 Dr.T.V.Rao MD 50

51. Future of
Antibiograms•The future of
antibiograms would
be the incorporation
of patient related
data to make
information more
reliable and for
predicting outbreaks03-08-2016 Dr.T.V.Rao MD 51

52. Mobile Application on Iphone and IPad
• Antibiograms help healthcare
professionals and clinical
microbiologists choose the most
effective antibiotics to
empirically treat infections,
based on local susceptibility
patterns. Now this valuable
information can be available to
them on iPhone/iPad mobile
devices.
03-08-2016 Dr.T.V.Rao MD 52

53. Antibiogram app
•With the
Antibiograms app,
you simply select a
bacterium, select a
patient group, and you
are given the proportion
of susceptible organisms
for each antibiotic tested
in your local laboratory.
03-08-2016 Dr.T.V.Rao MD 53

54. For Better Understanding on
Antibiograms
• For more detailed information, look at the WHO's
technical manual.
• Ref 1 The Facts about Antibiogram - Dr Yonatan Segal
• 2 Hospital antibiogram: a necessity. Joshi PubMed . Indian J
Med Microbiol. 2010 Oct-Dec;28(4):277-80. doi:
10.4103/0255-0857.71802
• 3 Concise Antibiogram Toolkit - EFwww.ahrq.gov/NH-ASP
Guide • May 2014 AHRQ Pub. No. 14-0012-1-EFwww
03-08-2016 Dr.T.V.Rao MD 54

55. • Program Created By Dr.T.V.Rao MD for basic understanding
on Creation and Documentation of Hospital Antibiograms
for New Generation of Medical Microbiologists practicing
World Wide for better health care
•Email
•doctortvrao@gmail.com
03-08-2016 Dr.T.V.Rao MD 55