Antimicrobial susceptibility pattern of bacterial isolates from wound infection and their sensitivity to tests

1. Antimicrobial susceptibility pattern of bacterial isolates
from wound infection and their sensitivity to tests
Presented by:
Roll: PG/ VUOGP57/ BIT- IVS No: 041
Reg no: 02171 of 2020-2021

2. Introduction
The skin serves as a defence barrier against pathogen invasion. As a result a wound is formed when
the normal anatomical structures is disrupted by a accidents or by surgical operation, chemical,
physical, mechanical or thermal events, resulting in a change in skin function.
Skin is exposed to injuries scratches, thus it is more susceptible to colonization by pathogen. Wound
infection can be caused by a single pathogen (mono-microbial) or by multiple pathogen (poly-
microbial). Any wound is at some risk of becoming infected. Infected wounds are likely to be more
painful, hypersensitive, and odorous resulting in amplified uneasiness and discomfort for the patient.
Wound infection has a significant impact on patient morbidity and mortality. Wound infection can be
caused by a variety of pathogens including Bacteria, Viruses, and Fungal parasites.
Gram positive cocci like Staphylococcus aureus , Streptococcus sp, are the most Common bacteria
found in infected wounds.
Gram negative bacteria such as Pseudomonas aeruginosa, Klebsiella pneumoniae, Proteus sp,
Escherichia coli, and Enterobacter sp are the most Common bacteria found in infected wounds.
Due to the widespread proliferation of antibiotic resistance bacteria, wound care has become more
difficult. So, appropriate antibiotics selected by antimicrobial sensitivity testing have great
importance.

3. Aim of the study
• Isolate and identify the bacteria responsible for wound infection.
• The determination of Antibiotic Susceptibility Pattern of Bacteria.

4. Classification of wounds
Wounds can be classified in several ways like depending on the healing time,depth of wound,
level of contamination etc.
Classification of Wounds
Healing time Depth of wound Based on contamination of wound
Acute Chronic Partial
Thickness
Clean
Wound
Superficial Full
Thickness
infected
wound
Colonized
wound
Contaminated
wound

5. Materials and methods
Sample inoculated in growth medium
Incubated at 37°c for overnight.
Plates were observed for colonies appearance.
Gram staining
Biochemical tests
i) For Gram positive cocci (GPC) Catalase and coagulase tests
were done routinely
ii) For Gram negative bacilli (GNB) , common biochemical tests
done are abbreviated as ICUT.
A) Indole test
B) Citrate test
C) Urease test
D) Triple sugar iron test ( TSI)

6. Antibiotic susceptibility test
For AST, were prepared lawn culture with test organisms On Mueller
Hinton agar plate. The susceptibility of bacterial isolates against different
antibiotics were tested by the modified kirby Bauer disc diffusion
method.Amoxyclav, Amikacin, Cefepime, Ceftazidime,
Ceftriaxone,Ciprofloxin, CoTrimoxazole, Doxycycline, Gentamicin,
Levofloxacin, Linezolid, Piperacillin/Tazobactam, Vancomycin were used
in this study for Antibiotic Susceptibility tests. Antibiotic discs were
placed on agar plate by sterile Forceps .
Measuring the clear of zone by ruler and classified
as sensitive or resistant according to the
standard CLSI table.

7. Results
A total numbers of 70 wound samples received at
Microbiology Department. Out of 70 samples,
50(71.42%) samples showed positive Bacterial
growth and 20( 28.58%) samples showed no
growth. There were 37 Females and 33 Males, age
ranged from 15 to 80 year. Among 50 positive
samples of wound infection, 42( 84%) were Gram
negative bacilli and 8(16%) were Gram positive
cocci and their 27 were Females and 23 were
Males.
Age: There were greater incidence of wound
infection in the 46-55 year age group.
Sex: According to the overall results analysis,
Females were more infected than Males.
Gram negative bacilli (GNB) were the most
prevalent bacteria isolated from the wound swabs.
Pseudomonas aeruginosa isolated higher
percentage (28%) followed by Klebsiella
pneumoniae (24%), Escherichia coli (20%), others
Gram-negative organisms (12%).
Staphylococcus aureus (16%) was the only Gram
positive organism isolated in this study.
Pseudomonas
aeruginosa, 28%
Klebsiella
pneumoniae, 24%
Escherichia coli.,
20%
Staphylococcus
aureus, 16%
Other
organisms,
12%
Age Group
Total No. of
Positive Swab
No. of Positive Swab
Female Male
15-25 8 5 3
26-35 8 5 3
36-45 9 5 4
46-55 15 6 9
56-65 3 1 2
>65 7 5 2
Total 50 27 23

8.  Antibiotic susceptibility pattern of Pseudomonas aeruginosa
Gram negative pseudomonas
aeruginosa was the predominant
organism responsible for wound
infection. This organism was highly
sensitive to Piperacillin-Tazobactum
(85.71%) followed by Gentamicin
(78.57%), Ceftazidime (64.28%),
Cefepime (57.14%). Where as it was
totally resistant to Amoxyclav &
Levofloxacin.
0
10
20
30
40
50
60
70
80
90
100
AMC PIT LE CAZ CPM GEN
Sensitive
Resistant
No. of Organism (%) RXN No. & (%) of Sensitivity and Resistant to Various Antibiotics
AMC PIT LE CAZ CPM GEN
14(28%)
S -
12
(85.71)
-
9
(64.28)
8
(57.14)
11
(78.57)
R
14
(100)
2
(14.29)
14
(100)
5
(35.72)
6
(42.86)
3
(21.43)

9. Antibiotic Susceptibility Pattern of Klebsiella pneumoniae, Escherichia coli
and other gram negative organisms.
Antibiotic Susceptibility Pattern of Staphylococcus aureus.
No. of Organism (%) RXN No (%) of Sensitivity and Resistant to Various Antibiotics
AMC VA GEN LZ CIP DO
8(16%)
S 2
(25)
7
(87.5)
6
(75)
7
(87.5)
3
(37.5)
6
(75)
R 6
(75)
1
(12.5)
2
(25)
1
(12.5)
5
(62.5)
2
(25)
No. of Organism (%) RXN No (%) of Sensitivity and Resistant to Various Antibiotics
AMC PIT LE AK COT CTR
12(24%)
S
4
(33.33)
10
(83.34)
9
(75)
11
(91.66)
8
(66.66)
2
(16.66)
R
8
(66.67)
2
(16.66)
3
(25)
1
(8.34)
4
(33.34)
10
(83.34)
10(20%)
S
7
(70)
10
(100)
3
(30)
8
(80)
6
(60)
1
(10)
R
3
(30)
-
7
(70)
2
(20)
4
(40)
9
(90)
6(12%)
S -
4
(66.66)
3
(50)
5
(83.33)
4
(66.66)
-
R
6
(100)
2
(33.34)
3
(50)
1
(16.67)
2
(33.34)
6
(100)

10. Discussion
 The knowledge of bacteriology of an infection and Laboratory susceptibility
testing of microorganisms could make drug selection in antimicrobial
chemotherapy more rational.
Wound infection is one of the most common and serious complication among
hospital acquired infection. Wound infection can increase the length of hospital
stay, delay of recovery and account for mortality rate up to 70%-80%.
In the present study, it was demonstrated that there was high prevalence
(71.42%) of pathogenic bacteria found in Wounds.
The results of percentage prevalence of the bacteria isolates from this study
also indicated that the rate of isolation of Gram negative bacteria was more
than Gram positive bacteria.

11. Name of the Scientist What was found in previous study Which was found in the presence study
Messele A, Estifanos T et. al in 2018 Found that, 68.4% pathogenic bacteria in
Wounds.
It was found that, 71.42% pathogenic
bacteria in Wounds.
Priscilla R et.al in 2019 and Pondei k
et.al in 2013
Found that, 86.20% & 85.05% Gram negative
bacilli.
It was found that, 84% GNB and
Pseudomonas aeruginosa was the most
prevalent gram negative organisms.
Baba et.al in 2016 and Maharjan N et.al
in 2020
Found that, 54.54% & 60.6% GPC in Wounds.
Also reported that Staphylococcus aureus was
the predominant bacterial species.
It was found that, 16% GPC &Staphylococcus
aureus was the only Gram positive organism.
Maharjan N et.al in 2020 Found that, Piperacillin/Tazobactam(94.1%) was
the most effective antibiotic for Pseudomonas
aeruginosa.
Pseudomonas aeruginosa was sensitive to
piperacillin/Tazobactam (85.71%) &
Gentamicin (78.57%).
Baba et.al in 2016 Reported that, Staphylococcus aureus was
sensitive to Rifampicin (96%) &Ciprofloxin (65%).
It was found that, Staphylococcus aureus
was highly sensitive to Vancomycin,
Linezolid, Gentamicin.
Mama M et al.2014 Found that, Ciprofloxin & Doxycycline were the
most effective drugs for Klebsiella Pneumoniae.
Klebsiella pneumoniaewas sensitive to
Amikacin, Piperacillin/Tazobactam,
Levofloxacin.
Tinajanaserafimovskaet.alin 2020 Reported that, Escherichia coli was 88% sensitive
to Clindamycin &Ciprofloxin.
Escherichia coli was totally susceptible to
Piperacillin/Tazobactam, 80% to Amikacin.
Mahamedet.al Found that, Enterobacter sp was multiple drugs
resistant.
It was found that, Enterobacter sp was 100%
resistant to Amikacin & Ceftriaxone.

12. Conclusion
 It can be concluded that in the present study Gram negative pseudomonas
aeruginosa was the main bacteria responsible for wound infection, followed
by Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus and other
Gram negative bacteria.
 The results of the study is helpful for identifying the common causes of
wound infection in the locality.
 It will be helpful to Select the appropriate antibiotic in appreciate dosage
to control the infection.
 The accumulated results on different pathogens and their sensitivity will
guide the physician in choosing empirical treatment of serious patients before
the individual’s laboratory results are analysed.
 Helps the local pattern of antibiotic susceptibility.

13. THANK YOU