Gender-wise distribution of MRSA in sample population
Out of 400 samples taken, 123 were MRSA positive isolates out of which 67 (54.4%) were from males and 56 (45.5%) were from females.
Table 1: Gender-wise distribution of MRSA in sample population
Gender
|
Presence% (n)
|
Male (105)
|
67 (63.80%)
|
Female (95)
|
56 (58.94%)
|
Total 200
|
123
|
Gender-wise distribution of MRSA positive in sample population
Out of 400 samples taken, 123 were MRSA positive isolates among which 34 MRSA were isolated from barber’s populations. Similarly, 32 MRSA were isolated from beautician’s populations. In municipal waste worker’s population, 19 MRSA isolates were obtained from males whereas 10 were isolated from female’s population whereas in healthy population, 14 MRSA isolates were obtained from males and 14 were from female’s population.
Comparative study of MRSA isolated from total samples
In this study, all samples were analyzed for MRSA. Higher number of MRSA was isolated from hand (36.5%). The prevalence of MRSA isolates from nasal was 25% and from hand was 36.5%.
Table 2: Comparative study of MRSA isolated from total samples
Samples
|
Total sample
|
MRSA
|
p-value
|
Hand
|
200
|
73 (36.5%)
|
0.013
|
Nasal
|
200
|
50 (25%)
|
Total
|
400
|
123
|
|
Comparative study of MRSA isolated from different samples
The MRSA isolated from hand were 73 and from nasal were 50. In 24 individuals the MRSA was isolated from both the hand and nasal. The higher frequency of MRSA was isolated from hand than in nasal. Maximum MRSA isolates were obtained from skin surface of barber’s hand.
Table 3: Comparative study of MRSA isolated from different samples
Samplepopulation
|
Source
|
|
Hand (Only)
|
Nasal (Only)
|
Both
|
p-value
|
Barber
|
23
|
11
|
8
|
0.011
|
Beauticians
|
19
|
13
|
4
|
0.086
|
Municipal waste workers
|
16
|
13
|
4
|
0.509
|
Healthy
|
15
|
13
|
8
|
1.00
|
Total
|
73
|
50
|
24
|
|
MRSA isolated from different age groups of male and female
Among 123 MRSA isolated, MRSA from male were 67 (54.4%) and MRSA were from female 56 (45.5%). In male the highest number of MRSA, 27 (40.2%) was from the age group of 20-29 years followed by 25 (37.3%) from 30-39 years of age. In female the highest number of MRSA, 18 (32.1%) was isolated from age group of 20-29 years and 30-39 years of age.
Table 4: MRSA isolated from different age groups of male and female
Age Groups
|
Prevalence of MRSA
|
Barbers Males
|
Barbers Females
|
Beauticians Males
|
Beauticians Females
|
Municipal Waste Workers Males
|
Municipal Waste Workers Females
|
Healthy Males
|
Healthy Females
|
Below 20
|
10.4%
|
-
|
-
|
5.3%
|
0.0
|
0.0
|
2.9%
|
1.7%
|
20-29
|
17.9%
|
-
|
-
|
17.8%
|
8.9%
|
1.7%
|
13.4%
|
12.5%
|
30-39
|
16.4%
|
-
|
-
|
21.4%
|
17.9%
|
10.7%
|
2.9%
|
0.0
|
40-49
|
4.4%
|
-
|
-
|
10.7%
|
1.4%
|
5.3%
|
0.0
|
5.3%
|
Above 50
|
1.4%
|
-
|
-
|
1.7%
|
0.0
|
0.0
|
1.4%
|
5.3%
|
Comparative study of biofilm formation by MRSA in potential risk population
The biofilm formation assay showed that maximum isolates were biofilm producer. The biofilm producing MRSA was found maximum in beautician (56.2%), followed by barber (52.9%). Similarly, in municipal waste workers and healthy population biofilm producing MRSA were 48.2% and 46.4% respectively.
Table 5: Comparative study of biofilm formation by MRSA in potential risk population
Biofilm
|
Barber
|
Beautician
|
Municipal waste workers
|
Healthy
|
p-value
|
Strong
|
7 (20.5%)
|
5 (15.6%)
|
2 (6.8%)
|
5 (17.8%)
|
0.032
|
Moderate
|
11 (32.3%)
|
13 (40.6%)
|
12 (41.3%)
|
8 (28.5%)
|
0.033
|
Weak
|
16 (47%)
|
14 (43.7%)
|
15 (51.7%)
|
15 (53.5%)
|
0.045
|
Total
|
34
|
32
|
29
|
28
|
|
Biofilm formation assay
The biofilm forming ability of isolated MRSA was performed by three methods: microtitre plate method, tube method and congo red agar method.
Table 6: Biofilm formation by MRSA by three methods
Biofilm formation
|
Microtitre plate method
|
Tube method
|
Congo red agar method
|
p-value
|
High
|
19 (15.4%)
|
14 (11.3%)
|
11 (8.9%)
31 (25.2%)
|
|
Moderate
|
44 (35.7%)
|
37 (30%)
|
0.000
|
Weak/None
|
60 (48.7%)
|
72 (58.5%)
|
81 (65.8%)
|
|
Total Isolates
|
123
|
123
|
123
|
|
Sensitivity and specificity of biofilm screening methods
The microtitre plate method was found to be most efficient standard method for studying biofilm formation as compared to tube method and congo red agar method. The parameters like sensitivity, specificity, negative predictive value, positive predictive value and accuracy were calculated. True positives were biofilm producers by microtitre, tube and congo red agar method. False positive were biofilm producers by tube method (TM) and congo red agar (CRA) method and not by microtitre method. False negative were the isolates which were non-biofilm producers by microtitre plate and CRA but were biofilm producer by microtitre method. True negatives are those which were non biofilm producers by all three methods [12].
Table 7: Sensitivity and specificity of biofilm screening methods
Biofilm screening method
|
Sensitivity
(%)
|
Specificity
(%)
|
PPV
(%)
|
NPV
(%)
|
Accuracy (%)
|
Tube method
|
75
|
74.6
|
58.8
|
86.1
|
64.2
|
Congo red agar method
|
54.8
|
85.2
|
79
|
65
|
21.4
|
Antibiotic susceptibility pattern of MRSA isolates
The provided table shows the resistance and sensitivity pattern of isolated MRSA strains towards different antibiotics. It was found that MRSA was most sensitive towards ciprofloxacin (93.4%), chloramphenicol (80.4%) and co-trimoxazole (74.7%) which was statistically significant (P<0.05).The isolated MRSA were resistant to ampicillin (100%), amoxicillin (100%) and trimethoprim (23.5%).
Table 8: Antibiotic susceptibility pattern of MRSA isolates
Antibiotics
|
Resistant
|
Sensitive
|
p-value
|
MRSA
|
%
|
MRSA
|
%
|
|
Ampicillin
|
123
|
100
|
0
|
0
|
-
|
Amoxicillin
|
123
|
100
|
0
|
0
|
-
|
Cefotaxime
|
65
|
52.8
|
58
|
47.1
|
0.00
|
Chloramphenicol
|
25
|
20.3
|
98
|
80.4
|
0.00
|
Ciprofloxacin
|
8
|
6.5
|
115
|
93.4
|
0.00
|
Co-Trimoxazole
|
31
|
25.2
|
92
|
74.7
|
0.00
|
Erythromycin
|
90
|
73.1
|
33
|
26.8
|
0.01
|
Gentamicin
|
42
|
34.1
|
81
|
65.8
|
0.04
|
Norfloxacin
|
76
|
61.7
|
47
|
38.2
|
0.00
|
Ofloxacin
|
38
|
30.8
|
85
|
69.1
|
0.00
|
Teicoplanin
|
55
|
44.7
|
68
|
55.2
|
0.82
|
Tetracycline
|
59
|
47.9
|
64
|
52
|
0.62
|
Trimethoprim
|
94
|
76.4
|
29
|
23.5
|
0.00
|
Resistance pattern of biofilm producing MRSA
The biofilm producing MRSA showed resistance to cefotaxime, chloramphenicol, teicoplanin, co-trimoxazole, erythromycin, norfloxacin, trimethoprim. The non-biofilm producing MRSA showed resistance to tetracycline, ofloxacin, gentamicin, and ciprofloxacin. Ampicillin and amoxicillin were resisted by both biofilm producers and non-biofilm producers.
Table 9: Resistance pattern of biofilm producing MRSA
Antibiotics
|
% of biofilm producing resistant
|
% of non-biofilm producing resistant
|
Ampicillin
|
100%
|
100%
|
Amoxicillin
|
100%
|
100%
|
Cefotaxime
|
56.6%
|
38%
|
Chloramphenicol
|
20.6%
|
15%
|
Ciprofloxacin
|
1.5%
|
10%
|
Co-trimoxazole
|
25.3%
|
25%
|
Erythromycin
|
73%
|
65%
|
Gentamicin
|
33.3%
|
38.3%
|
Norfloxacin
|
66.6%
|
60.3%
|
Ofloxacin
|
25.3%
|
36.6%
|
Teicoplanin
|
48.3%
|
34.9%
|
Tetracycline
|
30.1%
|
55%
|
Trimethoprim
|
78.3%
|
77.7%
|
Multidrug resistant (MDR) CA-MRSA
Multidrug resistant community-acquired methicillin resistant S. aureus (CA-MRSA) were identified by their antibiotic resistivity pattern on, three or more than three commonly prescribed antibiotics of different classes. The prevalence of MDR CA-MRSA was 91%.
Table 10: Multidrug resistant (MDR) CA-MRSA
Isolates
|
CA-MRSA
|
Total isolates
|
123
|
Multi-drug resistant
|
112 (91%)
|
Vancomycin sensitivity of total MRSA isolates
The MIC of vancomycin to the MRSA isolates was screened by microbroth dilution assay performed in microtitre wells. In our study, out of 123 MRSA samples the VSSA isolates were 9.7%, VISA isolates were 49.5% and VRSA isolates were 40.6%. In our study the high prevalence of VISA and VRSA isolates were screened.
MIC of vancomycin to MRSA isolates from different sample population
In our study the VSSA, VISA and VRSA strains of MRSA were screened from all sample populations under study. The highest prevalence of VISA strain was found in healthy population (15.4%). The highest prevalence of VRSA was found in barbers (15.4%).
Table 11: MIC of vancomycin to MRSA isolates from different sample population
Sample population
|
MIC Vancomycin
|
Total
|
VSSA(≤2µg/ml)
|
VISA(4-8µg/ml)
|
VRSA(≥16µg/ml)
|
MWW
|
2 (1.6%)
|
18 (14.6%)
|
9 (7.3%)
|
29 (23.5%)
|
Barbers
|
3 (2.4%)
|
12 (9.7%)
|
19 (15.4%)
|
34 (27.6%)
|
Beauticians
|
4 (3.2%)
|
12 (9.7%)
|
16 (13%)
|
32 (26%)
|
Healthy
|
3 (2.4%)
|
19 (15.4%)
|
7 (5.6%)
|
28 (22.7%)
|
Total
|
12
|
61
|
50
|
123
|
|
MIC of vancomycin to MRSA isolates from different gender population
The highest prevalence of VISA and VRSA were found to be in male population than in female population. However, the sample populations of female were less than that of male in our study.
Table 12: MIC of vancomycin to MRSA isolates from different gender population
MIC vancomycin
|
Male
|
Female
|
Total
|
p-value
|
VSSA (≤2µg/ml)
|
5 (4%)
|
7 (5.6%)
|
12
|
0.348
|
VISA (4-8µg/ml)
|
33 (26.8%)
|
28 (22.7%)
|
61
|
0.113
|
VRSA (≥16µg/ml)
|
29 (23.5%)
|
21 (17%)
|
50
|
0.515
|
Total
|
67
|
56
|
123
|
|
MIC of vancomycin to MRSA isolates from hand and nasal sample
In this study, the highest prevalence of VISA was found to be in hand (31.7%) than in nasal (17.8%). Similarly, the highest prevalence of VRSA was found to be in hand (21.9%) than in nasal (18.6%). However, VSSA isolates were found more in hand (5.6%) sample than in nasal (4%) sample.
Table 13: MIC of vancomycin to MRSA isolates from hand and nasal sample
MIC vancomycin
|
Hand
|
Nasal
|
Total
|
p-value
|
VSSA (≤2µg/ml)
|
7 (5.6%)
|
5 (4%)
|
12
|
0.940
|
VISA (4-8µg/ml)
|
39 (31.7%)
|
22 (17.8%)
|
61
|
0.304
|
VRSA (≥16µg/ml)
|
27 (21.9%)
|
23 (18.6%)
|
50
|
0.317
|
Total
|
73
|
50
|
123
|
|
MIC of vancomycin to MRSA isolates from different age groups of sample population
Among 123 MRSA isolates, the highest VISA isolates were screened from the age group 20-29 years (21.1%). Even the highest percentage of VRSA was screened from the age group of 20-29 years (14.6%).
Table 14: MIC of vancomycin to MRSA isolates from different age groups of sample population
Age group
|
VSSA
(≤2µg/ml)
|
VISA
(4-8µg/ml)
|
VRSA
(≥16µg/ml)
|
Total
|
Below 20 Years
|
0
|
10 (8.1%)
|
10 (8.1%)
|
20 (16.2%)
|
20-29 Years
|
3 (2.4%)
|
26 (21.1%)
|
18 (14.6%)
|
47 (38.2%)
|
30-39 Years
|
2 (1.6%)
|
15 (12.1%)
|
15 (12.1%)
|
32 (26%)
|
40-49 Years
|
2 (1.6%)
|
8 (6.5%)
|
6 (4.8%)
|
16 (13%)
|
50 and Above
|
5 (4%)
|
2 (1.6%)
|
1 (0.8%)
|
8 (6.5%)
|
Total
|
12
|
61
|
50
|
123
|