ported in 33.8% cases Maximum susceptibility was seen to Amikacin, Nitrofurantoin and cefotaxime. All MRSA isolates showed 100% susceptibility to ...
Antimicrobial Susceptibility Pattern in Urinary Bacterial Isolates A Sonavane*, M Mathur, D Turbadkar, V Baradkar Abstract Objectives : To study antimicrobial susceptibility pattern in urinary bacterial isolates. Methods : A retrospective analysis was done for the resistance pattern of urinary bacterial isolates was done over a period of 2 years (July 2004 – 2006) in a tertiary care hospital. Results : Commonest isolates were E. coli (41.3%) followed by Klebsiella spp. (15.8%), pseudomonas spp. (11.4%), Enterobacter spp. (8%) and Proteus spp. (6.2%) in gram negative whereas Staphylococcus Aureus (7.8%) and Enterococcus spp. (5.8%) in gram positive organisms. Antibiotic susceptibility pattern of these isolates revealed that Amikacin susceptibility in gram negative isolates was more than 40% except for Pseudomonas spp. Co-trimoxazole, Augmentin and quinolones were not found to be effective. In MDR strains cefotaxime + sulbactam, imipenem and meropenem were effective. In Pseudomonas spp. Piperacillin , ceftazidime and Amikacin and piperacillin + Tazobactam (MDR Strains) were effective. Methicillin resistance was reported in 33.8% cases Maximum susceptibility was seen to Amikacin, Nitrofurantoin and cefotaxime. All MRSA isolates showed 100% susceptibility to vancomycin. No Vancomycin resistant enterococcus were encountered in the study. Conclusion : Routine urine culture and susceptibility before therapy should be encouraged and periodic evaluation of predominant organisms and their antimicrobial susceptibility pattern should be studied for appropriate selection of antibiotic for effective management UTI cases.
Introduction
Material
U
Retrospective analysis of 15,973 midstream urine specimens from outpatient and inpatient departments over a period of two years (July 2004 – July 2006) were processed for bacteriological examination. Urine specimens were processed within one hour of collection.
rinary tract infection (UTI) remains the commonest bacterial infection.1 Empiric antimicrobial therapy usually given to reduce the incidence of postoperative UTI, to prevent development of sepsis, to reduce duration of hospital stay cost of patient care.2 So, periodic evaluation of predominant organisms and their antimicrobial susceptibility pattern necessary. 3 In view of this, retrospective analysis was carried out to see changing pattern of antimicrobial susceptibility in urinary isolates.
*Lecturer, Department of Microbiology, LTMMC and LTMGH, Sion, Mumbai - 22 , India. 240
And
Methods
Gram staining was done to find out pus cells and organisms. Bacterial culture was done by semiquantitative method using calibrated loop delivering 0.001 ml of urine on blood agar and MacConkey agar. For Gram negative bacilli more than 100 colonies corresponding to 10 5 cfu / ml, whereas Gram positive cocci irrespective of the colony count Bombay Hospital Journal, Vol. 50, No. 2, 2008
were considered as significant.4 More than two growth and diphtheroids was considered as contamination. Colony count of less than 10 5 cfu / ml for gram negative bacilli were considered as insignificant bacteriuria. Significant bacterial isolates were identified using standard bacteriological tests.5 Antimicrobial susceptibility pattern was studied on Mueller Hinton Agar (MHA) by Kirby Bauer disc diffusion method recommended by National committee for Clinical Laboratory Standards (NCCLS). 6 Candida albicans grown were reported separately. For Gram negative isolates antibiotic discs put up were Amikacin (30 µg), Amoxycillin / Clavulanic acid (20 µg/10 µg), Cotrimoxazole (1.25 µg/23.75 µg), Nalidixic acid (30 µg), Norfloxacin (300µg) and ceftriaxone (30 µg). For pseudomonas Ofloxacin (5 µg), Piperacillin (100 µg) and Ceftazidime (30 µg) were put up. In strains resistant to first line of antibiotics Cefpirome (30 µg), Cefotaxime + Sulbactam (30/15µg), Netilmicin (30 µg) and Piperacillin + Tazobactam (100/10 µg) (In Pseudomonas spp.) were put up as a second line. Imipenem (10 µg) and Meropenem (10 µg) were reserved as a third line in strains resistant to second line of antibiotics. For Gram positive isolates Penicillin (10 IU), Cefotaxime (30 µg) and Cefuroxime (30 µg) were added. For resistant strains of Staphylococcus Vancomycin (30 µg), Linezolid and Netilmicin (30 µg) were tested. Results Out of 15,973 bacterial isolates of UTI 6907 (43.2%) were culture sterile, 2236 (14%) were mixed (More than two) growth. 1548 (9.7%) showed insignificant growth, whereas significant isolates were obtained in 4686 (29.3%). In 143 (0.99%) diphtheroids grown suggestive of contamination. Candida albicans grown in 453 (2.8%). Of the significant bacterial isolates 3926 Bombay Hospital Journal, Vol. 50, No. 2, 2008
(83.8%) were Gram negative and 760 (16.2%) were Gram positive isolates. Amongst Gram negative isolates maximum were Escherichia coli 1937 (41.3%) followed by Klebsiella species 622 (15.8%) followed by Pseudomonas species 534 (11.4%) followed by Enterobacter species 376 (8%) and Proteus species 245 (6.2%). Amongst gram positive isolates maximum were Staphylococcus aureus 361 (7.8%) followed by Enterococcus species 278 (5.9%).Table 1 shows percentage of antimicrobial susceptibility pattern in Gram negative isolates. Table 2 shows percentage of antimicrobial susceptibility pattern in Gram positive isolates. In Gram negative isolates Amikacin susceptibility was more than 40% except Pseudomonas spp. (26.6%). Antimicrobial resistance was seen to quinolones (Nalidixic acid and Norfloxacin), Augmentin (Amoxycillin + Clavulinic acid) and Cotrimoxazole. In strains resistant to first line of antibiotics Cefotaxime + Sulbactam showed maximum susceptibility followed by Cefpirome. Most of the strains were resistant to Netilmicin. Imipenem and Meropenem were found to be effective in strains which were resistant to second line of drugs. In Pseudomonas spp. Piperacillin and Ceftazidime were found to be effective. 61% susceptibility to Piperacillin + Tazobactam was seen in strains resistant to first line of antibiotics. In Gram positive isolates Methicillin resistance was reported in 33.8% of Staphylococcus isolates. Maximum susceptibility was seen to Amikacin (31.4%), Nitrofurantoin (31%) and Cefotaxime (61.6%). All MRSA isolates showed 100% susceptibility to Vancomycin. In Enterococcus spp. Nitrofurantoin, Augmentin, Penicillin and Cefotaxime were found to be effective. No Vancomycin resistant Enterococcus (VRE) 241
Table 1 : Percentage of antimicrobial susceptibility in gram negative isolates E.coli (%)
Klebsiella spp. (%)
Pseudomonas spp. (%)
Enterobacter spp. (%)
Proteus spp. (%)
Amikacin
63.9
50.3
Nitrofurantoin
54.2
32.9
26.6
41
51.8
4.1
24.5
Cefuroxime
1.5
22.4
4
ND
10
1
Ceftriaxone Cotrimoxazole
25.1
21
ND
21.3
45.3
10.9
15.4
0.8
14.9
18.4
Nalidixic acid
9.1
27.3
0.8
15.4
14.3
Norfloxacin
11.5
21.5
ND
18.4
37.6
Augmentin
5.3
2.3
ND
5.6
10.6
Piperacillin
ND
ND
36.5
ND
ND
Ceftazidime
ND
ND
30
ND
ND
Ofloxacin
ND
ND
14.8
ND
ND
Piperacillin + Tazobactam
ND
ND
61
ND
ND
Cefotaxime + Sulbactam
32.6
32
16.4
39.1
66.1
Cefpirome
32.9
21.3
9.7
24.4
38.4
Netilmicin
15.3
0
6.4
4.3
1.9
Imipenem
98.3
97.5
76.7
98.2
96.8
Meropenem
100
100
100
100
100
ND – Not done Table 2 : Percentage of antimicrobial susceptibility in gram positive isolates MSSA (%)
MRSA (%)
CoNS (%)
Enterococcus spp. (%)
Amikacin
68.9
36.9
100
9
Nitrofurantoin
68.9
63.1
75
42
Cotrimoxazole
22.2
5.7
0
2.2
Nalidixic acid
19.2
2.5
0
1.8
Augmentin
55.2
4.9
50
37.7
Cefuroxime
6.7
0
50
3.2
Cefotaxime
64.9
0
50
31.3
Penicillin
20.9
0
0
36.7
Ciprofloxacin
30.5
6.6
75
8.3
Vancomycin
ND
100
ND
100
Netilmicin
ND
67.2
ND
ND
Linezolid
ND
100
ND
ND
ND – Not done
242
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were encountered in the study. Discussion This study shows that commonest isolates were E. coli (41.3%), Klebsiella spp. (15.8%), Psedomonas spp. (11.4%), Enterobacter spp. (8%) and Proteus spp. (6.2%) in Gram negative isolates, whereas in Gram positive isolates maximum were Staphylococcus aureus (7.8%) and Enterococcus spp. (5.9%). In study from GMC Chandigarh E.coli was the commonest isolate followed by Klebsiella spp., Pseudomonas spp., Acinetobacter spp. and Enterococcus spp.7 In a study of urinary isolates from Delhi E.coli, Klebsiella spp., Staphylococcus aureus, Proteus spp. and Pseudomonas spp. were commonest isolates.8 In a study from Aurangabad, in combined group, indoor as well as outdoor Klebsiella spp. was commonest followed by E.coli, Pseudomonas spp. and Staphylococcus aureus.9 In Gram negative isolates Aminoglycoside susceptibility was effective (More than 40%) followed by Nitrofurantoin and third generation cephalosporin (20-55%). Nitrofurantoin was found to be effective because it is not used in other infections, which is in concordance with other studies. 1 0 In Pseudomonas spp. Piperacillin, Ceftazidime and Amikacin were found to be effective. Acinetobacter spp. showed high degree of resistance (More than 60%) to almost all the antibiotics used routinely necessitating its susceptibility testing for newer antibiotics. Our study results matches with that of GMC Chandigarh study. 7 In strains resistant to first line of antibiotics Cefotaxime + Sulbactam showed maximum susceptibility followed by Cefpirome. Most of the strains were resistant to Netilmicin. Imipenem and Meropenem were found to be effective in strains resistant to second line of drugs. Pseudomonas strains resistant to baseline antibiotics showed 61% susceptibility to Piperacillin + Tazobactam.
Bombay Hospital Journal, Vol. 50, No. 2, 2008
In Gram positive isolates Methicillin resistance was reported in 33.8% of Staphylococcus isolates. In other study it was 23.8% from Chandigarh.7 Maximum susceptibility was seen to Amikacin (31.4%), Nitrofurantoin (31%) and Cefotaxime (61.6%). All MRSA isolates showed 100% susceptibility to Vancomycin. In Enterococcus spp. Nitrofurantoin, Augmentin, Penicillin and Cefotaxime were found to be effective. No Vancomycin resistant Enterococcus (VRE) were encountered in this study. In view of this inappropriate and empiric antimicrobial therapy should be avoided to prevent emergence of MDR strains. Routine urine culture and susceptibility before therapy should be encouraged and periodic evaluation of predominant organisms and their antimicrobial susceptibility pattern should be studied for appropriate selection of antibiotic for effective management UTI cases. References 1.
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Larsen EH, Gasser TC, Madsen PO. Antimicrobial prophylaxis in urologic surgery. Urol Clin North Am 1986;13 : 591-604
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Fu KP, Neu HC. Betalactamase stability of HR 756 a novel cephalosporin, compared to that of cefuroxime and cefotaxime. Antimicrob Agents Chemother 1978; 14:322-26.
4.
Microorganisms encountered in the urinary tract. In Bailey & Scott’s diagnostic microbiology (9th edition). Baron EJ, Finegold SM, Eds (Mosby publishers, St. Louis, Missouri) 1994:25
5.
Collee JG, Miles RS, Watt B. Test for the identification of bacteria. In: collee JG, Fraser AG, Marmion BP, Simmons A (editors). Mackie and McCartney. Practical Medical Microbiology 14th ed. London: Churchill Livingstone 1996;p.131-145
6.
National committee for Clinical Laboratory Standards. Performance standards for antimicrobial disk susceptibility tests NCCLS document M2-A7, Approved Standard, 7th edition: Wayne, PA: NCCLS, 2000.
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Gupta V, Yadav A, Joshi RM. Antibiotic resistance 243
pattern in uropathogens. Ind J Med Microbiol 2002; 20 (2) : 96-98. 8.
Varma NC, Taneja OP, Saxena SN. Recurrent urinary tract infections in females. J Ind Med Ass 1972; 58 : 155-58.
9.
Bajaj JK, Karyokarte RP, Kulkarni JD, Deshmukh AB. Changing aetiology of urinary tract infections and emergence of drugs resistance as a major problem. J Commun Dis 1999; 31 (3) : 181-84.
10. Mandal P, Kapil A, Goswami K, Das B, Dwivedi SN. Uropathogenic Escherichia Coli causing urinary tract infections. Indian J Med Res 2001; 114 : 207-11.
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