micobial profile of wound muhammad saaiq

Microbial Profile and Antibiotic Susceptibility of the Bacterial contaminants of infected Wounds… Hameed-ud Din et al

Original Article

Microbial Profile and Antibiotic Susceptibility of the Bacterial contaminants of infected Wounds- Experience at a Plastic and Reconstructive Unit Objective: To study the microbial profile of the infected wounds and to detect the antibiotic susceptibility pattern of the microbes in our setup. Study design: Single centre non-interventional descriptive study. Place and duration of the study: Department of plastic and Reconstructive Surgery, Pakistan Institute of Medical Sciences (PIMS), Islamabad from Jan 2004 to Dec. 2005. Subjects and Methods: A total of 193 adult patients of either gender having clinical features of infected wound were included in the study. Patients with healthy wounds, those who had been taking antibiotic therapy within the preceding 72 hours and those not consenting to participate in the study were excluded. Specimens for culture and sensitivity were collected by employing standard collection techniques and analyzed at a single microbiological laboratory. All the samples were incubated for 24 hours at 37 C for obtaining aerobic and anaerobic growths. Microbes were identified by their colonial morphology and characteristic biochemical tests. Results: There was male predominance with a male : female of 2.11 : 1 . The mean age was 33 + 16.21 years with a range of 15-68 years. Bacterial growths were obtained in 127 (65.8 % ) specimens while the remaining 66 (34.2 %) specimens yielded no growth. 119 (93.7 % ) isolates were monobacterial whereas 8 (6.29 %) were polybacterial . Pseudomonas aeruginosa 49 ( 36.02%) was the most frequent isolate followed by Escherichia coli 31 (22.79 %), Staphylococcus aureaus 17 ( 12.5 %), Klebsiella pneumoniae 12 (8.82%) , Methicillin resistant Staphylococcus aureaus (MRSA) 10 ( 7.35 %), Acinetobacter 8 (5.88%), Proteus and Enterobacter each 4 (2.94%) and Serratia 1 (0.73%). Sensitivity tests showed variable response to different antibiotics. Conclusion: In this era of evidence based medicine and evidence based surgery the importance of objectivity can’t be overemphasized. For evidence based antibiotic prescribing practices it is mandatory to have periodic audits of the infected wounds to know about the invading microbes and their antibiotic susceptibility. This will also help not only to prevent the emergence of antibiotic resistance owing to the irrational and indiscriminate use of antibiotics but also reduce the financial sufferings of our patients. Key words: Wound infection, Culture and sensitivity, Antibiotic resistance.

Hameed-ud-Din* Muhammad Saaiq** Muhammad ibrahim Khan*** *Assistant Professor **Postgraduate Resident *** Senior Registrar Department of Plastic Surgery, PIMS, Islamabad

Introduction

Surgeon has no greater enemy than wound infection. The history of wound infection is probably as old as that of surgery itself. The ancient Egyptians were the first civilization to have a definite protocol for wound

management with the application of various potions and grease to assist wound healing. 1,2 For centuries the process of wound healing remained a mystery as highlighted by the famous saying by French military surgeon Ambroise Pare’ “I dressed the wound , God healed it . 3 German microbiologist Koch laid down the first scientific definition of infection through his famous

Ann. Pak. Inst. Med. Sci. 2006; 2(2): 93-98 93


Koch’s postulates.4 The discovery of Penicillins by Alexander Fleming (1881-1955) heralded a new era in wound management that led to the proliferation of many other antibiotics especially Cephalosporins in 1950s .4,5 Despite of significant advances in antimicrobial and surgical therapy wound infection continues to pose a major challenge in the context of surgery and trauma. The wound may become infected either by the patient’s own endogenous flora present on the skin, mucosa or in hollow viscera or by exogenous microbes. The chance of developing an established wound infection depends on a variety of factors most notably the count and virulence of the microbes and the host defense mechanisms. Generally infection is associated with a bacterial count of over 10,000 per gram tissue or per square cm in case of burns.6

In Plastic and Reconstructive surgery, wound infection in an elective procedure rather happens to be a catastrophe. As the bacterial spectrum of wounds and their antibiotic susceptibility vary from unit to unit and center to center, the present study was conducted to establish our own database regarding the microbial profile of infected wounds as well as their antibiotic sensitivity profile. Such studies would ensure more appropriate and rational use of antibiotics thereby not only reducing the financial sufferings of the ailing humanity but also help to prevent the emerging antibiotic resistance which poses a major threat to the existing antimicrobial therapies

Materials and Methods This non-interventional descriptive study was undertaken at the department of Plastic and Reconstructive Surgery, Pakistan Institute of Medical Sciences (PIMS), Islamabad from Jan 2004 to Dec. 2005. It prospectively included 193 adult patients of either sex by convenience sampling technique. All patients with local or systemic clinical features of wound infection were included in the study. Patients with healthy wounds, those who had been taking antibiotic therapy within the preceding 72 hours and those not consenting to participate in the study were excluded from the study Specimens for culture and sensitivity were collected by employing standard collection techniques 7 and analyzed at a single microbiological laboratory for culture and sensitivity. After inoculation on appropriate culture media, the specimens were incubated for 24 hours at 37 C for obtaining aerobic and anaerobic growths. The microbes were identified by their colonial morphology and characteristic biochemical tests. Antibiotic susceptibility was tested by employing disc diffusion method according to NCCLS (National Committee for Clinical Laboratory Standards) guidelines using standard antibiotic discs. 8

Sensitivity tests showed variable response to different antibiotics. Table I shows the antibiotic susceptibility profile of the various isolates of Aerobic gram negative bacilli (AGNB). The antibiotic sensitivity of the Methicillin sensitive staphylococcus aureaus (MSSA) and Methicillin resistant staphylococcus aureaus is depicted in table II.

STASTICAL ANALYSIS:

The data were analyzed through SPSS for Windows version 10. The nominal variables were reported as frequency and percentages. The numerical data was reported as mean + standard deviation.

Results Their was male predominance with a male: female of 2.11: 1. The mean age was 33 + 16.21 years with a range of 15-68 years. Fig. I show the various types of wounds from which the bacterial growths were obtained. Bacterial growths were obtained in 127 (65.8%) specimens while the remaining 66(34.2 %) specimens yielded no growth. 119 (93.7 %) isolates were monobacterial whereas 8 (6.29 %) were polybacterial. Pseudomonas aeruginosa 49 (36.02 %) was the most frequent isolate followed by Escherichia coli 31 (22.79 %), Staphylococcus aureaus 17 (12.5 %), Klebsiella pneumoniae 12 (8.82%), Methicillin resistant Staphylococcus aureaus (MRSA) 10 (7.35 %), Acinetobacter 8 (5.88%), Proteus and Enterobacter 4 (2.94%) each and Serratia 1 (0.73%).

Truamatic wounds

75%

Postoperative

wounds5%

Burns19%

Miscellaneous1%

TYPES OF WOUNDS

Fig. I The various types of wounds from which bacterial cultures were obtained.

Discussion Aerobic gram negative bacilli have always been problematic nosocomial pathogens encountered by surgeons as well as physicians, often acquiring antibiotic resistance that limits our therapeutic choices in their management.



TABLE I : THE SENSITIVITY PROFILE OF THE CULTURED AEROBIC GRAM NEGATIVE BACILLI (AGNB). (n=109) ANTIBIOTICS

TESTED Pseudomonas

Aeruginosa (n=49)

E.Coli

(n=31)

Klebsiella Pneumoniae (n=12)

Acinetobacter

(n=8)

Enterobacter

(n=4)

Proteus

(n=4)

Serratia Marcescen

s (n=1) CEPHALOSPORINS

Cefoclor Sensitive Resistant

4(8.1%) 45(91.8%)

3(9.67%) 28(90.32%)

- 12(100%) 1(12.7%) 7(87.5%)_

1(25%) 3(75%)

1(25%) 3(75%)

- 1(100%)

Cefotaxime

Sensitive Resistant

8(16.32%) 41(83.67%)

8(25.80%) 23(74.19%)

5(41.66%) 7(58.33%)

1(12.7%) 7(87.5%)_

2(50%) 2(50%)

- 4(100%) - 1(100%)

Ceftriaxone

Sensitive Resistant

5(10.20%) 44(89.79%)

8(25.80%) 23(74.19%)

6(50%) 6(50%)

1(12.7%) 7(87.5%)

2(50%) 2(50%)

- 4(100%) - 1(100%)

Cefoperazone

Sensitive Resistant

26(53.06%) 23(46.93%)

9(29.03%) 22(70.96%)

2(16.66%) 10(83.33%)

- 8(100%)

3(75%) 1(25%)

1(25%) 3(75%)

- 1(100%)

Cefoperazone+Sulbactum

Sensitive Resistant

49(100%) -

28(90.32%) 3(9.67%)

12(100%) - 6(75%) 2(25%)

3(75%) 1(25%)

4(100%) - - 1(100%)

Ceftazidime

Sensitive Resistant

12(24.48%) 37(75.51%)

15(48.38%) 16(51.61%)

11(91.66%) 1(8.33%)

- 8(100%)

3(75%) 1(25%)

3(75%) 1(25%)

- 1(100%)

Cefpodoxime

Sensitive Resistant

- 49(100%)

- 31(100%) - 12(100%)

- 8(100%)

1(25%) 3(75%)

1(25%) 3(75%)

- 1(100%)

QUINOLONES Ofloxacin

Sensitive Resistant

19(38.77%) 30(61.22%)

2(6.45%) 29(93.54%)

2(16.66%) 10(83.33%)

2(25%) 6(75%)

4(100%) -

- 4(100%) - 1(100%)

Ciprofloxacin

Sensitive Resistant

22(44.89%) 27(55.10%)

4(12.90%) 27(87.04%)

2(16.66%) 10(83.33%)

5(62.5%) 3(37.5%)

4(100%) -

- 4(100%) - 1(100%)

Enoxacin Sensitive Resistant

17(34.69%) 32(65.30%)

2(6.45%) 29(93.54%)

6(50%) 6(50%)

6(75%) 2(25%)

2(50%) 2(50%)

- 4(100%) - 1(100%)

Sparfloxacin

Sensitive Resistant

18(36.73%) 31(63.26%)

15(48.38%) 16(51.61%)

6(50%) 6(50%)

6(75%) 2(25%)

4(100%) -

3(75%) 1(25%)

- 1(100%)

PENICILLINS & ALIKE AGENTS

Carbenicillin

Sensitive Resistant

- 49(100%)

26(83.87%) 5(16.12%)

10(83.33%) 2(16.66%)

7(87.5%) 1(12.7%)

4(100%) -

1(25%) 3(75%)

- 1(100%)

Co-amoxilav Sensitive Resistant

- 49(100%)

15(48.38%) 16(51.61%)

6(50%) 6(50%)

2(25%) 6(75%)

2(50%) 2(50%)

- 4(100%) - 1(100%)

Ampicil+Sulbactm

Sensitive Resistant

- 49(100%)

9(29.03%) 22(70.96%)

1(8.33%) 11(91.66%)

7(87.5%) 1(12.7%)

1(25%) 3(75%)

- 4(100%)

- 1(100%)

Piperacillin+Tazobactum

Sensitive Resistant

35(71.42%) 14(28.57%)

26(83.82%) 5(16.12%)

8(66.66%) 4(33.33%)

4(50%) 4(50%)

4(100%) -

3(75%) 1(25%)

1(100%) -

Imipenem

Sensitive Resistant

47(95.91%) 2(4.08%)

26(83.82%) 5(16.12%)

10(83.88%) 2(16.66%)

7(87.5%) 1(12.7%)

4(100%) -

1(25%) 3(75%)

1(100%) -

Aztreonam

Sensitive Resistant

12(24.48%) 37(75.51%)

2(6.45%) 29(93.54%)

3(25%) 9(75%)

- 8(100%)

2(50%) 2(50%)

2(50%) 2(50%)

- 1(100%)

AMINOGLYCOSIDES Gentamicin

Sensitive Resistant

24(48.97%) 25(51.02%)

21(67.74%) 10(32.25%)

10(83.88%) 2(16.66%)

6(75%) 2(25%)

- 4(100%)

- 4(100%)

- 1(100%)

Tobramycin

Sensitive Resistant

26(53.06%) 23(46.93%)

- 31(100%)

6(50%) 6(50%)

- 8(100%)

1(25%) 3(75%)

1(25%) 3(75%)

- 1(100%)

Amikicin Sensitive Resistant

30(61.22%) 19(38.77%)

26(83.87%) 5(16.12%)

12(100%) - 6(75%) 2(25%)

1(25%) 3(75%)

2(50%) 2(50%)

- 1(100%)



In our study Pseudomonas aeruginosa (36.02%) was

TABLE II : Antibiotic Susceptibility profile of the isolated Gram positive organisms . (n=27

ANTIBIOTICS TESTED MSSA ( n=17)

Sensitive Resistant

MRSA (n=10)

Sensitive Resistant PENICILLINS

Oxacillins 16(94.11%) 1 (5.89%) - 10(100%)

Amoxycillin 15(88.23%) 2(11.76%) - 10(100%)

Co-amoxiclav 17(100%) - - 10(100%)

Penicillin G 2(11.78%) 15(88.23%) - 10(100%)

Ampicillin + Salbactum 8(47.05%) 9(52.94%) - 10(100%)

Piperacillin + Tazobactum 17(100%) -

Impipenem 17(100%) - 2(20%) 8(80%)

CEPHALOSPORINS

Cefazolin 9(52.94%) 8(47.05%) - 10(100%)

Cefaclor 8(47.05%) 9(52.94%) - 10(100%)

Cefotaxime 11(64.70%) 6(35.29%) - 10(100%)

Ceftriaxone 11(64.70%) 6(35.29%) - 10(100%)

Cefoperazone 10(58.82%) 7(41.17%) - 10(100%)

Cefoperazone + Salbactum 17(100%) - - 10(100%)

Ceftazidime 16(94.11%) 1(5.89%) - 10(100%)

QUINOLONES Ofloxacin 16(94.11%) 1(5.89%) - 10(100%)

Ciprofloxacin 14(82.35%) 3(17.64%) - 10(100%)

Sparfloxacin 15(88.23%) 2(11.76%) - 10(100%)

Enoxacin 16(94.11%) 1(5.89%) - 10(100%)

MISCELLANEOUS Erythrocin 6(35.29%) 11(64.70%) 2(20%) 8(80%)

Vancomycin 17 (100%) - 10(100%) -

Fusidic acid 17(100%) - 7(70%) 3(30%)

Teicoplanin 17(100%) - 7(70% 3(30%)



the most frequently cultured microbe followed by Escherichia coli 22.79% and Staphylococcus aureus 19.85%. Khan JS et al 9 reported Staphylococcus aureus (45%), E.Coli (14%) and Pseudomonas aeruginosa ( 6 % ) as the three most frequent isolates from skin and soft tissue infections. In an other study on the microbial profile of patients in intensive care unit Mahmood A 10 reported Staphylococcus aureus (39.53 %), Pseudomonas aeruginosa (15.11 %) and Escherichia Coli (10.4%) as the commonest bacterial isolates. Batool T et al 11 recorded Pseudomonas aeruginosa, Staphylococcus aureus and Klebsiella pneumoniae as the most common microbial isolates from burn wounds. Unlike the other studies , Pseudomonas aeruginosa and Escherichia Coli were the two most frequent microbial isolates in our study. This reflects our local microbial flora and negates the common perception that gram positive cocci are the dominant pathogens causing wound infection. With this evidence based new scenario , if our initial empiric antibiotic cover is still merely directed against gram positive organisms it would simply be irrational and counterproductive leading to wasteful use of our limited resources. In our study MRSA isolates were 37 % of the Staphylococcal contaminants. Other local studies have reported variable incidence ranging from 5 % 12 to 38.5% 13 Internationally the reported incidence of MRSA among Staphylococcal isolates range from less than 10 % to over 65 % . 14,15 The emergence of MRSA was first reported in Europe in the early 1960s and even today it continues to be a major threat to antimicrobial therapy as Methicillin resistance means resistance to all beta lactam antibiotics .16 ,17 It has rather proven to be one of the most widespread and durable nosocomial pathogens of the late 20th century. 18 MRSA is spread by direct contact and healthcare workers are the most frequent culprits responsible for their transmission from one patient to another by their transiently colonized hands. This cross infection can be effectively prevented by adoption of standard aseptic measures by all hospital workers. Emergence of antibiotic resistance is a major concern as it limits our therapeutic choices for infection control. Pseudomonas aeruginosa is one of the difficult to treat microbes. Ceftazidime has historically been perceived as an effective antibiotic against it, however in our study only 24.48 % of its isolates were sensitive to it. Rather there was 100% sensitivity to Cefoperazone + Sulbactum, 95.91 % to Imipenem and 53 % to Cefoperazone. The antibiotic susceptibility of various other AGNB showed remarkable variability as shown in table I .

The MRSA isolates in our study were generally multi drug resistant. Except for Vancomycin to which 100 % sensitivity of MRSA was found, there was variable

antibiotic susceptibility pattern. Sensitivity to Fuscidin and Teicoplanin was 70 % each while there was only 20 % sensitivity to both imipenem and Erythromycin. Table II shows the in vitro activity of the various tested antimicrobial agents against MRSA in our study. Bukhari MH et al 13 reported 96 % , 94 % and 86 % susceptibility of MRSA to Vancomycin, Teicoplanin and Fuscidic acid respectively. Qureshi AH 19 and Latif S 20 also reported 100 % sensitivity of MRSA to Vancomycin which is in conformity with our study. Our study proves that Vancomycin is the only agent that can be confidently employed on empirical basis to combat life threatening infection caused by multi drug resistant strains of MRSA, however the worldwide reports of intermediate resistance to Vancomycin warrants regular periodic monitoring of the prevalence and antibiotic sensitivity of this challenging microbe . 21-23

Conclusion In this era of evidence based medicine and evidence based surgery the importance of objectivity can’t be overemphasized. For evidence based antibiotic prescribing practices it is mandatory to have periodic audits of the infected wounds to know about the invading microbes and their antibiotic susceptibility. This will also help to prevent the emergence of antibiotic resistance owing to the irrational and indiscriminate use of antibiotics but also reduce the financial sufferings of our patients.

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micobial profile of wound muhammad saaiq

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