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Egyptian Journal of Medical Microbiology Volume 24 / No. 3 / July 2015 95-102 ORIGINAL ARTICLE Diabetic foot Infection: Microbiological Causes with Special Reference to their Antibiotic Resistance Pattern 1 Reham Dwedar*, 2Dalia Kadry Ismail and 3Amr Abdulbaky Lecturer of Medical Microbiology& Immunology Faculty of Medicine, Cairo University Lecturer of Clinical and Chemical pathology Department, Faculty of Medicine, Cairo University 3 Associate Professor in General and Vascular Surgery Faculty of Medicine, Cairo University 1 2 ABSTRACT Key words: Diabetic foot infections, Polymicrobial, ESB, Carbapenemases Producers, MRSA, MDR Background: Foot infections are one of the major complications of diabetes mellitus and are a significant risk factor for lower extremity amputation. Providing effective antimicrobial therapy is an important component in treating these infections. Objectives: This study investigates the microbial causes of diabetic foot infections and their antibiotic susceptibility pattern. Methodology: A prospective study of 80 patients with diabetic foot infections admitted to Cairo university hospitals was undertaken. Samples were collected by using sterile swabs and they were processed. Detailed antimicrobial susceptibility testing was performed according to CLSI guidelines 2014, including testing for Methicillin Resistant Staphylococcus aureus (MRSA), ESBL and carbapenemase production. Results: In the present study, a single organism was isolated from 48.75% patients and mixed bacterial growths were seen in 51.15% patients. Gramnegative bacteria (56.08%), were more commonly isolated compared with Gram-positive bacteria (27.7%), while gram-negative anaerobes accounted for (8.1%),and Candida species (8.1%). The commonest isolate was Proteus mirabilis (16.8%) followed by Escherichia coli (13.5%), Methicillin Sensitive Staphyloccus aureus (MSSA) (11.4%), Pseudomonas spp (10.8%), and MRSA (10.1%). Among the gram-negative bacteria 49% were ESBL producers and 3.6%were carbapenemases producerswhile46.8% Staphylococcus aureus were methicillin resistant Staphylococcus aureus. Overall 42.5% isolates were identified as MDR. Vancomycin was found to be the most effective against Gram-positive bacteria, whereas imipenem, amikacin and colistin were most effective against Gram-negative bacteria. Conclusion: This study showed a preponderance of gram negative bacilli among the isolates from the diabetic foot ulcers. Knowledge on the antibiotic sensitivity pattern of the isolates will be helpful in determining the drugs for the empirical treatment of diabetic ulcers INTRODUCTION Diabetic foot is one of the most feared complications of diabetes and is the leading cause of hospitalisation in diabetic patients1,2. Diabetic patients have a lifetime risk as high as 25% for developing foot ulceration 3. Diabetic ulcers have 15 to 46 times higher risk of limb amputation than foot ulcers due to other causes 4. Every year more than a million diabetic patients require limbamputation1. The impaired microvascular circulation in patients with diabetic foot limits the access of phagocytes favouring development of infection2,5. * Corresponding Author: Reham Ali Dwedar Lecturer of Medical Microbiology& Immunology, Faculty of medicine, Cairo University E-mail: [email protected], Tel: 01222744624 Egyptian Journal of Medical Microbiology Diabetic foot infections are oftenpolymicrobial.4,5 Escherichia coli, Proteus spp., Pseudomonas spp., Staphylococcus aureus and Enterococcus spp. are the most frequent pathogens contributing to progressive and widespread tissue destruction2,5. The increasing association of multi-drug resistant (MDR) pathogens with diabetic foot ulcers further compounds the challenge faced by the physician or the surgeon in treating diabetic ulcers without resorting to amputation6. Infection with MDR pathogens is also responsible for the increased duration of hospitalization and cost of management. AIM OF THE WORK The present study was carried out to determine the relative frequency of different microbial isolates cultured from community-acquired diabetic foot 95 Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 infections and to determine their in-vitro susceptibility to the commonly used antibiotics. METHODOLOGY The current study is an observational prospective study that was carried out at the Department of General Surgery, Kasr Alainy Hospitals, Cairo University. 80 diabetic patients with foot ulcers were included in this study, which was conducted from July 2014 to December 2014.The demographics of the participants with regards to age, sex, the duration of diabetes, complications of diabetes, the type of treatment which was received and the presence of other systemic illnesses were recorded. The patients were also assessed clinically and the ulcers were graded according to Wagner’s grade7. Wagner’s Classification of Diabetic Foot Ulcers Grade 0: no ulcer in a high-risk foot. Grade 1: superficial ulcer involving the full skin thickness but not underlying tissues. Grade 2: deep ulcer, penetrating down to ligaments and muscles, but no bone involvement or abscess formation. Grade 3: deep ulcer with cellulitis or abscess formation often with osteomyelitis. Grade 4: localized gangrene. Grade 5: extensive gangrene involving the whole foot. Sample collection. The samples were collected after obtaining informed consents from the patients. Samples were collected from the deeper portion of the ulcers by asterileswab, which was dipped in sterile glucose broth. The samples were collected by making a firm, rotatory movement with the swabs. A direct Gram stained smear of the specimen was examined. The specimens were incubated aerobically on blood agar, Chocolate agar and MacConkey’s agar and anaerobically on blood agar for isolation of aerobic and anaerobic bacteria at 37oC, the plates were examined for growth the next day for facultative anaerobic bacteria and after 4-5 days for anaerobic bacteria. Further processing was done according to the nature of the isolate, as was determined by Gram staining and the colony morphology and, necessary biochemical tests were performed. Gram negative organisms were identified using oxidase test, citrate utilization, urea hydrolysis, triple sugar iron (TSI), lysin decarboxylation, indole production and API 20 E identification panel for Enterobacteriaceae were performed for species level identification. Staphylococcus spp. was identified on the basis of positive catalase test, coagulase enzyme and growth on mannitol salt agar. Streptococcus spp. was identified by negative catalase test and esculin hydrolysis. Yeasts were identified by Gram's staining and germ tube test (GTT) 8 . 96 Antibiotic Susceptibility testing: The antibiotic susceptibility testing was done by the Kirby Bauer disc diffusion method, as per the CLSI guidelines, 20149. The antimicrobial discs which were used were those of Ampicillin (20μg), Aztreonam (30μg), Gentamicin (10μg), Amikacin (30μg), Cefaclor (30μg), Cefazolin (30μg), Cefoxitin (30μg), Cefotaxime (30μg) Cefepime (30μg), AUG=Amoxicillin-Clavulenic acid30 (20+10 μg), Piperacillin/tazobactam (100+10μg), Imipenem (10μg), Meropenem (10 μg), Ciprofloxacin, (5μg), Levofloxacin (5μg), Sulph-trimethoprim (1.25 + 23.75 μg) and Colistin (10μg) for the Gram negative bacilli. Ampicillin (20μg),AUG= Amoxicillin-Clavulenic acid 30 (20+10 μg), Cefoxitin (30μg), Cefotaxime (30μg), Imipenem (10μg) Clindamycin (2μg), Erythromycin (15μg), Vancomycin (30μg), Gentamicin (10μg), Amikacin (30μg), Ciprofloxacin (5μg), Levofloxacin (5μg), Sulph-trimethoprim (1.25+23.75μg), Fusidic (10 μg), and Rifampin (5μg), were used to study the susceptibility patterns of the Gram positive cocci. MRSA, ESBL and carbapenemase production were detected as per the CLSI guidelines 20149. MRSA detection: The phenotypic test for the detection of MRSA was done by using a cefoxitin (30 μg) disc. A zone of inhibition which was equal to or more than 22 mm was considered as susceptible to Cefoxitin and the organism was reported as Methicillin Sensitive Staphylococcus aureus. Those isolates which produced a zone of inhibition which was less than or equal to 21 mm were considered as Methicillin Resistant Staphylococcus aureus (MRSA). ESBL production was confirmed by using discs of Ceftazidime (30 μg) and Ceftazidime Clavulanic acid (30/10μg) respectively. The test organism was inoculated as a lawn on a Muellar Hinton agar plate and the above mentioned discs were placed on the plate. The plates were incubated at 370C overnight and they were examined next day. An increase in the zone diameter, which was equal to or more than 5 mm for the antimicrobial agent which was tested in combination with clavulanic acid, in comparison to the antimicrobial which was tested alone, indicated that the strain was an ESBL producer. Carbapenemase production was detected by using the Modified Hodge test. A 0.5 Mac Farland’s suspension of ATCC Escherichia coli 25922, was diluted 1 in 10 in sterile saline. This was inoculated on a Muellar Hinton agar plate, as for the routine disc diffusion testing. The plate was dried for 5 minutes and a disc of Meropenem 10 μg was placed in the centre of the agar plate. [3-5] colonies of the test organism were picked and inoculated in a straight line, from the edge of the disc, upto a distance of at least 20mm. The plates were incubated at 370C overnight and they were Egyptian Journal of Medical Microbiology Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 examined next day. They were checked for an enhanced growth around the test organism, at the intersection of the streak and for a zone of inhibition. The presence of an enhanced growth indicated Carbapenemase production, and the absence of an enhanced growth meant that the test isolate did not produce carbapenemase. RESULTS A total of 80 diabetic patients, 48males (57%) and 32 females (43%), aged between 35 to 75 years and duration of diabetes from 5 to 32 years were investigated. The maximum number of patients (33%) was in the age group of 60 to 65 years. The next most prevalent age group was between 50 and 55 years (27%). Out of 80 test samples, 36 Diabetic foot ulcer cases were included in Wagner’s grade 1,40 were included in Wagner’s grade 2, and 4 were included in Wagner’s grade3. Out of 80 lesions only 3 proved sterile, in the remaining 77 patients a total of 148bacteria were isolated resulting in an average of 1.92organisms per lesion. In this study, gram negative bacilli were isolated more frequently than gram positive cocci with gramnegative aerobes accounting for 83 (56.08%), aerobic gram-positive cocci 41(27.7%), gram-negative anaerobes 12 (8.1%) and Candida species 12 (8.1%). The commonest isolate was Proteus mirabilis(16.8%) followed by Escherichia coli(13.5%), Methicillin Sensitive Staphyloccus aureus (MSSA) (11.4%), Pseudomonas spp (10.8%), and Methicillin Resistant Staphylococcus aureus (MRSA) (10.1%).The other organisms which were isolated were Proteus vulgaris, Klebsiella oxytoca Streptococcus pyogenes, Klebsiella pneumoniae, Enterococcus spp, Acinetobacter spp, Citrobacter spp, CoNS and Enterobacter, gram-negative aerobes and Candida species. In the present study, single organisms were isolated from 39(48.75%)patients and polymicrobial infections were seen in 41 (51.15%) patients. The details of the organisms which were isolated from the infected foot lesions have been tabulated in [Table1]. Gram-positive organisms were found as the only isolate in 14 (17.5%) patients, while 25 (31.25 %) patients had only gramnegative organisms. Table 1: Monomicrobial and Polymicrobial isolates from the diabetic foot infections No. of isolates No. of isolates Bacteria (Mono microbial) (Poly microbial) 39 109 Proteus mirabilis 6 19 Escherichia coli 5 15 MSSA 5 12 Pseudomonas spp 7 9 MRSA 7 8 12 Fungi anaerobic gram-negative bacilli 12 Enterococcus spp 2 4 Proteus vulgaris 2 4 Klebsiella oxytoca 1 5 Klebsiella pneumonia 4 Acinetobacter spp 2 1 Streptococcus pyogenes 2 Citrobacter spp 2 CoNS 1 Enterobacter spp 1 Total No. of isolates (%) 148 25 (16.89%) 20(13.5%) 17(11.48%) 16(10.8%) 15(10.1%) 12(8.1%) 12(8.1%) 6(4%) 6(4%) 6(4%) 4(2.7%) 3(2%) 2(1.35%) 2(1.35%) 1(0.67%) 1(0.67%) The antibiotic susceptibility patterns of the isolates have been tabulated in [Table2] which displays the antibiotic resistance patterns of the gram negative bacilli and [Table 3] displays the antibiotic resistance patterns of the gram positive cocci. Egyptian Journal of Medical Microbiology 97 Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 Table 2: Antibiotic Resistance pattern of the Gram negative bacilli. (% of resistance) Antimicrobial category Antimicrobial agent Proteus (n=31) E.coli (n=20) Pencillins AMP 100 Combined penicillins AUG TZP CFZ CEC CTX CPM Non-extended spectrum cephalosporins; 1st and 2nd generation cephalosporins Extended-spectrum cephalosporins; 3rd and 4th generation cephalosporins Cephamycins Monobactams Carbapenem Klebsiella spp. (n =10) 100 Acinetobacter spp (n=3) ….. Citrobacter spp (n=2) 100 Enterobacter (n=1) 100 Pseudomonas aeruginosa (n=16) ……. 6.5 13 100 77 25 25 100 65 25 100 75 100 30 100 60 66.6 33.3 100 100 50 0 100 50 0 0 100 100 58 48 60 50 68.7 68.7 50 50 66.6 66.6 50 0 100 100 100 FOX 32 10 31 20 33.3 50 0 ATM 58 60 75 60 66.6 50 100 IPM 0 0 6.25 10 33.3 0 0 MEM 0 0 33.3 Aminoglycosides AK 12 10 21 20 0 0 0 GN 64.5 40 37.5 30 66.6 0 0 Quinolones CIP 12 40 37.5 30 66.6 50 100 LEV 14 20 31 20 33.3 0 0 SulphTrimetoprims SXT 80 40 ……. 60 100 100 100 Polymyxins CST 100 0 0 0 0 0 0 AMP= Ampicillin ,AUG= Amoxicillin-Clavulenic acid ,TZP=Piperacillin+Taobactam , CFZ=Cefazolin,, CEC=Cefaclor, CTX = Cefotaxime, CPM= Cefepime , FOX=Cefoxitin, ATM=Aztreonam IPM=Imipenem ,MEM= Meropenem ,AK= Amikacin ,GN= Gentamicin ,CIP= Ciprofloxacin ,LEV= Levofloxacin , ,SXT= Sulphameth-Trimeth ,TM= Trimethoprim, CST=Colistin Table 3: Antibiotic Resistance pattern of the Gram positive cocci. (% of resistance) Antimicrobial category Antimicrobial agent MSSA (n=17) MRSA (n =15) Enterococcus spp (n= 6) Streptococcus pyogen (n =2) CoNS (n= 1) Anti-staphylococcal b-lactams Pencillins FOX 0 100 …….. 0 0 AMP 58.8 100 0 100 Combined penicillins Extended-spectrum cephalosporins; 3rd Cephalosporins Carbapenim AUG CTX 0 0 100 100 0 0 0 0 ………. 0 100 33.3 0 0 IPM CLI 23.5 33 ……….. 0 0 E 29 46.6 50 50 100 FUS 0 20 33.3 0 VA 0 0 0 0 0 CIP 11.7 33 50 0 LEV 0 26.6 66.6 0 Aminoglycosides AK 0 20 33.3 0 GN 0 33 66.6 0 SulphTrimethoprims SXT 29 66.6(10 …… 100 Ansamycins RIF 0 6.66(1 0 0 0 FOX=Cefoxitin ,AMP= Ampicillin ,AUG= Amoxicillin-Clavulenic acid, CTX = Cefotaxime, IPM= Imipenem , CLI=Clindamycin ,E= Erythromycin, FUS=Fusidic acid, VA= Vancomycin, , CIP= Ciprofloxacin, LEV= Levofloxacin, AK= Amikacin ,GN= Gentamicin ,SXT= Sulphtrimethoprim , RIF=Rifampin. Cefoxitin represents all other b-lactams (and cephamycins) and resistance to either of these predicts non-susceptibility to all categories of b-lactam antimicrobials Lincosamides Macrolides Fucidanes Glycopeptides quinolones Among the 83 isolates belonging to Enterobacteriaceae and the non-fermenting gram-negative bacteria 41(49%) were ESBL producers and 3(3.6%) were carbapenemases producers as shown in [ Fig-1] while 15 out of the 32 (46.8%) Staphylococcus aureuswere resistant to cefoxitin and were therefore considered as methicillin resistant Staphylococcus aureus (MRSA). 98 Egyptian Journal of Medical Microbiology Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 Fig. 1: Percentage of ESBL and carbapenamases producers within the Gram Negative bacilli. Overall 63 out of the 148 (42.5%) isolates were identified as MDR by being resistant to three or more antimicrobial classes and none were described as extensively drug-resistant (XDR) by being nonsusceptible to at least one agent in all but two or fewer antimicrobial categories. DISCUSSION Diabetic patients often have chronic non-healing foot ulcers due to several underlying factors such as neuropathy, high plantar pressures and peripheral arterial disease; such chronic long-standing ulcers are more prone for infection which further delays the wound healing process. A wide range of bacteria can cause infection in these patients.10 In cases of chronic and deep foot ulcers with tissue necrosis and gangrene or in patients with recent antibiotic treatment has failed, infection usually occurs with 3-5 different species of bacteria2,11,12. In the present study, single organisms was isolated from 39 (48.75%) patients and mixed bacterial growths were seen in 41 (51.15%) patients The findings of this study correlate with Shanmugam et al13and Renina et al.14in which single bacterial isolate was seen in 50% and 41.1% of the samples respectively and mixed bacterial growth was seen in 50 % and 58.9% of the samples respectively. However our finding was not matching with Zubair et al.,15, Anandi et al., 2, Ramakant et al. 16, Pappu et al.17 and Citron et al.18whoreported 56.6%, 19%, 23 %, 92% and 16.2 % of their isolates respectively were monomicrobial infections and 33%, Egyptian Journal of Medical Microbiology 67%, 66%, 7.7% and 83 % respectively were polymicrobial infections . The present study revealed that Gram-negative bacteria were the predominant pathogens constituting 83 (56.08%) of the isolates, while aerobic gram-positive cocci 41(27.7%), gram-negative anaerobes 12 (8.1%) and Candida species 12 (8.1%). This difference could be explained by different types of infections as most mild infections are caused byaerobic gram-positive cocci such as S.aureus, and Streptococci while deeper limb threatening infections are usually polymicrobial and caused by aerobic gram-positive cocci, gramnegative bacilli and anaerobes 19. Similarly, in several recent studies, gram-negative bacteria were the commonest agents as observed by Benwan et al., 20 in Kuwait, Pappu et al.,17, Bansal et al.21 Shankar et al.22, Gadepalli et al.5, Raja 23 and Renina et al. 14who reported that gram negative bacilli comprised 51.2%,76% 76 %, 57.6 %,, 51.4 %,52 % , 67 respectively of the total organisms which were isolated in their studies. Our findings were not matching with earlier studies by Citron et al., 18 and Abdulrazak et al.24who reported gram-positive bacteria mainly Staphyloccus aureus was the predominant pathogen, which comprised 57.2% and73.6% of their isolates respectively Therefore, there seems to be a changing trend in the organisms causing diabetic foot infections, with gram-negative bacteria replacing gram-positive bacteria as commonest agents. Thus, it may be essential to select antibiotics that are more effective against Gram-negative bacteria in contrast to Gram-positive organisms, which clinicians are inclined to prescribe on observing deep tissue infection or infected gangrene. 99 Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 The present study showed that Proteus mirabilis was the commonest gram-negative aetiological agent, followed by Escherichia coli, Pseudomonas spp, while Staphylococcus aureus was the commonest grampositive bacteria. This was matching with a study by Raja23 which showed that Proteus spp were the commonest gram-negative aetiological agent also this was in agreement with Ramakant et al.16 who studied the changing microbiological profile of pathogenic bacteria isolated from DFU in, Lucknow, India over a period of 8 years; 1632 cultures were isolated from 434 patients with diabetic foot infections, showing that Gram-negative bacterial infection was increasing from 50.6% to 66% and the most common isolates were P. aeruginosa, E. coli and Proteus spp. Anaerobic bacteria are almost always isolated with aerobes from diabetic foot infections. Gram-negative anaerobes were recoverd from 12 (8.1%) patients and in mixed infections, this was in agreement with Abdulrazak et al.24, Ako Nai et al.25, El-Tahawy19 and Hayat 26in which anaerobes was recovered in 10.5%, 9.2% ,7%, 2% of their isolates respectively. But at a lower rate than Benwan et al.,20in which anaerobes accounted for15.3%.of their isolates. Candida was recovered from 12 (8.1%) patients and in mixed infections. This was consistent with Abdulrazak et al.24, El-Tahawy19 andHayat26 in which fungi were recovered in 7%., 5% and4% of their isolates respectively. The awareness about the antibiotic susceptibility pattern of the isolates from diabetic foot infections is crucial for appropriate treatment of cases. It was observed that 49% of the members of Enterobacteriaceae and the non-fermenting gramnegative bacteria were ESBL producers and 3.6% were carbepenemase producers. Similarly Gadepalli et al.,5also have documented ESBL production in 44.7% of bacterial isolates while Umadevi et al.27and, Akhi et al28demonstrated that ESBLproduction was observed in 56% and 31.3%. of Enterobacteriaceae members respectively. ESBL producers are resistant to all extended-spectrumcephalosporins and aztreonam. Imipenem and piperacillin-tazobactam and recently polymixins are the drugs of choice for successful control of such ESBL producers. Among the 83 isolates belonging to Enterobacteriaceae and the non-fermenting gramnegative bacteria, only3 (3.6%) were carbepenemase producers which is not matching with Shanmugam et al13, who demonstrated that carbapenamase production was observed in 31% of their gram negative isolates. 46.8% of the Staphylococcus aureus were considered as MRSA. Staphylococcus aureus isolates in our study were found to be uniformly susceptible to vancomycin, Umadevi et al., 27 demonstrated that 65.5% of S aureus were MRSA positive while other studies on diabetic foot infections which have reported only 10 – 100 44% MRSA5,22,29,30. A British study 31 compared the prevalence of pathogenic organisms isolated from foot ulcer in diabetic patients at a diabetic foot clinic. MRSA was isolated in 30.2% of the patient in 2001 almost double the proportion carrying this organisms in 1998. Enterococci are considered commensals with low virulence except in compromised patients, such as diabetics, in whom they can act as opportunistic pathogens. All the Enterococcus spp. Were susceptible to vancomycin, though they showed varying susceptibility to other antibiotics. Similarly, in another study all enterococcal isolates were noted to be uniformly susceptible to vancomycin5. Hence, vancomycin can be considered as an important drug in the empirical regimen for treatment of diabetic foot infections especially in settings with high resistance to other antibiotics. Overall 63 of the 148 (42.5%) isolates were identified as MDR by being resistant to three or more antimicrobial classes. In our study, infection with microorganisms resistant to multiple drugs was associated with history of recent antibiotic therapy. A similar result was obtained by kandrmir et al.32Earlier studies on diabetic foot infections reported 20 - 40% of the isolates to bemulti-drug-resistant22. However higher rates were observed by Gadepalli et al5in which 72% of the patients with diabetic ulcers were found to be infected with MDR organisms .It is known that the group of multi-resistant bacteria usually causes more damage to the infected patients when compared to those outcomes of patients afflicted by susceptible strains from the same species. This data can be seen in infections caused by bacteria such as Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter, and others. The reason for such unsatisfactory results is not necessarily linked to the virulence profile of the strain, but to the antimicrobial empiric treatment that was given to these patients in the beginning of the infection33. All isolated Gram-positive bacteria sensitive to vancomycin, while imipenem and amikacin had acceptable sensitivity against Gram-negative bacteria. This is compatible with results of other studies 20,22,23,27. This may be due to the decrease in the use of amikacin in diabetic patients because of its nephrotoxic effect. In our study all aerobic gram-negative strains were fully susceptible to Colistin. Parenteral use of polymyxins was abandoned ~20 years ago in most countries, except for treatment of patients with cystic fibrosis, because of reports of common and serious nephrotoxicity and neurotoxicity. Recent studies of patients who received intravenous polymyxins for the treatment of serious P. aeruginosa and Acinetobacter baumannii infections of various types, including pneumonia, bacteremia, and urinary tract infections, have led to the conclusion that these antibiotics have Egyptian Journal of Medical Microbiology Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 acceptable effectiveness and considerably less toxicity than was reported in old studies34. A combination regimen consisting of amikacin, piperacillin-tazobactam or imipenem and vancomycin seems to be the most prudent empirical treatment of diabetic foot infection. This empirical therapy can be later modified appropriately based on the antibiogram of the isolates from the individual patients. CONCLUSION This study showed a preponderance of gram negative bacilli among the isolates from the diabetic foot ulcers. Knowledge of the antibiotic susceptibility pattern of the isolates from diabetic foot infections is crucial for planning the appropriate treatment of these cases prior to getting the susceptibility reports from the laboratory. REFERENCES 1. Khanolkar MP, Bain SC, Stephens JW. The diabetic foot. QJM 2008; 101: 685-95. 2. Anandi C, Alaguraja D, Natarajan V, Ramanathan M, Subramaniam CS, Thulasiram M, et al.Bacteriology of diabetic foot lesions. Indian J Med Microbiol 2004; 22: 175-8. 3. Singh N, Armstrong DG, Lipsky BA. Preventing foot ulcers in patients with diabetes. JAMA. 2005; 293: 217-28. 4. .Alavi SM, Khosravi AD, Sarami A, Dashtebozorg A, Montazeri EA. Bacteriologic study of diabetic foot ulcer. Pak J Med Sci 2007; 23: 681-4. 5. Gadepalli R, Dhawan B, Sreenivas V, Kapil A, Ammini AC , Chaudhry R . Aclinico microbiological study of diabetic foot ulcers inan Indian tertiary care hospital. Diabetes Care 2006; 29: 1727-32. 6. Yoga R, Khairul A, Sunita K, Suresh C. Bacteriology of diabetic foot lesions. Med J Malaysia 2006; 61:14-6. 7. Wagner. Orthopedics 1987;10:163-72. 8. Collee JG and Marr W. Specimen collection, culture containers andmedia. In: Collee JG, Fraser AG, Marmion BP, Simmons A.eds. Mackie & McCartney Practical Medical Microbiology,14th edition New York. Churchill Livingstone, 1996; 85-111. 9. Clinical and Laboratory Standards Institute. Performance standards for antimicrobial susceptibility testing; 24th informational supplement. CLSI M100-S24.2014; Clinical and Laboratory Standards Institute, Wayne, PA. 10. Frykberg RG, Armstrong DG, Giurini J, Edwards A, Kravette M, Kravitz S, et al. Diabetic foot disorders: a clinical practice guideline. American College of Foot and Ankle Surgeons. J Foot Ankle Surg 2000; 39: S1-60. Egyptian Journal of Medical Microbiology 11. Lipsky BA, Berendt AR, Gunner DH, Embil JM, Joseph WS, Karchmer AW, et al. Diagnosis and treatment of diabetic foot infection. Clin Infect Dis 2004;39(7):885-910. 12. Lipsky BA, Berendt AR. The Diabetic Foot: Essentials of Managing Infection Complications. London: Current Medicine Group; 2008. 13. Shanmugam P, Jeya M, Linda S. Bacteriology of diabetic foot ulcers, with a special reference to multidrug resistant strains. Journal of Clinical and Diagnostic Research. 2013 ;7(3): 441-445. 14. Renina L, Llanes I, Pena AC, Cauton-Valera R. Clinical microbiological profile and outcome of diabetic patients with foot ulcers admitted at the Quirino Memorial Medical Center. Phil J Microbiol Infect Dis 2001; 30:101–107. 15. Zubair M, Malik A, Ahmad J. Clinico-bacteriology and risk factors for the diabetic foot infection with multidrug resistant microorganisms in North India. Biol Med. 2010; 2 (4): 22-34. 16. Ramakant P, Verma AK, Misra R, Prasad KN. Changing Microbiological profile of pathogenic bacteria in diabetic foot infections: time to rethink on which empirical therapy to chose? Diabetologica. 2011; 54 (1): 58-64. 17. Pappu AK, Sinha A, Johnson A. Microbiological profile of diabetic foot ulcer. Calicut Med Journal. 2011; 9(3):e:1-4. 18. Citron DM, Goldstein EJC, Merriam VC, Lipsky BA. Bacteriology of moderate to severe diabetic foot infections and invitro activity of antimicrobial agents. J Clin Microbiol. 2007; 45 (9):2819–28. 19. El-Tahawy AT. Bacteriology of diabetic foot Infections Saudi Medical Journal 2000; Vol. 21 (4): 344-347. 20. Benwan KA, Mulla AA, Rotimi VO. A study of the microbiology of diabetic foot infections in a teaching hospital in Kuwait. J Infect Public health. 2012; 5(1):1-8. 21. Bansal E, Garg A, Bhatia S, Attri A, Chander J. Spectrum of microbial flora in diabetic foot ulcers. Indian J Pathol Microbiol 2008; 51:204–208. 22. Shankar EM, Mohan V, Premalatha G, Srinivasan RS, Usha AR. Bacterial etiology of diabetic foot infections in South India. Eur J Intern Med 2005;16:567–570. 23. Raja NS. Microbiology of diabetic foot infections in a teaching hospital in Malaysia: a retrospective study of 194 cases. J Microbiol Immunol Infect 2007; 40:39–44. 24. Abdulrazak A, Bitar ZI, Al-Shamali AA, and Mobasher LA. Bacteriological study of diabetic foot infections. J. Diabetes Complications 2005; 19:138-141. 25. Ako Nai AK, Ikem IC, Akinloye OO, Aboderin AO, Ikem RT, Kassim OO. Characterization of bacterial isolates from diabetic foot infections in Ile-Ife, Southwestern Nigeria. 2006; 16(3):158-164. 101 Dwedar et al. / Diabetic foot Infection: Microbiological Causes with Special Reference, Volume 24 / No. 3 / July 2015 95-102 26. Hayat AS., Khan AH., Masood N. and Shaikh N. Study for microbiological pattern and in vitro antibiotic susceptibility in patients having diabetic foot infections at Tertiary Care Hospital in Abbottabad. World Appl. Sci.J.2011;12: 123-131 27. Umadevi S, Kumar S, Joseph NM, Easow JM, Kandhakumari G, Srirangaraj S, Raj S, Stephen S. Microbiological study of diabetic foot infections. Indian Journal of Medical Specialities 2011; 2(1):12-17. 28. Akhi MT, Ghotaslou R, Asgharzadeh M, Varshochi M, Pirzadeh T, Memar, MY, Alizadeh, N Bacterial etiology and antibiotic susceptibility pattern of diabetic foot infections in Tabriz, Iran. GMS Hygiene and Infection Control. 2015;10:Doc02. 29. Tentolouris N, Jude EB, Smirnof I, Knowles EA, Boulton AJ. Methicillin-resistant Staphylococcus aureus: an increasing problem in a diabetic foot clinic. Diabet Med 1999; 16:767-71. 102 30. Goldstein EJ, Citron DM, Nesbit CA. Diabetic foot infections. Bacteriology and activity of 10 oralantimicrobial agents against bacteria isolated from consecutive cases. Diabetes Care 1996; 19: 638-41. 31. Dang CA, Prasad YD, Boulton AJ, Jude EB. Methicillin resistant Staphylococcus aureus in diabetic foot clinic:a worsening problem. Diabet Med 2003; 20:159-61. 32. Kandemir O, Akbay E, Sahin E, Milcan A, Gen R. Risk factors for infection of the diabetic foot with multi-antibiotic resistant microorganisms. J Infect 2007; 54:439-45. 33. Isturiz RE. Optimizing antimicrobial prescribing. Int J Antimicrob Agents. 2010;36(Suppl 3):S19– S22. 34. Falagas ME, Kasiakou SK. Colistin: the revival of polymyxins for the management of multidrugresistant gram-negative bacterial infections. Clin Infect Dis 2005;40:1333-41 Egyptian Journal of Medical Microbiology