European Journal of Cardiovascular Medicine

Diabetic foot is one of the most critical complications of diabetes mellitus (DM) and is a leading cause of morbidity and disability, especially in developing countries. The World Health Organization (WHO) defines the diabetic foot as infection, ulceration, and destruction of deep tissues associated with neurological and various degrees of peripheral vascular disease in the lower limb2. Furthermore, diabetic ulcers have a 30 times higher risk of limb amputation when compared with foot 

ulcers due to other causes3. The number of cases and the problems associated with diabetic foot infections (DFIs) have dramatically increased in recent years4. Many approaches classify DFIs as the Infectious Disease Society of America (IDSA) system, the University of Texas System, and the Wagner system5. The Wagner system has been widely used for 25 years ago for the classification of DFIs. This classification system assesses ulcer depth and the presence of osteomyelitis or gangrene by using the following six grades: grade 0 (pre-or post-ulcerative lesion), grade 1 (partial/full-thickness ulcer), grade 2 (probing to tendon or capsule), grade 3 (deep with osteitis), grade 4 (partial foot gangrene), grade 5 (whole foot gangrene6.

The microbial Etiology of diabetic foot ulcers is usually complex. Many of these infections are either mono-microbial or poly-microbial. In recent years, multidrug-resistant organisms have been reported frequently, further complicating the treatment regimens7. Pathogenic bacteria that cause these infections either originate from the external environment or physiological microflora of the skin8. Furthermore, most foot ulcerations may contain mixed flora that consists of aerobic strains such as S. aureus, Streptococcus pyogenes, E. coli, Proteus mirabilis, Pseudomonas aeruginosa, E. faecalis, Klebsiella spp., and anaerobic bacteria, for example, Bacteroides fragilis Clostridium perfringens and Pepto streptococcus spp9.

Up to 60% of diabetic patients who are treated for a foot ulcer receive antibiotic therapy10. Initial therapy for infected wounds is usually empirical and based on the severity of the infection, gram-stained smear findings, and recent culture results10. It is recommended to start with parenteral broad-spectrum agents for severe infections to chronic moderate infections. After the infection responds, most patients can switch their treatments to oral therapy. Whereas mild and moderate infections can be treated with narrow-spectrum antibiotics11. However, although topical antimicrobial treatment has many advantages, including high local drug levels and avoidance of systemic adverse effects, only limited data supports using local antimicrobial therapy for mildly infected foot ulcers12. Because antibiotics use may result in antimicrobial resistance, high financial cost, and drug-related adverse effects, much-published evidence discourages therapy of uninfected ulcers with antibiotics from enhancing wound healing or as prophylaxis against infection13.

This retrospective study was carried out between January 2023 and June 2023 in the Microbiology Government Medical College Anantapur department. Two hundred fifty wound swabs were collected from diabetic foot ulcer patients and processed per the standard procedure. Antibiotic sensitivity testing was performed by the Kirby Bauer disc diffusion method by CLSI guidelines.

Antibiotic susceptibility testing: -Kirby Bauer disc diffusion method tested All isolates for their susceptibility to various antibiotics. The following antibiotics were tested against all strains: Imipenem10mcg, Amikacin 30mcg, Piperacillin/Tazobactam 110mcg, Ciprofloxacillin 30 mcg, Gentamycin 10 mcg, Cefoxitin, Piperacillin, Cefotaxime 30mcg, Vancomycin 30 mcg, Rifampicin 5mcg, Teicoplanin, Gatifloxacin, Clindamycin 10 mcg, Erythromycin 15 mcg,

Out of 250 samples, 175 (70%) samples yielded growth. Among 175 GNB 124 (70.8%) and GPC 51 (21.6%). The isolates of GNB are shown in Table 1. GPC in Table 2.

Among Gram-positive cocci majority of isolates were Staphylococcus aureus 27 (52.9%), followed by Coagulase-negative Staphylococci 18 (35.3%) & Enterococci species 6(11.8%).

Table – II showing distribution of Gram-Positive cocci isolation

All Gram-negative bacilli were sensitive to Imipenem 124 (100%) followed by Amikacin 75 (60%), Piperacillin /Tazobactam 60(40%), Ciprofloxacillin 51(41%), Gentamycin 39(31%), Cefoxitin 45(36.2%), Piperacillin 35(28.2%) and Cefotaxime 15(27%).

                                  Table – III showing Antibiotic susceptibility pattern of Gram-negative bacilli.

Among 27 Staphylococcus aureus, 12 (44.4%) were resistant to Methicillin (MRSA), and 15 (55.6%) were sensitive to Methicillin (MSSA). All strains of Gram-positive cocci were sensitive to Vancomycin 51 (100%) followed by Rifampicin 47(92.5%), Teicoplanin 46(90.1%), Gatifloxacin 45(82.6%), Amikacin 26 (51%) Clindamycin 25(51%), Erythromycin 16(31.4%) and Cefoxitin 14(27.6%).

Table – IV showing Antibiotic susceptibility pattern of Gram-Positive cocci.

The present study was conducted at the Government Medical College, Anantapur. Most of the patients with diabetic foot ulcer were in the age group 51 to 60 (34.1%) (6) years .out of 250 samples, 175 (70%) samples were culture positive, and among positive samples, 124 (70.8%) were GNB, and 51 (21.6%) were GPC. Among gram-negative bacilli, the majority of isolates were Pseudomonas aeruginosa 45 (36.2%), followed by Escherichia coli 32(25.8%), Proteus species 20 (16.12%), Klebsiella species 14 (11.29%), Citrobacter species 9 (7.25%) and Providencia species 4 (3.2%). Among Gram-positive cocci, the majority of isolates were Staphylococcus aureus 27 (52.9%), followed by Coagulase-negative Staphylococci 18 (35.3%) and Enterococci species 6(11.8%). In the present study, the most common isolates were Pseudomonas aeruginosa 45(36.2%), which was comparable to the study conducted by N Prity et.al2 where the majority of the isolates showed to be   Pseudomonas aeruginosa 41(24.70%) followed by Staphylococcus aureus 33(19.88%), Escherichia.coli,30(18.08%), Klebsiella pneumoniae 21(12.65%), and Proteus spp. 17(10.2%). The present study was also comparable to the result of the study conducted by Bulolo et al. 5, which showed Pseudomonas aeruginosa 43(56%) followed by Escherichia. Coli 23(19%), Klebsiella pneumoniae 15(9%), and staphylococcus aureus 34 (25%).In our study, All Gram-negative bacilli were sensitive to Imipenem 124 (100%) followed by Amikacin 75 (60%), Piperacillin /Tazobactam 60(40%), Ciprofloxacillin 51(41%), Gentamycin 39(31%), Cefoxitin 45(36.2%), Piperacillin 35(28.2%) and Cefotaxime 15(27%), which was comparable to the study by  N Prity et al. two which showed Pseudomonas aeruginosa was sensitive to imipenem (95%), piperacillin/tazobactam (87%) and least sensitive to ciprofloxacin (31%), co-trimoxazole (26%).In the present study of 27 Staphylococcus aureus, only 12 (44.4%) were resistant to Methicillin (MRSA), and the remaining 15 (55.6%) were sensitive to Methicillin (MSSA). All strains of Gram-positive cocci were sensitive to Vancomycin 51(100%) followed by Rifampcin47(92.5%), Teicoplanin 46(90.1%), Gatifloxacin 45(82.6%), Amikacin 26 (51%) Clindamycin 25(51%), Erythromycin 16(31.4%) and Cefoxitin 14(27.6%), which was comparable to the study conducted by C Andersen et.al (3). In the present study, Pseudomonas aeruginosa was the most common isolated organism (36.2%.), This was comparable to study of Prity et al. 2, Kashef et al. 4, Bulolo et al. 5, and Andersen et al. 3, which showed Pseudomonas aeruginosa was the most common organism, 34%, 30%, 33%, and 29%, respectively.

Diabetic foot ulcer is considered one of the most threatening and disabling complications for a diabetic patient. In this study, Gram-negative bacilli Pseudomonas aeruginosa was the predominant organism 45(36.2%), followed by Escherichia coli32(25.8%). Among Gram positives, Staphylococcus aureus27 (52.9%) were predominant organisms; out of 27 samples, 12 (44.4%) were resistant to Methicillin [MRSA]. Early detection and treatment will reduce the complications of limb will decrease. The selection of the antibiotic treatment should be based on the predominant organisms that are isolated and their antimicrobial susceptibility patterns. This will improve the overall antibiotic utilization and reduce the emergence of multidrug-resistant organisms

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