Changing microbiological profile of pathogenic bacteria in diabetic foot infections: time for a rethink on which empirical therapy to choose?

Abstract

Aims/hypothesis We studied the bacterial aetiology and antibiotic sensitivity pattern of diabetic foot ulcers in India. Methods Records of 447 hospitalised patients between 1991 and 2008 were retrospectively analysed between two time periods (before and after 1999) to compare bacterial aetiology and antimicrobial sensitivity patterns. The first three consecutive cultures from the same wound during treatment were evaluated. Results Of 1,632 cultures, 66% were polymicrobial, 23% monomicrobial and 11% sterile. In the monomicrobial group, 14% (n=228) of cultures were Gram-negative, whereas 9% (n=147) were Gram-positive. The most common pathogens in the first culture were Pseudomonas aeruginosa (20.1%), Staphylococcus aureus (17.2%) and Escherichia coli (16.3%). Results for the third cultures showed persistence of P. aeruginosa (15.3%) and E. coli (14.2%). Gramnegative isolates dominated over Gram-positive ones (25.3% vs 15.1%, p<0.05). Antibiotic sensitivity patterns before and after 1999 were: piperacillin-tazobactam 74% vs 66% (p<0.005), imipenem 77% vs 85% (NS), cefoperazone-sulbactam 47% vs 44% (p<0.005), amikacin 62% vs 78% (NS), ceftriaxone 41% vs 36% (p<0.005), amoxicillinclavulanate 51% vs 43% (p<0.05) and clindamycin 43% vs 36% (p<0.005), respectively.

Prevalence of TEM and SHV Genes among Extended Spectrum Beta-Lactamase (ESBL) Producing Escherichia coli Isolates from Infected Diabetic Foot Ulcers in a Tertiary Care Hospital

“…In this study 52% of specimens had witnessed the growth of mixed flora and is in agreement with other studies (Anandi et al, 2004;Shankar et al, 2005;Ramakant et al, 2011;Citron et al, 2007;Dowd et al, 2008). Deep ulcers with large surface area and those of longer duration bear a diverse flora with predominance of aerobic gram negative bacilli and anaerobes (Gardener et al, 2013).…”

“…The study by Zubair et al, (2011) had reported that the Escherichia coli (41 out of 97 gram negative bacilli, 42.2%) was the most common organism isolated. But the study by Ramakant et al, (2011) had found Pseudomonas aeruginosa as the predominant isolate, which was the third most common among gram negative bacilli in this study. Staphylococcus aureus (27 out of 173, 15.61%) was the most common among gram positive cocci isolates.…”

“…A study by Tiwari et al, (2012) reported exactly similar figure of 68% gram negative bacilli and 32% gram positive cocci from 82 strains isolated from 62 patients with infected diabetic foot ulcer. Some of the possible reasons cited for this discrepancy include hot climate causing foot sweating, unfitting footwear, frequent foot washing and the suboptimal perineal/hand hygiene (Uckay et al, 2015;Ramakant et al, 2011) The Escherichia coli, 38 out of 173 total isolates (21.96%) was the predominant organism identified followed by Klebsiella spp (31 out of 173, 17.92%) in this study. The study by Esmat et al, (2012) had reported similar results.…”

“…The factors such as antibiotic therapy, hospitalization and severity of ulcer cause longitudinal shift in microbial flora. In prolonged ulcer with higher Wagner"s grade, the infection is usually caused by mixed aerobic and anaerobic bacteria (Ramakant et al, 2011). In temperate and western countries the aerobic gram positive cocci, Staphylococcus aureus is the predominant organism isolated often methicillin resistant in recent times.…”

“…In temperate and western countries the aerobic gram positive cocci, Staphylococcus aureus is the predominant organism isolated often methicillin resistant in recent times. In warm subtropical countries like India, many studies reported mixed polymicrobial infection with the predominant organisms being aerobic gram negative bacilli such as Enterobactericeae, Pseudomonas aeruginosa (Uckay et al, 2015;Ramakant et al, 2011). Bacteroides fragilis, Peptostreptococcus spp., are some of the frequently implicated obligate anaerobic bacteria in the infection of diabetic foot ulcer (Halpati et al, 2014).…”