A study of 24 patients with colistin-resistant Gram-negative isolates in a tertiary care hospital in South India

Abstract

Background:As the use of colistin to treat carbapenem-resistant Gram-negative infections increases, colistin resistance is being increasingly reported in Indian hospitals.Materials and Methods:Retrospective chart review of clinical data from patients with colistin-resistant isolates (minimum inhibitory concentration >2 mcg/ml). Clinical profile, outcome, and antibiotics that were used for treatment were analyzed.Results:Twenty-four colistin-resistant isolates were reported over 18 months (January 2014-June 2015). A history of previous hospitalization within 3 months was present in all the patients. An invasive device was used in 22 (91.67%) patients. Urine was the most common source of the isolate, followed by blood and respiratory samples. Klebsiella pneumoniae constituted 87.5% of all isolates. Sixteen (66.6%) were considered to have true infection, whereas eight (33.3%) were considered to represent colonization. Susceptibility of these isolates to other drugs tested was tigecycline in 75%, chloramphenicol 62.5%, amikacin 29.17%, co-trimoxazole 12.5%, and fosfomycin (sensitive in all 4 isolates tested). Antibiotics that were used for treatment were combinations among the following antimicrobials-tigecycline, chloramphenicol, fosfomycin, amikacin, ciprofloxacin, co-trimoxazole, and sulbactam. Among eight patients who were considered to have colonization, there were no deaths. Bacteremic patients had a significantly higher risk of death compared to all nonbacteremic patients (P = 0.014).Conclusions:Colistin resistance among Gram-negative bacteria, especially K. pneumoniae, is emerging in Indian hospitals. At least one-third of isolates represented colonization only rather than true infection and did not require treatment. Among patients with true infection, only 25% had a satisfactory outcome and survived to discharge. Fosfomycin, tigecycline, and chloramphenicol may be options for combination therapy.

Risk Factors for Colistin Resistance among Gram-Negative Rods and Klebsiella pneumoniae Isolates

“…Infection with colistin-resistant organisms is associated with a substantially increased risk for mortality, and options for treatment are limited (9)(10)(11)(17)(18)(19)(20). Prior studies have typically been relatively small or limited in scope, either following a relatively small number of patients (9,10,17,18,24,26,(30)(31)(32)(33) or focusing on a single organism (16,21,22,27), and none have resulted in a clinically meaningful prediction tool. Our score can be calculated by providers at the time of decision making without the help of a computer.…”

“…The prevalence of colistin resistance among GNRs has been increasing over the past 2 decades, particularly among isolates of Klebsiella pneumoniae (8,10,(12)(13)(14)(15)(16), limiting the potential utility of colistin. Infection with Col r GNRs is associated with a higher mortality than infection with colistin-susceptible (Col s ) isolates (9,10,(17)(18)(19)(20), making the rapid identification of resistance important. However, the early identification of Col r GNRs is challenging.…”

“…Prior literature has identified multiple risk factors for colistin resistance in GNRs, including recent prior hospitalization (17,21,22), prior carbapenem resistance (10, 13-15, 21, 23), prior treatment with colistin (18,21,23,24), exposure to chlorhexidine (25), the presence of multiple comorbidities in the patients (21,22), and increasing age, male sex, length of hospitalization, and the presence of indwelling urinary catheters (22). Other risk factors for the development of MDROs in general included prior residence in a nursing home, hemodialysis, intensive care unit (ICU) admission (26), the presence of a medical comorbidity (19,27), and prior beta-lactam usage and invasive surgery (27).…”

Risk factors for colistin-resistant Enterobacteriaceae in a low-endemicity setting for carbapenem resistance – a matched case–control study

“…Colistin resistance was associated with higher resistance rates to quinolones, fosfomycin and tobramycin, but not carbapenem resistance. Carbapenem-resistant Enterobacteriaceae are known to have concurrent resistance to colistin, fosfomycin and quinolones [ 16 - 18 ], but resistance clusters without concomitant carbapenem resistance have not been described so far and its role and aetiology remains unclear. High rates of colistin resistance in human samples have mainly been reported in countries with high proportions of carbapenem-resistant Gram-negative bacteria and subsequent widespread use of colistin in healthcare settings.…”

ChloS-HRM, a novel assay to identify chloramphenicol-susceptible Escherichia coli and Klebsiella pneumoniae in Malawi

“…Reports of returning chloramphenicol susceptibility are increasing 9 . Studies in Indian hospitals have found that 68% of MDR Gram-negative bacteria 12 and 62.5% colistin-resistant Gram-negative bacteria 13 were susceptible to chloramphenicol. In Malawi chloramphenicol was used in combination with benzylpenicillin as the first-line therapy in the empirical management of suspected sepsis, until 2015 4 .…”