Multidrug-Resistant Gram-Negative Infections

Is There a Role for the Therapeutic Drug Monitoring of Colistin? An Overview

Colistin is used as a last-line antibiotic for the treatment of Gram-negative multiresistant bacteria. Due to its high nephrotoxicity, Therapeutic Drug Monitoring (TDM) is recommended for dose adjustment. We aimed to evaluate the available evidence of TDM in patients given colistin to treat Gram-negative infections. In this paper, we offer an overview, using an electronic search of the literature (published up to June 2019, without language restrictions) that compares the clinical outcomes and measurements of colistin TDM. Ultimately, the Therapeutic Drug Monitoring (TDM) of colistin in Plasma could prevent nephrotoxicity risk.

The growing threat of carbapenem resistant enterobacteriaceae (CRE) within in-patient spinal rehabilitation units

This case report highlights the present threat and challenges with treatment and transmission of infections caused by carbepenem-resistant enterobacteriaceae (CRE) within in-patient spinal rehabilitation units. The setting is within the Spinal Cord Injury Unit, Royal North Shore Hospital, Sydney, Australia. We report the case of a 45-year-old female with T9 complete paraplegia who developed CRE urinary tract infection (UTI) and sepsis 1 month post injury while in an in-patient spinal rehabilitation unit. We describe the challenges in treatment with colistin, the implications of infection on her rehabilitation and challenges in containing the spread of CRE to other patients in the unit. We present our experience with the management of CRE bactaeraemia in a spinal rehabilitation unit and the enhanced importance of infection control and surveillance strategies required to successfully contain risk of transmission.

Advanced amperometric respiration assay for antimicrobial susceptibility testing

A ferricyanide-based electrochemical cell respiration assay was adapted for use in broad-spectrum antimicrobial susceptibility testing (AST). Total bacterial respiration was converted into faradaic current by electro-oxidation of ferrocyanide, produced when ferricyanide is reduced by bacterial electron-transport. For Escherichia coli (E. coli), the signal was linear with 5-13 × 10(8) colony-forming units in measuring buffer. For AST, test cells were treated with drugs before ferricyanide addition; cell counts from the amperometric assay provided a measure of drug-induced cell death. Initial trials with six antimicrobial agents produced incorrect susceptibility classifications for drugs that were electroactive at the potential used to detect ferrocyanide or which affected cellular respiration rates. We therefore changed the procedure from drug-treatment and assay in the same buffer to sequential drug exposure in treatment buffer, centrifugal separation of surviving cells, cell resuspension, incubation in the presence of ferricyanide and finally ferrocyanide amperometry in drug-free buffer. Data analysis with E. coli led to an activity classification that agreed with cell culture-based ASTs, obtained by a quicker, more convenient procedure. The potential of this approach was confirmed by trials with the highly virulent bacterium Burkholderia pseudomallei, a particularly antimicrobial-resistant pathogen that is the cause of lethal melioidosis in tropical climates and is currently of concern as a potential bioterrorism agent.

Risk factors for tracheobronchial acquisition of resistant Gram-negative bacterial pathogens in mechanically ventilated ICU patients

The aim of this study was to identify risk factors for tracheobronchial acquisition with the most common resistant Gram-negative bacteria in the intensive care unit (ICU) during the first week after intubation and mechanical ventilation. Tracheobronchial and oropharyngeal cultures were obtained at admission, after 48 hours, and after 7 days of mechanical ventilation. Patient characteristics, interventions, and antibiotic usage were recorded. Among 71 eligible patients with two negative bronchial cultures for resistant Gram-negative bacteria (at admission and within 48 hours), 41 (58%) acquired bronchial resistant Gram-negative bacteria by day 7. Acquisition strongly correlated with presence of the same pathogens in the oropharynx: Acinetobacter baumannii [odds ratio (OR) = 20·2, 95% confidence interval (CI): 5·5-73·6], Klebsiella pneumoniae (OR = 8·0, 95% CI: 1·9-33·6), and Pseudomonas aeruginosa (OR = 27, 95%: CI 2·7-273). Bronchial acquisition with resistant K. pneumoniae also was associated with chronic liver disease (OR = 3·9, 95% CI: 1·0-15·3), treatment with aminoglycosides (OR = 4·9, 95% CI: 1·4-18·2), tigecycline (OR = 4·9, 95% CI: 1·4-18·2), and linezolid (OR = 3·9, 95% CI: 1·1-15·0). In multivariate analysis, treatment with tigecycline and chronic liver disease were independently associated with bronchial resistant K. pneumoniae acquisition. Our results show a high incidence of tracheobronchial acquisition with resistant Gram-negative microorganisms in the bronchial tree of newly intubated patients. Oropharynx colonization with the same pathogens and specific antibiotics use were independent risk factors.

Nephrotoxicity Of Polymyxin B: Experimental Study In Cells And Implications For Nursing Practice

The aim of the study was to characterize the cell damage mechanisms involved in the pathophysiology of cytotoxicity of polymyxin B in proximal tubular cells (LLC - PK1) and discuss about the nurses interventions to identify at risk patients and consider prevention or treatment of nephrotoxicity acute kidney injury. This is a quantitative experimental in vitro study, in which the cells were exposed to 375μM polymyxin B sulfate concentration. Cell viability was determined by exclusion of fluorescent dyes and morphological method with visualization of apoptotic bodies for fluorescence microscopy. Cells exposed to polymyxin B showed reduced viability, increased number of apoptotic cells and a higher concentration of the enzyme lactate dehydrogenase. The administration of polymyxin B in vitro showed the need for actions to minimize adverse effects such as nephrotoxicity.


The Occurrence of blaCTX-M, blaSHV, and blaTEM Genes in Extended-Spectrum β-Lactamase-Positive Strains of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis in Poland

Bacteria belonging to the Enterobacteriaceae family that produce extended-spectrum β-lactamase (ESBL) enzymes are important pathogens of infections. Increasing numbers of ESBL-producing bacterial strains exhibiting multidrug resistance have been observed. The aim of the study was to evaluate the prevalence of blaCTX-M, blaSHV, and blaTEM genes among ESBL-producing Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis strains and to examine susceptibility to antibiotics of tested strains. In our study, thirty-six of the tested strains exhibited blaCTX-M genes (blaCTX-M-15, blaCTX-M-3, blaCTX-M-91, and blaCTX-M-89). Moreover, twelve ESBL-positive strains harbored blaSHV genes (blaSHV-18, blaSHV-7, blaSHV-2, and blaSHV-5), and the presence of a blaTEM gene (blaTEM-1) in twenty-five ESBL-positive strains was revealed. Among K. pneumoniae the multiple ESBL genotype composed of blaCTX-M-15, blaCTX-M-3, blaSHV-18, blaSHV-7, blaSHV-2, and blaSHV-5 genes encoding particular ESBL variants was observed. Analysis of bacterial susceptibility to antibiotics revealed that, among β-lactam antibiotics, the most effective against E. coli strains was meropenem (100%), whereas K. pneumoniae were completely susceptible to ertapenem and meropenem (100%), and P. mirabilis strains were susceptible to ertapenem (91.7%). Moreover, among non-β-lactam antibiotics, gentamicin showed the highest activity to E. coli (91.7%) and ciprofloxacin the highest to K. pneumoniae (83.3%). P. mirabilis revealed the highest susceptibility to amikacin (66.7%).

Role of heme oxygenase-1 in polymyxin B-induced nephrotoxicity in rats

Polymyxin B (PMB) is a cationic polypeptide antibiotic with activity against multidrug-resistant Gram-negative bacteria. PMB-induced nephrotoxicity consists of direct toxicity to the renal tubules and the release of reactive oxygen species (ROS) with oxidative damage. This study evaluated the nephroprotective effect of heme oxygenase-1 (HO-1) against PMB-induced nephrotoxicity in rats. Adult male Wistar rats, weighing 286 ± 12 g, were treated intraperitoneally once a day for 5 days with saline, hemin (HO-1 inducer; 10 mg/kg), zinc protoporphyrin (ZnPP) (HO-1 inhibitor; 50 μmol/kg, administered before PMB on day 5), PMB (4 mg/kg), PMB plus hemin, and PMB plus ZnPP. Renal function (creatinine clearance, Jaffe method), urinary peroxides (ferrous oxidation of xylenol orange version 2 [FOX-2]), urinary thiobarbituric acid-reactive substances (TBARS), renal tissue thiols, catalase activity, and renal tissue histology were analyzed. The results showed that PMB reduced creatinine clearance (P < 0.05), with an increase in urinary peroxides and TBARS. The PMB toxicity caused a reduction in catalase activity and thiols (P < 0.05). Hemin attenuated PMB nephrotoxicity by increasing the catalase antioxidant activity (P < 0.05). The combination of PMB and ZnPP incremented the fractional interstitial area of renal tissue (P < 0.05), and acute tubular necrosis in the cortex area was also observed. This is the first study demonstrating the protective effect of HO-1 against PMB-induced nephrotoxicity.

The crisis of no new antibiotics--what is the way forward?

Antibiotic use not only underpins modern medicine, but has brought huge changes to the world, especially in expectations of survival of children into adulthood. The theme of World Health Day, 2011, was "antimicrobial resistance: no action today and no cure tomorrow". The demise of antibacterial drug discovery brings the spectre of untreatable infections. To prevent this crisis immediate action is needed and a new initiative, Antibiotic Action, has been launched. By bringing together communities who need these drugs with academia, health-care professionals, and pharmaceutical companies, this initiative aims to strengthen and enhance academic-industrial partnerships, bring about revision of costly and laborious processes of licensing and regulation of new antibiotics, and address the economics of antimicrobial drugs (cost of use vs profit). A global alliance for antibiotic drug discovery and development would provide a platform for these initiatives.