Impact of the national shortage of polymyxin B in critically ill patients during the COVID-19 pandemic / Impacto da escassez nacional de polimixina B em pacientes gravemente enfermos durante a pandemia de COVID-19 / Impacto del desabasto nacional de polimixina B en pacientes críticos durante la pandemia de COVID-19

Background and Objectives: during the COVID-19 pandemic, the number of critical patients requiring intensive care increased considerably, resulting in an increase in infections due to multi-resistant microorganisms. In Brazil, in 2021, due to the high demand for polymyxin B use, there was a national shortage of the medication. One strategy used to overcome this situation was aminoglycoside use. The work aimed to analyze the impact of replacing polymyxin B with amikacin and gentamicin in the final stage of patients. Method: an analytical study with an observational, cross-sectional design, with a quantitative approach, through a retrospective analysis through the analysis of medical records, with the primary stages being discharges or deaths. Results: mortality was similar between the group treated with aminoglycoside and the group treated with polymyxin B. Within the aminoglycoside group, mortality was higher in the group that had bacteria resistant to the drug than in the group that had infection with an organism sensitive to this drug. Mortality was not affected by comorbidities, age, or number of hospital infections. The main factor that led to the need for dialysis was the combination of two nephrotoxic medications. Conclusion: two hypotheses emerged: the first would be that replacing polymyxin B with aminoglycosides did not impact mortality; the other would be that, regardless of the antibiotic group used, patients had a high risk of death. Despite sample limitations, the study corroborates the adoption of strategies for the rational use of antimicrobials.(AU)

Justificativa e Objetivos: durante a pandemia de COVID-19, o número de pacientes críticos que necessitaram de cuidados intensivos aumentou consideravelmente, resultando em aumento de infecções por microrganismos multirresistentes. No Brasil, em 2021, devido à grande demanda pelo uso da polimixina B, houve escassez nacional do medicamento. Uma estratégia utilizada para superar essa situação foi o uso de aminoglicosídeos. O trabalho teve como objetivo analisar o impacto da substituição da polimixina B por amicacina e gentamicina na fase final dos pacientes. Método: estudo analítico com desenho observacional, transversal, com abordagem quantitativa, por meio de análise retrospectiva por meio de análise de prontuários, sendo as etapas primárias as altas ou óbitos. Resultados: a mortalidade foi semelhante entre o grupo tratado com aminoglicosídeo e o grupo tratado com polimixina B. Dentro do grupo aminoglicosídeo, a mortalidade foi maior no grupo que apresentava bactérias resistentes ao medicamento do que no grupo que apresentava infecção por organismo sensível a este medicamento. medicamento. A mortalidade não foi afetada por comorbidades, idade ou número de infecções hospitalares. O principal fator que levou à necessidade de diálise foi a combinação de dois medicamentos nefrotóxicos. Conclusão: surgiram duas hipóteses: a primeira seria que a substituição da polimixina B por aminoglicosídeos não impactou a mortalidade; a outra seria que, independentemente do grupo de antibióticos utilizado, os pacientes apresentavam alto risco de morte. Apesar das limitações amostrais, o estudo corrobora a adoção de estratégias para o uso racional de antimicrobianos.(AU)

Antecedentes y Objetivos: durante la pandemia de COVID-19, el número de pacientes críticos que requirieron cuidados intensivos aumentó considerablemente, resultando en un aumento de infecciones por microorganismos multirresistentes. En Brasil, en 2021, debido a la alta demanda del uso de polimixina B, hubo escasez nacional del medicamento. Una estrategia utilizada para superar esta situación fue el uso de aminoglucósidos. El trabajo tuvo como objetivo analizar el impacto de la sustitución de la polimixina B por amikacina y gentamicina en la etapa final de los pacientes. Método: estudio analítico con diseño observacional, transversal, con enfoque cuantitativo, mediante un análisis retrospectivo mediante el análisis de historias clínicas, siendo las etapas primarias las altas o defunciones. Resultados: la mortalidad fue similar entre el grupo tratado con aminoglucósido y el grupo tratado con polimixina B. Dentro del grupo de aminoglucósido, la mortalidad fue mayor en el grupo que tenía bacterias resistentes al fármaco que en el grupo que tenía infección con un organismo sensible a este. droga. La mortalidad no se vio afectada por las comorbilidades, la edad o el número de infecciones hospitalarias. El principal factor que llevó a la necesidad de diálisis fue la combinación de dos medicamentos nefrotóxicos. Conclusión: surgieron dos hipótesis: la primera sería que la sustitución de polimixina B por aminoglucósidos no impactó la mortalidad; la otra sería que, independientemente del grupo de antibióticos utilizado, los pacientes tenían un alto riesgo de muerte. A pesar de las limitaciones de la muestra, el estudio corrobora la adopción de estrategias para el uso racional de antimicrobianos.(AU)

Efficacy and safefy of Polymyxin B treatment for neutropenic patients suffering from refractory Gram-negative bacterial bloodstream infection / 中华血液学杂志

Objective: To assess the efficacy and safety of polymyxin B in neutropenic patients with hematologic disorders who had refractory gram-negative bacterial bloodstream infection. Methods: From August 2021 to July 2022, we retrospectively analyzed neutropenic patients with refractory gram-negative bacterial bloodstream infection who were treated with polymyxin B in the Department of Hematology of the First Affiliated Hospital of the Soochow University between August 2021 to July 2022. The cumulative response rate was then computed. Results: The study included 27 neutropenic patients with refractory gram-negative bacterial bloodstream infections. Polymyxin B therapy was effective in 22 of 27 patients. The median time between the onset of fever and the delivery of polymyxin B was 3 days [interquartile range (IQR) : 2-5]. The median duration of polymyxin B treatment was 7 days (IQR: 5-11). Polymyxin B therapy had a median antipyretic time of 37 h (IQR: 32-70). The incidence of acute renal dysfunction was 14.8% (four out of 27 cases), all classified as "injury" according to RIFLE criteria. The incidence of hyperpigmentation was 59.3%. Conclusion: Polymyxin B is a viable treatment option for granulocytopenia patients with refractory gram-negative bacterial bloodstream infections.

Chinese consensus guidelines for therapeutic drug monitoring of polymyxin B, endorsed by the Infection and Chemotherapy Committee of the Shanghai Medical Association and the Therapeutic Drug Monitoring Committee of the Chinese Pharmacological Society / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Polymyxin B, which is a last-line antibiotic for extensively drug-resistant Gram-negative bacterial infections, became available in China in Dec. 2017. As dose adjustments are based solely on clinical experience of risk toxicity, treatment failure, and emergence of resistance, there is an urgent clinical need to perform therapeutic drug monitoring (TDM) to optimize the use of polymyxin B. It is thus necessary to standardize operating procedures to ensure the accuracy of TDM and provide evidence for their rational use. We report a consensus on TDM guidelines for polymyxin B, as endorsed by the Infection and Chemotherapy Committee of the Shanghai Medical Association and the Therapeutic Drug Monitoring Committee of the Chinese Pharmacological Society. The consensus panel was composed of clinicians, pharmacists, and microbiologists from different provinces in China and Australia who made recommendations regarding target concentrations, sample collection, reporting, and explanation of TDM results. The guidelines provide the first-ever consensus on conducting TDM of polymyxin B, and are intended to guide optimal clinical use.

Analysis and evaluation of the application of polymyxin B in inpatients based on clinical guidelines and consensuses / 中国药房

OBJECTIVE To evaluate the rationality of clinical application of polymyxin B in the inpatients of a third grade class A hospital，so as to provide evidence for the optimization of clinical scheme of the drug. METHODS A retrospective method was conducted on the electronic medical records of inpatients treated with Polymyxin B sulfate for injection from January 2020 to March 2022 to collect the basic information of patients， inpatient departments and time， infection diagnosis， results of pathogenic bacteria test， laboratory test indicators， usage and dosage， and combined medication，etc. Based on the drug instructions， according to relevant guidelines and consensus， the rationality， efficacy and safety of polymyxin B in inpatient were evaluated. RESULTS & CONCLUSIONS A total of 101 inpatients were included， respiratory system infection was the main cause （62.4%）. All patients had received the etiological examination， and the pathogen with the highest detection rate was carbapenem‑resistant Acinetobacter baumannii （40.6%）. One hundred patients were treated by intravenous drip， and 4 patients were treated by combination of aerosol inhalation or intrathecal injection； 99 patients were given the dose of 500 thousand units by continuous intravenous infusion， q12 h. Totally 51.5% of patients were treated for 7-14 days； and 77 patients were treated with other anti-Gram-negative drugs. There were unreasonable phenomena including too short time of medication （29.7%）， no combination of medication （23.8%）， and no indication of medication （17.8%）. The clinical effective rate of 101 patients treated with polymyxin B was 49.5%， and 16 patients （15.8%） had acute kidney injury during the treatment. Clinical pharmacists should actively participate in the clinical treatment of polymyxin B， formulate individualized treatment plans according to the guidelines/consensus and in combination with the patient’s condition and infection status to improve the rationality of clinical medication.

Determination of polymyxin B concentration in plasma and its application in critically ill patients / 中国药房

OBJECTIVE To establish a method for the determination of polymyxin B concentration in plasma and apply it to clinical practice. METHODS After precipitated with 5% trichloroacetic acid solution， using polymyxin E2 as internal standard， the concentrations of polymyxin B1 and B2 in plasma sample were determined by UPLC-MS/MS. The determination was performed on BEH C18 chromatographic column with water （0.1% formic acid）-acetonitrile （0.1% formic acid） as mobile phase （gradient elution） at the flow rate of 0.5 mL/min. The sample size was 10 µL. The detection was accomplished with electrospray ionization operated in positive ion scanning by multi-reaction monitoring mode. The ion pairs for quantitative analysis were m/z 603.2→101.2 （polymyxin B1）， m/z 595.7→101.1 （polymyxin B2） and m/z 578.5→101.1 （internal standard）. The plasma concentration of polymyxin B in 79 critically ill patients was measured by the above method， the occurrence of acute renal injury （AKI） was recorded and the relationship of polymyxin B concentration in plasma with AKI was analyzed. RESULTS The linear ranges of polymyxin B1 and polymyxin B2 were 200-20 000， 50-5 000 ng/mL （r＞0.995）， and the lower limits of quantification were 200 and 50 ng/mL， respectively. RSDs of intra‐day and inter‐day precision tests were not higher than 12.06%， the average extraction recovery was 103.04%-117.44%， and RSDs of matrix effect test and stability test were all not higher than 7.42%. Steady state trough and peak plasma concentration were （2.54±2.52） and （8.17±5.20） mg/L for 79 clinical patients using polymyxin B. Eighteen patients out of 27 included patients developed AKI， with an incidence of 66.67%. The peak concentration of polymyxin B of patients without AKI was significantly lower than that of patients with AKI （P＜0.05）， but there was no significant difference in the trough concentration between two groups （P＞0.05）. CONCLUSIONS The established UPLC-MS/MS has the advantages of simple operation and high sensitivity， and can be used to monitor the plasma concentration of polymyxin B in patients. The occurrence of AKI is correlated with the peak concentration of polymyxin B.

Clinical observation of polymyxin B in the treatment of CRKP-BSI in patients with hematological malignancies / 中国药房

OBJECTIVE To analyze the efficacy and safety of polymyxin B in the treatment of carbapenem-resistant Klebsiella pneumoniae （CRKP）-bloodstream infection （BSI） in patients with hematologic malignancies. METHODS The medical records of patients with hematologic malignancies with CRKP-BSI who received polymyxin B for at least 3 days in our hospital from September 2019 to June 2021 were retrospectively analyzed. All patients were initially treated with a triple therapy namely polymyxin B+tigecycline+carbapenems for anti-infection therapy. RESULTS A total of 10 patients were enrolled as the study subjects. Eleven strains of CRKP were cultured in blood， including 10 strains of CRKP produced Klebsiella pneumoniae carbapenemase（KPC） and 1 strain of CRKP produced both KPC and metal-beta-lactamase； 9 strains were sensitive to colistin， 7 strains were sensitive to tigecycline， 5 strains were sensitive to amikacin and 2 strains were sensitive to compound sulfamethoxazole. All patients were accompanied by neutropenia， with an average duration of （14.1±6.4） days. They were all characterized by fever， chills and fatigue. After treatment， 6 patients were cured and discharged， 4 patients died of ineffective treatment of septic shock. No serious adverse events related to polymyxin B occurred in all patients. CONCLUSIONS Polymyxin B can be used as a therapeutic drug for CRKP-BSI in patients with hematological malignancies. No serious adverse event related to polymyxin B occurs during the treatment.

Polymyxin Acute Kidney Injury: a case of severe tubulopathy / Nefropatia por polimixina B: a tubulopatia pode ser muito séria!

Abstract Polymyxins are antibiotics developed in the 1950s. Polymyxin-induced neurotoxicity has been often described in medical literature. The same cannot be said of nephrotoxicity or tubulopathy in particular. This report describes the case of a patient prescribed polymyxin B to treat a surgical wound infection, which led to significant increases in fractional excretion of calcium, magnesium, and potassium and subsequent persistent decreases in the levels of these ions, with serious consequences for the patient. Severe hypocalcemia, hypomagnesemia, and hypokalemia may occur during treatment with polymyxin. Calcium, magnesium and potassium serum levels must be monitored during treatment to prevent life-threatening conditions.

Resumo Polimixinas são um grupo de antibióticos desenvolvidos na década de 1950. Seus efeitos neurotóxicos são comumente descritos na literatura, porém há menos relatos sobre seus efeitos nefrotóxicos, especialmente tubulopatias. O objetivo deste relato é descrever o uso de polimixina B em uma paciente para tratamento de infecção de ferida operatória, promovendo grande aumento das frações de excreção de cálcio, magnésio e potássio e acarretando reduções graves e persistentes desses íons, com sérias consequências para a paciente. Hipocalcemia, hipomagnesemia e hipocalemia severas podem ocorrer durante terapia com polimixina e é sugerido que sejam monitorizadas as concentrações séricas desses eletrólitos durante o tratamento como forma de evitar condições de risco à vida.

Combination of polymyxin B and Aquilaria malaccensis extract enhanced the killing and inhibited the growth of Acinetobacter baumannii and Klebsiella pneumoniae

Aims@#Polymyxins are an important last-line treatment for infections caused by multidrug-resistant Gram-negative bacteria. Nonetheless, the emergence of polymyxin-resistance and the limiting of polymyxin monotherapy urgently demands its optimisation. Aquilaria malaccensis (Agarwood) has been widely used as traditional medicine. Many parts of the plant including leaves exhibit a considerable in vitro antibacterial activity against microbial pathogens. Exploiting A. malaccensis in combination with polymyxins provides a novel strategy in fighting antimicrobial resistance. The objective of this study was to evaluate the combination effects of A. malaccensis extract with polymyxins against Acinetobacter baumannii and Klebsiella pneumoniae.@*Methodology and results@#In vitro time-kill studies and GC-MS analysis were performed to evaluate the bacterial killing of polymyxin B and extract combination and analyse chemical compounds of the extract, respectively. The combination of polymyxin B (1 mg/L) and A. malaccensis extract (32 mg/mL and 64 mg/mL) treatments exhibited enhanced bacterial killing compared to polymyxin B alone at 4 h and 24 h. Combination treatments also inhibited the bacterial growth of both A. baumannii and K. pneumoniae observed throughout the 24 h. More than sixty compounds including phytol, 9,12-octadecadienal, fatty acid, alkanes and terpenoids were putatively identified as the compounds that likely contributed to the antibacterial activity.@*Conclusion, significance and impact of study@#This study was the first to report the potential application of A. malaccensis extract in combination with polymyxin B in treatment against A. baumannii and K. pneumoniae and can be further investigated and optimized for the treatment of bacterial infectious diseases.

Clinical efficacy of polymyxin B in combination with tigecycline in pneumonia caused by pan-drug resistant Klebsiella pneumoniae / 国际生物医学工程杂志

Objective:To investigate the clinical efficacy of injectable polymyxin B combined with tigecycline in pneumonia caused by pan-drug resistant Klebsiella pneumonia (PDR-KP). Methods:The retrospective analysis utilized clinical data of 71 patients with PDR-KP admitted to the Neurointensive Care Unit of Beijing Chaoyang Integrative Medicine Emergency Medical Center between September 2018 and August 2021. All patients received injectable polymyxin B combined with tigecycline. The response rate, bacterial clearance rate, and safety of this therapeutic option were evaluated according to the clinical symptoms and biochemical parameters before treatment (baseline), 7 days after the treatment, and at the end of the treatment.Results:The treatment time of 71 patients ranged from 8 to 14 days, with an average of 11 days. The symptoms, signs, laboratory tests, and chest CT findings of most patients significantly improved after the treatment using polymyxin B combined with tigecycline. On the 7th day after the treatment, 37 patients were clinically effective, with a total effective rate of 52.1%(37/71); 41 patients obtained bacteriological clearance, with a bacterial clearance rate of 57.7%(41/71). At the end of treatment, 51 patients were clinically effective, with a total effective rate of 71.8%(51/71); 56 patients obtained bacteriological clearance, with a bacterial clearance rate of 78.9%(56/71). Compared with the results on the 7th day after the treatment, the total effective rate ( χ2=5.86, P=0.016) and bacterial clearance rate ( χ2=7.32, P=0.007) of patients at the end of treatment were significantly increased. Skin pigmentation occurred in 39.4%(28/71) of patients during the treatment. Conclusions:Polymyxin B combined with tigecycline can be tried as a treatment option for pneumonia caused by PDR-KP, but more reliable clinical evidence is still needed.

Efficacy and nephrotoxicity of high-dose polymyxin B in treatment of multidrug-resistant Gram-negative bacterial infections / 中华全科医师杂志

Objective:To investigate the efficacy and nephrotoxicity of high-dosepolymyxin B (PMB) in treatment of patients with multidrug-resistant Gram-negative bacteria (MDR-GNB) infections.Methods:Clinical data of 90 patients with MDR-GNB infections who admitted to the Affiliated Huaian First People′s Hospital from January 2018 to December 2020 were retrospectively analyzed. Thirty one patients receivedhigh-dose PMB(≥25 000 U·kg?1·d?1) for treatment (high-dose group) and 59 patients received standard-dose PMB(<25 000 U·kg?1·d?1) for treatment (control group). The curative effect and renal function of the two groups were compared. The factors related toacute kidney injury (AKI) were analyzed with logistic regression.Results:The daily PMB dose and treatment course in high-dose group were (29 800±4 500) U/kg and (9.16±4.15) d, while those of the control group were (17 300±3 500)U/kg and (7.32±3.87) d ( P<0.01). The effective rate of the high-dose group was higher than that of control group (83.9% vs. 61.0%, χ2=4.95, P<0.05).The creatinine levels in high-dose group were increased significantly from 69.40(47.00, 94.70)μmol/L before treatment to 116.20(59.20, 213.20)μmol/L after treatment ( Z=-2.99, P<0.01); while there were no significant changesin control group before and after treatment [55.00(37.00, 92.47)μmol/L vs. 50.10(34.00, 156.00)μmol/L, Z=-1.78, P=0.78]. The 30-day mortality rate in the high-dose group was 32.3% (10/31), that in the standard-dose group was 49.2% (29/59)(χ2=2.36, P=0.12). The AKI incidence rate in high-dose group was higher than that in standard-dose group [ 67.7% (21/31) vs. 45.8% (27/59), χ2=3.94, P=0.04]. There were 4 and 10 deaths due to AKI in the high-dose and standard-dose groups, respectively (χ2=0.25, P=0.61). Logistic regression analysis showed that daily high-dose PMB was independently associated with AKI( OR=2.662, 95% CI:1.082-6.549, P=0.03). Conclusion:Thehigh-dose PMB is effective in treatment of patients with multidrug-resistant Gram-negative bacteriainfections, but the incidence of AKI is also significantly increased. Therefore, when using daily high-dose PMB, the pros and cons must be weighed to avoid increasing the risk of AKI.

Long course of polymyxin B for the treatment of brain abscess caused by carbapenem resistant Acinetobacter baumannii: a case report / 中华危重病急救医学

The clinical efficacy of polymyxins in severe infection caused by carbapenem resistant organism (CRO) has gradually been recognized, and the course of treatment is generally 2 to 4 weeks. The most common complications after intravenous injection are nephrotoxicity and neurotoxicity, however, there are few reports on the efficacy and safety of the long course use of polymyxins. A patient with carbapenem resistant Acinetobacter baumannii (CRAB) infection after neurosurgery was admitted to the department of neurosurgical intensive care unit (NICU) of Lanzhou University Second Hospital. As the family refused the excision of brain abscess and Ommaya reservoir placement, polymyxin B was given intravenous (3.0 mg·kg -1·d -1) combined with intrathecal (5 mg once daily) injection, and high-dose sulbactam (8 g/d) was intravenously injected for anti-infection therapy. Finally, the brain abscess was absorbed and the patient was successfully cured. The total course of polymyxin B was 69 days with a cumulative dosage of 7 500 mg. There were no complications such as polymyxin-related nephrotoxicity and neurotoxicity during the period, and no symptoms of respiratory inhibition or neuromuscular blockage were observed, but polymyxin-related skin pigmentation appeared about 1 month after intravenous administration of polymyxins B, which subsided after drug withdrawal. It is suggested that long course of polymyxins B is safe and effective for intracranial infection caused by CRAB.

Inappropriate Doses of Intravenous Polymyxin B after Renal Adjustment Lead to Treatment Failure

Sub-therapeutic doses, shorter duration of therapy, female gender, bacteremia, and renal impairment were among independent predictors of polymyxin B treatment failure. In this study, we found an association between inappropriate doses of polymyxin B (<15000 or >25000 unit/kg/day) and renal impairment. Inappropriate doses of polymyxin B were significantly associated with CrCl 20-50 mL/min (p = 0.021, ORadj 6.660, 95% CI 1.326, 33.453) and CrCl <20 mL/min (p = 0.001, ORadj 22.200, 95% CI 3.481, 141.592). By conducting sub-group analysis only using subjects with appropriate dosage, renal impairment was not associated with polymyxin B treatment failure, thus indicating that treatment failure was due to an inappropriate dose of polymyxin B, rather than renal impairment. In conclusion, renal impairment was not directly associated with treatment failure but was due to an inappropriate dosage of polymyxin B after renal adjustment

mcr-1-carrying Enterobacteriaceae isolated from companion animals in Brazil / Enterobacteriaceae portadora de mcr-1 em isolados clínicos de animais de companhia: primeiro relato no Brasil

Plasmid-mediated polymyxin resistance was first described in 2015, in China, in Escherichia coli carrying the mcr-1 (Mobile Colistin Resistance-1) gene. Since then, it has become a major public health challenge worldwide, representing a major threat to human and animal health. In addition, there are still few reports on the prevalence of mcr-1 in Enterobacteriaceae isolated from humans, animals and food. Therefore, the purpose of the study was to investigate the occurrence of the mcr-1 gene in bacterial isolates with phenotypic resistance to polymyxin B obtained from clinical specimens of companion animals. Phenotypic resistance to polymyxin B were determined by broth microdilution and the susceptibility profile to other antimicrobials (amikacin, amoxicillin/clavulanate, ampicillin, ampicillin/sulbactam, aztreonam, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, chloramphenicol, ciprofloxacin, doxycycline, ertapenem, gentamicin, imipenem, marbofloxacin, meropenem, phosphomycin, piperacillin/tazobactam, tetracycline, ticarcillin/clavulanate, tobramycin and trimethoprim/sulfamethoxazole) by disc-diffusion agar method. The extraction of bacterial DNA was performed via heat shock followed by spectrophotometric evaluation. To verify the presence of mcr-1, the Polymerase Chain Reaction was employed using specific primers, followed by agarose gel electrophoresis. The positive isolates had the corresponding amplicons sequenced. In this study, there were identified the first isolates of Escherichia coli, Klebsiella spp. and Enterobacter spp. carrying the mcr-1 gene derived from specimens of companion animals in Brazil. Our results suggest the dissemination of resistance to polymyxins in the community and the environment, highlighting the need for surveillance and optimized treatment guidelines.(AU)

A resistência à polimixina mediada por plasmídeo teve sua primeira descrição em 2015, na China, em Escherichia coli portadora do gene mcr-1 (Mobile Colistin Resistance-1) e a partir de então tornou-se um grande desafio para a saúde pública em todo o mundo, constituindo uma grande ameaça à saúde humana e animal. Além disso, ainda existem poucos relatos sobre a prevalência de mcr-1 em Enterobacteriaceae isoladas de humanos, animais e alimentos. Sendo assim, o objetivo do estudo foi investigar a ocorrência do gene mcr-1 em isolados bacterianos com resistência fenotípica à polimixina B, oriundos de materiais clínicos de animais de companhia. A resistência fenotípica à polimixina B foi determinada por microdiluição em caldo e o perfil de sensibilidade aos demais antimicrobianos (amicacina, amoxicilina/clavulanato, ampicilina, ampicilina/sulbactam, aztreonam, cefazolina, cefepime, cefotaxima, cefoxitina, ceftazidima, ceftriaxona, cloranfenicol, ciprofloxacina, doxiciclina, ertapenem, gentamicina, imipinem, marbofloxacino, meropenem, fosfomicina, piperacilina/tazobactam, tetraciclina, ticarcilina/clavulanato, tobramicina sulfametoxazol/trimetoprim) foram determinados pelo método disco difusão. A extração do DNA bacteriano foi realizada via choque térmico, seguido de avaliação espectrofotométrica. Para a verificação da presença do mcr-1 foi utilizada a Reação em Cadeia da Polimerase com emprego de iniciadores específicos, seguida de eletroforese em gel de agarose. Os isolados positivos tiveram os correspondentes amplicons sequenciados. Nesse estudo foram identificados os primeiros isolados de Escherichia coli, Klebsiella spp. e Enterobacter spp. portadores do gene mcr-1 derivados de espécimes de animais de companhia no Brasil. Este estudo sugere a disseminação da resistência às polimixinas na comunidade e no meio ambiente, destacando a necessidade de vigilância e diretrizes otimizadas de tratamento.(AU)

Development and validation method for simultaneous quantification of neomycin and polymyxin B by HPLC-ELSD and comparison with microbiological method

The aim of this study is to develop the first simultaneous method for quantification of neomycin and polymyxin B inthe presence of dexamethasone using High Performance Liquid Chromatography (HPLC) with an Evaporative LightScattering Detector (ELSD). The analysis was performed using a phenyl Waters X Bridge column, an evaporationtemperature of 50oC, and a nitrogen pressure of 320 kPa. The mobile phase consists of a combination of methanoland trichloroacetate acid (40 mM, pH 1.70–1.80) in gradient mode, flow rate at 1.0 ml/minute, detector gain of 6,and analysis time of 35 minutes. The linearity was achieved with a concentration of 100–500 µg/ml (r = 0.99955)for neomycin and concentration of 30–100 µg/ml (r = 0.99703) for polymyxin B. Recovery results were obtainedbetween 99.150% and 104.773% for neomycin and 96.538% and 105.139% for polymyxin B. The analysis samplefrom the market was found to be 102.27% for neomycin and 100.79% for polymyxin B. The result was compared tothe standard microbiological method. Based on the T-test results of two samples with a 95% confidence level (α =0.05), it was concluded that there was no significant difference between HPLC-ELSD and microbiological methodsfor determining neomycin and polymyxin B. The HPLC-ELSD method has a potential for routine analysis due toadvantages in terms of increasing precision, accuracy, and shorter testing time.

Clinical study of sodium hypochlorite, polymyxin b and limewater effect on mmp-3,-8,-9 in apical periodontitis

Abstract This study aimed to evaluate sodium hypochlorite (NaOCl), limewater (LW), and Polymyxin B (PMB) as irrigants over MMP-3, MMP-8 and MMP-9. Thirty-three patients with apical periodontitis of single-rooted teeth were treated according to three-experimental groups (n=11): group-1: 2.5% NaOCl was used as irrigant; group-2: 2.5% NaOCl for the first two files and LW: [0.14% Ca(OH)2] for the last two files; group-3: 2.5% NaOCl for the first two files and PMB for the last two files. The association of Ca(OH)2 and CHX was used as an intracanal medication in all groups. Four root canal samplings (S) were collected: S1) immediately after access cavity; S2) after biomechanical preparation; S3) after EDTA application; and S4) after removal of the intracanal medication. After quantification of MMP-3, MMP-8, and MMP-9, the data were analyzed by Friedman and Kruskal-Wallis tests and completed by Dunn test (5%). Regardless the used irrigant, there was no difference in reducing MMP-3 or MMP-8 (P=0,5273, P=0,7048 respectively). However, in reducing MMP-9 (P=0,0246) the NaOCl group was the most effective followed by NaOCl+LW group and NaOCl+PMB group respectively. The intracanal medication [Ca(OH)2 + CHX] with the NaOCl and NaOCl+LW was effective in reducing MMP-8 (P<0,0001, P=0,0025) and MMP-9 (P=0,0007, P=0,0047) respectively, but not for the group of NaOCl+PMB which was not effective in reducing MMP-8 or MMP-9 (P=0,1718, P=0,1953) respectively. NaOCl and NaOCl+LW were effective in reducing MMP-9 levels, and this effectivity could be improved by the use of the intracanal medication [Ca(OH)2 + CHX] in reducing MMP-8 and MMP-9 levels.

Resumo O objetivo deste estudo foi avaliar o hipoclorito de sódio (NaOCl), água de cal (LW) e polimixina B (PMB) como soluções irrigadoras sobre MMP-3, MMP-8 e MMP-9. Trinta e três pacientes com periodontite apical de dentes unirradiculares foram tratados de acordo com três grupos experimentais (n= 11): grupo 1: 2,5% NaOCl foi usado como solução irrigadora; grupo-2: NaOCl a 2,5% para as duas primeiras limas e LW: [0,14% Ca(OH)2] para as duas últimas limas; group-3: 2.5% NaOCl para as duas primeiras limas e PMB para as duas últimas limas. A associação de Ca(OH)2 e CHX foi utilizada como medicação intracanal em todos os grupos. Quatro amostras de canais radiculares (S) foram coletadas: S1) imediatamente após a cirurgia de acesso; S2) após o preparo biomecânico; S3) após aplicação do EDTA; e S4) após a remoção da medicação intracanal. Após a quantificação das MMP-3, MMP-8 e MMP-9, os dados foram analisados pelos testes de Friedman e Kruskal-Wallis e completados pelo teste de Dunn (5%). Independentemente da solução irrigadora utilizada, não houve diferença na redução de MMP-3 ou MMP-8 (P= 0,5273, P= 0,7048 respectivamente). No entanto, na redução de MMP-9 (P= 0,0246) o grupo NaOCl foi o mais eficaz, seguido pelo grupo NaOCl+LW e grupo NaOCl+PMB, respectivamente. A medicação intracanal [Ca(OH)2 + CHX] com o NaOCl e NaOCl+LW foi eficaz na redução de MMP-8 (P<0,0001, P= 0,0025) e MMP-9 (P= 0,0007, P= 0,0047) respectivamente, mas não para o grupo de NaOCl+PMB que não foi eficaz na redução de MMP-8 ou MMP-9 (P= 0,1718, P= 0,1953), respectivamente. NaOCl e NaOCl+LW foram eficazes na redução dos níveis de MMP-9, e esta efetividade pode ser melhorada pelo uso da medicação intracanal [Ca(OH)2+CHX] na redução dos níveis de MMP-8 e MMP-9.

Prevalence of Klebsiella pneumoniae carbapenemase - and New Delhi metallo-beta-lactamase-positive K. pneumoniae in Sergipe, Brazil, and combination therapy as a potential treatment option

Abstract INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae infection lacks treatment options and is associated with prolonged hospital stays and high mortality rates. The production of carbapenemases is one of the most important factors responsible for this multi-resistance phenomenon. METHODS: In the present study, we analyzed the presence of genes encoding carbapenemases in K. pneumoniae isolates circulating in one of the public hospitals in the city of Aracaju, Sergipe, Brazil. We also determined the best combination of drugs that display in vitro antimicrobial synergy. First, 147 carbapenem-resistant K. pneumoniae isolates were validated for the presence of blaKPC, bla GES, bla NDM, bla SPM, bla IMP, bla VIM, and bla OXA-48 genes using multiplex polymerase chain reaction. Thereafter, using two isolates (97 and 102), the role of double and triple combinational drug therapy as a treatment option was analyzed. RESULTS: Seventy-four (50.3%) isolates were positive for bla NDM, eight (5.4%) for bla KPC, and one (1.2%) for both bla NDM and bla KPC. In the synergy tests, double combinations were better than triple combinations. Polymyxin B and amikacin for isolate 97 and polymyxin B coupled with meropenem for isolate 102 showed the best response. CONCLUSIONS: Clinicians in normal practice use multiple drugs to treat infections caused by multi-resistant microorganism; however, in most cases, the benefit of the combinations is unknown. In vitro synergistic tests, such as those described herein, are important as they might help select an appropriate multi-drug antibiotic therapy and a correct dosage, ultimately reducing toxicities and the development of antibiotic resistance.

Research progress in pharmacokinetics/pharmacodynamics and nephrotoxicity of polymyxin B / 中国药理学与毒理学杂志

In recent years, polymyxin B has played an important role in the salvage treatment of Gram-negative bacterial infections involving multi-drug-resistant bacteria and pan-drug-resistant bacteria. Its clinical value has been re-studied. However, it is difficult to use this antibitotoxin accurately under its potential nephrotoxicity and empirical administration, which restricts its rational use in clinic. In this paper, the pharmacokinetics and pharmacodynamics of polymyxin B, the mechanism of nephrotoxicity and the risk factors affecting nephrotoxicity were analyzed. It was possible that polymyxin B was mainly eliminated through the non-renal pathway. Clinically, loading doses are required for patients with severe infection. The incidence of nephrotoxicity can be reduced by controlling other covariates, and polymyxin B-induced nephrotoxicity involves the mitochondrial pathway and cell death receptor pathway. This paper is expected to provide reference for the clinical rational use of polymyxin B.

Dois casos de hiperpigmentação cutânea induzido pela polimixina B / Two cases of skin hyperpigmentation induced by polymyxin B

INTRODUÇÃO: O processo de hiperpigmentação cutânea envolve mecanismos bioquímicos e imunológicos que estimulam a melanogênese e apesar da nefrotoxicidade consistir na reação adversa mais relevante da polimixina B, o antimicrobiano também está associado a esta alteração. RELATO DE CASO: Caso 1: paciente masculino diagnosticado com Linfoma de Hodgkin, que desenvolveu hiperpigmentação cutânea após iniciar tratamento com meropenem, anidulafungina e polimixina B devido a um quadro de choque séptico. Caso 2: paciente masculino admitido na UTI por rebaixamento do nível de consciência e suspeita de IAMCSST, diagnosticado com endocardite e pericardite, que também apresentou hiperpigmentação cutânea durante terapia com anfotericina B e polimixina B. CONCLUSÃO: Após criteriosa avaliação da ordem cronológica e medicamentos utilizados pelos pacientes, concluímos que a polimixina B desencadeou a hiperpigmentação em ambos. Por fim, baseado ao mecanismo desta reação e aos achados científicos, estudos clínicos que possam evidenciar um provável efeito farmacológico com o uso de antagonistas H2 são necessários.

INTRODUCTION: The skin hyperpigmentation process involves biochemical and immunological mechanisms that stimulate melanogenesis and although nephrotoxicity consists of the most relevant adverse reaction of polymyxin B, it is also associated with this changes. CASE REPORT: Case 1: male patient, diagnosed with Hodgkin's Lymphoma, who developed skin hyperpigmentation after starting treatment with meropenem, anidulafungin and polymyxin B due to a septic shock. Case 2: male patient, admitted to the ICU for decreased level of consciousness and suspected STEMI, diagnosed with endocarditis and pericarditis, who also presented skin hyperpigmentation during therapy with amphotericin B and polymyxin B. CONCLUSION: After careful evaluation of chronological order and drugs used by patients, we conclude that polymyxin B caused hyperpigmentation in both patients. Finally, based on the mechanism of this reaction and the scientific findings, clinical studies that may evidence a probable pharmacological effect with the use of H2 antagonists are required.

Early use of polymyxin B reduces the mortality of carbapenem-resistant Klebsiella pneumoniae bloodstream infection

ABSTRACT Polymyxin B is one of the last resort option for carbapenem-resistant Klebsiella pneumoniae (CRKP) bloodstream infection in China. Therefore, the timing of administration of polymyxin is frequently delayed. We collected 40 cases of CRKP bloodstream infections (BSIs) treated with combinations based on polymyxin B over 30 months. The primary outcome, 30-day mortality rate, was 52.5% (21/40). Early administration of polymyxin B is meant to administer the drug within 48 h of diagnosing bacteremia. Delayed administration was considered when polymyxin B was administered after 48 h of bacteremia onset. Polymyxin B duration and total dosages were similar in the two groups (11.57 days versus 11.76 days, p = 0.919; 1306.52 mg versus 1247.06 mg, p = 0.711). Compared with delayed administration, early use of polymyxin B-based combination therapy had a significant increase in the rate of bacterial clearance (65.22% versus 29.41%, p = 0.025; OR = 0.533) and decreased 30-day mortality (39.13% versus 70.59%, p = 0.045; OR = 0.461) and overall mortality (43.48% versus 82.35%, p = 0.022; OR = 0.321).

Design, synthesis, and biological evaluation of novel polymyxin B analogues / 药学学报

Polymyxin B and polymyxin E (colistin) are increasingly used as last-resort drugs for treatment of infections caused by multidrug-resistant gram-negative pathogens. Unfortunately, the application was limited due to the serious side effects, especially nephrotoxicity. Very recently, the need for developing more tolerated and more effective polymyxin analogues has grown. This study details the design, synthesis, and evaluation of two classes of polymyxin B analogues with varying hydrophobicity and bulkiness at the N-terminal fatty acyl chain or position 6 amino acid. 20 polymyxin B analogues were synthesized and the chemical structures of the analogues were confirmed by HR-MS and 1H NMR spectra. Compounds 7e (MIC: 0.5-4 μg·mL-1) and 7l (MIC: 0.25-2 μg·mL-1) showed similar or better antimicrobial activity against both susceptible and resistant strains of Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa compared to polymyxin B (MIC: 0.5-2 μg·mL-1). Besides, compound 7l (CC50: 217.1±13.2 μg·mL-1) displayed noticeably decreased renal cytotoxicity compared to polymyxin B (CC50: 120.3±6.0 μg·mL-1). This work establishes the base of further study on the structure-activity relationship of polymyxin B.