Developing major histocompatibility markers in a species of concern: the Sacramento perch Archoplites interruptus

Primers targeting two non‐neutral major histocompatibility complex (mhc) II β genes were developed and assayed across several disjoint Sacramento perch Archoplites interruptus sampling locations. Variability at the two mhc loci among sampling stocks strongly correlated to previous estimates with neutral markers, suggesting that the effect of genetic drift was not limited to neutrally evolving regions of the genome. The novel mhc primers will help develop admixture schemes in A. interruptus captive breeding programmes and will increase the success of future reintroductions of this species of concern.     

重症监护病房患者多重耐药鲍曼不动杆菌感染及病死危险因素分析

目的 探讨重症监护病房患者多重耐药鲍曼不动杆菌（MDRAb）感染的危险因素及MDRAb感染患者病死的危险因素,为防治MDRAb提供依据。方法 回顾性分析2014年1月至2017年10月遂宁市中心医院重症监护病房197例鲍曼不动杆菌（Ab）感染患者,采用病例对照研究,根据抗生素敏感实验结果,将111例MDRAb感染者作为病例组,86例非MDRAb感染者作为对照组,收集其人口学资料、感染前的临床资料和实验室数据,应用单因素分析及多因素Logistic回归分析其感染的危险因素。同时将病例组分为病死组与存活组,分析其病死危险因素。结果 MDRAb检出率为56.35%。单因素Logistic分析显示,ICU停留时间、使用抗生素＞7 d、使用喹诺酮类抗生素、有创通气和胃管插管可能是MDRAb感染的危险因素（P＜0.05）。多因素Logistic回归分析显示,使用抗生素＞7 d（OR=2.338,95%CI：1.252~4.368）、使用喹诺酮类抗生素（OR=3.703,95%CI：1.665~8.234）、有创通气（OR=4.356,95%CI：1.695~11.192）是MDRAb感染的独立危险因素。单因素Logistic分析显示,年龄、高血压、血红蛋白量、昏迷可能是MDRAb感染患者病死的危险因素。多因素Logistic回归分析显示,高血压（OR=5.185,95%CI：2.012~13.361）、血红蛋白量（OR=0.976,95%CI：0.957~0.996）和昏迷（OR=4.061,95%CI：1.517~10.873）是MDRAb感染患者病死的独立危险因素。结论 使用抗生素＞7 d、使用喹诺酮类抗生素、有创通气是MDRAb感染的独立危险因素;高血压、血红蛋白量、昏迷是MDRAb感染患者病死的危险因素。     

Prevalence of multidrug resistant and extended spectrum beta-lactamase producing Pseudomonas aeruginosa in a tertiary care hospital

Resistance to broad-spectrum beta-lactams, mediated by extended-spectrum beta-lactamase enzymes (ESBL), is an increasing problem worldwide. The present study was undertaken to determine the incidence of ESBL-production among the clinical isolates of Pseudomonas aeruginosa and their susceptibility to selected antimicrobials. A total of one eighty-seven clinical specimens were tested for the presence of ESBL production using the double-disc synergy test. Of these, 25.13% (n = 47) isolates of P. aeruginosa were observed as ESBL positive. The maximum number of ESBL-producing strains were found in sputum (41.67%; n = 24) followed by pus (28.36%; n = 19), cerebrospinal fluid and other body fluids (21.74%; n = 5), urine (20.45%; n = 9) and blood (13.79%; n = 4). ESBL producing isolates exhibited co-resistance to an array of antibiotics tested. Imipenem and meropenem can be suggested as the drugs of choice in our study.     

P-glycoprotein as multidrug transporter: a critical review of current multidrug resistant cell lines

MDR has been studied extensively in mammalian cell lines. According to usual practice, the MDR phenotype is characterized by the following features: cross resistance to multiple chemotherapeutic agents (lipophilic cations), defective intracellular drug accumulation and retention, overexpression of P-gp (often accompanied by gene amplification), and reversal of the phenotype by addition of calcium channel blockers. An hypothesis for the function of P-gp has been proposed in which P-gp acts as a carrier protein that actively extrudes MDR compounds out of the cells. However, basic questions, such as what defines the specificity of the pump and how is energy for active efflux transduced, remain to be answered. Furthermore, assuming that P-gp acts as a drug transporter, one will expect a relationship between P-gp expression and accumulation defects in MDR cell lines. A review of papers reporting 97 cell lines selected for resistance to the classical MDR compounds has revealed that a connection exists in most of the reported cell lines. However, several exceptions can be pointed out. Furthermore, only a limited number of well characterized series of sublines with different degrees of resistance to a single agent have been reported. In many of these, a correlation between P-gp expresson and transport properties can not be established. Co-amplification of genes adjacent to the mdr1 gene, mutations [122], splicing of mdr1 RNA [123], modulation of P-gp by phosphorylation [124] or glycosylation [127], or experimental conditions [26,78] could account for some of the complexity of the phenotype and the absence of correlation in some of the cell lines. However, both cell lines with overexpression of P-gp without increased efflux [i.e., 67,75] and cell lines without P-gp expression and accumulation defects/increased efflux [i.e., 25,107] have been reported. Thus, current results from MDR cell lines contradict - but do not exclude - that P-gp acts as multidrug transporter. Other models for the mechanism of resistance have been proposed: (1) An energy-dependent permeability barrier working with greater efficacy in resistant cells. This hypothesis is supported by studies of influx which, although few, all except one demonstrate decreased influx in resistant cells; (2) Resistant cells have a greater endosomal volume, and a greater exocytotic activity accounts for the efflux. Furthermore, large amounts of P-gp in the plasma membrane altering the ultrastructure and generalized changes, such as increases or decreases in membrane fluidity, alterations in lipid composition, changes in transmembrane pH gradient and membrane potential have been described in MDR cell lines and could account for some of the findings.     

P-glycoprotein as multidrug transporter: a critical review of current multidrug resistant cell lines.

MDR has been studied extensively in mammalian cell lines. According to usual practice, the MDR phenotype is characterized by the following features: cross resistance to multiple chemotherapeutic agents (lipophilic cations), defective intracellular drug accumulation and retention, overexpression of P-gp (often accompanied by gene amplification), and reversal of the phenotype by addition of calcium channel blockers. An hypothesis for the function of P-gp has been proposed in which P-gp acts as a carrier protein that actively extrudes MDR compounds out of the cells. However, basic questions, such as what defines the specificity of the pump and how is energy for active efflux transduced, remain to be answered. Furthermore, assuming that P-gp acts as a drug transporter, one will expect a relationship between P-gp expression and accumulation defects in MDR cell lines. A review of papers reporting 97 cell lines selected for resistance to the classical MDR compounds has revealed that a connection exists in most of the reported cell lines. However, several exceptions can be pointed out. Furthermore, only a limited number of well characterized series of sublines with different degrees of resistance to a single agent have been reported. In many of these, a correlation between P-gp expression and transport properties can not be established. Co-amplification of genes adjacent to the mdr1 gene, mutations [122], splicing of mdr1 RNA [123], modulation of P-gp by phosphorylation [124] or glycosylation [127], or experimental conditions [26,78] could account for some of the complexity of the phenotype and the absence of correlation in some of the cell lines. However, both cell lines with overexpression of P-gp without increased efflux [i.e., 67,75] and cell lines without P-gp expression and accumulation defects/increased efflux [i.e., 25,107] have been reported. Thus, current results from MDR cell lines contradict--but do not exclude--that P-gp acts as multidrug transporter. Other models for the mechanism of resistance have been proposed: (1) An energy-dependent permeability barrier working with greater efficacy in resistant cells. This hypothesis is supported by studies of influx which, although few, all except one demonstrate decreased influx in resistant cells; (2) Resistant cells have a greater endosomal volume, and a greater exocytotic activity accounts for the efflux.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparative genomics of multidrug resistance in Acinetobacter baumannii

Acinetobacter baumannii is a species of nonfermentative gram-negative bacteria commonly found in water and soil. This organism was susceptible to most antibiotics in the 1970s. It has now become a major cause of hospital-acquired infections worldwide due to its remarkable propensity to rapidly acquire resistance determinants to a wide range of antibacterial agents. Here we use a comparative genomic approach to identify the complete repertoire of resistance genes exhibited by the multidrug-resistant A. baumannii strain AYE, which is epidemic in France, as well as to investigate the mechanisms of their acquisition by comparison with the fully susceptible A. baumannii strain SDF, which is associated with human body lice. The assembly of the whole shotgun genome sequences of the strains AYE and SDF gave an estimated size of 3.9 and 3.2 Mb, respectively. A. baumannii strain AYE exhibits an 86-kb genomic region termed a resistance island—the largest identified to date—in which 45 resistance genes are clustered. At the homologous location, the SDF strain exhibits a 20 kb-genomic island flanked by transposases but devoid of resistance markers. Such a switching genomic structure might be a hotspot that could explain the rapid acquisition of resistance markers under antimicrobial pressure. Sequence similarity and phylogenetic analyses confirm that most of the resistance genes found in the A. baumannii strain AYE have been recently acquired from bacteria of the genera Pseudomonas, Salmonella, or Escherichia. This study also resulted in the discovery of 19 new putative resistance genes. Whole-genome sequencing appears to be a fast and efficient approach to the exhaustive identification of resistance genes in epidemic infectious agents of clinical significance.     

Endemic Acinetobacter baumannii in a New York hospital

Background

Acinetobacter baumannii is an increasingly multidrug-resistant (MDR) cause of hospital-acquired infections, often associated with limited therapeutic options. We investigated A. baumannii isolates at a New York hospital to characterize genetic relatedness.

Methods

Thirty A. baumannii isolates from geographically-dispersed nursing units within the hospital were studied. Isolate relatedness was assessed by repetitive sequence polymerase chain reaction (rep-PCR). The presence and characteristics of integrons were assessed by PCR. Metabolomic profiles of a subset of a prevalent strain isolates and sporadic isolates were characterized and compared.

Results

We detected a hospital-wide group of closely related carbapenem resistant MDR A. baumannii isolates. Compared with sporadic isolates, the prevalent strain isolates were more likely to be MDR (p = 0.001). Isolates from the prevalent strain carried a novel Class I integron sequence. Metabolomic profiles of selected prevalent strain isolates and sporadic isolates were similar.

Conclusion

The A. baumannii population at our hospital represents a prevalent strain of related MDR isolates that contain a novel integron cassette. Prevalent strain and sporadic isolates did not segregate by metabolomic profiles. Further study of environmental, host, and bacterial factors associated with the persistence of prevalent endemic A. baumannii strains is needed to develop effective prevention strategies.     

Sex and the emergence of species

We argue that the existence of species as distinct and relatively homogeneous groupings of individuals is a consequence of the nonlinear dynamics inherent in sexual reproduction. This approach provides an answer to two interrelated problems which Darwin posed and tried to solve. Why are there missing links (i.e. gaps) between species in habitat space, and why are there missing links between species in time as evidenced in the fossil record? A crucial difference between outcrossing sexual organisms (i.e. organisms in which mating is between different individuals) and obligate selfers or parthenogens lies in the dynamic of the underlying replication process. Replication is a linear function of density for obligate selfers or parthenogens but nonlinear for outcrossing sexuals. The non-linearity stems from the simple fact that with outcrossing, two individuals must come together to mate. We argue that this fact leads to density dependent fitness (per capita rate of increase) with an intrinsic disadvantage of low population density. This cost of rarity results in a distribution of distinct species. By establishing the causal connections in evolution between outcrossing sex and the very existence of species as distinct collections of organisms, our account lends theoretical support to a unitary concept of species with interbreeding as the fundamental defining property.     

Predictor of multidrug resistant tuberculosis in southwestern part of Ethiopia: a case control study

Background

Curable disease tuberculosis is becoming incurable or difficult to treat due to drug resistance. Multi drug resistance tuberculosis is a major health problem for less developed countries. Development of drug resistance is mainly as result of man related factors and poor lifestyle. Identifying predictors of drug resistance and working on them is the important way of reducing the expansion in high burden countries. Ethiopia is one of TB, TB/HIV, and multi-drug resistant tuberculosis (MDR-TB) high burden country globally. This study was aimed to assess predictor of MDR-TB in southwest part of Ethiopia.

Methods

Unmatched case control study was conducted in case to control ratio of 1:1.2 in southwest part of Ethiopia. The cases were recruited from confirmed MDR-TB patient enrolled on second line treatment in Shenen Gibe Hospital (MDR-TB treatment center of the prefecture) and the controls were recruited from previously TB patients who cured or patient with smear negative at the end of treatment month during the study period in the same area. The data was collected by structured questionnaire by interview and logistic regression analyses were used to identify predictors of MDR-TB. Odds ratios with 95% CI were computed to determine the predictors.

Result

From the total 132 participants about 45% of them were cases. None disclosed tuberculosis infected to relatives [AOR?=?3.4, 95% CI (1.2–9.8)], insufficient instruction on how to take anti-TB drug [AOR?=?4.7, 95% CI (1.4–14.6)], contact history with MDR-TB [AOR?=?8.5, 95% CI (2.9–25.5)], interruption of first-line anti-TB treatment for at list 1 day [AOR?=?7.9, 95% CI (2.5–24.9)], and having alcohol drinking habits [AOR?=?5.1, 95% CI (1.4–18.7)] were identified predictors for MDR-TB infection in study area.

Conclusion

TB infection disclosure status, insufficient instruction on drug usage, contact history with MDR-TB, interruption of first-line anti-TB drugs, and alcohol drinking habits were identified predictor of MDR-TB case. Therefore, early detection and proper treatment of drug susceptible TB, strengthening directly observed treatment, short-course on daily bases, community involvement, and supporting the patient to intervene identified factors is paramount.

     

多重耐药鲍曼不动杆菌消毒剂耐药基因检测及同源性分析

目的探讨多重耐药鲍曼不动杆菌（MDRAB）临床分离株对医院常用消毒剂苯扎溴铵和醋酸氯已定的耐药表型与qacE△1-sul1基因型的相关性并分析菌株的同源性。方法用微量肉汤稀释法检测菌株的最低抑菌浓度（MIC）和最低杀菌浓度（MBC）,用PCR方法检测qacE△1-sul1基因,用脉冲场凝胶电泳（PFGE）分析菌株的同源性。结果20株MDRAB中,18株（90％）qacE△l-sul1阳性,2株（10％）qacE△1-sul1阴性。qacE△1-sul1阳性株对苯扎溴铵的MIC50、MIC90、MBC50和MBC90分别是qacE△1-sul1阴性株的2倍、2倍、8倍和8倍。而qacE△1-sul1阳性株对醋酸氯已定的MIC50、MIC90、MBC50和MBC90分别是qacE△1-sul1阴性株的2倍、2倍、4倍和8倍。PF-GE显示：18株qacE△1-sul1阳性MDRAB可分为A～F6个PFGE克隆。2株qacE△1-sul1阴性MDRAB均为B克隆。结论MDRAB对消毒剂耐药性升高与qacE△1-sul1基因相关,临床存在多个克隆株的传播。     

On the evolution of SARS-CoV-2 and the emergence of variants of concern

The epidemiology of COVID-19 has dramatically changed since the beginning of the pandemic as we witnessed significant changes in transmissibility and pathogenicity with the emergence of SARS-CoV-2 variants of concern (VoCs). Here I present and comment on working hypotheses about the evolutionary dynamics of the emergence of VoCs.     

Evolution of antimicrobial resistance of Acinetobacter baumannii in a university hospital

Aims: To investigate the susceptibility pattern and the molecular epidemiology of Acinetobacter baumannii isolates in two periods (1994–1996 and 2004–2007) in Londrina University Hospital. Methods and Results: Antimicrobial susceptibility of 150 A. baumannii isolates was assessed by disc diffusion and agar dilution methods. Genetic similarity amongst the isolates was evaluated by ERIC–PCR. Resistance of A. baumannii to carbapenems increased from 2% (1994–1996) to 73% (2004–2007). Thirty‐eight clones were detected. Conclusions: The results of the study suggest that the high prevalence of carbapenem resistance amongst Acinetobacter baumannii organisms in this institution is not caused by the spread of a predominant clone. Significance and Impact of the Study: This work reinforces the importance monitoring antimicrobial susceptibility rates.     

Detection of P-glycoprotein in the nuclear envelope of multidrug resistant cells

P-glycoprotein is a plasma membrane efflux pump which is responsible for multidrug resistance of many cancer cell lines. A number of studies have demonstrated the presence of P-glycoprotein molecules, besides on the plasma membrane, also in intracellular sites, such as the Golgi apparatus and the nucleus. In this study, the presence and function of P-glycoprotein in the nuclear membranes of human breast cancer cells (MCF-7 WT) and their multidrug resistant variants (MCF-7 DX) were investigated. Electron and confocal microscopy immunolabelling experiments demonstrated the presence of P-glycoprotein molecules in the nuclear membranes of MCF-7 DX cells. Moreover, the labelling pattern was strongly dependent on pH values of the incubation buffer. At physiological pH (7.2), a strong labelling was detected in the cytoplasm and the nuclear matrix in both sensitive and resistant MCF-7 cells. By raising the pH to 8.0, the P-glycoprotein molecules were easily detected in the cytoplasm (transport vesicles and Golgi apparatus), plasma and nuclear membranes exclusively in MCF-7 DX cells. Furthermore, drug uptake and efflux studies, performed by flow cytometry on isolated nuclei in the presence of the P-glycoprotein inhibitor cyclosporin A, suggested the presence of a functional P-glycoprotein in the nuclear membrane, but not in the nuclear matrix, of drug resistant cells. Therefore, P-glycoprotein in the nuclear envelope seems to represent a further defense mechanism developed by resistant cells against antineoplastic agents.     

危重病房耐碳青霉烯酶鲍曼不动杆菌同源性研究

目的探讨杭州市第一医院危重病房耐碳青霉烯酶鲍曼不动杆菌之间的同源性,进行分子流行病学调查,旨在为制定预防和控制其院内感染的措施提供依据。方法收集该院危重病房2005年1月至12月分离到的34株亚胺培南耐药鲍曼不动杆菌。采用全自动微生物分析系统VITEK-AMS60对34株耐碳青霉烯酶鲍曼不动杆菌进行鉴定及药敏;用琼脂稀释法和E-test法测定14种抗菌药物的最低抑菌浓度(MIC),脉冲场凝胶电泳(PF-GE)分析其耐药株的同源性,对碳青霉烯类基因OXA-23型、OXA-24型、IMP型、VIM型基因进行PCR扩增及序列分析。结果PFGE发现34株鲍曼不动杆菌菌株为同一耐药克隆株,在危重病房呈爆发流行。所有对亚胺培南耐药鲍曼不动杆菌明确产OXA-23型碳青霉烯酶,未检出OXA-24、IMP、VIM基因型。34株菌株质粒提取未成功。结论该院同一个耐药克隆株在危重病房不同患者身上流行,可能与行气管插管、呼吸机、氧气湿化瓶、护士手操作有关。     

A potato cDNA encoding a homologue of mammalian multidrug resistant P-glycoprotein

A homologue of the multidrug resistance (MDR) gene was obtained while screening a potato stolon tip cDNA expression library with³⁵S-labeled calmodulin. The mammalian MDR gene codes for a membrane-bound P-glycoprotein (170–180 kDa) which imparts multidrug resistance to cancerous cells. The potato cDNA (PMDR1) codes for a polypeptide of 1313 amino acid residues (ca. 144 kDa) and its structural features are very similar to the MDR P-glycoprotein. The N-terminal half of the PMDR1-encoded protein shares striking homology with its C-terminal half, and each half contains a conserved ATP-binding site and six putative transmembrane domains. Southern blot analysis indicated that potato has one or two MDR-like genes. PMDR1 mRNA is constitutively expressed in all organs studied with higher expression in the stem and stolon tip. The PMDR1 expression was highest during tuber initiation and decreased during tuber development.     

The MODS method for diagnosis of tuberculosis and multidrug resistant tuberculosis

Patients with active pulmonary tuberculosis (TB) infect 10-15 other persons per year, making diagnosing active TB essential to both curing the patient and preventing new infections. Furthermore, the emergence of multidrug resistant tuberculosis (MDRTB) means that detection of drug resistance is necessary for stopping the spread of drug-resistant strains. The microscopic-observation drug-susceptibility (MODS) assay is a low-cost, low-tech tool for high-performance detection of TB and MDRTB. The MODS assay is based on three principles: 1) mycobacterium tuberculosis (MTB) grows faster in liquid media than on solid media 2) microscopic MTB growth can be detected earlier in liquid media than waiting for the macroscopic appearance of colonies on solid media, and that growth is characteristic of MTB, allowing it to be distinguished from atypical mycobacteria or fungal or bacterial contamination 3) the drugs isoniazid and rifampicin can be incorporated into the MODS assay to allow for simultaneous direct detection of MDRTB, obviating the need for subculture to perform an indirect drug susceptibility test. Competing current diagnostics are hampered by low sensitivity with sputum smear, long delays until diagnosis with solid media culture, prohibitively high cost with existing liquid media culture methods, and the need to do subculture for indirect drug susceptibility testing to detect MDRTB. In contrast, the non-proprietary MODS method has a high sensitivity for TB and MDRTB, is a relatively rapid culture method, provides simultaneous drug susceptibility testing for MDRTB, and is accessible to resource-limited settings at just under $3 for testing for TB and MDRTB.Download video file.^{(243M, mp4)}