In Vitro Bactericidal Effect of a β-lactam + Aminoglycoside Combination Against Multiresistant Pseudomonas aeruginosa and Acinetobacter baumannii

Abstract

Pseudomonas aeruginosa and Acinetobacter baumannii are frequently isolated in hospital outbreaks of nosocomial infections. In our hospital, among 1018 strains isolated one year in an intensive care unit, 84 strains (8.3%) of P. aeruginosa and 155 strains (15.2%) of A. baumannii were considered responsible for infections. The major problem related to these bacteria is their multiresistant characteristic which confers great difficulty in treating infections. We carried out a 24 h time-kill study to assess the bactericidal effect of three β-lactams [imipenem (IPM), ticarcillin + clavulanic acid (TCC), piperacillin + tazobactam (PTB)] in combination with each other and with sulbactam (SUL) and amikacin (AKN) against 8 P. aeruginosa strains and 8 A. baumannii strains. The initial inoculum was 10⁶ cfu/ml. Antibiotics were tested at clinically achievable concentrations: TCC (112 mg/l), PTB (100 mg/l), IPM (25 mg/l) and AKN (15 mg/l). The results showed: IMP+TCC+AKN = PTB+SUL+AKN = PTB+TCC+ AKN >> IMP+SUL+AKN against P. aeruginosa; and PTB+SUL+AKN = PTB+TCC+AKN > IMP+SUL+AKN or IMP+TCC+AKN against A. baumannii. When infection due to these multiresistant strains was suspected, PTB+AKN combined with either TCC or SUL was bactericidal against both strains. These combinations appeared to be an alternative therapy in the treatment of undocumented nosocomial infections in intensive care units. These In Vitro results are being evaluated in patients and seem to give good results for the moment.     

In Vitro Activity of β-Lactam Antimicrobial Agents in Combination with Aztreonam Tested Against Metallob-β-Lactamase-Producing Pseudomonas aeruginosa and Acinetobacter baumannii

Abstract

We evaluate the antimicrobial interactions between aztreonam and selected beta-lactams when tested against metallo-β-lactamase (MβL)-producing clinical strains. Ten Pseudomonsa aeruginosa strains, including nine MβL-producers (IMP- 1, -2, -13, -16, VIM-1, -2, -7, SPM-1 and GIM-1) and five Acinetobacter baumannii strains, including three MβL-producers (IMP-1 and -2) were tested using time kill/bactericidal activity methods. Aztreonam at 4, 8 and 16 mg/L was combined with four other β-lactam antimicrobials (cefepime, ceftazidime, meropenem and piperacillin/tazobactam or ampicillin/sulbactam), each tested at the recognized susceptible breakpoint concentration. Enhanced activity (synergism or additive effect) was observed with four P. aeruginosa strains (IMP-16, VIM-2, SPM-1 and GIM-1 containing strains) and four A. baumannii strains, while antagonism was observed with two P. aeruginosa (IMP-16 and SPM-1-producing strains) and one A. baumannii (non-MβL) strain. All other strains showed indifferent interaction (variation of ± 1 log₁₀ CFU/ml) with any combination evaluated.     

In- Vitro Sensitivity of Amoxicillin/Clavulanic Acid (Augmentin®) to Isolated Beta-Lactamases and In- Vitro Antibacterial Activity

Summary

The in vitro sensitivity of amoxicillin alone and combined with clavulanic acid (ratio 4:1) as been studied by a spectrophotometric method utilizing crude extract of the following enzymes: TEMI, TEM2, SHV1, SHV2, TLE1, HMS1, LXA, P99, ENT208. The in-vitro antibacterial activity of ampicillin, amoxicillin alone and associated with clavulanic acid was also determined by an agar dilution method.

Clavulanate protects amoxicillin from the hydrolytic activity of plasmid mediated beta-lactamase, conferring a stability on the beta-lactam comparable with that of cefotaxime.

The protection of amoxicillin by means of clavulanic acid reduces the minimal concentration of antibiotic necessary to inhibit most bacterial species and allows bacteria to remain sensitive to the drug which might otherwise be resistant.     

Extended-Spectrum β-Lactamases Conferring Resistance to Monobactams and Oxyimino-Cephalosporins in Clinical Isolates of Serratia marcescens

Abstract

We studied antibiotic resistance patterns and extended-spectrum β-lactamases (ESβLs) production in Serratia marcescens strains isolated in our hospital during 1993. We examined 210 S. marcescens isolates. Of these, 172 were obtained from 49 patients admitted to an intensive care ward; 157 out of 172 were obtained from February to October and presented the same pattern of antibiotic resistance, including monobactams and oxyimino-cephalosporins. The remaining 15 out of 172 isolates (obtained from September to December) were susceptible to all drugs tested, with the exception of first generation cephalosporins. Thirty-eight additional isolates were recovered, during the same period, from 28 patients admitted to wards other than the intensive care unit; also these strains showed the high susceptibility pattern reported above.

Epidemic strains of S. marcescens produced three different types of β-lactamase with pI 5.4, 5.5, and 8.4. In contrast, non-epidemic strains produced only one type of β-lactamase with pI 8.4. Conjugation experiments showed that the β-lactamases having a pI of 5.4 and 5.5 (but not the one with pI 8.4) were plasmid-mediated. Since the β-lactamase with pI 5.5 was capable of hydrolyzing monobactams and oxyimino-cephalosporins it was classified as ESβL. Electrophoretic analysis showed that plasmids obtained from multiresistant strains were of about 54 kb; these plasmids appeared also to code for aminoglycoside resistance. Our data indicate that the plasmid-mediated production of ESβLs may contribute to the epidemic spread of Serratia marcescens in high-risk wards.     

Does ertepenem alter the susceptibility of Pseudomonas aeruginosa to carbapenems?

We investigated the effect of ertapenem on carbapenem susceptibility of Pseudomonas aeruginosa. Antibiotic consumption was recorded monthly in defined daily doses (DDD)/100 patient-days in the infectious diseases (ID), abdominal surgery (AS), and surgical intensive care units (SICU) of a teaching hospital from January 2005 to December 2008. Trends of decreased susceptibility of P. aeruginosa were observed in all three units. After the introduction of ertapenem, the number of P. aeruginosa isolates/ 1000 patients-days per month increased in AS and in SICU (p=0.05). The increase in carbapenem non-susceptible isolates/1000 patients-days in the same units was less significant (p=0.07 and p=0.054). Correlations between ertapenem and the carbapenem non-susceptibility for the lagtime of 1 to 6 months ahead gave no significant result. In the SICU, 30% of variability of carbapenem non-susceptibility could be predicted by the consumption of ertapenem. There is no evidence that ertapenem alters the P. aeruginosa susceptibility to carbapenems, but the relationship deserves further observation.     

Antimicrobial Resistance and Prevalence of Extended Spectrum β-Lactamase Among Clinical Isolates of Gram-Negative Bacteria in Riyadh

Abstract

The activity of ciprofloxacin, imipenem and 12 other commonly used antibiotics was evaluated against 106 documented clinical isolates from a medical Intensive Care Unit (ICU). The resistance rates to ceftriaxone, cefotaxime, aztreonam and ceftazidime were 42, 25, 24 and 21%, respectively. Apart from Pseudomonas aeruginosa, all isolates were sensitive to ciprofloxacin and imipenem. Complete cross resistance among tested β-lactam groups was uniformly evident in Enterobacter cloacae, Citrobacter freundii and P. aeruginosa. On the other hand, penicillins and second generation cephalosporins showed cross resistance among Escherichia coli and Klebseilla pneumoniae isolates. Induction experiments indicate that 70 and 62% of P. aeruginosa and E. cloacae or C. freundii produce class I cephalosporinase, respectively.

Among all tested isolates, plasmid mediated extended spectrum β-lactamase (ESBL) was detected in one isolate of K. pneumoniae. The plasmid mediated β-lactamase is transferable and inhibited by β-lactamase inhibitors. The transconjugates not only expressed resistance to extended spectrum β-lactams and aztreon-am but also toward tested aminoglycoside antibiotics, with the exception of gentamicin. The obtained transconjugates conferred high level resistance to cef-tazidime and aztreonam but considerably low resistance to ceftriaxone and cefotaxime. The isoelectric point for the extended-spectrum β-lactamase is 8.2.     

Nosocomial Spread of ArmA-Mediated High-Level Aminoglycoside Resistance in Enterobacteriaceae Isolates Producing CTX-M-3 β-Lactamase in a Cancer Hospital in Bulgaria

Abstract

1,310 Enterobacteriaceae 242 Pseudomonas aeruginosa and 97 Acinetobacter baumannii clinical isolates collected at a cancer hospital in Bulgaria were screened for the presence of 16S rRNA methylases. The armA methylase gene was identified in 20 (1.5%) Enterobacteriaceae (7 Klebsiella pneumoniae, 3 Escherichia coli, 3 Serratia marcescens, 3 Citrobacter freundii, 3 Enterobacter cloacae and 1 Klebsiella oxytoca). ArmA-mediated aminoglycoside resistance was transferable by conjugation and carried by closely related IncL/M plasmids which also carried ant3”9, dfrXII, sul1, bla _TEM-1, and bla _CTX-M-3 genes encoding resistance to streptomycin-spectinomycin, trimethoprim, sulfonamides, and β-lactams, respectively. Most of the isolates were genetically different according to PFGE but shared similar restriction patterns of the armA-encoding plasmids. Our findings highlight the strong association of armA and bla _CTX-M-3 extended-spectrum β-lactamase genes across various species in the family Enterobacteriaceae. The spread of multiresistant isolates expressing 16S rRNA methylases and ESBLs is a worrisome development requiring continuous monitoring.     

In Vitro and In Vivo Efficacy of YTR-830H and Piperacillin Combinations Versus β-Lactamase-Producing Bacteria

Summary

YTR-830H, a β-lactamase inhibitor, is a non-amino penicillanic sulfone. In vitto synergistic activity with piperacillin was determined for 226 β-lactamase producing clinical cultures. Combination of piperacillin: YTR in ratios of 2:1, 4:1, and 8:1 were highly effective vs Escherichia coli, Proteus, Providencia, Morganella, Staphylococcus, and Bacteroides. Minimum inhibitory concentrations (MICs) of piperacillin were reduced from the resistant to susceptible range. The higher ratios were less effective vs Enterobacter, Serratia, and Citrobacter. YTR-830H was not antagonistic with piperacillin. Combinations of 2:1, 4:1, and 8:1 increased the therapeutic effectiveness of piperacillin 8 - to 36 - fold against acute lethal infections produced in mice with piperacillin-resistant Escherichia coli, Klebsiella pneumoniae, Morganella morganii, and Staphylococcus aureus.     

Clinical significance of axin and β-catenin protein expression in primary hepatocellular carcinomas

The aim of the present research was to investigate clinicopathologic correlations of immunohistochemically- demonstrated axin (axis inhibition) and β-catenin expression in primary hepatocellular carcinomas (HCCs), in comparison with paraneoplastic, cirrhotic and normal liver tissues. Variation in Axin expression across groups were significant (P < 0.01), correlating with alpha fetoprotein (AFP), HBsAg, cancer plugs in the portal vein, and clinical stage of HCCs(P < 0.05); however, there were no links with sex, age, and tumour size (P > 0.05). Differences in cell membrane β-catenin expression were also statistically significant (P < 0.01), again correlated with AFP, HBsAg, cancer plugs in the portal vein, and clinical stage in HCCs (P < 0.05) but not with sex, age, and tumour size (P > 0.05). Axin expression levels in tissues with reduced membrane β-catenin were low (P < 0.05), also being low with nuclear β-catenin expression (P < 0.05). Axin and β-catenin may play an important role in the genesis and progression of HCC via the Wnt signal transmission pathway. Simultaneous determination of axin, β-catenin, AFP, and HBsAg may be useful for early diagnosis, and metastatic and clinical staging of HCCs.     

Comparative In Vitro Activity of Telithromycin and β-Lactam Antimicrobials Against Bacterial Pathogens from Community-Acquired Respiratory Tract Infections: Data from the First Year of PROTEKT (1999-2000)

Abstract

The In Vitro activity of telithromycin, a new ketolide, was compared with β-lactam antimicrobials against pathogens commonly associated with community-acquired respiratory tract infections. These pathogens were collected during 1999-2000 as part of the ongoing PROTEKT surveillance study. Globally, penicillin non-susceptibility among Streptococcus pneumoniae (n=3362) was 36.3%, ranging from 21.5% (Australasia) to 68.0% (Far East). Telithromycin showed higher potency (MIC₉₀ 0.12 mg/L) than β-lactams against S. pneumoniae; 99.9% of all and 99.6% of multi-resistant isolates were susceptible to telithromycin. Among Streptococcus pyogenes isolates (n=1485), 100% were susceptible to β-lactams, and the telithromycin MIC₅₀ and MIC₉₀ were both 0.015 mg/L. Among Haemophilus influenzae (n=2948), 16.6% produced β-lactamase, which reduced the activity of ampicillin, cefaclor and cefprozil. 99.9% of H. influenzae were susceptible to telithromycin and the MIC range for M. catarrhalis was 0.004-0.5 mg/L. The first year results of PROTEKT confirmed high potency for telithromycin against common respiratory tract pathogens, including β-lactam-resistant strains.     

Clinical value of β2-MG and LDH determination in the patients with myelodysplastic syndrome

目的:探讨骨髓增生异常综合征(myelodysplastic syndrome,MDS)患者血清β 2-微球蛋白(β 2-microglobulin,β 2-MG)和乳酸脱氢酶(lactic dehydrogenase,LDH)检测的临床价值.方法:采用放射免疫法测定血清β2-MG,速率法检测LDH,比较两者在30例健康体检者和45例不同亚型MDS患者中的水平,并对两者均增高和均正常的MDS患者进行生存分析.结果:各组MDS患者血清β 2-MG水平均明显高于正常对照组(P＜0.01),其中难治性贫血伴原始细胞过多-Ⅱ(refractory anemia with excessive blasts Ⅱ,RAEB-Ⅱ)组明显高于难治性贫血(refractory anemia,RA)、难治性血细胞减少伴有多系发育异常(refractory cytopenia with multilineage dysplasia,RCMD)和难治性贫血伴原始细胞过多-Ⅰ(refractory anemia with excessive blasts Ⅰ,RAEB-Ⅰ)组,差异均有统计学意义(P均＜0.0 1);RAEB-Ⅰ、RAEB-Ⅱ组血清LDH水平明显高于RA、RCMD组(P＜0.0 1);血清LDH、β 2-MG均增高的患者中位生存期明显短于两者均正常者(P＜0.01).结论:联合检测血清β2-MG和LDH水平,对于MDS的诊断、分型及预后分析具有重要的临床价值.     

Influence of Comorbidity and Severity on the Clinical Outcome of Bacteremic Pneumococcal Pneumonia Treated with β-lactam Monotherapy

Abstract

The influence of the severity of pneumonia and comorbidity factors, as predictors of clinical outcome, was assessed in patients with microbiologically documented pneumococcal bacteremic pneumonia treated with penicillin or third generation cephalosporin monotherapy in a 5-year retrospective study. Among 288 patients admitted to three Spanish hospitals with bacteremic pneumococcal pneumonia, 65 (23%) were included. Twenty-four were treated with penicillins and 41 with a third-generation cephalosporin. Twenty-seven patients (42%) had severe pneumonia and 41 (63%) had a comorbidity index >1. Twenty-one patients (32%) were infected with penicillin-resistant strains. Four cases (2 with penicillin-resistant strains; 3 treated with cephalosporins) were clinical failures. Four cases (3 with penicillin-resistant strains; 2 treated with cephalosporins) died, i.e. 6% mortality rate. The only factor that influenced empirical treatment election was HIV-positive condition. Clinical outcome was not influenced by treatment election, penicillin susceptibility of the infecting pneumococci, patient basal conditions or severity of pneumonia, but the latter was associated with mortality and length of hospitalization.     

Antibiotic Resistance and Adherence Properties of Hafnia alvei Clinical Isolates: A 19-Month Study in the Hospital of Orléans,France

Abstract

We studied the epidemiology of antibiotic resistance and adherence properties among all Hafnia alvei clinical isolates collected from August 2003 to February 2005 from patients hospitalized in the hospital of Orléans, France. The isolates were typed by random amplified polymorphic DNA (RAPD), screened for antibiotic resistance and bacterial adherence to A549 respiratory and T24 bladder cells. Six intestinal, 3 respiratory, and 8 isolates from different body sites were collected. A total of 12 RAPD profiles were found, demonstrating a high genetic diversity. All the isolates were resistant to amoxicillin + clavulanate and cephalothin and sensitive to aminoglycosides, fluoroquinolones, cefepime and imipenem. Six isolates had a high-level and constitutive cephalosporinase production phenotype. Three independent isolates were resistant or had intermediate sensitivity to nalidixic acid, sulfonamide and trimethoprim or chloramphenicol. All the isolates adhered efficiently to the two cell lines with a higher effectiveness of adherence to bladder cells. The respiratory isolates adhered more efficiently to epithelial cells than intestinal isolates. No relationship was found between antibiotic resistance phenotypes, adherence properties, and RAPD types. In conclusion, H. alvei is an unusual nosocomial pathogen with little acquired antibiotic resistance able to adhere to human epithelial cells from different human body compartments.     

Epithelial Paradox: Clinical Significance of Coexpression of E-cadherin and Vimentin With Regard to Invasion and Metastasis of Breast Cancer

Background

E-cadherin and vimentin are regarded as major conventional canonical markers of the epithelial–mesenchymal transition. It is commonly assumed that E-cadherin is uniformly lost during the process of epithelial–mesenchymal transition. Breast tumor cells typically invade as a cohesive multicellular unit in a process called collective invasion. The aim of this study was to reveal the clinical importance of the expression pattern of E-cadherin and vimentin in breast cancer.

Could Anthropometric and Lipid Parameters Reflect Susceptibility to Breast Cancer? Comparison of Newly Diagnosed Breast Cancer and Apparently Healthy Women

Objectives: To determine and compare the serum lipid profiles and anthropometric parameters of newly diagnosedBC patients and healthy women. Methods: Serum total cholesterol (TC), high density lipoprotein cholesterol (HDL-C),low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), triglyceride (TG)and TC: HDL-C were measured in consent obtained newly diagnosed BC patients (n=155) and age matched apparentlyhealthy females (n=75). Weight (W), height (H), waist circumference (WC), hip circumference (HC) and mid upper armcircumference (MUC) of each women were recorded. Cut off values for each parameter was found by receiver operativecharacteristic (ROC) curves and risk associated with was calculated using SPSS version 16. Results: Majority (67%)of BC women were postmenopausal. The mean TC, HDL-C, LDL-C, VLDL-C, TC: HDL-C, TG concentrations ofBC patients who were not on cholesterol lowering drugs (n= 126) were 234 mg/dL (±51), 43 mg/dL (±10), 164 mg/dL(±44), 27 mg/dL (±14), 5.7(±1.7) and 135 mg/dL (±69) respectively. TC, LDL-C and TC: HDL-C of BC patients weresignificantly elevated when compared with healthy females. Significant difference in serum lipid profile parameters wasnot observed (p> 0.05) according to the menopausal status of BC and healthy women. One third (30.3%) of BC patientswere overweight and 45% were obese. Majority had elevated WC (72%), W: H ratios (89%) and MUC (89%). BMI,W: H and MUC of BC women were significantly higher (p<0.05) when compared with healthy females. Conclusions:The lipid parameters TC, LDL-C and TC: HDL-C above 203 mg/dL, 139 mg/dL and 3.9 respectively were risk factors.Among anthropometric measures, BMI>25 kg/m2 showed the highest risk while elevated W:H and MUC were alsosignificant risk factors among the study group.     

Clinical Use of a Drain Incision Placed Below and Bilaterial to Near Total Thyroidectomy Incision

Objective： To design a new draining method for near total thyroidectomy at the lower two sides of the neck. Methods： Near total thyroidectomies in 63 cases were performed with new drain incisions at the lower two sides of the neck between December 1998 and July 2004. Results： All the draining operative procedures were performed smoothly, and all produced cosmetic scars were effective. The mean amount drained was 38 ml （minimum 10 ml, maximum 120 ml） and no patient developed wound infection. Conclusion： The drain incision for near total thyroidectomy placed at the lower sides of the neck results in a cosmetic scar which is easily covered by the collar, and was safe and effective. We thereby recommend the use of this drain incision for near total thyroidectomy.     

Update of the Activity of Cefditoren and Comparator Oral β-lactam Agents Tested Against Community-Acquired Streptococcus pneumoniae Isolates (USA, 2004-2006)

Abstract

Cefditoren and other orally administered cephalosporins are infrequently included in resistance surveillance studies. Here we evaluated 359 contemporary (2004-2006) strains of Streptococcus pneumoniae, including penicillin-intermediate (12.0%) and -resistant (22.8%) subsets from United States patients by reference broth microdilution methods. Cefditoren was the most potent cephalosporin tested (MIC₅₀, 0.015 mg/L), including against penicillin-intermediate strains (MIC₅₀, 0.12 mg/L), and was two-, fourand eight-fold more active than cefuroxime, cefdinir and cefprozil, respectively. Penicillin- resistant strains were largely resistant to all tested β-lactams. We confirm the continued spectrum and potency for cefditoren against S. pneumoniae that surpasses that of other orally administered cephalosporins.     

Responses of human glioblastoma cells to human natural tumor necrosis factor-α: Susceptibility,mechanism of resistance and cytokine production studies

Summary Responses and susceptibility of 14 human glioblastoma cell lines to human natural tumor necrosis factor- (TNF) were studiedin vitro.Susceptibility of glioblastoma cells to TNF varied in experimental conditions applied. Most of glioblastoma cell lines were resistant to cytotoxic activity of TNF in a MTT assay at concentrations below 16U/ml for 72 h exposure. However, TNF at higher dose, in prolonged exposure and against low density of target cells was antiproliferative for certain glioblastoma cultures. TNF exposure at 10U/ml for 48 h suppressed DNA synthesis in 9 of 14 glioblastoma cultures, but increased in 3 cultures. In addition, colony forming assay showed anti-clonogenic activity of TNF in 5 of 6 glioblastoma cell lines tested.In spite of their low susceptibility to TNF, glioblastoma cells well responded to TNF stimulation at low dose (10U/ml) for a short period in the absence of cell damage. Productions of Interleukin-6 (IL-6), IL-8-like activity, granulocyte-macrophage colony stimulating factor (GM-CSF), prostaglandin E₂ (PGE₂) and manganous Superoxide dismutase (Mn-SOD) were enhanced or induced by the low-dose TNF stimulation.Mn-SOD, a protein protective against oxidative cell damage, was well induced in time- and dose-dependent manner, however did not correlate with TNF resistance. Whereas the levels of PGE₂ in TNF-susceptible cell lines, H-4 and SF-188, were higher than those of other lines.In conclusion, most of glioblastoma cells are resistant to TNF cytotoxic effects, but highly responsive to TNF stimulation. Its effect on glioblastoma cells appears to modulate cell differentiation rather than to kill the cells.