Alterations in regulatory regions of erm(B) genes from clinical isolates of enterococci resistant to telithromycin

We determined rates of resistance to the ketolide telithromycin in 56 Enterococcus faecalis isolates and 44 Enterococcus faecium isolates collected from hospitals in Korea between 2005 and 2006. Twenty nine (51.8%) isolates of E. faecalis and 35 (79.5%) isolates of E. faecium were resistant to telithromycin (minimum inhibitory concentrations, ≥ 4 μg/mL). All of the telithromycin-resistant E. faecalis carried the erm(B) gene only. Of the telithromycin-resistant E. faecium, 29 resistant strains carried erm(B) only, the other six carried erm(A) and erm(B) together. The nucleotide sequence of the erm(B) regulatory regions from 29 E. faecalis and 29 E. faecium isolates with erm(B) only was analyzed. Five types of alterations were detected. The first and second types had point mutations that destabilize the secondary structure of erm(B) mRNA sequestering the translation initiation region of the structural gene. The third type was identical to erm(Bv1), a previously reported variant of erm(B) with different induction specificity. The fourth and fifth types had point mutations within the critical sequence for induction and a point mutation destabilizing the stem-loop of erm(B) mRNA sequestering the translation initiation region of the structural gene.     

Characteristics of clinical and environmental vanM-carrying vancomycin-resistant enterococci isolates from an infected patient

vanM, an uncommon glycopeptide resistance gene, was first identified in an Enterococcus faecium isolate (Efm-HS0661) from Shanghai, China, in 2006 and has been predominant in this city since 2011. A vanM-carrying E. faecium was isolated from the bloodstream of a patient in an intensive care unit (ICU) in Hangzhou, China, in 2014. Further surveillance screening of a rectal swab and environmental surfaces of the patient yielded a large number of vanM-positive E. faecium. These isolates (including 1 from the bloodstream, 1 from the rectal swab and 43 representative isolates from environmental samples) were classified into four pulsed-field gel electrophoresis (PFGE) patterns and two sequence types (ST78 and ST564). PCR amplification and sequence analysis indicated that the genetic structure surrounding the vanM gene of these isolates was similar to that of the original vanM-carrying isolate Efm-HS0661. This study highlights the emergence of infections and environmental contamination caused by vanM-carrying E. faecium in an ICU of another Chinese city outside of Shanghai.     

Spread of vancomycin-resistant Enterococcus faecium in two haematological centres in Russia

This paper describes the clonal diversity of vancomycin-resistant Enterococcus faecium isolated from patients with haematological malignancies in Russia. Pulsed-field gel electrophoresis (PFGE) typing of 129 vanA-positive E. faecium strains revealed 23 independent restriction profiles with two predominant clonal types. Multilocus sequence typing (MLST) of 16 strains selected from two predominant PFGE types showed that they belong to the epidemic clonal complex (CC) 17. Tn1546-like elements of isolates were compared with the prototype element from E. faecium BM4147 by polymerase chain reaction (PCR). Four different Tn1546 types were distinguished according to structural alternations. Polymorphism in the orf1 and vanSH genes was detected. However, a significant prevalence of the prototype Tn1546 was revealed. Tn1546-like elements with the same structures were observed in strains of different PFGE types. The virulence genes esp, gelE and hyl were detected by PCR in 118 isolates (91%), 87 isolates (67%) and 35 isolates (27%), respectively. In contrast, agg and cylA genes were not found. The detection frequency of esp was higher in epidemic strains than in sporadic ones (100% vs. 56%; P < 0.05). This study describes a genetically variable population of vancomycin-resistant E. faecium in two Russian haematological centres. The spread of vancomycin resistance was mostly due to the distribution of the two subclones of E. faecium CC17, enriched with the virulence marker esp. At the same time, dissemination of an altered Tn1546 also occurred.     

Teicoplanin for treating enterococcal infective endocarditis: A retrospective observational study from a referral centre in Spain

This study aimed to evaluate the effectiveness and safety of teicoplanin for treating enterococcal infective endocarditis (EIE). A retrospective analysis of a prospective cohort of definite EIE patients treated with teicoplanin in a Spanish referral centre (2000–2017) was performed. The primary outcome was mortality during treatment. Secondary outcomes were mortality during 3-month follow-up, adverse effects and relapse. A total of 22 patients received teicoplanin, 9 (40.9%) as first-line (8 Enterococcus faecium and 1 Enterococcus faecalis) and 13 (59.1%) as salvage therapy (13 E. faecalis). Median (IQR) age was 71.5 (58.3–78) years and Charlson comorbidity index was 4.5 (3–7). Five (22.7%) affected prosthetic valves. Median duration of treatment in survivors was 53 (42.5–61) days for antibiotics and 27 (17–41.5) days for teicoplanin [median dose 10 (10–10.8) mg/kg/day]. Reasons for teicoplanin use were resistance to β-lactams (40.9%), adverse events with previous regimens (31.8%) and outpatient parenteral antimicrobial therapy (OPAT) (27.3%). Teicoplanin was withdrawn due to adverse events in 2 patients (9.1%). Five patients (22.7%) died during treatment: four in the first-line (three with surgery indicated but not performed) and one in the salvage therapy group (surgery indicated but not performed). Two deaths (11.8%) occurred over the 3-month follow-up. There were no relapses during a median of 43.2 (22.1–69.1) months. Teicoplanin can be used as an alternative treatment for susceptible E. faecium IE and as a salvage therapy in selected patients with E. faecalis IE when adverse events develop with standard regimens or to allow OPAT.     

High rates of colonisation by ampicillin-resistant enterococci in residents of long-term care facilities in Porto,Portugal

This study evaluated the occurrence of enterococci resistant to clinically relevant antibiotics in long-term care facility (LTCF) residents in Porto, Portugal, a region with high rates of multidrug-resistant enterococci in infected patients and healthy carriers. Faecal samples from 48 residents in two LTCFs (2015–2016) were enriched (with/without antibiotics) and plated on Slanetz–Bartley with/without the same antibiotics (ampicillin/vancomycin/linezolid). Two colonies per morphology/sample were selected for susceptibility testing and species identification. Clonality was established by PFGE and MLST. Genes coding for vancomycin resistance (vanA/vanB), virulence and plasmids (replicases) were searched by PCR. A total of 285 isolates were obtained, comprising Enterococcus faecalis, Enterococcus faecium, Enterococcus raffinosus and Enterococcus avium colonising 83%, 77%, 27% and 10% of residents, respectively. Residents from both LTCFs were colonised with vancomycin-resistant E. faecium (VanA-VREfm) (4 residents; 8%) and/or ampicillin-resistant (AmpR) (24 residents; 50%) E. raffinosus, E. faecium and E. avium. Enterococcus faecium previously associated with major human clonal lineages (ST18/ST78) or animal clones (ST393) were identified. Some PFGE types of E. faecium, E. raffinosus and E. avium were shared by residents of both LTCFs. Recent antibiotic exposure was significantly associated with colonisation by AmpR enterococci. Residents from Portuguese LTCFs were colonised with high rates of AmpR enterococci and similar rates of VREfm compared with other EU countries. A high colonisation rate with widespread enterococcal lineages that could be selected by antibiotic consumption in LTCFs was uncovered. These findings suggest that antimicrobial stewardship is warranted in LTCFs, which constitutes a significant challenge in a home-based setting.     

Non-susceptibility to tigecycline in enterococci from hospitalised patients, food products and community sources

In this study, the in vitro activity of tigecycline against 1140 enterococci collected from humans, food products, animals and the environment in Portugal (1996-2008) was analysed. Ten isolates (seven Enterococcus faecalis and three Enterococcus spp.) non-susceptible to tigecycline (minimum inhibitory concentrations of 0.5-1.0 mg/L), which were also resistant to tetracycline and minocycline, were mostly observed in samples collected before the introduction of tigecycline in the therapeutic arsenal. The E. faecalis isolates were recovered from hospitalised patients (n = 2; ST319/CC2 and ST34), healthy humans (n = 2; ST21/CC21), chicken meat (n = 1; ST260) as well as from two swine samples. The remaining isolates were also recovered from chicken meat (n = 1; Enterococcus gallinarum) and swine (n = 2; Enterococcus hirae and Enterococcus spp.). Recovery of enterococcal isolates with reduced susceptibility to tigecycline amongst different reservoirs, including animals for food consumption, suggests that selection of tigecycline-resistant isolates by antibiotics other than tigecycline might occur in non-clinical settings.     

In Vitro Evaluation of High-Level,Gentamicin-Resistant Enterococci Isolated from Bacteremic Patients

We attempted to characterize the susceptibility of high-level, gentamicin-resistant (HLGR, minimum inhibitory concentration [MIC] >2000 μg/ml) enterococcal blood isolates and evaluated a small subset of these isolates for bactericidal synergy. Thirteen Enterococcus faecalis and three Enterococcus faecium isolates that were HLGR were prospectively collected. Standard broth macrodilution techniques were used to determine the MICs and minimum bactericidal concentrations to a variety of antibiotics. Two isolates were evaluated for synergy by time-kill curve methods using combinations of penicillin and streptomycin, teicoplanin and rifampin, and vancomycin and ciprofloxacin. Teicoplanin was the most active antibiotic tested, with all isolates exhibiting susceptibility to this agent. Four E. faecalis isolates and one E. faecium isolate expressed only low-level resistance to streptomycin (LLSR, MlCs 32–64 μg/ml). Penicillin and streptomycin produced bactericidal synergy in the LLSR isolate. The other antibiotic combinations did not result in bactericidal synergy in the two isolates tested. For HLGR enterococci that are only LLSR, the combination of penicillin-streptomycin appears to provide adequate bactericidal activity. Teicoplanin may potentially be useful for streptomycin-resistant HLGR isolates.     

Daptomycin for the treatment of enterococcal bacteraemia: results from the Cubicin Outcomes Registry and Experience (CORE)

Enterococcal infections are a common cause of nosocomial bloodstream infections. Vancomycin resistance and the emergence of linezolid resistance necessitate alternative therapies. Studies in vitro as well as animal and case studies suggest that daptomycin may be effective in enterococcal infections. Patients with positive blood cultures for enterococci in the Cubicin^® Outcomes Registry and Experience (CORE) 2005–2006 were identified. Patients with endocarditis, intracardiac foreign body infections or non-speciated enterococci were excluded. Outcome was assessed using protocol-defined criteria. Of 159 patients included in the efficacy population, Enterococcus faecium and Enterococcus faecalis were isolated in 120 (75.5%) and 39 (24.5%) patients, respectively. Vancomycin resistance was detected in 91% and 23% of patients with E. faecium and E. faecalis infections, respectively. Prior to daptomycin, 94/159 (59.1%) and 35/159 (22.0%) patients had received vancomycin and linezolid, respectively. Daptomycin was first-line therapy in 27/159 cases (17%). Success was observed in 139/159 patients (87%) and in 104/120 (87%) and 35/39 (90%) patients with E. faecium and E. faecalis infections, respectively. Among the safety population (n = 211), 20 (9.5%) experienced 28 adverse events possibly related to daptomycin, 8 of which were considered serious. Daptomycin may be a useful agent for treating enterococcal bacteraemia caused by E. faecium or E. faecalis. Further studies are warranted.     

Antimicrobial resistance phenotypes and genotypes of methicillin-resistant Staphylococcus aureus CC398 isolates from Spanish hospitals

Livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) of lineage CC398 is an emerging clone causing human infections but is mostly found in pigs. The aim of this study was to characterize the antimicrobial resistance phenotypes/genotypes of a collection of 137 MRSA CC398 isolates obtained in a previous study from 17 Spanish hospitals, using tetracycline resistance as marker for selection. A multidrug-resistant (MDR) phenotype was present in 79% of analysed isolates, with 17% of them resistant to at least six different antimicrobial families. All tetracycline-resistant isolates (n=137) carried the tetM gene and 75% also carried the tetK gene. Almost 50% of MRSA CC398 isolates showed macrolide and/or lincosamide resistance: a) 39% of isolates were ERY^R-CLI^R (all with constitutive phenotype), with 87% of them carrying the ermC gene, followed by msrA (25%), ermB (21%), vgaA (17%), ermA (6%), lsaB (4%), linA (2%), linB (2%), and ermT (2%, this isolate with the new spa-type t18071); and b) 9% of MRSA CC398 isolates showed the dissociated ERY^S-CLI^R phenotype carrying the linA, linB, lsaB and vgaA genes. Other antimicrobial resistance phenotypes in these MRSA CC398 isolates included resistance to ciprofloxacin (67%), aminoglycosides (21%), mupirocin (6%), chloramphenicol (4%) or fusidic acid (2%). The more common resistance genes detected for some of these antimicrobials were: aac(6’)-Ie-aph(2’’)-Ia (16%) and ant(4’)-Ia (12%) for aminoglycosides, and fexA (3%) for chloramphenicol. The high rate of MDR phenotypes with a wide range of antimicrobial resistance genes shown in this study reduce the potential therapeutic options in case of infections.     

Prevalence of clinical meticillin-resistant Staphylococcus aureus (MRSA) with high-level mupirocin resistance in Shanghai and Wenzhou,China

A total of 803 clinical meticillin-resistant Staphylococcus aureus (MRSA) isolates obtained from Shanghai and Wenzhou in China were subjected to a screening test by disk diffusion for detection of mupirocin resistance. Among the 803 strains, 53 (6.6%) were mupirocin-resistant. Of these 53 strains, all were discovered by the agar dilution method and polymerase chain reaction (PCR) to be high-level mupirocin-resistant and to harbour the mupA gene. Plasmid DNA hybridisation and curing experiments disclosed that mupA was located on a large plasmid varying in size between 23.0 kb and 52.4 kb in all strains. Susceptibility testing of 10 antibiotics revealed that resistance rates between the Shanghai isolates and the Wenzhou isolates to trimethoprim/sulfamethoxazole and rifampicin differed significantly. Molecular typing by pulsed-field gel electrophoresis (PFGE), staphylococcal chromosomal cassette mec (SCCmec) and staphylococcal protein A (spa) revealed that PFGE A–SCCmec IIIA–spa t030 and PFGE B–SCCmec IIIA–spa t030 represented all of the Wenzhou strains, whereas PFGE N–SCCmec I–spa t318, PFGE P–SCCmec III–spa t037, PFGE I–SCCmec III–spa t037 and PFGE M–SCCmec IIIA–spa t002 were the predominant profiles among Shanghai isolates. These findings indicated that high-level mupirocin resistance mediated by plasmids prevailed in the clinical mupirocin-resistant MRSA from Shanghai and Wenzhou and was mainly related to the transmission of clones.     

High-level ciprofloxacin resistance among hospital-adapted Enterococcus faecium (CC17)

Hospital-adapted Enterococcus faecium differ from their colonising variants in humans and animals by additional genomic content. Molecular typing based on multilocus sequence typing (MLST) allows allocation of isolates to specific clonal complexes (CCs), such as CC17 for hospital-adapted strains. Acquired ampicillin resistance is a specific feature of these hospital isolates, especially in Europe. A few recent reports have described acquired high-level ciprofloxacin resistance as a supposed feature of hospital-adapted E. faecium strains. In the present retrospective analysis, ciprofloxacin minimum inhibitory concentrations (MICs) of 609 clinical isolates from German hospital patients (1997–2007) were determined and a breakpoint for high-level resistance was deduced (>16 mg/L). Acquired high-level ciprofloxacin resistance was distributed among isolates of 26 different MLST types (all CC17), indicating a wide prevalence of this acquired resistance trait among the hospital-adapted E. faecium population. High-level ciprofloxacin resistance was linked to gyrA and parC mutations in 98 investigated isolates. Eleven different allele types or combinations thereof were identified. Their allocation to specific MLST and pulsed-field gel electrophoresis (PFGE) types revealed differences in the emergence and spread of corresponding mutations and strains.     

Molecular characterization and evolution of the first outbreak of vancomycin-resistant Enterococcus faecium in Western Australia

The first outbreak of vancomycin-resistant Enterococcus faecium (VREfm) in Western Australia was recorded in 2001. A state-wide infection control effort that oversaw patient screening and transfers successfully terminated the outbreak within six months; however, the outbreak re-emerged two years later. Over the two outbreaks, the vanB-positive multilocus sequence type (ST) 173 E. faecium strain was isolated from 201 patients.Our objective was to identify differences in genetic traits leading to successful transmission of ST173 VREfm compared with non-ST173 VREfm isolated during the same period. We also aimed to describe the changes observed in the ST173 VREfm genome collected during the two outbreaks.Virulence factors ecbA, fss3, psaA and scm identified in the non-ST173 isolates were largely absent in the ST173 isolates. The esp gene was not identified beyond 45% coverage for any isolate in this study. In terms of resistance genes, tet(U) was identified in 94.7% of ST173 VREfm isolated in the first outbreak but was largely absent in ST173 VREfm isolated in the second outbreak and in non-ST173 VREfm. Seven ST173 VREfm isolates (Clade A) carried dfrG but not tet(M) resistance genes. The average genome size of ST173 VREfm isolated in the first outbreak was significantly larger than the genome size of ST173 VREfm isolated in the second outbreak.The reduced number of virulence factors in ST173 isolates may explain the low infection and high colonization rates observed during the outbreak. In addition, isolates with larger genomes were found to be associated with outbreaks.     

Daptomycin activity tested against 164 457 bacterial isolates from hospitalised patients: Summary of 8 years of a Worldwide Surveillance Programme (2005–2012)

We report the results of 8 years (2005–2012) of the Daptomycin Surveillance Programme Worldwide. Consecutive non-duplicate bacterial isolates (prevalence design) were collected from patients with documented infections in 410 medical centres and were susceptibility tested by reference broth microdilution methods. A total of 164 457 Gram-positive isolates were evaluated, including 97 542 Staphylococcus aureus, 21 413 coagulase-negative staphylococci (CoNS), 29 619 enterococci and 15 883 β-haemolytic streptococci. The prevalence of daptomycin-non-susceptible isolates was extremely low for all species in all geographic regions. Overall, the highest occurrence of non-susceptible isolates was observed among CoNS (0.19%), followed by Enterococcus faecium (0.18%), S. aureus (0.05%), Enterococcus faecalis (0.02%) and β-haemolytic streptococci (0.00%). Moreover, no trend towards increased daptomycin resistance (non-susceptibility) was observed for any species in any geographic region during the study interval. Against S. aureus, the daptomycin MIC_50/90 was 0.25/0.5 mg/L in all geographic regions (99.95% susceptible overall). Only 53 daptomycin-non-susceptible S. aureus isolates were observed and the vast majority (49; 92.5%) had a daptomycin MIC value only 1 log₂ dilution above the published susceptible breakpoint. Daptomycin was also active against CoNS (MIC_50/90, 0.25/0.5 mg/L; 99.81% susceptible), E. faecalis (MIC_50/90, 1/2 mg/L; 99.98% susceptible), E. faecium (MIC_50/90, 2/4 mg/L; 99.82% susceptible) including vancomycin-non-susceptible isolates (4521 isolates; MIC_50/90, 2/2 mg/L; 99.76% susceptible), and β-haemolytic streptococci (MIC_50/90, ≤0.06/0.25 mg/L; 100.0% susceptible). In conclusion, daptomycin has remained very active against indicated species worldwide, and no significant year-to-year or regional variation in daptomycin activity has been detected.     

Emergence of carbapenem resistance in Bacteroides fragilis in China

The antimicrobial resistance crisis makes it critically important for laboratories to closely monitor trends and mechanisms of emerging antimicrobial resistance in clinical isolates. Bacteroides fragilis is an anaerobic pathogen that causes several serious infections and is increasingly resistant to antimicrobial agents. However, data from China regarding antimicrobial resistance in B. fragilis are limited. In this work, the mechanism underlying carbapenem resistance in 44 B. fragilis isolates collected from a Chinese hospital was investigated. Antimicrobial susceptibility testing for 13 antimicrobial agents was performed by the agar dilution method, and the contribution of efflux pumps to carbapenem resistance was analysed. Genetic relatedness of the isolates was determined by PFGE. Outer membrane porins were analysed in isolates with reduced carbapenem susceptibility. Potential carbapenemase-encoding genes were identified, and the location and environment of the cfiA gene was analysed. Among the 44 isolates, 18.2%, 29.5%, 22.7%, 100%, 100%, 29.5%, 15.9%, 81.8%, 88.6% and 47.7% were resistant to imipenem, meropenem, ertapenem, penicillin, ampicillin, amoxicillin/clavulanic acid, piperacillin/tazobactam, clindamycin, tetracycline and moxifloxacin, respectively. None of the isolates were resistant to metronidazole, cefoxitin or chloramphenicol. A chromosomally located gene (cfiA) encoding a metallo-β-lactamase was identified in 16 isolates (36.4%). A conserved insertion sequence of IS1187 or IS613 was upstream of cfiA in eight isolates with high-level carbapenem resistance. The insertion sequences were associated with increased carbapenem resistance in B. fragilis by upregulating the expression of cfiA as shown by RT-qPCR. This is the first study to describe a mechanism of carbapenem resistance in B. fragilis in mainland China.     

2017年福州市第二医院病原菌的分布及耐药性分析

目的 了解2017年福州市第二医院临床分离病原菌的分布及对抗菌药物的敏感性,为临床用药提供指导。方法 共收集2 720株非重复分离菌,采用纸片扩散法或自动化仪器法进行药敏试验,按CLSI标准判读药敏结果。结果 2 720株细菌中,标本主要来源于伤口分泌物（989株）,占36.3%。革兰阴性菌1 786株,占65.7%,主要为大肠埃希菌、肺炎克雷伯菌、铜绿假单胞菌、鲍曼不动杆菌、嗜麦芽窄食单胞菌和阴沟肠杆菌;革兰阳性菌934株,占34.3%,主要为金黄色葡萄球菌、粪肠球菌和凝固酶阴性葡萄球菌。耐甲氧西林耐药株金黄色葡萄球菌、凝固酶阴性葡萄球菌的检出率分别为42.7%、84.2%。未发现对万古霉素、替考拉宁和利奈唑胺耐药的葡萄球菌。粪肠球菌对大多数抗菌药物的耐药率明显低于屎肠球菌。肠球菌属中未发现万古霉素、利奈唑胺、替考拉宁耐药的肠球菌。除对黏菌素100%敏感外,铜绿假单胞菌对其他常见抗菌药物的耐药率均较低,鲍曼不动杆菌除对黏菌素敏感外,对其他药物的耐药性均较高,均达46.2%以上。结论 2017年福州市第二医院病原菌耐药形势依旧严峻,应加强合理用药,避免交叉感染。     

Bacteriocin production and distribution of bacteriocin-encoding genes in enterococci from dogs

Many enterococcal strains produce bacteriocins, which could be useful as natural food preservatives through inhibition of pathogenic and spoilage microorganisms. There is little knowledge of the distribution and spectrum of bacteriocin activity and the distribution of bacteriocin-encoding genes in enterococci isolated from dogs. Therefore, we subjected 160 enterococcal isolates (E. faecium n=92, E. faecalis n=35, E. hirae n=28, E. casseliflavus n=3, E. mundtii n=2) from 105 samples of dog faeces to polymerase chain reaction (PCR) detection of genes for enterocin A, P, B, L50A, L50B, AS-48, and bac31 and to screening for bacteriocin activity. The results showed the presence of at least one of the tested genes in 54/160 isolates, with E. faecium the most common gene-possessing species. The most frequently occurring gene for production of enterocin A was observed in combination with enterocin P and B. Bacteriocin activity was observed in 76/160 isolates against at least one of 5 indicator bacteria from the genus Listeria, Enterococcus, Streptococcus and Staphylococcus. Four selected strains (IK25, Bri, I/Dz, P10) were active mostly against different species of Enterococcus (in the range 400-25 600 AU/mL) and Listeria sp. (800-12 800 AU/mL) but no Gram-negative bacteria were inhibited. Protein character, thermostability (up to 121°C) and stability at different pH values (3.0–10.0) were confirmed for crude bacteriocins of these four strains. The antimicrobial substance of E. faecium IK25 strain was identified as enterocin B using molecular weight detection and the presence of genes.     

2013-2015年宝鸡市中心医院不同年龄段住院患者病原菌的分布及耐药性分析

目的 了解宝鸡市中心医院不同年龄段患者的病原菌分布及对常用抗菌药物的耐药性.方法 将宝鸡市中心医院2013年1月—2015年12月病原菌培养阳性的住院患者,按照0~14岁、15~64岁、≥65岁分为3个不同的年龄阶段,对3个年龄段患者病原菌的分布及其耐药情况进行统计与分析.结果 共分离出病原菌4077株,主要来源于呼吸道和尿,其中革兰阳性菌702株,占17.2%,主要为葡萄球菌中的金黄色葡萄球菌、凝固酶阴性葡萄球菌和肠球菌中的粪肠球菌和屎肠球菌;革兰阴性菌3375株,占82.8%,主要为肠杆菌中的大肠埃希菌、肺炎克雷伯菌和非发酵菌中的铜绿假单胞菌、鲍曼不动杆菌.大肠埃希菌、铜绿假单胞菌、鲍曼不动杆菌、金黄色葡萄球菌及肠球菌等多种病原菌对抗菌药物的耐药率随着患者年龄的增长而增高.结论 不同年龄住院患者的病原菌分布及其耐药性有所不同,抗感染治疗时应充分考虑患者的年龄因素,合理使用抗菌药物.     

Antibiotic resistance and molecular characterization of shigella isolates recovered from children aged less than 5 years in Manhiça,Southern Mozambique

The objective of this study was to assess antibiotic resistance and the molecular epidemiology of shigella isolates from a case–control study of diarrhoea, conducted from 2007 to 2012 in children aged less than 5 years in Manhiça district, southern Mozambique. All isolates were tested for antimicrobial susceptibility using the disc diffusion method. Polymerase chain reaction was used to detect different molecular mechanisms of antibiotic resistance. Serotyping was performed using specific antisera. The clonal relationship of Shigella flexneri and Shigella sonnei was assessed by pulsed-field gel electrophoresis (PFGE). Of the 67 shigella isolates analysed, 59 were diarrhoeal cases and eight were controls. S. flexneri (70.1%; 47/67) was the most common species, followed by S. sonnei (23.9%; 16/67). The most prevalent S. flexneri serotypes were 2a (38.3%; 18/47), 6 (19.2%; 9/47) and 1b (14.9%; 7/47). High rates of antimicrobial resistance were observed for trimethoprim-sulfametoxazole (92.5%; 62/67), tetracycline (68.7%; 46/67), chloramphenicol (53.7%; 36/67) and ampicillin (50.7%; 34/67). Multi-drug resistance (MDR) was present in 55.2% (37/67) of the isolates and was associated with a case fatality rate of 8.1% (3/37). PFGE revealed 22 clones (16 S. flexneri and 6 S. sonnei), among which P1 (31.9%; 15/47), P9 (17%; 8/47) and P2 (10.6%; 5/47) were the most prevalent clones of S. flexneri. In conclusion, S. flexneri was the most prevalent species, with MDR isolates mainly belonging to three specific clones (P1, P9 and P2). The case fatality rate observed among MDR isolates is a matter of concern, indicating the need for appropriate treatment.     

Role of Combination Antimicrobial Therapy for Vancomycin‐Resistant Enterococcus faecium Infections: Review of the Current Evidence

Enterococcus species are the second most common cause of nosocomial infections in the United States and are particularly concerning in critically ill patients with preexisting comorbid conditions. Rising resistance to antimicrobials that were historically used as front‐line agents for treatment of enterococcal infections, such as ampicillin, vancomycin, and aminoglycosides, further complicates the treatment of these infections. Of particular concern are Enterococcus faecium strains that are associated with the highest rate of vancomycin resistance. The introduction of antimicrobial agents with specific activity against vancomycin‐resistant Enterococcus (VRE) faecium including daptomycin, linezolid, quinupristin‐dalfopristin, and tigecycline did not completely resolve this clinical dilemma. In this review, the mechanisms of action and resistance to currently available anti‐VRE antimicrobial agents including newer agents such as oritavancin and dalbavancin will be presented. In addition, novel combination therapies including β‐lactams and fosfomycin, and the promising results from in vitro, animal studies, and clinical experience in the treatment of VRE faecium will be discussed.     

Surveillance of tigecycline activity tested against clinical isolates from a global (North America,Europe, Latin America and Asia-Pacific) collection (2016)

Tigecycline and comparators were tested by the reference broth microdilution method against 33 348 non-duplicate bacterial isolates collected prospectively in 2016 from medical centres in the Asia-Pacific (3443 isolates), Europe (13 530 isolates), Latin America (3327 isolates) and the USA (13 048 isolates). Among 7098 Staphylococcus aureus isolates tested, >99.9% were inhibited by ≤0.5?mg/L tigecycline (MIC_50/90, 0.06/0.12?mg/L), including >99.9% of methicillin-resistant S. aureus and 100.0% of methicillin-susceptible S. aureus. Tigecycline was slightly more active against Enterococcus faecium (MIC_50/90, 0.03/0.06?mg/L) compared with Enterococcus faecalis (MIC_50/90, 0.06/0.12?mg/L) and its activity was not adversely affected by vancomycin resistance when tested against these organisms. Tigecycline potency was comparable for Streptococcus pneumoniae (MIC_50/90, 0.03/0.06?mg/L), viridans group streptococci (MIC_50/90, 0.03/0.06?mg/L) and β-haemolytic streptococci (MIC_50/90, 0.06/0.06?mg/L) regardless of species and penicillin susceptibility. Tigecycline was active against Enterobacteriaceae (MIC_50/90, 0.25/1?mg/L; 97.8% inhibited at ≤2?mg/L) but was slightly less active against Enterobacteriaceae isolates expressing resistant phenotypes: carbapenem-resistant Enterobacteriaceae (MIC_50/90, 0.5/2?mg/L; 98.0% susceptible); multidrug-resistant (MIC_50/90, 0.5/2?mg/L; 93.1% susceptible); and extensively drug-resistant (MIC_50/90, 0.5/4?mg/L; 87.8% susceptible). Tigecycline inhibited 74.4% of 888 Acinetobacter baumannii isolates at ≤2?mg/L (MIC_50/90, 2/4?mg/L) and demonstrated good in vitro activity against Stenotrophomonas maltophilia (MIC_50/90, 1/2?mg/L; 90.6% inhibited at ≤2?mg/L) Tigecycline was active against Haemophilus influenzae (MIC_50/90, 0.12/0.25?mg/L) regardless of β-lactamase status. Tigecycline represents an important treatment option for resistant Gram-negative and Gram-positive bacterial infections.