Presence of hypervirulence-associated determinants in Klebsiella pneumoniae from hospitalised patients in Germany

BACKGROUND

Klebsiella (K.) pneumoniae is a ubiquitous Gram-negative bacterium and a common coloniser of animals and humans. Today, K. pneumoniae is one of the most persistent nosocomial pathogens worldwide and poses a severe threat/burden to public health by causing urinary tract infections, pneumonia and bloodstream infections. Infections mainly affect immunocompromised individuals and hospitalised patients. In recent years, a new type of K. pneumoniae has emerged associated with community-acquired infections such as pyogenic liver abscess in otherwise healthy individuals and is therefore termed hypervirulent K. pneumoniae (hvKp). The aim of this study was the characterisation of K. pneumoniae isolates with properties of hypervirulence from Germany.

METHODS

A set of 62 potentially hypervirulent K. pneumoniae isolates from human patients was compiled. Inclusion criteria were the presence of at least one determinant that has been previously associated with hypervirulence: (I) clinical manifestation, (II) a positive string test as a marker for hypermucoviscosity, and (III) presence of virulence associated genes rmpA and/or rmpA2 and/or magA. Phenotypic characterisation of the isolates included antimicrobial resistance testing by broth microdilution. Whole genome sequencing (WGS) was performed using Illumina® MiSeq/NextSeq to investigate the genetic repertoire such as multi-locus sequence types (ST), capsule types (K), further virulence associated genes and resistance genes of the collected isolates. For selected isolates long-read sequencing was applied and plasmid sequences with resistance and virulence determinants were compared.

RESULTS

WGS analyses confirmed presence of several signature genes for hvKp. Among them, the most prevalent were the siderophore loci iuc and ybt and the capsule regulator genes rmpA and rmpA2. The most dominant ST among the hvKp isolates were ST395 capsule type K2 and ST395 capsule type K5; both have been described previously and were confirmed by our data as multidrug-resistant (MDR) isolates. ST23 capsule type K1 was the second most abundant ST in this study; this ST has been described as commonly associated with hypervirulence. In general, resistance to beta-lactams caused by the production of extended-spectrum beta-lactamases (ESBL) and carbapenemases was observed frequently in our isolates, confirming the threatening rise of MDR-hvKp strains.

CONCLUSIONS

Our study results show that K. pneumoniae strains that carry several determinants of hypervirulence are present for many years in Germany. The detection of carbapenemase genes and hypervirulence associated genes on the same plasmid is highly problematic and requires intensified screening and molecular surveillance. However, the non-uniform definition of hvKp complicates their detection. Testing for hypermucoviscosity alone is not specific enough to identify hvKp. Thus, we suggest that the classification of hvKp should be applied to isolates that not only fulfil phenotypical criteria (severe clinical manifestations, hypermucoviscosity) but also (I) the presence of at least two virulence loci e.g. iuc and ybt, and (II) the presence of rmpA and/or rmpA2.

[Therapy of cystitis with nitroxoline-NitroxWin : Prospective, multicenter, non-interventional study and microbiological resistance surveillance]

BACKGROUND

According to German AWMF S3 guideline nitroxoline is recommended as one of the first-choice antibiotics for treatment of acute uncomplicated cystitis (UC) in women. Under real-world conditions the clinical efficacy of nitroxoline should be checked in a noninterventional, prospective and multicenter study (NIS) and the prevalence of nitroxoline resistance in E. coli be monitored.

MATERIALS AND METHODS

Female patients with UC treated with nitroxoline (recommended dosage 250 mg tid for 5 days) were included by urologists, general practitioners (GPs), and internists in family medicine throughout Germany from April-December 2022 and followed for 21-28 days. The diagnosis and course of therapy were judged by the Acute Cystitis Symptom Score (ACSS) questionnaire and laboratory investigations (leukocyturia etc). Separately, a nationwide resistance surveillance was performed during 2019-2020 in collaboration with 23 laboratories to collect urinary E. coli isolates and test their susceptibility to nitroxoline.

RESULTS

Of the 316 patients with mean (SD) age of 57.2 (±20.4 [median 62.5]) years who were included in the NIS, 193/248 (86.3%) in the per-protocol group and in 193/263 (81.44%) in the intention-to-treat group were clinically successful. Furthermore, 96% of the patients rated the tolerability of nitroxoline as "very good" or "good". All 272 E. coli isolates tested were susceptible to nitroxoline.

CONCLUSIONS

Nitroxoline showed very good clinical results in the NIS, and 100% of the tested E. coli urine isolates were susceptible to nitroxoline. Nitroxoline can still be recommended as one of the first-choice antibiotics for treatment of UC in women.

Escherichia coli resistance, treatment patterns and clinical outcomes among females with uUTI in Germany: a retrospective physician-based chart review study

Real-world data were collected to examine antimicrobial resistance (AMR) prevalence, treatment patterns, and clinical outcomes among female patients with uncomplicated urinary tract infection (uUTI) in Germany. Data were from a retrospective physician-based chart review completed by physicians treating patients with uUTI. Non-pregnant women aged ≥ 12 years, with a uUTI diagnosis, an E. coli-positive urine culture between January 2017-December 2019, and susceptibility test results for ≥ 4 drug classes were eligible. Patients were stratified into three cohorts by drug class susceptibility: susceptible to all (SUS), resistant to one or two drug classes (DR1/2), and resistant to ≥ 3 (MDR) drug classes tested. Among 386 eligible patients [SUS (67.1%); DR1/2 (29.0%); MDR (3.9%)], AMR prevalence was highest for FMIs (18.3%) and lowest for fluoroquinolones (5.2%). The most prescribed drugs were fosfomycin in SUS (44.0%), DR1/2 (41.4%), and fluoroquinolones in MDR (40.0%). Treatment for uUTI failed for 8.8% of patients; failure was more likely in MDR versus SUS [adjusted odds ratio [95% CI] = 4.21 [1.14-1.50]; P = 0.031); incidence of recurrent infection in the 6-months post-index period was higher in DR1/2 versus SUS. These findings may have implications for empiric prescribing, suggesting an unmet need for new treatments.

In Vitro Activity of Cefiderocol against a Global Collection of Carbapenem-Resistant Acinetobacter baumannii Isolates

Background: Cefiderocol is a novel siderophore cephalosporin with potent activity against multi-drug-resistant Gram-negative pathogens including carbapenem-resistant Acinetobacter baumannii (CRAB). Methods: The susceptibility of 313 non-duplicate CRAB isolates with defined carbapenem resistance mechanisms from a global collection to cefiderocol, ceftazidime, ceftazidime/avibactam, ceftolozane/tazobactam, ciprofloxacin, colistin, imipenem/relebactam, meropenem, meropenem/vaborbactam, minocycline, and piperacillin/tazobactam was determined using the broth microdilution method. Isolates were obtained from various body sites from patients in 47 countries in five world regions between 2012 and 2016. The identification of carbapenem resistance mechanisms and assignment to A. baumannii international clonal lineages were based on whole genome sequencing. Results: Cefiderocol showed greater activity than comparator antimicrobials of the β-lactam class, including novel β-lactams combined with β-lactamase inhibitors, ciprofloxacin, and minocycline. Cefiderocol MIC₅₀ and MIC₉₀ values were 0.5 mg/L and 4 mg/L, respectively, while colistin had comparable activity with a higher MIC₅₀ at 1 mg/L and a lower MIC₉₀ value of 2 mg/L. Many isolates with elevated cefiderocol MICs ≥ 4 mg/L represented A. baumannii international clone (IC) 1 and harbored a metallo-β-lactamase. Conclusions: While cefiderocol is a useful addition to the limited armamentarium of drugs targeting this problematic pathogen, a considerable part of CRAB isolates had elevated MIC values in a range of 4 -> 32 mg/L, including all isolates with a metallo-β-lactamase.

In Vitro Activity of Cefiderocol against Clinical Gram-Negative Isolates Originating from Germany in 2016/17

Antimicrobial resistance poses a global threat to public health. Of great concern are Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacterales with resistance to carbapenems or third-generation cephalosporins. The aim of the present study was to investigate the in vitro activity of the novel siderophore cephaloporin cefiderocol (CID) and four comparator β-lactam-β-lactamase-inhibitor combinations and to give insights into the genetic background of CID-resistant isolates. In total, 301 clinical Enterobacterales and non-fermenting bacterial isolates were selected for this study, including randomly chosen isolates (set I, n = 195) and challenge isolates (set II, n = 106; enriched with ESBL and carbapenemase producers, as well as colistin-resistant isolates). Isolates displayed CID MIC_50/90 values of 0.12/0.5 mg/L (set I) and 0.5/1 mg/L (set II). Overall, the CID activity was superior to the comparators against A. baumannii, Stenotrophomonas maltophilia and set II isolates of P. aeruginosa. There were eight CID-resistant isolates detected (MIC > 2 mg/L): A. baumannii (n = 1), E. cloacae complex (n = 5) and P. aeruginosa (n = 2). Sequencing analyses of these isolates detected the acquired β-lactamase (bla) genes bla_NDM-1,bla_SHV-12 and naturally occurring bla_OXA-396, bla_ACT-type and bla_CMH-3. In conclusion, CID revealed potent activity against clinically relevant organisms of multidrug-resistant Enterobacterales and non-fermenters.

Multicenter Clinical Evaluation of ETEST Eravacycline for Susceptibility Testing of Enterobacteriaceae and Enterococci

Eravacycline (ERV) (brand name Xerava [Tetraphase]) is a new tetracycline-class antibacterial that has been approved by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for treatment of complicated intra-abdominal infections (cIAIs). ETEST is a gradient diffusion method that represents a simple alternative to the broth microdilution (BMD) method for performing antimicrobial susceptibility testing (AST). A multicenter evaluation of the performance of the new ETEST ERV (bioMérieux) in comparison with BMD was conducted following FDA and International Standards Organization (ISO) recommendations, using FDA- and EUCAST-defined breakpoints. Clinical isolates of Enterobacteriaceae (n = 542) and Enterococcus spp. (n = 137) were included. Based on the BMD reference method, 92 Enterobacteriaceae isolates and 9 enterococcal isolates were nonsusceptible to ERV according to the FDA breakpoints, while 7 Escherichia coli isolates and 3 Enterococcus sp. isolates were classified as ERV resistant according the EUCAST breakpoints. Referring to FDA performance criteria, the ETEST ERV demonstrated 99.4% and 100.0% essential agreement (EA), 98.0% and 94.9% categorical agreement (CA), very major error (VME) rates of 5.4% and 33.33%, and major error (ME) rates of 1.3% and 3.1% with clinical and challenge isolates, respectively, of Enterobacteriaceae and Enterococcus spp. According to EUCAST breakpoints, E. coli and Enterococcus sp. isolate results also met ISO acceptance criteria for EA and CA (EA of 99.0% and 100.0%, respectively, and CA of 100.0% for both), without any VMEs or MEs. In conclusion, we report that ETEST ERV represents an accurate tool for performing ERV AST of Enterobacteriaceae and Enterococcus sp. isolates.

Susceptibility of Multidrug-Resistant Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa from Germany to Ceftolozane-Tazobactam, Ceftazidime-Avibactam, and Imipenem-Relebactam

This cross-sectional in-vitro resistance surveillance study involving 10 medical laboratories was conducted in 2018. Each study site was asked to collect 30 consecutive nonduplicate isolates per species from hospitalized patients with documented infections. Minimum inhibitory concentrations were determined at a central laboratory. European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints were used for interpretation. A total of 860 isolates were collected, including 298 Escherichia coli, 268 Klebsiella pneumoniae, and 294 Pseudomonas aeruginosa. Fifty (16.8%) E. coli and 63 (23.5%) K. pneumoniae isolates were found to be resistant to third-generation cephalosporins. Resistance to carbapenems (imipenem and/or meropenem) was identified in 5 (1.9%) K. pneumoniae and 64 (21.8%) P. aeruginosa, but not in E. coli. Thirty-three (11.2%) P. aeruginosa isolates were resistant to both carbapenems and 30 (10.2%) P. aeruginosa showed resistance to ≥3 antimicrobials/antimicrobial groups (among piperacillin-tazobactam, ceftazidime, tobramycin, carbapenems, and fluoroquinolones). The susceptibility rates of these multidrug-resistant (MDR) phenotypes to ceftolozane-tazobactam, ceftazidime-avibactam, and imipenem-relebactam were 70-100%, with the exception of carbapenem-resistant K. pneumoniae. Only two K. pneumoniae and four P. aeruginosa isolates were resistant to all three beta-lactam/beta-lactamase-inhibitor combinations. However, this favorable result should be viewed in light of the relatively low prevalence of MDR organisms that require these agents in Germany.

In vitro activity of gepotidacin against urine isolates of Escherichia coli from outpatient departments in Germany

BACKGROUND

Escherichia coli is the leading pathogen of community-acquired urinary tract infections. Gepotidacin is a novel, bactericidal, first-in-class triazaacenaphthylene oral antibiotic that inhibits bacterial DNA replication by a distinct mechanism of action that confers activity against most strains of target pathogens, such as E. coli, Staphylococcus saprophyticus and Neisseria gonorrhoeae, including those resistant to other antibiotics.

OBJECTIVES

This study assessed the in vitro activity of gepotidacin in comparison with ciprofloxacin and other oral standard-of-care antibiotics using a large collection of urine isolates of E. coli obtained from outpatients in Germany.

METHODS

Four hundred and sixty E. coli collected from 23 laboratories during a surveillance study in 2019/2020 were tested. Forty-six isolates (10.0%) produced an ESBL of the CTX-M family, half of which belonged to MDR clonal subgroups of E. coli ST131. Antibiotic susceptibilities were tested at a reference laboratory by broth microdilution according to the standard ISO 20776-1.

RESULTS

Fifty-three (11.5%) isolates were ciprofloxacin resistant, 25 (47.2%) of which also produced an ESBL. Overall, MIC50/90 values for gepotidacin were 2/4 mg/L (MIC range 0.125-16 mg/L), with no differences in activity between ciprofloxacin-susceptible and ciprofloxacin-resistant isolates, ESBL-producing and non-ESBL isolates, O25b-ST131 isolates, and isolates susceptible or resistant to fosfomycin, mecillinam or nitrofurantoin.

CONCLUSIONS

Gepotidacin showed promising in vitro activity against urine isolates of E. coli, including ciprofloxacin-resistant isolates, ESBL-producing isolates and isolates resistant to oral standard-of-care antibiotics.

The evolution of carbapenem resistance determinants and major epidemiological lineages among carbapenem-resistant Acinetobacter baumannii isolates in Germany, 2010-2019

The aim of this study was to investigate and compare the molecular epidemiology and carbapenem resistance determinants in clinical Acinetobacter baumannii isolates collected during four multicentre surveillance studies conducted by the Paul-Ehrlich-Society for Infection Therapy. Isolates were collected prospectively from hospital in-patients at 17 medical centres in Germany over four periods of three- to six-months starting in October of each of 2010, 2013, 2016 and 2019. Species identification was performed by MALDI-TOF, gyrB multiplex polymerase chain reaction (PCR), and detection of the intrinsic bla_OXA-51-like gene. Minimum inhibitory concentrations were determined by broth microdilution. The prevalence of carbapenemase-encoding genes was investigated by OXA-multiplex PCR and whole-genome sequencing. Molecular epidemiology was examined by rep-PCR and core-genome multi-locus sequence typing. A total of 302 A. baumannii isolates were collected. Resistance to imipenem and/or meropenem was detected in 58 isolates (19.2%) from 14 centres. The proportion of carbapenem-resistant isolates increased from 21.3% in 2010 to 33.3% in 2013, and then decreased to 13.8% in 2016 and 12.3% in 2019. Forty-six of these isolates were associated with the international clonal lineage IC2 and five with IC1. The most prevalent carbapenemase gene detected was bla_OXA-23-like (n=51). Further carbapenem-resistance determinants were bla_OXA-40-like (n=1), bla_OXA-58-like (n=3) and bla_NDM-1 (n=2). In one isolate, ISAba1 was detected upstream of bla_OXA-51-like. In conclusion, IC2 was the most prevalent clonal lineage detected in this study. Interestingly, in Germany, carbapenem resistance seems to have decreased in A. baumannii between 2013 and 2019.

Resistance to Mecillinam and Nine Other Antibiotics for Oral Use in Escherichia coli Isolated from Urine Specimens of Primary Care Patients in Germany, 2019/20

Urinary tract infections (UTIs) are among the most common bacterial infections in humans. Escherichia coli is by far the leading cause of community-acquired UTIs. Pivmecillinam, the oral prodrug of the penicillin derivative mecillinam (amdinocillin), was re-introduced in Germany in March 2016 for first-line treatment of acute uncomplicated cystitis. This study aimed to evaluate the prevalence of resistance to mecillinam in comparison to nine other antibiotics used for oral treatment in E. coli urine isolates after the re-introduction of pivmecillinam. A total of 460 isolates were collected at 23 laboratories of clinical microbiology between October 2019 and March 2020. Forty-six isolates (10.0%) produced an extended-spectrum β-lactamase (ESBL) of the CTX-M family. Resistance to amoxicillin (43.3%) was most widespread, followed by resistance to trimethoprim-sulfamethoxazole (27.0%), amoxicillin-clavulanic acid (18.0%), cefuroxime (11.3%), and ciprofloxacin (11.1%). Twenty-four E. coli isolates (5.2%) were resistant to mecillinam. The concentrations of mecillinam needed to inhibit 50/90% of the ESBL-producing isolates and the remaining isolates were 1/4 mg/L and 0.5/4 mg/L, respectively. The findings support the recommendation to regard pivmecillinam as a first-line option for the treatment of uncomplicated lower UTIs.

Glycopeptide resistance in Enterococcus spp. and coagulase-negative staphylococci from hospitalized patients in Germany: occurrence, characteristics, and susceptibility to dalbavancin

OBJECTIVE

To evaluate the occurrence of glycopeptide resistance in enterococci and coagulase-negative staphylococci (CoNS), and to determine the susceptibilities of the identified glycopeptide-resistant isolates to dalbavancin.

METHODS

Twenty-two medical laboratories participated in the study conducted in 2016/17 by the Paul-Ehrlich-Society for Chemotherapy. Each laboratory was asked to collect 30 Enterococcus spp. (limited to faecalis/faecium) and 30 CoNS isolates consecutively from hospitalized patients who had a proven or suspected infection.

RESULTS

A total of 1285 isolates were collected, comprising 364 E. faecalis, 291 E. faecium and 630 CoNS. No Enterococcus faecalis isolate but 76 (26.1%) E. faecium isolates were vancomycin-resistant, of which 21 showed the VanA-type and 55 the VanB-type. The proportion of vancomycin-resistant strains among E. faecium isolates from patients in intensive care units (21.6%) was significantly lower than that from patients on regular wards (30.5%). Among the CoNS, 67 (10.6%) isolates were teicoplanin-resistant, but none were vancomycin-resistant, with resistance merely detected in Staphylococcus epidermidis (12.2%), S. haemolyticus (17.9%) and S. hominis (13.2%). Dalbavancin at ≤ 0.25 mg/l inhibited all VanB-type enterococci and 95.5% teicoplanin-resistant CoNS.

CONCLUSIONS

The level of glycopeptide resistance in E. faecalis remains very low in Germany but achieved 26% in E. faecium and was > 10% in CoNS. Dalbavancin seems to be a feasible option for treating infections caused by VanB-type vancomycin-resistant E. faecium and teicoplanin-resistant CoNS.

Comparative in vitro activity of piperacillin-tazobactam and temocillin against third-generation cephalosporin-resistant, carbapenem-susceptible Escherichia coli and Klebsiella pneumoniae

Carbapenems are considered the drugs of choice for first-line treatment of severe infections caused by carbapenem-susceptible, extended-spectrum β-lactamases (ESBL)-producing Enterobacterales, while piperacillin-tazobactam has been recommended as an alternative for treatment of non-severe infections. Temocillin is stable to ESBL and AmpC enzymes and may thus represent another treatment option. This study assessed the in vitro activity of piperacillin-tazobactam and temocillin against third-generation cephalosporin (3GC)-resistant Esch erichia coli and Klebsiella pneumoniae, as compared to 3GC-susceptible isolates of either species. One hundred and nine isolates from hospitalized patients with bloodstream and urinary tract infections were tested. All isolates were collected during the resistance surveillance study of the Paul-Ehrlich-Society for Chemotherapy in 2016/17. Minimum inhibitory concentrations (MICs) were determined by broth microdilution according to the standard ISO 20776-1 and interpreted using EUCAST clinical breakpoints (version 11.0). Seventy-nine isolates (E. coli, n=58; K. pneumoniae, n=21) were 3GC-resistant and 30 (E. coli, n=15; K. pneumoniae, n=15) were 3GC-susceptible. Susceptibility to piperacillin-tazobactam was detected in 93.3% of 3GC-susceptible isolates (for both E. coli and K. pneumoniae) and in 79.3% and 57.1% of the 3GC-resistant E. coli and K. pneumoniae, respectively. In contrast, 3GC-susceptible isolates were 100% susceptible to temocillin as were 94.8% and 90.5% of the 3GC-resistant E. coli and K. pneumoniae, respectively. In conclusion, temocillin demonstrated potent in vitro activity against carbapenem-susceptible, 3GC-resistant E. coli and K. pneumoniae from bloodstream and urinary tract infection samples, with susceptibility rates exceeding those of piperacillin-tazobactam.

Evaluation of a Phenotypic Algorithm to Direct Carbapenemase Testing in Pseudomonas aeruginosa: Validation in a Multicenter German Cohort

Pseudomonas aeruginosa remains a prominent nosocomial pathogen. Detection of carbapenemase-producing P. aeruginosa is vital to dictate antimicrobial therapy and infection control measures. A pragmatic, minimum inhibitory concentration-based algorithm using imipenem AND meropenem-resistant plus ceftazidime-, cefepime-, and piperacillin/tazobactam-nonsusceptible criterion was derived to guide carbapenemase testing in P. aeruginosa. This study was an assessment of the algorithm's test performance in a cohort of 985 nonduplicate P. aeruginosa isolates collected from 20 German medical laboratories. Susceptibility data were assessed in the algorithm using both Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility Testing (EUCAST) interpretations. Sensitivity and specificity were calculated to evaluate algorithm test performance. The original algorithm criteria resulted in high specificity (95-97%) using both CLSI and EUCAST criteria; however, it failed to capture five carbapenemase-harboring isolates testing piperacillin/tazobactam susceptibility (CLSI/EUCAST). Two carbapenemase-producing isolates were also meropenem susceptible per EUCAST. A modified algorithm utilizing imipenem OR meropenem-resistant plus ceftazidime and cefepime nonsusceptible, improved the sensitivity of the criteria without significantly compromising specificity (CLSI sensitivity/specificity: 96%/94% and EUCAST sensitivity/specificity: 96%/95%). Application of the modified algorithm criteria resulted in high sensitivity and specificity using both CLSI and EUCAST interpretations in a large cohort of clinical P. aeruginosa. Utilization of this algorithm can improve the efficiency of carbapenemase testing in the clinical laboratory.

1227. Plazomicin Susceptibility Testing using ETEST® MIC for Enterobacterales

Background

Plazomicin (PLZ) approved by FDA in June of 2018, is an aminoglycoside class antibacterial indicated for the treatment of adults with complicated urinary tract infections (cUTI) including pyelonephritis caused by Enterobacterales. It is used in patients who have limited or no alternative treatment options, e.g. CRE and MDRO patients. The drug has bactericidal activity, it is active against organisms producing ESBL, Carbapenemase and aminoglycoside-modifying enzymes. The purpose of this study was to compare ETEST® PLZ bioMérieux to the broth microdilution reference method (BMD) for Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca and pneumoniae, Morganella morganii, Providencia stuartii, Proteus mirabilis and vulgaris and Serratia marcescens isolates.

Methods

A total of 598 isolates were tested by ETEST® (PLZ) and BMD at four clinical trial sites.

Isolates were subcultured on tryptic soy or Columbia agar plates supplemented with 5% sheep blood. Suspensions of the isolates were prepared in 0.85% saline, which were used to inoculate BMD and Mueller Hinton agar for ETEST®. Results were read after 16-20 hours incubation at 35°C +2°C in ambient air. QC organisms were tested with each run following CLSI QC guidelines.

Results were analyzed using FDA breakpoints for PLZ (Susceptible <2 µg/mL, Intermediate 4 µg/mL, Resistant >8 µg/mL).

Performance was evaluated using FDA performance criteria, EA and CA (≥ 90%), major error rate (≤3.0%) and very major error rate (≤2.0%).

Results

Conclusion

ETEST® PLZ clinical performance met the FDA acceptance criteria and was found useful for determining Plazomicin MIC of Enterobacterales, including ESBL, CRE (MBL, KPC, Oxa-48), high level AmpC and aminoglycoside resistant strains. Percent susceptibility of Plazomicin is at 80% among the 598 isolates tested, the mode MIC is 0.5 ug/ml as Susceptible.

Disclosures

Tom Armstrong, BS, bioMérieux (Employee) Laurine Blanchard, PhD, bioMérieux (Employee) Michael Kresken, PhD, bioMérieux (Scientific Research Study Investigator, Research Grant or Support) Gilles Zambardi, biomerieux (Employee) Marion Pompilio, BioMérieux (Employee)

Thirty years of VRE in Germany - "expect the unexpected": The view from the National Reference Centre for Staphylococci and Enterococci

Enterococci are commensals of the intestinal tract of many animals and humans. Of the various known and still unnamed new enterococcal species, only isolates of Enterococcus faecium and Enterococcus faecalis have received increased medical and public health attention. According to textbook knowledge, the majority of infections are caused by E. faecalis. In recent decades, the number of enterococcal infections has increased, with the increase being exclusively associated with a rising number of nosocomial E. faecium infections. This increase has been accompanied by the dissemination of certain hospital-acquired strain variants and an alarming progress in the development of antibiotic resistance namely vancomycin resistance. With this review we focus on a description of the specific situation of vancomycin resistance among clinical E. faecium isolates in Germany over the past 30 years. The present review describes three VRE episodes in Germany, each of which is framed by the beginning and end of the respective decade. The first episode is specified by the first appearance of VRE in 1990 and a country-wide spread of specific vanA-type VRE strains (ST117/CT24) until the late 1990s. The second decade was initially marked by regional clusters and VRE outbreaks in hospitals in South-Western Germany in 2004 and 2005, mainly caused by vanA-type VRE of ST203. Against the background of a certain "basic level" of VRE prevalence throughout Germany, an early shift from the vanA genotype to the vanB genotype in clinical isolates already occurred at the end of the 2000s without much notice. With the beginning of the third decade in 2010, VRE rates in Germany have permanently increased, first in some federal states and soon after country-wide. Besides an increase in VRE prevalence, this decade was marked by a sharp increase in vanB-type resistance and a dominance of a few, novel strain variants like ST192 and later on ST117 (CT71, CT469) and ST80 (CT1065). The largest VRE outbreak, which involved about 2,900 patients and lasted over three years, was caused by a novel and until that time, unknown strain type of ST80/CT1013 (vanB). Across all periods, VRE outbreaks were mainly oligoclonal and strain types varied over space (hospital wards) and time. The spread of VRE strains obviously respects political borders; for instance, both vancomycin-variable enterococci which were highly prevalent in Denmark and ST796 VRE which successfully disseminated in Australia and Switzerland, were still completely absent among German hospital patients, until to date.

In vitro activity of cefiderocol against aerobic Gram-negative bacterial pathogens from Germany

OBJECTIVES

Cefiderocol (CID), also known as S-649266, a novel siderophore cephalosporin, possesses potent activity against multidrug-resistant aerobic Gram-negative bacteria (GNB). This study aimed to determine the in vitro activity of CID against two different sets of GNB: i) a random sample of 213 clinical isolates, including 17 extended-spectrum beta-lactamase (ESBL) producers, obtained from intensive care unit patients with nosocomial infections collected during a multicentre surveillance study (set I); and ii) a group of 59 challenge GNB producing various types of carbapenemases (CP; set II).

METHODS

Minimum inhibitory concentrations (MICs) were determined using the microdilution method according to the standard ISO 20776-1. Iron-depleted medium was used for testing CID.

RESULTS

CID inhibited 97.2% of set I isolates at the EUCAST susceptibility breakpoint of ≤ 2 mg/L. The concentrations of CID inhibiting 50% and 90% (MIC50/90) of the Enterobacterales isolates (n = 146) were 0.12/1.0 mg/L, with ESBL-positive isolates tending to exhibit higher MICs than ESBL-negative isolates to CID. MIC50/90 values of CID for isolates of the Acinetobacter baumannii group (n = 13) and Pseudomonas aeruginosa (n = 54) were 0.06/0.12 mg/L and 0.12/0.5 mg/L, respectively. Further, CID inhibited 88.1% of set II CP-producing isolates at ≤ 2 mg/L. All seven class D CP-producing Acinetobacter baumannii were inhibited at ≤ 0.25 mg/L. MIC50/90 values for CP-producing Enterobacterales (n = 30) and Pseudomonas aeruginosa (n = 22) were 1/4 mg/L and 0.5/2 mg/L, respectively.

CONCLUSION

CID showed potent activity against Acinetobacter baumannii, Enterobacterales and Pseudomonas aeruginosa, including CP-producing isolates. Overall, CID inhibited 259 of 272 (95.2%) GNB at ≤ 2 mg/L.

In vitro activity of sulbactam/durlobactam against global isolates of carbapenem-resistant Acinetobacter baumannii

Objectives

To evaluate the activity of the novel broad-spectrum serine β-lactamase inhibitor durlobactam (ETX2514) combined with sulbactam against global isolates of carbapenem-resistant Acinetobacter baumannii with defined carbapenem resistance mechanisms compared with reference antimicrobials with known activity against Acinetobacter spp.

Methods

The susceptibility of 246 carbapenem-resistant non-duplicate A. baumannii isolates to sulbactam/durlobactam, amikacin, colistin, imipenem/sulbactam/durlobactam, imipenem, meropenem, minocycline and sulbactam was tested using broth microdilution. Isolates were obtained from various body sites from patients in 37 countries and from six world regions between 2012 and 2016. Identification of carbapenem resistance mechanisms and assignment to A. baumannii clonal lineages was based on WGS.

Results

Sulbactam/durlobactam showed excellent activity comparable to colistin but superior to amikacin, minocycline and sulbactam. The sulbactam/durlobactam MIC50/90 values were 1/4 and 2/4 mg/L and the colistin MIC50/90 values were 0.5 and 1 mg/L, respectively. Comparatively, amikacin, minocycline and sulbactam MIC50/90 values were 256/≥512, 2/16 and 16/64 mg/L, respectively.

Conclusions

Sulbactam/durlobactam had excellent in vitro potency against A. baumannii isolates, including those that were resistant to imipenem/meropenem, amikacin, minocycline and colistin, compared with other compounds. Sulbactam/durlobactam has the potential to become a useful addition to the limited armamentarium of drugs that can be used to treat this problem pathogen.

The phylogenetic landscape and nosocomial spread of the multidrug-resistant opportunist Stenotrophomonas maltophilia

Recent studies portend a rising global spread and adaptation of human- or healthcare-associated pathogens. Here, we analyse an international collection of the emerging, multidrug-resistant, opportunistic pathogen Stenotrophomonas maltophilia from 22 countries to infer population structure and clonality at a global level. We show that the S. maltophilia complex is divided into 23 monophyletic lineages, most of which harbour strains of all degrees of human virulence. Lineage Sm6 comprises the highest rate of human-associated strains, linked to key virulence and resistance genes. Transmission analysis identifies potential outbreak events of genetically closely related strains isolated within days or weeks in the same hospitals.

Multidrug resistance of the opportunistic pathogen Stenotrophomonas maltophilia is an increasing problem. Here, analyzing strains from 22 countries, the authors show that the S. maltophilia complex is divided into 23 monophyletic lineages and find evidence for intra-hospital transmission.

Dissemination of carbapenem-resistant Pseudomonas aeruginosa isolates and their susceptibilities to ceftolozane-tazobactam in Germany

Pseudomonas aeruginosa (PA) is a major cause of healthcare-associated infections. Antipseudomonal carbapenems are among the antimicrobial agents used to treat PA infections, but several mechanisms of resistance, including the production of a carbapenemase (CP), may compromise their clinical efficacy. The objectives of this study were to determine: (i) the dissemination of carbapenem-resistant CP-negative and CP-positive PA isolates; and (ii) the in-vitro activity of ceftolozane-tazobactam (CTT) against carbapenem-susceptible and carbapenem-resistant isolates. Isolates were collected prospectively from January 2016 to April 2017 at 20 German medical laboratories. Each centre was asked to provide 50 consecutive isolates from hospitalized patients. Overall, 985 isolates were collected, of which 34% were obtained from intensive care patients. Seven hundred and thirty-eight (74.9%) isolates were susceptible to both imipenem and meropenem (Subgroup I), and 247 (25.1%) isolates were resistant to carbapenems (Subgroup II): 125 (12.7%) were imipenem-resistant but meropenem-susceptible, 12 (1.2%) were meropenem-resistant but imipenem-susceptible, and 110 (11.2%) were resistant to both carbapenems (Subgroup III). A CP was detected in 28 (2.8%) isolates (predominantly VIM-2). Nine hundred and fifty (96.4%) isolates were CTT-susceptible. Susceptibility to CTT was seen in 99.6% of Subgroup I isolates, 87% of Subgroup II isolates and 74.5% of Subgroup III isolates. Overall, 2.8% of PA produced a CP, while 22.2% were carbapenem-resistant, CP-non-producing isolates. Based on these findings, CTT may be considered for treatment of PA infections, particularly those caused by multi-drug-resistant CP-non-producing isolates.

Calculated parenteral initial treatment of bacterial infections: Microbiology

This is the second chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. Preliminary microbiological findings regarding the patient and their immediate environment are crucial for the calculation of treatment with antibiotics in each case, as well as the resistance situation of the ward on which the patient is being cared for. If such data is not available, regional or supra-regional data can be used as a fallback. This chapter describes the methods of susceptibility testing, informs about the resistance situation in Germany and describes the main resistance mechanisms of bacterial pathogens against antibiotics. Further, the chapter informs about collateral damage of antibiotics as well as medical measures against increasing resistance.

Calculated parenteral initial treatment of bacterial infections: Introduction and antibiotics

This is the first chapter of the guideline "Calculated initial parenteral treatment of bacterial infections in adults - update 2018" in the 2nd updated version. The German guideline by the Paul-Ehrlich-Gesellschaft für Chemotherapie e.V. (PEG) has been translated to address an international audience. This guideline is a revision of the recommendations published in 2010, taking into account recent substances and studies. As with previous revisions, the current situation of pathogen resistance and the results of new clinical trials are considered. The results are the present recommendations for parenteral calculated initial therapy of bacterial infections in adults. If several treatment options are mentioned, they are not always equivalent in their spectrum of microbiological activity. Therapeutic alternatives offer the opportunity to consider pathogen epidemiology, to avoid antibiotic intolerances or to escalate or de-escalate treatment in a manner suited to the situation. This article describes the different therapy options.

[S2k guidelines of the PEG on calculated parenteral initial treatment of bacterial diseases in adults : Focussed summary and supplementary information on antibiotic treatment of critically ill patients]

In January 2018 the recent revision of the S2k guidelines on calculated parenteral initial treatment of bacterial diseases in adults-update 2018 (Editor: Paul Ehrlich Society for Chemotherapy, PEG) was realized. It is a helpful tool for the complex infectious disease setting in an intensive care unit. The present summary of the guidelines focuses on the topics of anti-infective agents, including new substances, pharmacokinetics and pharmacodynamics as well as on microbiology, resistance development and recommendations for calculated drug therapy in septic patients. As in past revisions the recent resistance situation and results of new clinical studies are considered and anti-infective agents are summarized in a table.

[In-vitro activity of mecillinam against urine isolates of Escherichia coli from outpatient departments in Germany]

National and international guidelines recommend fosfomycin trometamol, nitrofurantoin, nitroxoline, and pivmecillinam as first-line agents for the treatment of acute uncomplicated cystitis. Escherichia coli is by far the leading cause of community-acquired urinary tract infections. Pivmecillinam (X-SYSTO^®) is an oral prodrug of mecillinam, a penicillin derivative that was reintroduced to the German market in March 2016. This study aimed to investigate the proportion of mecillinam-resistant strains among E. coli isolates prior to the introduction of X-SYSTO^® in Germany.An in-vitro study was carried out to determine the minimal inhibitory concentrations (MICs) of mecillinam against 494 urine isolates of E. coli (including multidrug-resistant strains). Isolates were obtained from outpatients and collected in 25 laboratories between October and December 2013. MIC breakpoints defined by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) were applied for classifying the bacterial isolates as mecillinam-susceptible (MIC ≤ 8 mg/l) or resistant (MIC > 8 mg/l).The concentrations of mecillinam needed to inhibit 50 % and 90 % of the test isolates were 1 and 4 mg/l, respectively, for isolates displaying the extended spectrum β-lactamase phenotype, and 0.25 and 4 mg/l, respectively, for the remaining isolates. Overall, 98 % of the isolates were found to be mecillinam-susceptible (MIC ≤ 8 mg/l), and 2 % were found to be resistant (MIC > 8 mg/l).These findings support the recommendation to regard pivmecillinam as a first-line option for the treatment of acute uncomplicated cystitis.

Temporal trends of the in vitro activity of tigecycline and comparator antibiotics against clinical aerobic bacterial isolates collected in Germany, 2006-2014: results of the Tigecycline Evaluation and Surveillance Trial (TEST)

Given the rapidly changing landscape of antimicrobial resistance, continuous monitoring of antimicrobial susceptibility in clinically relevant bacterial isolates plays an important role in the management of infectious diseases. The Tigecycline Evaluation and Surveillance Trial (TEST) is an ongoing worldwide surveillance programme monitoring the in vitro activity of tigecycline and a panel of representative comparator antibiotics. We report longitudinal susceptibility data on a large set of isolates (n=36,044) from clinically significant bacterial species collected in 25 microbiological laboratories from 2006 to 2014. Trends include a strong increase of carbapenem and levofloxacin resistance in Acinetobacter spp., and smaller increasing rates of ESBL-producing Escherichia coli and vancomycin-resistant enterococci. Across the reporting period, the tigecycline minimum inhibitory concentrations (MICs) at which 50% and 90% of isolates were inhibited remained stable and susceptibility rates were consistently high (93–100%) for all bacterial species.

Occurrence of multidrug resistance to oral antibiotics among Escherichia coli urine isolates from outpatient departments in Germany: extended-spectrum β-lactamases and the role of fosfomycin

The in vitro activities of fosfomycin and seven other antibiotics commonly used for oral treatment of urinary tract infections (UTIs) were evaluated for 499 Escherichia coli isolated from urine samples during a nationwide laboratory-based surveillance study in 2010. Overall, the highest resistance rates were found for amoxicillin (42.9%), followed by amoxicillin/clavulanic acid (32.7%), trimethoprim/sulfamethoxazole (SXT) (30.9%), ciprofloxacin (19.8%), cefuroxime (10.0%), cefpodoxime (8.6%) and cefixime (8.2%). One-half of the isolates (n=252; 50.5%) were fully susceptible to the eight drugs, whilst only 6 strains (1.2%) were resistant to fosfomycin. Combined resistance to amoxicillin, cefuroxime, ciprofloxacin and SXT was detected in 29 isolates (5.8%). Moreover, 40 isolates (8.0%) produced an extended-spectrum β-lactamase (ESBL), including CTX-M-type ESBLs detected in 39/40 isolates (97.5%) and a TEM-52 ESBL in 1 strain (2.5%). The predominant CTX-M-type ESBL was CTX-M-15 (27/39; 69.2%). Of the 27 CTX-M-15 producers, 19 (70.4%) belonged to the clonal lineage E. coli O25b-ST131. All but one ESBL-producing strains were fosfomycin-susceptible. In view of the emergence of multidrug resistance to standard oral antibiotics, these data support that oral fosfomycin (trometamol salt) may represent a valuable option in the treatment of uncomplicated UTIs.

Antimicrobial susceptibility and molecular epidemiology of Neisseria gonorrhoeae in Germany

Antimicrobial drug resistance in Neisseria gonorrhoeae has become an increasing public health problem. Hence, surveillance of resistance development is of crucial importance to implement adequate treatment guidelines. Data on the spread of antibiotic resistance among gonococcal isolates in Germany, however, is scarce. In a resistance surveillance study conducted by the Paul Ehrlich Society for Chemotherapy between October 2010 and December 2011, 23 laboratories all over Germany were requested to send N. gonorrhoeae isolates to the study laboratory in Frankfurt am Main. Species verification was performed biochemically using ApiNH and with Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS). Antimicrobial susceptibility testing was performed using the Etest method. For molecular epidemiological analysis, N. gonorrhoeae strains were genotyped by means of N. gonorrhoeae multi-antigen sequence typing. A total of 213 consecutive gonococcal isolates were analyzed in this nationwide study. Applying EUCAST breakpoints, high resistance rates were found for ciprofloxacin (74%) and tetracycline (41%). Penicillin non-susceptibility was detected in 80% of isolates. The rate of azithromycin resistance was 6%, while all strains were susceptible to spectinomycin, cefixime, and ceftriaxone. Molecular typing of gonococcal isolates revealed a great heterogeneity of 99 different sequence types (ST), but ST1407 predominated (n=39). This is the first comprehensive German multi-centre surveillance study on antibiotic susceptibility and molecular epidemiology of N. gonorrhoeae with implications for antibiotic choice for treatment of gonorrhoea. The World Health Organization supports the concept that an efficacious treatment of gonorrhoea results in at least 95% of infections being cured. Accordingly, as spectinomycin is not available on the German market, only the third generation cephalosporins cefixime and ceftriaxone are regarded as valuable drugs for empirical treatment of gonorrhoea in Germany.

[Surveillance of antibiotic consumption : clarification of the "definition of data on the nature and extent of antibiotic consumption in hospitals according to § 23 paragraph 4 sentence 2 of the IfSG"]

According to § 23 paragraph 4 of the German Infection Prevention Act (IfSG; July 2011), hospitals and clinics for ambulatory surgery are obliged to establish a continuous monitoring system of antibiotic consumption. This is aimed at contributing to an optimization of antibiotic prescription practices in order to confine the development and spread of resistant pathogens. The general requirements (restricted to hospitals) on the method and extent of data collection are provided by the national public health institution after discussion with representatives of various professional societies (Robert Koch-Institut, Bundesgesundheitsblatt Gesundheitsforschung Gesundheitsschutz 59, 2013). The article aims to clarify these specifications and to provide background details. In agreement with national and European surveillance systems, the Anatomical Therapeutic Chemical (ATC)/Defined Daily Dose (DDD) classification system recommended by the WHO should be used as reference standard. Antibiotic consumption should be expressed as the number of DDDs per 100 patient days and per 100 admissions. The categories of antimicrobials and hospital organizational units to be monitored and the time intervals in which analyses should be conducted are determined. Furthermore, various approaches of data assessment are described.

Urinary concentrations and antibacterial activities of nitroxoline at 250 milligrams versus trimethoprim at 200 milligrams against uropathogens in healthy volunteers

Because of the increasing bacterial resistance of uropathogens against standard antibiotics, such as trimethoprim (TMP), older antimicrobial drugs, such as nitroxoline (NTX), should be reevaluated. This randomized crossover study investigated the urinary concentrations of parent drugs and their metabolites and their antibacterial activities (urinary inhibitory titers [UITs] and urinary bactericidal titers [UBTs]) against uropathogens at three different urinary pH values within 24 h in six healthy volunteers after a single oral dose of NTX at 250 mg versus TMP at 200 mg. In three additional volunteers, urinary bactericidal kinetics (UBK) were studied after oral administration of NTX at 250 mg three times a day. The mean urinary concentrations of NTX and NTX sulfate in 24 h were 0.012 to 0.507 mg/liter and 0.28 to 27.83 mg/liter, respectively. The mean urinary concentrations of TMP were 18.79 to 41.59 mg/liter. The antibacterial activity of NTX was higher in acidic urine than in alkaline urine, and that of TMP was higher in alkaline urine than in acidic urine. The UITs and UBTs of NTX were generally lower than those of TMP except for a TMP-resistant Escherichia coli strain, for which NTX showed higher UITs/UBTs than did TMP. UBK showed mainly bacteriostatic activity of NTX in urine. NTX exhibits mainly bacteriostatic activity and TMP also shows bactericidal activity in urine against susceptible strains. NTX is a more active antibacterial in acidic urine, and TMP is more active in alkaline urine. The cumulative effects of multiple doses or inhibition of bacterial adherence could not be evaluated. (This study has been registered at EudraCT under registration no. 2009-015631-32.).

[Multiresistant pathogens--a challenge for clinicians]

Gram-negative pathogens are currently isolated frequently in invasive nosocomial infections and give rise to major therapeutic problems due to their resistance pattern. Metaanalyses of randomised controlled studies have demonstrated that an antibiotic combination treatment is not indicated in many cases. However, in critically ill patients (septic shock) and also in immunocompromised patients with previous intensive care as well as broad spectrum antibiotic treatment, a combination of antibiotics is recommended. This therapy should be based on the source of the infection, on local resistance data, on antibiotic pretreatment, on basic diseases of the patient and on current liver and renal functions. The start of therapy should be as fast as possible after collection of optimal materials for microbiological analysis. Dosage of selected antibiotics should be based on rational pharmacokinetic and pharmacodynamic parameters. A de-escalation of antibiotics is strongly recommended in all international guidelines based on the microbiological results and the clinical response of the patient. New antibiotics or therapeutic strategies against multiresistant Gram-negative pathogens will not be available in the next 5 to 10 years; therefore, it is absolute mandatory to use the currently still effective antibiotics, like carbapenems and polymyxins, very rationally and restrictively.

Molecular epidemiology of Acinetobacter baumannii and Acinetobacter nosocomialis in Germany over a 5-year period (2005-2009)

To investigate the species distribution within the Acinetobacter calcoaceticus-Acinetobacter baumannii complex and the molecular epidemiology of A. baumannii and Acinetobacter nosocomialis, 376 Acinetobacter isolates were collected prospectively from hospitalized patients at 15 medical centres in Germany during three surveillance studies conducted over a 5-year period. Species identification was performed by molecular methods. Imipenem minimum inhibitory concentrations (MIC) were determined by broth microdilution. The prevalence of the most common carbapenemase-encoding genes was investigated by oxacillinase (OXA) -multiplex polymerase chain reaction (PCR). The molecular epidemiology was investigated by repetitive sequence-based PCR (rep-PCR; DiversiLab™). Acinetobacter pittii was the most prevalent Acinetobacter species (n = 193), followed by A. baumannii (n = 140), A. calcoaceticus (n = 10) and A. nosocomialis (n = 8). The majority of A. baumannii was represented by sporadic isolates (n = 70, 50%) that showed unique rep-PCR patterns, 25 isolates (18%) clustered with one or two other isolates, and only 45 isolates (32%) belonged to one of the previously described international clonal lineages. The most prevalent clonal lineage was international clone (IC) 2 (n = 34) and IC 1 (n = 6). According to CLSI, 25 A. baumannii isolates were non-susceptible to imipenem (MIC ≥ 8 mg/L), all of which produced an OXA-58-like or OXA-23-like carbapenemase. The rate of imipenem susceptibility among A. baumannii isolates decreased from 96% in 2005 to 76% in 2009. All other Acinetobacter isolates were susceptible to imipenem. The population structure of carbapenem-susceptible A. baumannii in Germany is highly diverse. Imipenem non-susceptibility was strongly associated with the clonal lineages IC 2 and IC 1. These data underscore the high clonality of carbapenem-resistant A. baumannii isolates.

Susceptibility of clinical isolates of frequently encountered bacterial species to tigecycline one year after the introduction of this new class of antibiotics: results of the second multicentre surveillance trial in Germany (G-TEST II, 2007)

Tigecycline, a broad-spectrum antibiotic for parenteral use, was introduced in Germany in May 2006. In the G-TEST-II trial, the susceptibility of isolates, recovered in 2007 from hospitalised patients in 15 centres, was assessed against tigecycline and comparators. Susceptibility tests were performed by the microdilution procedure. This study reports on the susceptibility of the isolates of 16 bacterial species and compares the results with those of a trial (G-TEST I) conducted prior to the introduction of tigecycline. Between 2005 and 2007, tigecycline retained activity against Gram-positive and Gram-negative organisms. By contrast, the rate of vancomycin-resistant strains among Enterococcus faecium isolates almost doubled. Moreover, an increase in resistance to broad-spectrum beta-lactams and fluoroquinolones was observed for members of the family Enterobacteriaceae. Against a background of a steadily rising number of pathogens that are resistant to various antibiotic classes, tigecycline represents an important treatment option.

Susceptibility of common aerobic pathogens to tigecycline: results of a surveillance study in Germany

Tigecycline is a novel antimicrobial agent for parenteral use encompassing a broad spectrum of bacterial pathogens, including multi-resistant organisms. Here, we report the results of the first nationwide surveillance trial that was conducted in order to evaluate the susceptibility of bacterial isolates to tigecycline in a European country prior to its clinical use. A total of 2,610 Gram-positive and Gram-negative organisms recovered from hospitalized patients were tested. Minimum inhibitory concentrations (MICs) were determined using the microdilution method. All enterococci, staphylococci (including methicillin-resistant Staphylococcus aureus; MRSA), and streptococci tested were tigecycline-susceptible, except one isolate of Staphylococcus haemolyticus. Among the Gram-negative bacteria, 100% of the Escherichia coli isolates (including extended spectrum beta-lactamase [ESBL]-producers) were tigecycline-susceptible, while about 10% of the Enterobacter cloacae and Klebsiella pneumoniae isolates were resistant. Based on the results of this surveillance study, tigecycline may represent a suitable option most notably for the empiric treatment of bacterial mixed infections, including in clinical situations in which multi-resistant organisms are suspected.

Bactericidal activity of daptomycin, vancomycin, teicoplanin and linezolid against Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium using human peak free serum drug concentrations

The bactericidal activities of daptomycin, vancomycin, teicoplanin and linezolid at human peak free serum concentrations (C(max,free)) were determined against Staphylococcus aureus (one methicillin-susceptible and two methicillin-resistant strains), Enterococcus faecalis and Enterococcus faecium (one vancomycin-susceptible and one vancomycin-resistant strain of each). Daptomycin was rapidly bactericidal against 7/7 strains at C(max,free) of 22.0 mg/L (corresponding to 63% protein binding) and against 3/7 strains at 4.8 mg/L (corresponding to 92% protein binding). Vancomycin (18.0 mg/L) was bactericidal against only two strains. Both teicoplanin (4.5 mg/L) and linezolid (10.4 mg/L) were consistently bacteriostatic. Daptomycin is a useful option for the treatment of Gram-positive infections owing to its strong bactericidal activity.

Surveillance of linezolid resistance in Germany, 2001–2002

A surveillance study was performed throughout Germany from November 2001 to June 2002 to assess the prevalence of linezolid-resistant isolates among Gram-positive bacteria from routine susceptibility data and to compare the in-vitro activity of linezolid to that of other antibacterial agents. Each of 86 laboratories provided routine susceptibility data for 100 consecutive isolates. Most laboratories (c. 60%) used the disk diffusion test. Laboratories were also requested to send a representative sample of their isolates, as well as all isolates reported as intermediate or resistant to linezolid, to a reference laboratory for MIC determination. Susceptibility data for 8594 isolates were evaluated. Sites of infection were skin and soft tissue (29.9%), upper and lower respiratory tract (19.1%), foreign body or catheter (10.5%), or urinary tract (9.8%). Routine linezolid susceptibility data were reported for 6433 isolates. The prevalence of linezolid resistance, as reported to the clinician, was 0.4% in Staphylococcus aureus, 0.3% in Staphylococcus epidermidis, 2.9% in Enterococcus faecalis, 2.3% in Enterococcus faecium, 1.4% in Streptococcus pyogenes and 2.9% in Streptococcus agalactiae. Linezolid resistance was not detected in Streptococcus pneumoniae or in viridans group streptococci. Sixty-nine of 115 isolates reported as intermediate or resistant to linezolid were retested, but none was resistant to linezolid. Linezolid exhibited excellent in-vitro activity against representative isolates of the six most frequently encountered species (MIC90, 1-2 mg/L). The prevalence of resistance to linezolid was very low in Germany. Organisms reported as linezolid-resistant should be retested, either in the same laboratory with an alternative method or in a reference laboratory.

Activities of various β-lactams and β-lactam/β-lactamase inhibitor combinations against Acinetobacter baumannii and Acinetobacter DNA group 3 strains

Acinetobacter baumannii and Acinetobacter DNA group 3 are members of the so-called A. calcoaceticus-A. baumannii complex and are important nosocomial pathogens. Multiresistance in these organisms is increasingly frequent, and alternative treatment options are needed. The beta-lactamase inhibitors clavulanate, sulbactam and tazobactam have intrinsic activity against Acinetobacter strains. In the present study, broth microdilution was used to assess the in-vitro activities of currently available beta-lactam/beta-lactamase inhibitor combinations and sulbactam alone against 469 Acinetobacter isolates (A. baumannii, n=395; Acinetobacter DNA group 3, n=74) collected from various laboratories in Germany. Fixed concentrations and fixed ratios of beta-lactamase inhibitors were used. Sulbactam-containing combinations (susceptibility rates of 90.4-92.7% for A. baumannii and 97.3-100% for Acinetobacter DNA group 3) and sulbactam alone were superior to clavulanate- and tazobactam-containing combinations. The activity of sulbactam-containing combinations against members of the A. calcoaceticus-A. baumannii complex was conferred exclusively by the intrinsic activity of the beta-lactamase inhibitor and did not result from enhanced beta-lactam activity. Testing with the inhibitor added at a fixed ratio of inhibitor to beta-lactam appeared to give more reliable results than testing at a fixed concentration of the inhibitor. Resistance to carbapenems (0.3%) remains low in Germany.

High prevalence of the ermB gene among erythromycin-resistant streptococcus pneumoniae isolates in Germany during the winter of 2000-2001 and in vitro activity of telithromycin

Of 595 isolates of Streptococcus pneumoniae from outpatients with respiratory tract infections, collected from 17 microbiology laboratories, 14.1% were resistant to erythromycin. Eighty-three erythromycin-resistant isolates were genetically analyzed, 83.1% of which harbored the ermB gene. Only four isolates (4.8%) harbored the mefA gene. Telithromycin exhibited potent activity against all isolates.

Prevalence of mupirocin resistance in clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis: results of the Antimicrobial Resistance Surveillance Study of the Paul-Ehrlich-Society for Chemotherapy, 2001

A multicentre surveillance study comprising 26 laboratories located in Austria, Germany, and Switzerland was carried out in November 2001. A total of 787 isolates of Staphylococcus aureus and 456 isolates of Staphylococcus epidermidis mainly recovered from hospitalised patients, were tested. MICs for mupirocin were determined using the broth microdilution procedure. Breakpoints were < or = 4 mg/l (susceptible), 8-256 mg/l (low-level resistance) and > or = 512 mg/l (high-level resistance). Rates of low- and high-level resistances were 2.9 and 0.9% in S. aureus, and 9.4 and 3.3% in S. epidermidis, respectively. Mupirocin resistance was almost exclusively observed in oxacillin-resistant isolates of S. aureus (MRSA) and S. epidermidis (MRSE). High-level mupirocin resistance was detected in 3.1 and 4.5% of MRSA and MRSE, respectively.