Epidemiology and Management of Emerging Drug-Resistant Gram-Negative Bacteria

Klebsiella pneumoniae clinical isolates with features of both multidrug-resistance and hypervirulence have unexpectedly low virulence

Klebsiella pneumoniae has been classified into two types, classical K. pneumoniae (cKP) and hypervirulent K. pneumoniae (hvKP). cKP isolates are highly diverse and important causes of nosocomial infections; they include globally disseminated antibiotic-resistant clones. hvKP isolates are sensitive to most antibiotics but are highly virulent, causing community-acquired infections in healthy individuals. The virulence phenotype of hvKP is associated with pathogenicity loci responsible for siderophore and hypermucoid capsule production. Recently, convergent strains of K. pneumoniae, which possess features of both cKP and hvKP, have emerged and are cause of much concern. Here, we screen the genomes of 2,608 multidrug-resistant K. pneumoniae isolates from the United States and identify 47 convergent isolates. We perform phenotypic and genomic characterization of 12 representative isolates. These 12 convergent isolates contain a variety of antimicrobial resistance plasmids and virulence plasmids. Most convergent isolates contain aerobactin biosynthesis genes and produce more siderophores than cKP isolates but not more capsule. Unexpectedly, only 1 of the 12 tested convergent isolates has a level of virulence consistent with hvKP isolates in a murine pneumonia model. These findings suggest that additional studies should be performed to clarify whether convergent strains are indeed more virulent than cKP in mouse and human infections.

Chicken Production and Human Clinical Escherichia coli Isolates Differ in Their Carriage of Antimicrobial Resistance and Virulence Factors

Contamination of food animal products by Escherichia coli is a leading cause of foodborne disease outbreaks, hospitalizations, and deaths in humans. Chicken is the most consumed meat both in the United States and across the globe according to the U.S. Department of Agriculture. Although E. coli is a ubiquitous commensal bacterium of the guts of humans and animals, its ability to acquire antimicrobial resistance (AMR) genes and virulence factors (VFs) can lead to the emergence of pathogenic strains that are resistant to critically important antibiotics. Thus, it is important to identify the genetic factors that contribute to the virulence and AMR of E. coli. In this study, we performed in-depth genomic evaluation of AMR genes and VFs of E. coli genomes available through the National Antimicrobial Resistance Monitoring System GenomeTrackr database. Our objective was to determine the genetic relatedness of chicken production isolates and human clinical isolates. To achieve this aim, we first developed a massively parallel analytical pipeline (Reads2Resistome) to accurately characterize the resistome of each E. coli genome, including the AMR genes and VFs harbored. We used random forests and hierarchical clustering to show that AMR genes and VFs are sufficient to classify isolates into different pathogenic phylogroups and host origin. We found that the presence of key type III secretion system and AMR genes differentiated human clinical isolates from chicken production isolates. These results further improve our understanding of the interconnected role AMR genes and VFs play in shaping the evolution of pathogenic E. coli strains. IMPORTANCE Pathogenic Escherichia coli causes disease in both humans and food-producing animals. E. coli pathogenesis is dependent on a repertoire of virulence factors and antimicrobial resistance genes. Food-borne outbreaks are highly associated with the consumption of undercooked and contaminated food products. This association highlights the need to understand the genetic factors that make E. coli virulent and pathogenic in humans and poultry. This research shows that E. coli isolates originating from human clinical settings and chicken production harbor different antimicrobial resistance genes and virulence factors that can be used to classify them into phylogroups and host origins. In addition, to aid in the repeatability and reproducibility of the results presented in this study, we have made a public repository of the Reads2Resistome pipeline and have provided the accession numbers associated with the E. coli genomes analyzed.

Epidemiology of Multidrug-Resistant Pseudomonas aeruginosa in the Middle East and North Africa Region

Over the last decades, there has been a dramatic global increase in multidrug-resistant (MDR) pathogens particularly among Gram-negative bacteria (GNB). Pseudomonas aeruginosa is responsible for various health care-associated infections, while MDR P. aeruginosa causes significant morbidity and mortality. Middle East and North Africa (MENA) represent an unexplored geographical region for the study of drug resistance since many of these countries are at crossroads of high volume of travel, diverse expatriate populations, as well as high antibiotic consumption despite attempts to implement antimicrobial stewardship programs. This minireview analyzes epidemiology, microbiological, and genomic characteristics of MDR P. aeruginosa in the MENA region. Published data on MDR P. aeruginosa prevalence, antimicrobial resistance patterns, and genetic profiles from studies published during the past 10 years from 19 MENA countries have been included in this minireview. There is wide variation in the epidemiology of MDR P. aeruginosa in the MENA region in terms of prevalence, antimicrobial characteristics, as well as genetic profiles. Overall, there is high prevalence of MDR P. aeruginosa seen in the majority of the countries in the MENA region with similarities between neighboring countries, which might reflect comparable population and antibiotic-prescribing cultures. Isolates from critical care units are significantly resistant particularly from certain countries such as Saudi Arabia, Egypt, Libya, Syria, and Lebanon with high-level resistance to cephalosporins, carbapenems, and aminoglycosides. Colistin susceptibility patterns remains high apart from countries with high-level antibiotic resistance such as Saudi Arabia, Syria, and Egypt.

Early prediction models for extended-spectrum β-lactamase-producing Escherichia coli infection in emergency department: A protocol for systematic review and meta analysis

BACKGROUND

Resistance in gram-negative bacteria has gained great importance in recent decades and one reason is the rapid increase of extended spectrum β-lactamase (ESBL)-producing bacteria as a growing problem worldwide. The increasing proportion of ESBL-producing Enterobacteriaceae (ESBL-E) infections acquired in the emergency community is a new feature of ESBLs epidemiology. Early recognition of patients with extended-spectrum β-lactamase-producing Escherichia coli infection is important in the emergency department. To mitigate the burden on the healthcare system, while also providing the best possible care for patients, early recognition of the infection is needed.

METHODS

For the acquisition of required data of eligible prospective/retrospective cohort study or randomized controlled trials (RCTs), we will search for publications from PubMed, Web of science, EMBASE, Cochrane Library, Google scholar. Two independent reviewers will read the full English text of the articles, screened and selected carefully, removing duplication. Then we evaluate the quality and analyses data by Review Manager (V.5.4). Results data will be pooled and meta-analysis will be conducted if there's 2 eligible studies considered.

RESULTS

This systematic review and meta-analysis will evaluate the value of the early prediction models for Extended-spectrum β-lactamase-producing E coli infection in emergency department.

CONCLUSIONS

This systematic review and meta-analysis will provide clinical evidence for predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department, inform our understanding of the value of the predictive model in predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department in the early stage. The conclusions drawn from this study may be beneficial to patients, clinicians, and health-related policy makers.

STUDY REGISTRATION NUMBER

INPLASY202130049.

Antibiotic Susceptibility Patterns of Bacterial Isolates from Routine Clinical Specimens from Referral Hospitals in Tanzania: A Prospective Hospital-Based Observational Study

Introduction

Antimicrobial resistance is one of the biggest threats of modern public health. Although sub-Saharan Africa is highly burdened with infectious diseases, current data on antimicrobial resistance are sparse.

Methods

A prospective study was conducted between October 2018 and September 2019 to assess the antibiotic susceptibility patterns of clinical bacterial isolates obtained from four referral hospitals in Tanzania. We used standard media and Kirby-Bauer disc diffusion methods as per Clinical and Laboratory Standards Institute (CLSI) standards.

Results

We processed a total of 2620 specimens of which 388 (14.8%) were culture-positive from patients with a median (IQR) age of 28 (12–44) years. Of the positive cultures, 52.3% (203) were from females. Most collected specimens were ear pus 28.6% (111), urine 24.0% (93), wound pus 20.6% (80), stool 14.9% (58), and blood 8.3% (32). Predominant isolates were S. aureus 28.4% (110), E. coli 15.2% (59), P. aeruginosa 10.6% (41), P. mirabilis 7.0% (27), V. cholerae 01 Ogawa 6.2% (24), Klebsiella spp. 5.2% (20) and Streptococcus spp. 4.6% (18). Generally, the isolates exhibited a high level of resistance to commonly used antibiotics such as Ampicillin, Amoxicillin-Clavulanic acid, Erythromycin, Gentamicin, Tetracycline, Trimethoprim, third-generation Cephalosporins (Ceftriaxone and Ceftazidime), and reserved drugs (Clindamycin and Meropenem). S. aureus isolates were resistant to most of the antibiotics tested; 66.7% were classified as MRSA infections.

Conclusion

Antibiotic resistance to commonly prescribed antibiotics was alarmingly high. Our findings emphasize the need for comprehensive national control programs to combat antibiotic resistance.

Ribaxamase, an Orally Administered β-Lactamase, Diminishes Changes to Acquired Antimicrobial Resistance of the Gut Resistome in Patients Treated with Ceftriaxone

Introduction

Intravenous (IV) β-lactam antibiotics, excreted through bile into the gastrointestinal (GI) tract, may disrupt the gut microbiome by eliminating the colonization resistance from beneficial bacteria. This increases the risk for Clostridium difficile infection (CDI) and can promote antimicrobial resistance by selecting resistant organisms and eliminating competition by non-resistant organisms. Ribaxamase is an orally administered β-lactamase for use with IV β-lactam antibiotics (penicillins and cephalosporins) and is intended to degrade excess antibiotics in the upper GI before they can disrupt the gut microbiome and alter the resistome.

Methods

Longitudinal fecal samples (349) were collected from patients who participated in a previous Phase 2b clinical study with ribaxamase for prevention of CDI. In that previous study, patients were treated with ceftriaxone for a lower respiratory tract infection and received concurrent ribaxamase or placebo. Extracted fecal DNA from the samples was subjected to whole-genome shotgun sequencing and analyzed for the presence of antimicrobial resistance (AMR) genes by alignment of sequences against the Comprehensive Antibiotic Resistance Database. A qPCR assay was also used to confirm some of the results.

Results

Database alignment identified ~1300 acquired AMR genes and gene variants, including those encoding β-lactamases and vancomycin resistance which were significantly increased in placebo vs ribaxamase-treated patients following antibiotic exposure. qPCR corroborated the presence of these genes and supported both new acquisition and expansion of existing gene pools based on no detectable copy number or a low copy number in pre-antibiotic samples which increased post-antibiotics. Additional statistical analyses demonstrated significant correlations between changes in the gut resistome and clinical study parameters including study drug assignment and β-lactamase and vancomycin resistance gene frequency.

Discussion

These findings demonstrated that ribaxamase reduced changes to the gut resistome subsequent to ceftriaxone administration and may help limit the emergence of AMR.

Treatment of hospital-acquired pneumonia with multi-drug resistant organism by Buzhong Yiqi decoction based on Fuzheng Quxie classical prescription: study protocol for a randomized controlled trial

BACKGROUND

Drug resistance in China is becoming a more and more serious issue. Infection by drug-resistant bacteria has become a major disease that seriously threatens the health of Chinese people and affects national medical finance. Therefore, it is of great scientific and clinical significance to actively carry out research on the prevention and treatment of infections by multi-drug resistant organisms (MDRO). Previous studies by the authors suggested that patients with hospital-acquired pneumonia caused by MDRO mostly showed the pathological state of "insufficient healthy Qi and internal accumulation of pathogenic Qi" and "acute deficiency syndrome" mainly characterized by Qi deficiency. Buzhong Yiqi decoction is a famous classic prescription in traditional Chinese medicine (TCM) for treating internal damage fever. This study intends to provide an evidence-based rationale for Buzhong Yiqi decoction in treating MDRO hospital-acquired pneumonia by conducting a multi-center randomized controlled clinical study.

METHODS/DESIGN

This study is designed to be a multi-center randomized controlled study in which patients are assigned randomly into control (standard therapy) and trial (standard therapy plus Buzhong Yiqi decoction) groups. The patients will be selected from the emergency department and the ICU inpatient department of five study sites and will all be diagnosed with MDRO hospital-acquired pneumonia and meet the inclusion criteria. Forty patients are to be enrolled in each study site, resulting in a total of 200 patients in the study. The treatment course is 28 days.

DISCUSSION

In this study: (1) the theory of "acute Qi deficiency" in MDRO hospital-acquired pneumonia is put forward for the first time, and the basic theories of TCM are further improved; (2) a multi-center randomized controlled clinical study will be performed for the first time with Buzhong Yiqi decoction, the classic prescription for reinforcing healthy Qi and eliminating pathogenic Qi, providing a reliable evidence-based rationale for the treatment of MDRO pulmonary infection with TCM; (3) the clinical application and modern disease spectrum of Buzhong Yiqi decoction is expanded, and the scientific notion of "treating different diseases with the same method" is enriched further.

TRIAL REGISTRATION

China Clinical Trial Registry, ChiCTR1900022429. Registered on April 11, 2019. http://www.chictr.org.cn/listbycreater.aspx.

Resistenze antibiotiche e nuove molecole: qual è lo scenario attuale?

Antibiotic resistance and new drugs in urologic setting: what we need to know? Urinary tract infections (UTIs) are among the most frequent infectious diseases, and represent an important public health problem with a substantial economic burden. In recent years the chemoresistance of the main uropathogens has significantly increased worldwide. Extended spectrum beta-lactamase (ESBL) production and multi-drug resistant (MDR) clones of Escherichia coli and Klebsiella pneumoniae are limiting available treatment options. Carbapenems and aminoglycosides are still effective in complicated UTI. New beta-lactam combinations such as ceftolozane-tazobactam and ceftazidime-avibactam may be highly useful in treating severe infections while contributing to the carbapenem sparing strategy. For uncomplicated UTI, within older antibiotics, fosfomycin trometamol may be considered a first-choice drug since it is still retaining a good activity against MDR uropathogens. On the other hand, there are extensive data showing that the administration of antimicrobials according to pharmacokinetic/pharmacodynamic (PK/PD) parameters improves the possibility of a positive clinical outcome, particularly in severely ill patients. Evidence is growing that when PK/PD parameters are used to target not only clinical cure. This article discusses the PK/PD characteristics of antimicrobial agents for the treatment of UTIs, and the pharmacological and therapeutic strategies for limiting or preventing bacterial resistance.

Multi-drug-resistant Gram-negative bacteria causing urinary tract infections: a review

Urinary tract infections (UTIs) are among the most frequent infectious diseases affecting humans, and represent an important public health problem with a substantial economic burden. Due to the high empiric use of antibiotics for the treatment of UTI, antibacterial resistance of Enterobacteriaceae, specifically the main uropathogens Escherichia coli and Klebsiella pneumoniae, has significantly increased worldwide. In this article the worldwide epidemiology of resistant Gram-negative bacteria causing UTIs, with a special focus on extended spectrum beta lactamase (ESBL) positive pathogens, as well as new threats such as multi-drug-resistant (MDR) clones (e.g. E. coli 131 (ST131) and K. pneumoniae ST258), are reviewed. The increased prevalence of MDR Enterobacteriaceae, limiting available treatment options for infections caused by these organisms, and the lack of new antibiotics provide good rationale for using older antibiotics, such as fosfomycin, that have been shown to retain some activity against MDR bacteria.

Genomic and Biochemical Characterization of Acinetobacter Podophage Petty Reveals a Novel Lysis Mechanism and Tail-Associated Depolymerase Activity

The increased prevalence of drug-resistant, nosocomial Acinetobacter infections, particularly from pathogenic members of the Acinetobacter calcoaceticus-baumannii complex, necessitates the exploration of novel treatments such as phage therapy. In the present study, we characterized phage Petty, a novel podophage that infects multidrug-resistant Acinetobacter nosocomialis and Acinetobacter baumannii Genome analysis reveals that phage Petty is a 40,431-bp ϕKMV-like phage, with a coding density of 92.2% and a G+C content of 42.3%. Interestingly, the lysis cassette encodes a class I holin and a single-subunit endolysin, but it lacks canonical spanins to disrupt the outer membrane. Analysis of other ϕKMV-like genomes revealed that spaninless lysis cassettes are a feature of phages infecting Acinetobacter within this subfamily of bacteriophages. The observed halo surrounding Petty's large clear plaques indicated the presence of a phage-encoded depolymerase capable of degrading capsular exopolysaccharides (EPS). The product of gene 39, a putative tail fiber, was hypothesized to possess depolymerase activity based on weak homology to previously reported phage tail fibers. The 101.4-kDa protein gene product 39 (gp39) was cloned and expressed, and its activity against Acinetobacter EPS in solution was determined. The enzyme degraded purified EPS from its host strain A. nosocomialis AU0783, reducing its viscosity, and generated reducing ends in solution, indicative of hydrolase activity. Given that the accessibility to cells within a biofilm is enhanced by degradation of EPS, phages with depolymerases may have enhanced diagnostic and therapeutic potential against drug-resistant Acinetobacter strains.IMPORTANCE Bacteriophage therapy is being revisited as a treatment for difficult-to-treat infections. This is especially true for Acinetobacter infections, which are notorious for being resistant to antimicrobials. Thus, sufficient data need to be generated with regard to phages with therapeutic potential, if they are to be successfully employed clinically. In this report, we describe the isolation and characterization of phage Petty, a novel lytic podophage, and its depolymerase. To our knowledge, it is the first phage reported to be able to infect both A. baumannii and A. nosocomialis The lytic phage has potential as an alternative therapeutic agent, and the depolymerase could be used for modulating EPS both during infections and in biofilms on medical equipment, as well as for capsular typing. We also highlight the lack of predicted canonical spanins in the phage genome and confirm that, unlike the rounding of lambda lysogens lacking functional spanin genes, A. nosocomialis cells infected with phage Petty lyse by bursting. This suggests that phages like Petty employ a different mechanism to disrupt the outer membrane of Acinetobacter hosts during lysis.

Management of bacterial infection in the liver transplant candidate

Bacterial infection (BI) is a common cause of impairment of liver function in patients with cirrhosis, especially in the liver transplant candidates. These patients share an immunocompromised state and increased susceptibility to develop community and hospital-acquired infections. The changing epidemiology of BI, with an increase of multidrug resistant strains, especially in healthcare-associated settings, represents a critical issue both in the waiting list and in the post-operative management. This review focused on the role played by BI in patients awaiting liver transplantation, evaluating the risk of drop-out from the waiting list, the possibility to undergo liver transplantation after recovery from infection or during a controlled infection.

Management of infections caused by extended-spectrum β-lactamase-producing Enterobacteriaceae: current evidence and future prospects

INTRODUCTION

The spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae has become a major public health threat worldwide. Area covered: A thorough systematic literature review describing the current evidence and future prospects of therapeutic options for infections caused by ESBL-producing Enterobacteriaceae. Expert commentary: The methods of detecting ESBLs have been evolving. The Clinical and Laboratory Standards Institute and the European Committee on Antimicrobial Susceptibility Testing lowered the MIC breakpoints of cephalosporins against ESBL-producing Enterobacteriaceae in 2010. Phenotypic testing for ESBLs is no longer recommended. Instead, the selection of appropriate antimicrobial agents largely depends on the report of minimum inhibitory concentrations (MICs). To date, therapeutic options for these multidrug-resistant organisms remain limited. The clinical efficacy of piperacillin/tazobactam and cefepime on in vitro-susceptible ESBL-producing Enterobacteriaceae remains a concern. Many studies found an in vitro-in vivo discordance based on current breakpoints. Carbapenems are the most reliable antibiotics for severe infections caused by ESBL-producing Enterobacteriaceae. However, their overuse has led to a serious problem of increasing drug resistance. Recently, ceftolozane/tazobactam and ceftazidime/avibactam have been approved for the treatment of complicated urinary tract infections and complicated intra-abdominal infections. The introduction of these new β-lactam/β-lactamase inhibitor combinations offers new carbapenem-sparing options for the treatment of ESBL infections.

Prevention of recurrent lower urinary tract infections in postmenopausal women with genitourinary syndrome: outcome after 6 months of treatment with ospemifene

Aim of this study was to evaluate the efficacy of ospemifene in the prevention of recurrent lower urinary tract infections in postmenopausal women with vulvovaginal atrophy. The study have a retrospective design. Thirty-nine patients were enrolled. Patients underwent clinical examination and urine culture. The urinary symptoms and the quality of life were evaluated with UTISA score, PUF and SF-36 questionnaires before and after treatment. All 39 patients received ospemifene 60 mg one tablet/daily for 6 months. Adverse effects and complications were assessed. Thirty-nine patients were enrolled in the study. Two patients experienced one new UTI episode and the mean number of positive urine culture decreased significantly after 6 months (3.65 ± 2.12 vs 0.25 ± 0.17, p < .0001). The mean number of urinary infection symptoms decreased significantly after treatment; dysuria reduced (4.76 ± 2.45 vs 0.89 ± 1.12). PUF score and SF-36 showed a statistically significant change (22.43 ± 5.89 vs 12.14 ± 3.21) and (52.86 ± 9.21 vs 83.43 ± 10.76). No adverse effects were reported and the total success rate was the 92.3% after 6 months at PGI-I. Ospemifene is a valid alternative with excellent tolerability for the UTI_S prevention in postmenopausal patients.

Klebsiella pneumoniae: a major worldwide source and shuttle for antibiotic resistance

Klebsiella pneumoniae is an important multidrug-resistant (MDR) pathogen affecting humans and a major source for hospital infections associated with high morbidity and mortality due to limited treatment options. We summarize the wide resistome of this pathogen, which encompasses plentiful chromosomal and plasmid-encoded antibiotic resistance genes (ARGs). Under antibiotic selective pressure, K. pneumoniae continuously accumulates ARGs, by de novo mutations, and via acquisition of plasmids and transferable genetic elements, leading to extremely drug resistant (XDR) strains harboring a 'super resistome'. In the last two decades, numerous high-risk (HiR) MDR and XDR K. pneumoniae sequence types have emerged showing superior ability to cause multicontinent outbreaks, and continuous global dissemination. The data highlight the complex evolution of MDR and XDR K. pneumoniae, involving transfer and spread of ARGs, and epidemic plasmids in highly disseminating successful clones. With the worldwide catastrophe of antibiotic resistance and the urgent need to identify the main pathogens that pose a threat on the future of infectious diseases, further studies are warranted to determine the epidemic traits and plasmid acquisition in K. pneumoniae. There is a need for future genomic and translational studies to decipher specific targets in HiR clones to design targeted prevention and treatment.

Characterization of Unexpressed Extended-Spectrum Beta-Lactamase Genes in Antibiotic-Sensitive Klebsiella pneumoniae Isolates

OBJECTIVE

The current investigation explores whether extended-spectrum β-lactamase (ESBL) genes exist in clinical non-ESBL-producing Klebsiella pneumoniae isolates.

METHODS

A total of 202 clinical isolates with non-ESBL-producing K. pneumoniae were collected from southern and middle of China. Thirteen β-lactamase genes (bla_SHV, _CTX-M, _TEM, _OXA-2, _OXA-10, _VEB, _PER, _SFO, _GES, _CSP, _TLA, _BEL, _{and IBC}) were screened by PCR and their identity confirmed by sequencing of PCR products. The ESBL-producing phenotype of the isolates that carried ESBL genes was tested and confirmed in 9 of the 18 isolates by a double-disc synergy test. The sequences upstream of ESBL genes of isolates with ESBL-producing genotype (+)/phenotype (-) were also subjected to PCR and sequencing. The ESBL genes and their upstream regions were cloned into Escherichia coli DH5α for functional evaluation.

RESULTS

A total of 8.9% (18/202) isolates carried ESBL genes. All of them harbored only one ESBL gene, including 33.3% (6/18) bla_SHV and 66.7% (12/18) bla_CTX-M. Among the isolates carrying ESBL genes, nine isolates were confirmed as ESBL phenotype (-). The ESBL genotype (+)/phenotype (-) isolates had bla_{SHV-27,38,41,42} (66.7%, 6/9) and bla_{CTX-M-3,15,24} (33.3%, 3/9). The upstream gene sequences, including promoters of these unexpressed ESBL genes, were intact without any mutations or spacers and effective among eight strains. The ISEcp1 element in the upstream region was not found in one isolate carrying an unexpressed bla_CTX-M-15 gene.

CONCLUSIONS

Clinical non-ESBL-producing K. pneumoniae isolates could carry ESBL genes with intact promoter, but without the correlated phenotype. Specific silencing mechanisms may play an important role in regulating ESBL gene expression. This kind of isolates has the potential to transfer their ESBL genes to other bacteria with effective promoters, resulting in ESBL phenotype.

Prospective cohort study of risk factors for extended-spectrum ß-lactamase-producing Escherichia coli urinary tract infections in elderly patients admitted to hospital

BACKGROUND

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are currently common in community-onset infections, limiting therapeutic options. In this work we aim to identify the prevalence of and risk factors for ESBL-producing E. coli in elderly patients with urinary tract infections (UTI) admitted to hospital.

METHODS

Prospective cohort study on elderly patients with E. coli UTI admitted to a university hospital in Spain, from January 2013 to December 2015. Clinical features, microbiology and outcomes were recorded from the electronic medical records and reviewed by two researchers. Cases were segregated according to ESBL-producing E. coli. Risk factors for ESBL-producing E. coli were analysed by multivariate analysis.

RESULTS

The prevalence of ESBL-producing E. coli was 27.4% (85/310). Healthcare-associated UTI was the only risk factor for ESBL-producing E. coli (OR 6.79; 95% CI 3.22-14.31, P < .001) by multivariate analysis. ESBL-producing E. coli was 43.9% in the healthcare-associated UTI group and 8.9% in the community-acquired UTI group (P < .001). Inadequate empirical antibiotic therapy and length of stay in hospital were higher in the ESBL-producing E. coli group than in the non-ESBL-producing E. coli group (62.3% vs 5.3% and 6.60 ± 3.69 days vs 5.61 ± 3.16 days, respectively). Mortality was not significantly different between groups (13% in ESBL-producing E. coli group vs 7.5% in non-ESBL-producing E. coli group, P = .140).

SUMMARY

Healthcare-associated UTI was a risk factor for ESBL-producing E. coli in elderly patients with UTI admitted to hospital. Our results might help clinicians in choosing empirical antibiotics in an overall high rate setting of ESBL-producing E. coli.

In vitro activity of fosfomycin trometamol and other oral antibiotics against multidrug-resistant uropathogens

Clinical midstream and urinary catheter isolates (n = 106) of extended-spectrum β-lactamase (ESBL)-positive Escherichia coli, Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae, Proteus mirabilis and meticillin-resistant Staphylococcus saprophyticus were tested against fosfomycin using the agar dilution method, the broth microdilution method and the gradient test described by the Clinical and Laboratory Standards Institute. Nitrofurantoin, co-trimoxazole, amoxicillin/clavulanic acid, cefuroxime, levofloxacin and ciprofloxacin were tested using the gradient test alone. Breakpoints from the European Committee on Antimicrobial Susceptibility Testing 2015 guidelines were used. Fosfomycin inhibited all of the ESBL-positive E. coli, P. mirabilis and meticillin-resistant S. saprophyticus strains isolated from urine, as well as 82% of KPC-producing K. pneumoniae isolates. Substantial agreement for fosfomycin activity was found for the three test methods, particularly for Enterobacteriaceae. This study confirmed that fosfomycin has good in vitro activity against more common multidrug-resistant uropathogens. Fosfomycin could be a reliable empirical therapeutic option for uncomplicated urinary tract infections caused by these organisms, and a valid option for sparing parenteral antibiotics, such as carbapenems.

The Oral β-Lactamase SYN-004 (Ribaxamase) Degrades Ceftriaxone Excreted into the Intestine in Phase 2a Clinical Studies

SYN-004 (ribaxamase) is a β-lactamase designed to be orally administered concurrently with intravenous β-lactam antibiotics, including most penicillins and cephalosporins. Ribaxamase's anticipated mechanism of action is to degrade excess β-lactam antibiotic that is excreted into the small intestine. This enzymatic inactivation of excreted antibiotic is expected to protect the gut microbiome from disruption and thus prevent undesirable side effects, including secondary infections such as Clostridium difficile infections, as well as other antibiotic-associated diarrheas. In phase 1 clinical studies, ribaxamase was well tolerated compared to a placebo group and displayed negligible systemic absorption. The two phase 2a clinical studies described here were performed to confirm the mechanism of action of ribaxamase, degradation of β-lactam antibiotics in the human intestine, and were therefore conducted in subjects with functioning ileostomies to allow serial sampling of their intestinal chyme. Ribaxamase fully degraded ceftriaxone to below the level of quantitation in the intestines of all subjects in both studies. Coadministration of oral ribaxamase with intravenous ceftriaxone was also well tolerated, and the plasma pharmacokinetics of ceftriaxone were unchanged by ribaxamase administration. Since ribaxamase is formulated as a pH-dependent, delayed-release formulation, the activity of ribaxamase in the presence of the proton pump inhibitor esomeprazole was examined in the second study; coadministration of these drugs did not adversely affect ribaxamase's ability to degrade ceftriaxone excreted into the intestine. These studies have confirmed the in vivo mechanism of action of ribaxamase, degradation of β-lactam antibiotics in the human intestine (registered at ClinicalTrials.gov under NCT02419001 and NCT02473640).

Risk factors for community-associated multidrug-resistant Pseudomonas aeruginosa in veterans with spinal cord injury and disorder: a retrospective cohort study

Study Design

Retrospective cohort study

Objectives

To identify independent risk factors associated with community-associated multidrug resistant P. aeruginosa (MDRPA) in a population of Veterans with spinal cord injury and disorders (SCI/D).

Setting

127 Veterans Affairs healthcare facilities

Methods

Laboratory results from January 1, 2012 to December 31, 2013 were collected and MDRPA cultures were compared to non-MDRPA cultures.

Results

One thousand four hundred forty one cultures were collected from Veterans with SCI/D, including 227 cultures with MDRPA isolates. Characteristics associated with an increased odds of MDRPA include age 50-64 (aOR= 1.80, 95% CI= 1.13-2.87), MDRPA culture in the past 365 days (aOR= 9.12, 95% CI= 5.88-14.15), and carbapenem exposure in the past 90 days (aOR= 2.56, 95% CI= 1.35-4.87). In contrast, paraplegia was associated with a 53% decreased odds of MDRPA compared to those with tetraplegia (aOR= 0.47, 95% CI= 0.32-0.69).

Conclusions

Risk factors for community-associated MDRPA include prior history of MDRPA and exposure to carbapenems. Awareness of these factors is important for targeted prevention and treatment of MDRPA in patients with SCI/D.

Establishment of a Simple and Quick Method for Detecting Extended-Spectrum β-Lactamase (ESBL) Genes in Bacteria

Extended-spectrum β-lactamase (ESBL) genes that render bacteria resistant to antibiotics are commonly detected using phenotype testing, which is time consuming and not sufficiently accurate. To establish a better method, we used phenotype testing to identify ESBL-positive bacterial strains and conducted PCR to screen for TEM (named after the patient Temoneira who provided the first sample), sulfhydryl reagent variable (SHV), cefotaxime (CTX)-M-1, and CTX-M-9, the 4 most common ESBL types and subtypes. We then performed multiplex PCR with 1 primer containing a biotin and hybridized the PCR products with gene-specific probes that were coupled with microbeads and coated with a specific fluorescence. The hybrids were linked to streptavidin-R-phycoerythrins (SA-PEs) and run through a flow cytometer, which sorted the fluorescently dyed microbeads and quantified the PEs. The results from single PCR, multiplex PCR, and cytometry were consistent with each other. We used this method to test 169 clinical specimens that had been determined for phenotypes and found 154 positive for genotypes, including 30 of the 45 samples that were negative for phenotypes. The CTX-M genotype tests alone, counting both positive and negative cases, showed 99.41% (168/169) consistency with the ESBL phenotype test. Thus, we have established a multiplex-PCR system as a simple and quick method that is high throughput and accurate for detecting 4 common ESBL types and subtypes.

Antibacterial Efficacy of Eravacycline In Vivo against Gram-Positive and Gram-Negative Organisms

Members of the tetracycline class are frequently classified as bacteriostatic. However, recent findings have demonstrated an improved antibacterial killing profile, often achieving ≥3 log10 bacterial count reduction, when such antibiotics have been given for periods longer than 24 h. We aimed to study this effect with eravacycline, a novel fluorocycline, given in an immunocompetent murine thigh infection model over 72 h against two methicillin-resistant Staphylococcus aureus (MRSA) isolates (eravacycline MICs = 0.03 and 0.25 μg/ml) and three Enterobacteriaceae isolates (eravacycline MICs = 0.125 to 0.25 μg/ml). A humanized eravacycline regimen, 2.5 mg/kg of body weight given intravenously (i.v.) every 12 h (q12h), demonstrated progressively enhanced activity over the 72-h study period. A cumulative dose response in which bacterial density was reduced by more than 3 log10 CFU at 72 h was noted over the study period in the two Gram-positive isolates, and eravacycline performed similarly to comparator antibiotics (tigecycline, linezolid, and vancomycin). A cumulative dose response with eravacycline and comparators (tigecycline and meropenem) over the study period was also observed in the Gram-negative isolates, although more variability in bacterial killing was observed for all antibacterial agents. Overall, a bacterial count reduction of ≥3 log was achieved in one of the three isolates with both eravacycline and tigecycline, while meropenem achieved a similar endpoint against two of the three isolates. Bactericidal activity is typically defined in vitro over 24 h; however, extended regimen studies in vivo may demonstrate an improved correlation with clinical outcomes by better identification of antimicrobial effects.

Klebsiella pneumoniae: Going on the Offense with a Strong Defense

Klebsiella pneumoniae causes a wide range of infections, including pneumonias, urinary tract infections, bacteremias, and liver abscesses. Historically, K. pneumoniae has caused serious infection primarily in immunocompromised individuals, but the recent emergence and spread of hypervirulent strains have broadened the number of people susceptible to infections to include those who are healthy and immunosufficient. Furthermore, K. pneumoniae strains have become increasingly resistant to antibiotics, rendering infection by these strains very challenging to treat. The emergence of hypervirulent and antibiotic-resistant strains has driven a number of recent studies. Work has described the worldwide spread of one drug-resistant strain and a host defense axis, interleukin-17 (IL-17), that is important for controlling infection. Four factors, capsule, lipopolysaccharide, fimbriae, and siderophores, have been well studied and are important for virulence in at least one infection model. Several other factors have been less well characterized but are also important in at least one infection model. However, there is a significant amount of heterogeneity in K. pneumoniae strains, and not every factor plays the same critical role in all virulent Klebsiella strains. Recent studies have identified additional K. pneumoniae virulence factors and led to more insights about factors important for the growth of this pathogen at a variety of tissue sites. Many of these genes encode proteins that function in metabolism and the regulation of transcription. However, much work is left to be done in characterizing these newly discovered factors, understanding how infections differ between healthy and immunocompromised patients, and identifying attractive bacterial or host targets for treating these infections.