Executive summary of the diagnosis and antimicrobial treatment of invasive infections due to multidrug-resistant Enterobacteriaceae. Guidelines of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC)

Molecular characterization of carbapenem resistance mechanisms and phenotypic correlations in clinical Klebsiella pneumoniae isolates from Ningbo, China

Objective

The purpose of this study is to understand the antimicrobial susceptibility and molecular distribution characteristics of carbapenem-resistant Klebsiella pneumoniae (CRKP) in the region, and to evaluate their correlation. Additionally, the study aims to investigate the transmission status of these strains.

Methods

A total of 150 CRKP collected from January 2019 to December 2021 in the Ningbo region were included in this study. Antimicrobial susceptibility testing was performed using broth microdilution method following CLSI guidelines (CLSI, 2023). The tested agents included: (1) basic antimicrobials (tigecycline, polymyxin B, ceftazidime-avibactam); and (2) combination therapy candidates (ertapenem, imipenem, levofloxacin, piperacillin-tazobactam, ceftriaxone, cefepime, trimethoprim-sulfamethoxazole, fosfomycin, amikacin, aztreonam, chloramphenicol, amoxicillin-clavulanate, ceftazidime). Resistance genes were detected using polymerase chain reaction (PCR). Multi-locus sequence typing (MLST) was employed to analyze the molecular characteristics and evolutionary trends of the strains to determine their clonal relationships.

Results

The 150 strains of CRKP exhibit high resistance rates to various conventional drugs; The sensitivity rates to tigecycline, polymyxin B, and ceftazidime-avibactam were 98.7, 98.0, and 68%, respectively; Conversely, the sensitivity rates to fosfomycin, amikacin, and chloramphenicol were 72.0, 40.0, and 16.7%, respectively; The main proportions of carbapemen genes producing in CRKP are as follows: KPC-2 (61.3%), NDM-5 (14.7%), IMP-4 (8.0%), OXA-232 (6.0%), and OXA-181 (1.3%); The main proportions of β-lactamase resistance genes are as follows: CTX-M-1 (13.33%), CTX-M-3 (25.33%), CTX-M-9 (17.33%), CTX-M-14 (34.67%), SHV-1 (26.66%), SHV-11 (66.66%), SHV-12 (18.66%), and SHV-28 (10.00%); CRKP carrying class A, B, and D carbapenemases had a sensitivity rate greater than 96% for tigecycline and polymyxin B, while their sensitivities to ceftazidime-avibactam, aztreonam, and amikacin varied significantly (p < 0.01). Analysis of the MLST results for CRKP revealed that ST11 strains were predominant in the region. There was a significant difference in the resistance genes carried by ST11 strains compared to non-ST11 strains. While different healthcare institutions exhibited variations in ST types, the strains generally showed high homogeneity.

Conclusion

In the region, CRKP showed high sensitivity to tigecycline, polymyxin B, ceftazidime-avibactam, fosfomycin, amikacin, and chloramphenicol. The main carbapenemase genes identified were KPC-2 and NDM-5. The inhibitory effects of ceftazidime-avibactam, aztreonam, and amikacin varied for CRKP carrying different enzyme types. ST11 strains were predominant in the region. There was a significant difference in the resistance genes carried by ST11 strains compared to non-ST11 strains. Clonal dissemination was observed both within the same healthcare institution and between different institutions.

The Impact of Fosfomycin on Gram Negative Infections: A Comprehensive Review

Multidrug-resistant or extended drug resistance has created havoc when it comes to patient treatment, as options are limited because of the spread of pathogens that are extensively or multidrug-resistant (MDR or XDR) and the absence of novel antibiotics that are effective against these pathogens. Physicians have therefore started using more established antibiotics such as polymyxins, tetracyclines, and aminoglycosides. Fosfomycin has just come to light as a result of the emergence of resistance to these medications since it continues to be effective against MDR and XDR bacteria that are both gram-positive and gram-negative. Fosfomycin, a bactericidal analogue of phosphoenolpyruvate that was formerly utilised as an oral medication for uncomplicated urinary tract infections, has recently attracted the interest of clinicians around the world. It may generally be a suitable therapy option for patients with highly resistant pathogenic infections, according to the advanced resistance shown by gram-negative bacteria. This review article aims to comprehensively evaluate the impact of fosfomycin on gram negative infections, highlighting its mechanism of action, pharmacokinetics, clinical efficacy, and resistance patterns.

Urinary Tract Infection and Antimicrobial Susceptibility of Bacterial Isolates in Saint Joseph Kitgum Hospital, Kitgum, Uganda

A cross-sectional study of microorganisms isolated from mid-stream urine samples obtained from 139 patients with suspected urinary tract infection (UTI) who presented leukocyturia was conducted from April to June 2019 at Saint Joseph Kitgum Hospital (Uganda). All microorganisms were identified by MALDI-TOF mass spectrometry in a laboratory in Spain. Antimicrobial susceptibility was determined on site using the disc diffusion method (Kirby–Bauer test) and these results were subsequently compared with those obtained in Spain using the Becton Dickinson Phoenix M50 device. The overall prevalence of UTI with bacterial growth was 64.0% (n = 89) (95% CI, 56.1–72.0), and 11 presented mixed infection. As a result, 100 microorganisms were isolated. The most common uropathogens were Enterococcus spp. (57%) and Escherichia coli (28%). Nitrofurantoin was the most effective drug (81.7% in Gram-positive and 87.3% in Gram-negative bacteria), followed by imipenem (94.2% and 74.5%, respectively). The highest resistance rates were observed for amoxicillin and ciprofloxacin (66.2% and 44.6%, respectively). Given the increasing trend toward antibiotic resistance, there is a need for bacteriological cultures and continuous surveillance of uropathogen antibiotic susceptibility. Use of amoxicillin and ciprofloxacin as empirical treatments for UTIs should be discontinued in Uganda. The findings of this study may be useful for clinicians, as they may improve empirical treatment.

Present and Future Perspectives on Therapeutic Options for Carbapenemase-Producing Enterobacterales Infections

Carbapenem-resistant Enterobacterales (CRE) are included in the list of the most threatening antibiotic resistance microorganisms, being responsible for often insurmountable therapeutic issues, especially in hospitalized patients and immunocompromised individuals and patients in intensive care units. The enzymatic resistance to carbapenems is encoded by different β-lactamases belonging to A, B or D Ambler class. Besides compromising the activity of last-resort antibiotics, CRE have spread from the clinical to the environmental sectors, in all geographic regions. The purpose of this review is to present present and future perspectives on CRE-associated infections treatment.

Indian consensus on the management of CRE infection in critically ill patients (ICONIC) - India

Background: The increasing burden of carbapenem-resistant Enterobacteriaceae (CRE) carriage and infection in different patient settings in India has created an acute need for guidance for clinicians regarding optimal strategies for the management of CRE infection in critically ill patients. Research design and methods: A multidisciplinary panel of 11 Indian experts in CRE infection assembled for comprehensive discussion and consensus development. The experts developed clinical statements through a systematic review of key literature. Main outcome measures: The panel voted anonymously on 60 clinically relevant questions, through a modified Delphi process. Results: Forty-six key clinical consensus statements (CCS) were proposed. The panel reached a consensus on several important issues, providing recommendations on surveillance, diagnosis, prevention, pharmacokinetic challenges, combination therapy, and cornerstone molecules in CRE infections. The panel also proposed a treatment algorithm for NDM-prevalent settings. Conclusion: These consensus statements may offer clinicians expert guidance on the management of CRE infections. There is a dearth of high-/moderate-level evidence on managing CRE infections; the recommendations presented herein are based on expert opinion.

Prognosis of urinary tract infection caused by KPC-producing Klebsiella pneumoniae: The impact of inappropriate empirical treatment

INTRODUCTION

There is scarce information on the prognosis of urinary tract infections (UTI) caused by KPC carbapenemase-producing Klebsiella pneumoniae (KPC-Kp).

OBJETIVE

To investigate the association between KPC-Kp aetiology and clinical failure and all cause mortality and to explore the impact of inappropriate empirical treatment.

MATERIAL AND METHODS

This is a retrospective observational study of hospitalized patients with UTI due to K. pneumoniae. We explored clinical failure at day 21 and 30-day all-cause mortality using different models of adjusted analysis.

RESULTS

We analyzed 142 episodes of UTI; 46 episodes (32.4%) were due to KPC-Kp and 96 episodes (67.6%) were due to non-KPC-Kp strains (62 wild type and 34 EBSL producer). Clinical failure was more frequent in the KPC-Kp group (41.3% vs. 15.6%, p = 0.001). KPC-Kp aetiology and inappropriate empirical therapy were associated in the non-adjusted analysis with clinical failure. When analysed in separate adjusted models, both were found to be associated; inappropriate empirical treatment (OR 2.51; 95% CI, 1.03-6.12; p = 0.04) and KPC-Kp (OR 2.73; 95% CI, 1.03-7.22; p = 0.04) were associated with increased risk of failure. All-cause 30-day mortality was higher in patients with KPC-Kp UTI (39.1% vs. 15.6%, p = 0.002). Bacteraemia was more frequent in patients with KPC-Kp etiology (23.9% vs. 10.4%; p = 0.034). In both cases, the association was not confirmed in the adjusted analysis.

CONCLUSION

KPC-Kp UTI is associated with higher clinical failure and may be due to an increase in inappropriate empirical treatment.

Non-intravenous carbapenem-sparing antibiotics for definitive treatment of bacteraemia due to Enterobacteriaceae producing extended-spectrum β-lactamase (ESBL) or AmpC β-lactamase: A propensity score study

Carbapenems are considered the treatment of choice for extended-spectrum β-lactamase (ESBL)- or AmpC β-lactamase-producing Enterobacteriaceae bacteraemia. Data on the effectiveness of non-intravenous carbapenem-sparing antibiotic options are limited. This study compared the 30-day mortality and clinical failure associated with the use of carbapenems versus alternative non-intravenous antibiotics for the definitive treatment of ESBL/AmpC-positive Enterobacteriaceae bacteraemia. This 12-year retrospective study (2004-2015) included all patients with bacteraemia due to ESBL/AmpC-producing Enterobacteriaceae at a Spanish hospital. Given the lack of randomisation of initial therapies, a propensity score for receiving carbapenems was calculated. There were 1115 patients with a first episode of bacteraemia due to Escherichia coli or Klebsiella pneumoniae, of which 123 (11.0%) were ESBL/AmpC-positive. There were 101 eligible patients: 59 in the carbapenem group and 42 in the alternative treatment group (trimethoprim/sulfamethoxazole 59.5%, quinolones 21.4%). The most frequent sources of infection were urinary (63%) and biliary (15%). Compared with the carbapenem group, patients treated with an alternative regimen had a shorter hospital stay [median (IQR) 7 (5-10) days vs. 12 (9-18) days; P < 0.001]. Use of an alternative non-intravenous therapy did not increase mortality (OR = 0.27, 95% CI 0.05-1.61; P = 0.15). After controlling for confounding factors with the propensity score, the adjusted OR of carbapenem treatment was 4.95 (95% CI 0.94-26.01; P = 0.059). Alternative non-intravenous carbapenem-sparing antibiotics could have a role in the definitive treatment of ESBL/AmpC-positive Enterobacteriaceae bacteraemia, allowing a reduction in carbapenem use. Use of trimethoprim/sulfamethoxazole in this series showed favourable results.

Lumbar arthrodesis infection by multi-resistant Klebsiella pneumoniae, successfully treated with implant retention and ceftazidime/avibactam

There are increasingly more patients with prosthetic implants (orthopaedic prostheses, lumbar instruments, osteosynthesis material). In the last decade, infections caused by carbapenem resistant Enterobacteriaceae have increased (bacteriaemia, abscesses, urinary tract infections...) with great difficulty in treatment and important associated comorbidity. We present the first case of infection of a lumbar instrumentation by Klebsiella pneumoniae producing carbapenemase D, OXA-48 type, and successfully treated.

Infections by carbapenemase-producing enterobacteriaceae in a department of urology. A new challenge

OBJECTIVES

To analyse infections by carbapenemase-producing enterobacteriaceae (CPE) and describe the characteristics and potential risk factors associated with patients of a department of urology.

MATERIAL AND METHODS

Observational and retrospective study. The inclusion criterion was hospitalisation in our department of Urology between August 2013 and December 2016. We analysed those patients who were positive for CPE in at least 1 culture. We reviewed their baseline characteristics, risk factors and variables such as the presence of previous urinary tract infections, subsequent readmissions, the microorganism, type of CPE, treatment, origin (hospital or community) and mortality.

RESULTS

Of the 5,657 patients who met the inclusion criterion, a CPE was isolated in 12 cases. CPE infections represented 3.6% of all healthcare-associated infections and 9.7% of those caused by enterobacteria. The analysed factors associated with CPE infection in our series were the presence of urinary catheters (100%), undergoing surgery (58.3%), previous ICU admission (8.3%) and immunosuppression (16.6%). In terms of mortality, 8.3% of the patients who presented CPE infection died during hospitalisation.

CONCLUSIONS

Approximately 10% of enterobacteria present a carbapenemase-resistance pattern in urological patients in our setting. Carrying a urinary catheter and/or undergoing surgery are risk factors associated with the development of these infections in urological patients in our setting. CPE infections increase morbidity and mortality.

Clinical features and outcomes of bacteraemia due to OXA-48-like carbapenemase-producing Klebsiella pneumoniae in a tertiary hospital

INTRODUCTION

Limited therapeutic options and high mortality make the management of OXA-48-like carbapenemase-producing Klebsiella pneumoniae (KPOXA-48) bacteraemia complicated. The aim of the study was to describe the clinical characteristics of KPOXA-48 bacteraemia between October 2013 and December 2016.

MATERIAL AND METHODS

The variables to analyse were retrospectively collected from medical records. Carbapenemase production was confirmed by phenotypic and molecular methods.

RESULTS

A total of 38 patients with bacteraemia were included, mainly classified as hospital-acquired (n=31). The majority of cases were secondary bacteraemia (n=26), most commonly arising from the urinary tract (n=11). All isolates presented a multidrug-resistant profile with the extended spectrum beta-lactamase CTX-M-15 and the carbapenemase OXA-48-like production. The crude mortality rate with adequate targeted antibiotic therapy was 0%, rising to 55% with inadequate treatment (p=0.0015).

CONCLUSIONS

This study highlights the importance of identifying this resistance mechanism, the patient factors, type of bacteraemia and adequacy of antibiotic therapy in the outcome of bacteraemia.

Community-Onset Bloodstream and Other Infections, Caused by Carbapenemase-Producing Enterobacteriaceae: Epidemiological, Microbiological, and Clinical Features

Background. Because most infections caused by carbapenemase-producing Enterobacteriaceae (CPE) begin during hospitalization, there are limited data about community-onset (CO) infections caused by CPE. Our aim is to describe the frequency of CO infections caused by CPE as well as the clinical features of CO bloodstream infections (CO-BSIs).

Methods. This study includes retrospective case series of CO infections caused by CPE in a tertiary hospital from January 2010 to July 2014. Any clinical sample with a positive culture for CPE that had been ordered by primary care doctors or by doctors at the emergency room (ER) were classified as CO. Epidemiological and microbiological features of CO cases were assessed as were clinical features of CO-BSIs.

Results. Of 780 clinical samples with CPE, 180 were requested at the ER or by primary care doctors (22.9%), 150 of which were produced by Klebsiella pneumoniae (83.3%). The bla_OXA−48 gene was detected in 149 isolates (82.8%) followed by the bla_VIM gene, 29 (16.1%). Sixty-one patients (33.9%) had a prior history of CPE infection/colonization. Thirty-four of the 119 (28.6%) patients without prior history of CPE infection/colonization did not fulfill Friedman criteria for healthcare-associated infections (HAIs). Considering previous hospitalization of up to 12 months as a criterion for defining HAI, only 16 (13.4%) cases were identified as community-acquired infections. The most frequent positive sample was urine (133 of 180; 73.9%). Twenty-one (11.7%) patients had a BSI, 9 of them secondary to urinary tract infections (42.9%). Thirty-day crude mortality among patients with BSI was 23.8% (5 of 21).

Conclusions. Community-onset infections caused by CPE are an important subgroup of all CPE infections. The urinary tract is the main source. Bloodstream infections accounted for more than 10% of the cases.

Carbapenemase-Producing Klebsiella pneumoniae, a Key Pathogen Set for Global Nosocomial Dominance

The management of infections due to Klebsiella pneumoniae has been complicated by the emergence of antimicrobial resistance, especially to carbapenems. Resistance to carbapenems in K. pneumoniae involves multiple mechanisms, including the production of carbapenemases (e.g., KPC, NDM, VIM, OXA-48-like), as well as alterations in outer membrane permeability mediated by the loss of porins and the upregulation of efflux systems. The latter two mechanisms are often combined with high levels of other types of β-lactamases (e.g., AmpC). K. pneumoniae sequence type 258 (ST258) emerged during the early to mid-2000s as an important human pathogen and has spread extensively throughout the world. ST258 comprises two distinct lineages, namely, clades I and II, and it seems that ST258 is a hybrid clone that was created by a large recombination event between ST11 and ST442. Incompatibility group F plasmids with blaKPC have contributed significantly to the success of ST258. The optimal treatment of infections due to carbapenemase-producing K. pneumoniae remains unknown. Some newer agents show promise for treating infections due to KPC producers; however, effective options for the treatment of NDM producers remain elusive.