Confronting carbapenemase-producing Klebsiella pneumoniae

Case Report: Management of a case of multidrug-resistant Klebsiella pneumoniae infection in a second-kidney transplant patient

This case report on recurrent urinary tract infections (UTIs) caused by multidrug-resistant (MDR) Klebsiella pneumoniae in a post-renal transplant patient underscores the significant clinical challenge of managing MDR infections in immunocompromised individuals, particularly in the context of renal transplantation. The patient was treated with an extended infusion of meropenem, which offers prolonged drug exposure and enhances bactericidal activity against MDR pathogens. This approach is critical in overcoming the resistance mechanisms inherent to Klebsiella pneumoniae, thereby improving the likelihood of therapeutic success. The findings presented here highlight the potential efficacy of extended meropenem infusion in treating MDR infections, providing a valuable therapeutic option for clinicians facing similar cases. This report contributes to the growing evidence supporting advanced antibiotic administration techniques in managing complicated urinary tract infections in transplant in resource limited countries.

Characterization of Multidrug-Resistant Biofilm-Producing Escherichia coli and Klebsiella pneumoniae in Healthy Cattle and Cattle with Diarrhea

This study describes comparative occurrence and characterization of multidrug-resistant (MDR) Escherichia coli and Klebsiella pneumoniae (KP) in healthy cattle (HC) and cattle with diarrhea (DC) in India. During 2018-2020, 72 MDR isolates, including 35 E. coli (DC: 27; HC 8) and 37 K. pneumoniae (DC: 34; HC: 3), from 251 rectal swabs (DC: 219; HC: 32) were investigated for extended-spectrum beta-lactamase (ESBL), AmpC type β-lactamase and carbapenemase production, antimicrobial susceptibility profile, biofilm production, and efflux pump activity. Fifty-five MDR isolates were ESBL producers (ESBLPs) (DC: 50; HC: 5) and ESBLPs from DC were coresistant to multiple antibiotics. The blaCTX-M gene (50) was the most frequently detected β-lactamases followed by blaAmpC (22), blaTEM1 (13), blaCMY-6 (6), blaOXA1 (5), blaPER (2), blaDHA, and blaFOX and blaSHV12 (1 each). Plasmid-mediated quinolone resistance determinants qnrB, qnrS, qnrA, and qepA were detected in 18, 16, 2, and 3 isolates, respectively. Twenty three isolates revealed mutation in gyrA and parC genes. Tetracycline-resistance markers tetA, tetB, tetC, and tetE were detected in 33, 10, 3, and 2 isolates, respectively. Only one of the 41 imipenem-resistant isolates harbored blaNDM-5 and two were colistin-resistant. Altogether, 20 MDR isolates were strong biofilm producers and 19 harbored different virulence factors. This is the first ever report from India on the presence of MDR Enterobacteriaceae with resistance to even last-resort antimicrobials in the bovine diarrhea.

Hypermucoviscous Klebsiella pneumoniae infections induce platelet aggregation and apoptosis and inhibit maturation of megakaryocytes

INTRODUCTION

Different Klebsiella pneumoniae strains carry different virulence factors and antibiotic resistance and may cause thrombocytopenia. This study aimed to investigate the effects of different infections caused by K. pneumoniae on platelets.

METHODS

Two hypermucoviscous K. pneumoniae strains and two classic strains were collected from clinical blood culture, and in both groups, there was a carbapenem-resistant strain and a carbapenem-sensitive strain. Mouse infection models were constructed by intraperitoneally injecting different strains, and mice injected with phosphate-buffered saline served as a control. Count, aggregation rate and apoptosis proportion of platelets within 12 h were examined. CD41 expression was measured in bone marrow cells to determine the maturation of megakaryocytes. The concentrations of lipopolysaccharides and related signaling molecules were also measured.

RESULTS

The platelet aggregation rate was much significantly higher in the two hypermucoviscous groups, while it showed no difference in the classic groups compared to the control group. All infections induced apoptosis of platelets, among which the highest apoptosis proportions were observed in infections caused by the hypermucoviscous carbapenem-sensitive strain. In both hypermucoviscous groups the CD41 mean fluorescence intensity was much lower than that in the control group, indicating that the maturation of megakaryocytes in the hypermucoviscous groups was significantly inhibited. Lipopolysaccharides were significantly higher and TLR4/Myd88 and JNK/MAPK pathways were strongly activated in hypermucoviscous groups.

CONCLUSIONS

The results indicate that hypermucoviscous K. pneumoniae can reduce platelet count by several pathways. Although antibiotic resistance is rapidly emerging worldwide, it has little influence on the decrease in platelets.

Comparison of Short Versus Prolonged Infusion of Standard Dose of Meropenem Against Carbapenemase-Producing Klebsiella pneumoniae Isolates in Different Patient Groups: A Pharmacokinetic-Pharmacodynamic Approach

Dose optimization is required to increase carbapenem's efficacy against carbapenemase-producing isolates. Four clinical Klebsiella pneumoniae isolates were used: one susceptible to meropenem with minimum inhibitory concentration (MIC) 0.031 mg/L and 3 verona integron-borne metallo bete-lactamase-1-producing isolates with MICs 8, 16, and 128 mg/L. The human pharmacokinetics of short (0.5-h) and prolonged (3-h) infusion regimens of 1 g meropenem every 8 h were simulated in an in vitro pharmacokinetic-pharmacodynamic model. Time-kill curves were constructed for each isolate and dosing regimen, and the %T > MIC associated with maximal bactericidal activity was estimated. The percentage of pharmacodynamic target attainment for isolates with different MICs was calculated for 350 ICU, surgical, and internal medicine patients. The isolates with MIC ≤8 mg/L were killed with both dosing regimens. The %T > MIC corresponding to maximal bactericidal activity was ∼40%. The percentages of target attainment were >90%, 61%-83%, 23%-33%, and <3% with the short infusion regimen and >90%, 98%-99%, 55%-79%, and <5% with the prolonged infusion regimen for isolates with MIC ≤2, 4, 8, and ≥16 mg/L, respectively. The lowest target attainment rates were observed for the ICU patients and the highest for internal medicine patients. The prolonged infusion regimen was more effective than the short infusion regimen against isolates with MIC 4-8 mg/L.

Impact of bacterial load on pharmacodynamics and susceptibility breakpoints for tigecycline and Klebsiella pneumoniae

OBJECTIVES

In the absence of other therapeutic options, tigecycline is used to treat bloodstream infections and pneumonia caused by carbapenemase-producing Klebsiella pneumoniae (CP-Kp). In this study, the standard and high tigecycline dosing regimens were simulated and tested against different inocula of CP-Kp isolates in an in vitro pharmacokinetic (PK)/pharmacodynamic (PD) model.

METHODS

Four susceptible isolates (EUCAST MICs of 0.125-1 mg/L) and two intermediately susceptible CP-Kp clinical isolates (MICs of 2 mg/L) were tested at three different inocula (10⁷, 10⁵ and 10³ cfu/mL), simulating tigecycline serum and lung fC_max concentrations of 0.15 and 1.5 mg/L, respectively, of 50 mg tigecycline every 12 h for 48 h. The exposure-effect relationships were described and the probability of target attainment was calculated for each inoculum in order to determine PK/PD susceptibility breakpoints.

RESULTS

No cfu reduction was observed at serum concentrations. At lung concentrations and low inocula, a bacteriostatic and killing effect was found for isolates with MICs of 0.25 and 0.125 mg/L, respectively. The fAUC_0-24/MIC (tAUC_0-24/MIC) associated with half-maximal activity was 16 (150) with 10³ cfu/mL, 28 (239) with 10⁵ cfu/mL and 79 (590) with 10⁷ cfu/mL. A PK/PD susceptibility breakpoint of ≤0.06 and ≤0.125 mg/L for bacteraemia with ≤10¹ cfu/mL and ≤0.25 and ≤0.5 mg/L for pneumonia with ≤10³ cfu/g was determined for the standard tigecycline dose of 50 mg and the higher dose of 100 mg, respectively.

CONCLUSIONS

Tigecycline monotherapy with either 50 or 100 mg would not be sufficient for most patients with bacteraemia, though the higher dose of 100 mg could be effective for patients with pneumonia with low bacterial load.

High prevalence of hospital-acquired infections caused by gram-negative carbapenem resistant strains in Vietnamese pediatric ICUs: A multi-centre point prevalence survey

There is scarce information regarding hospital-acquired infections (HAIs) among children in resource-constrained settings. This study aims to measure prevalence of HAIs in Vietnamese pediatric hospitals.Monthly point prevalence surveys (PPSs) in 6 pediatric intensive care units (ICUs) in 3 referral hospitals during 1 year.A total of 1363 cases (1143 children) were surveyed, 59.9% male, average age 11 months. Admission sources were: other hospital 49.3%, current hospital 36.5%, and community 15.3%. Reasons for admission were: infectious disease (66%), noninfectious (20.8%), and surgery/trauma (11.3%). Intubation rate was 47.8%, central venous catheter 29.4%, peripheral venous catheter 86.2%, urinary catheter 14.6%, and hemodialysis/filtration 1.7%. HAI was diagnosed in 33.1% of the cases: pneumonia (52.2%), septicemia (26.4%), surgical site infection (2%), and necrotizing enterocolitis (2%). Significant risk factors for HAI included age under 7 months, intubation and infection at admission. Microbiological findings were reported in 212 cases (43%) with 276 isolates: 50 Klebsiella pneumoniae, 46 Pseudomonas aeruginosa, and 39 Acinetobacter baumannii, with carbapenem resistance detected in 55%, 71%, and 65%, respectively. Staphylococcus aureus was cultured in 18 cases, with 81% methicillin-resistant Staphylococcus aureus. Most children (87.6%) received antibiotics, with an average of 1.6 antibiotics per case. Colistin was administered to 96 patients, 93% with HAI and 49% with culture confirmed carbapenem resistance.The high prevalence of HAI with carbapenem resistant gram-negative strains and common treatment with broad-spectrum antibiotics and colistin suggests that interventions are needed to prevent HAI and to optimize antibiotic use.

Development of a rapid diagnostic assay based on magnetic bead purification of OXA-β-lactamase mRNA

AIM

To countermeasure the global spread of β-lactamases, we developed a rapid molecular test for the highly variable OXA-β-lactamases that allows minimizing the time to effective treatment.

METHODS

OXA-mRNA was specifically enriched from total RNA using group-specific biotinylated DNA probes and streptavidin-coated magnetic beads. Phylogenetic OXA groups were distinguished by PCR product size.

RESULTS

This mRNA fishing method is highly sensitive, yielding specific results from as little as 1 ng total RNA. It enables discrimination of OXA-extended substrate spectrum β-lactamases and carbapenemases and the semi-quantitative detection of highly expressed ISAba1-controlled variants.

CONCLUSION

Targeting mRNA with specific probes on magnetic beads will allow for adaptation to automated systems, such as point-of-care diagnostics.

Carbapenem resistance confers to Klebsiella pneumoniae strains an enhanced ability to induce infection and cell death in epithelial tissue-specific in vitro models

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae strains (KPC-Kp) are emerging worldwide causing different nosocomial infections including those of the urinary tract, lung or skin wounds. For these strains, the antibiotic treatment is limited to only few choices including colistin, whose continuous use led to the emergence of carbapenem-resistant KPC-Kp strains resistant also to this treatment (KPC-Kp Col-R).

AIM

Very little is known about the capacity of the different strains of KPC-Kp to invade the epithelial cells in vitro. To verify if the acquisition of carbapenem-resistant and the colistin-resistant phenotypes are correlated with a different ability to infect a series of epithelial cell lines of various tissutal origin and with a different capacity to induce cellular death.

MATERIALS & METHODS

We used Klebsiella pneumoniae (KP), KPC-Kp and KPC-Kp Col-R strains, isolated from different patients carrying various tissue-specific infections, to infect a series of epithelial cell lines of different tissutal origin. The invasive capacity of the strains and the extent and characteristics of the cell damage and death induced by the bacteria were evaluated and compared.

CONCLUSION

Our results show that both KPC-Kp and KPC-Kp Col-R display a greater ability to infect the epithelial cells, with respect to KP, and that the bacterial cell invasion results in a nonprogrammed cell death.

Klebsiella pneumoniae Is Able to Trigger Epithelial-Mesenchymal Transition Process in Cultured Airway Epithelial Cells

The ability of some bacterial pathogens to activate Epithelial-Mesenchymal Transition normally is a consequence of the persistence of a local chronic inflammatory response or depends on a direct interaction of the pathogens with the host epithelial cells. In this study we monitored the abilities of the K. pneumoniae to activate the expression of genes related to EMT-like processes and the occurrence of phenotypic changes in airway epithelial cells during the early steps of cell infection. We describe changes in the production of intracellular reactive oxygen species and increased HIF-1α mRNA expression in cells exposed to K. pneumoniae infection. We also describe the upregulation of a set of transcription factors implicated in the EMT processes, such as Twist, Snail and ZEB, indicating that the morphological changes of epithelial cells already appreciable after few hours from the K. pneumoniae infection are tightly regulated by the activation of transcriptional pathways, driving epithelial cells to EMT. These effects appear to be effectively counteracted by resveratrol, an antioxidant that is able to exert a sustained scavenging of the intracellular ROS. This is the first report indicating that strains of K. pneumoniae may promote EMT-like programs through direct interaction with epithelial cells without the involvement of inflammatory cells.

Pharmacokinetic-pharmacodynamic modelling of meropenem against VIM-producing Klebsiella pneumoniae isolates: clinical implications

VIM-producing Klebsiella pneumoniae isolates are usually associated with high MICs to carbapenems. Preclinical studies investigating the pharmacokinetic-pharmacodynamic (PK-PD) characteristics of carbapenems against these isolates are lacking. The in vitro antibacterial activity of meropenem against one WT and three VIM-producing K. pneumoniae clinical isolates (median MICs 0.031, 8, 16 and 128 mg l- 1) was studied in a dialysis-diffusion PK-PD model and verified in a thigh infection neutropenic animal model by testing selected strains and exposures. The in vitro PK-PD target associated with bactericidal activity was estimated and the target attainment for different dosing regimens was calculated with Monte Carlo analysis. The in vitro model was correlated with the in vivo data, with log10CFU/ml reduction of < 1 for the VIM-producing (MIC 16 mg l- 1) and >2 for the WT (MIC 0.031 mg l- 1) isolates, with %f T >MIC 25 and 100%, respectively. The in vitro bactericidal activity for all isolates was associated with 40 % f T>MIC and attained in >90% of cases with the standard 1 g q8 0.5 h infusion dosing regimen only for isolates with MICs up to 1 mg l- 1. For isolates with MICs of 2-8 mg l- 1, prolonged infusion regimens (4 h infusion q8 or 2 h infusion q4) of standard (1 g) and higher (2 g) doses or continuous infusion regimens (3-6 g) are required. For isolates with a MIC of 16 mg l- 1 the unconventional dosing regimen of 2 g as 2 h infusion q4 or 12 g continuous infusion will be required. Prolonged and continuous infusion regimens of meropenem may increase efficacy against VIM-producing K. pneumoniae isolates.

Epidemiologic and Genotypic Review of Carbapenemase-Producing Organisms in British Columbia, Canada, between 2008 and 2014

Carbapenemase-producing organisms (CPOs) are a serious emerging problem for health care facilities worldwide. Owing to their resistance to most antimicrobial therapies, CPOs are difficult to treat and pose a challenge for infection prevention and control. Since 2010, lab-based surveillance for CPOs and PCR-based testing were implemented in British Columbia (BC), Canada. A review of CPOs in BC from 2008 to March 2014 was done to characterize the resistance mechanisms and possible clonal strain transmission and to compare pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and plasmid restriction fragment length polymorphism (RFLP) as molecular typing tools. During this study period, a total of 177 CPO cases were identified. Patient demographics and travel history were reviewed, and a descriptive analysis was carried out. PFGE profiles, MLST, and plasmid RFLP analysis for a subset of Escherichia coli, Klebsiella pneumoniae, and Enterobacter species isolates were obtained and analyzed. Our findings demonstrate that CPOs have been increasing in number in BC over time, from 1 isolate/year retrospectively identified in 2008 and 2009 to 82 isolates in 2013 and 30 isolates in the first quarter of 2014. Overall, K. pneumoniae isolates lack clonality, although some seemingly related clusters have been found. Plasmid analysis showed evidence of the spread of plasmids carrying carbapenemase-encoding genes between the examined isolates. Analysis of Enterobacter cloacae isolates revealed a more clonal nature of these CPOs in BC. The presence of related clusters provides evidence of interpatient organism transmission both within and between institutions. Although in our study, NDM-harboring E. cloacae isolates appeared to spread clonally, the spread of carbapenem resistance in K. pneumoniae seems to be plasmid mediated.

Klebsiella: a long way to go towards understanding this enigmatic jet-setter

Klebsiella pneumoniae is the causative agent of a variety of diseases, including pneumonia, urinary tract infections, septicemia, and the recently recognized pyogenic liver abscesses (PLA). Renewed efforts to identify and understand the bacterial determinants required to cause disease have come about because of the worldwide increase in the isolation of strains resistant to a broad spectrum of antibiotics. The recent increased isolation of carbapenem-resistant strains further reduces the available treatment options. The rapid geographic spread of the resistant isolates and the spread to other pathogens are of particular concern. For many years, the best characterized virulence determinants were capsule, lipopolysaccharide, siderophores, and types 1 and 3 fimbriae. Recent efforts to expand this list include in vivo screens and whole-genome sequencing. However, we still know little about how this bacterium is able to cause disease. Some recent clonal analyses of K. pneumoniae strains indicate that there are distinct clonal groups, some of which may be associated with specific disease syndromes. However, what makes one clonal group more virulent and what changes the disease pattern are not yet clear and remain important questions for the future.

Treating infections caused by carbapenemase-producing Enterobacteriaceae

Carbapenemase-producing Enterobacteriaceae (CPE) have spread worldwide, causing serious infections with increasing frequency. CPE are resistant to almost all available antibiotics, complicating therapy and limiting treatment options. Mortality rates associated with CPE infections are unacceptably high, indicating that the current therapeutic approaches are inadequate and must be revised. Here, we review 20 clinical studies (including those describing the largest cohorts of CPE-infected patients) that provided the necessary information regarding isolate and patient characteristics and treatment schemes, as well as a clear assessment of outcome. The data summarized here indicate that treatment with a single in vitro active agent resulted in mortality rates not significantly different from that observed in patients treated with no active therapy, whereas combination therapy with two or more in vitro active agents was superior to monotherapy, providing a clear survival benefit (mortality rate, 27.4% vs. 38.7%; p <0.001). The lowest mortality rate (18.8%) was observed in patients treated with carbapenem-containing combinations.