The effect of colistin resistance and other predictors on fatality among patients with bloodstream infections due to Klebsiella pneumoniae in an OXA-48 dominant region

Production of OXA-48 carbapenemase acts as an independent risk factor for poor outcome in Klebsiella pneumoniae infection

PURPOSE

To know whether the production of OXA-48 carbapenemase exerts an independent impact on the outcome of Klebsiella pneumoniae infection, once adjusted by clinical syndrome and baseline risk factors.

METHODS

We performed a case-cohort study including 117 infectious episodes due to OXA-48-producing K. pneumoniae (OXA-48-Kp) and 117 episodes due to non-OXA-48-producing strains (non-OXA-48-Kp). Both groups were matched (1:1 ratio) by clinical syndrome (source of infection, preceding invasive procedures and indwelling devices, and associated bacteremia) and hospitalization ward at infection onset. Multivariate Cox regression was used to investigate the association between OXA-48-Kp infection and clinical cure by day 14 (primary outcome) and 30-day all-cause mortality (secondary outcome).

RESULTS

Both study groups were well balanced regarding underlying conditions and comorbidity burden. Sepsis or septic shock were more frequent in OXA-48-Kp cases than non-OXA-48-Kp controls (41 [35.0%] vs. 17 [14.5%]; P-value < 0.0001). Clinical cure by day 14 was less commonly achieved in OXA-48-Kp cases (49 [41.9%] vs. 95 [81.2%]; P-value < 0.001), whereas 30-day all-cause mortality was higher (33 [28.2%] vs. 18 [15.4%]; P-value = 0.018). Multivariate analysis confirmed that OXA-48-Kp infection was independently associated with the lack of 14-day clinical cure (adjusted hazard ratio [aHR]: 0.45; 95% confidential interval [95%CI]: 0.29-0.70; P-value < 0.0001). A non-significant association was observed for 30-day all-cause mortality (aHR: 1.65; 95%CI: 0.92-2.94; P-value = 0.093).

CONCLUSION

Our matched analysis suggests that the production of OXA-48 carbapenemase acts as an independent risk factor for poor outcome in K. pneumoniae infection as compared to episodes due to non-carbapenemase-producing strains.

Emergence of colistin-resistant gram-negative rods in intensive care units: A cross-sectional study from a developing country

Objectives

To determine the clinical features, outcomes, and factors associated with the emergence of colistin-resistant gram-negative rods isolated from patients admitted to intensive care units.

Methods

This cross-sectional study was conducted at the intensive care units of Liaquat National Hospital, from April 2019 to February 2020. Gram-negative rods resistant to colistin with minimum inhibitory concentrations ⩾ 4 mcg/mL according to Clinical and Laboratory Standards Institute criteria as reported in cultures were included. Clinical, demographical data and treatment given were recorded and analyzed using SPSS version 25.

Results

A total of 93 patients were included; 58.1% were males. The mean age of patients was 59.48 ± 18.36 years. The most common organism isolated was Klebsiella pneumoniae (91.4%). The most common specimen was the tracheal (62.4%). Ventilator-acquired pneumonia was seen in 38.7%. The most common co-morbid disease seen in patients was diabetes (41%); 77% had a symptomatic infection and were treated with a combination of 2 or more antibiotics, most commonly meropenem plus fosfomycin. The most common susceptible antibiotics were fosfomycin (72%) and tigecycline (50.5%). Mean intensive care unit stay and total duration of hospital stay were prolonged (16.83 ± 12.93 and 23.34 ± 17.52 days, respectively). Forty-eight (62.3%) patients with symptomatic infection with colistin-resistant isolates were treated and discharged, and mortality was seen in 23 (29.9%). A significant association was found between mortality and symptomatic infection, endotracheal intubation with mechanical ventilation (p = 0.003), and a prolonged hospital stay of >20 days (p = 0.041).

Conclusion

Colistin-resistant gram-negative rods pose a significant problem especially in developing countries because of limited therapeutic options. Stringent infection control and comprehensive antimicrobial stewardship programs are needed to overcome this challenge.

Rescuing humanity by antimicrobial peptides against colistin-resistant bacteria

Abstract

It has been about a century since the discovery of the first antibiotic, and during this period, several antibiotics were produced and marketed. The production of high-potency antibiotics against infections led to victories, but these victories were temporary. Overuse and misuse of antibiotics have continued to the point that humanity today is almost helpless in the fight against infection. Researchers have predicted that by the middle of the new century, there will be a dark period after the production of antibiotics that doctors will encounter antibiotic-resistant infections for which there is no cure. Accordingly, researchers are looking for new materials with antimicrobial properties that will strengthen their ammunition to fight antibiotic-resistant infections. One of the most important alternatives to antibiotics introduced in the last three decades is antimicrobial peptides (AMPs), which affect a wide range of microbes. Due to their different antimicrobial properties from antibiotics, AMPs can fight and kill MDR, XDR, and colistin-resistant bacteria through a variety of mechanisms. Therefore, in this study, we intend to use the latest studies to give a complete description of AMPs, the importance of colistin-resistant bacteria, and their resistance mechanisms, and represent impact of AMPs on colistin-resistant bacteria.

Key points

• AMPs as limited options to kill colistin-resistant bacteria.

• Challenge of antibiotics resistance, colistin resistance, and mechanisms.

• What is AMPs in the war with colistin-resistant bacteria?

A meta-analysis for the role of aminoglycosides and tigecyclines in combined regimens against colistin- and carbapenem-resistant Klebsiella pneumoniae bloodstream infections

We aimed to describe the effect of aminoglycosides and tigecycline to reduce the mortality in colistin- and carbapenem-resistant Klebsiella pneumoniae (ColR-CR-Kp) infections. We included the studies with defined outcomes after active or non-active antibiotic treatment of ColR-CR-Kp infections. The active treatment was defined as adequate antibiotic use for at least 3 days (72 h) after the diagnosis of ColR-CR-Kp infection by culture. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement and the checklist of PRISMA 2020 was applied. Crude and adjusted odds ratios (OR) with 95% confidence interval (CI) were calculated and pooled in the random effects model. Adding aminoglycosides to the existing treatment regimen reduced overall mortality significantly (OR 0.34, 95% CI 0.20-0.58). Overall mortality was 34% in patients treated with aminoglycoside-combined regimens and was 60% in patients treated with non-aminoglycoside regimens. Treatment with tigecycline is not found to reduce mortality (OR: 0.76, 95% CI: 0.47-1.23). Our results suggest that aminoglycoside addition to the existing regimen of colistin- and carbapenem-resistant Klebsiella pneumoniae infections reduces mortality significantly.

Prognostic factors of OXA-48 carbapenemase-producing Klebsiella pneumoniae infection in a tertiary-care Spanish hospital: A retrospective single-center cohort study

OBJECTIVES

To describe the determinants of outcome of infections due to OXA-48 carbapenemase-producing Klebsiella pneumoniae (OXA-48-Kp).

METHODS

A retrospective cohort study of 117 episodes of OXA-48-Kp infection were conducted. Multivariate Cox models identified factors predicting 14-day clinical response and 30-day all-cause mortality.

RESULTS

Seventy-seven (65.8%) isolates were susceptible to imipenem/meropenem. 14-day clinical response and 30-day mortality rates were 41.9% and 28.2%. Catheter-related bloodstream infection (adjusted hazard ratio [aHR]: 8.33; 95% confidence interval [95%CI]: 3.19-21.72; P-value <0.001), urinary tract infection (aHR: 3.04; 95%CI: 1.39-6.66; P-value = 0.006) and early appropriate treatment (aHR: 1.77; 95%CI: 0.97-3.22; P-value = 0.064) predicted clinical response, whereas severe sepsis had a deleterious impact (aHR: 0.22; 95%CI: 0.10-0.50; P-value <0.001). Lower respiratory tract infection (aHR: 6.58; 95%CI: 2.83-15.29; P-value <0.001) and bloodstream infection (aHR: 2.33; 95%CI: 1.05-5.15; P-value = 0.037) were associated with 30-day mortality, whereas definitive therapy including ≥1 active agent (aHR: 0.26; 95%CI: 0.11-0.63; P-value = 0.003) and source control (aHR: 0.35; 95%CI: 0.14-0.91; P-value = 0.030) were protective. Combination therapy did not seem to be associated with better outcomes.

CONCLUSIONS

Appropriate antimicrobial treatment was protective for 30-day mortality in OXA-48-Kp infections. Carbapenems are usually active, whereas combination therapy appeared not to confer additional benefit.

Risk factors for infection and mortality caused by carbapenem-resistant Klebsiella pneumoniae: a large multicentre case-control and cohort study

OBJECTIVES

To elucidate the predictors of carbapenem-resistant Klebsiella pneumoniae (CRKP) infection and help clinicians better identify CRKP infection at an early age.

METHODS

We conducted a multicentre case-control study of 422 patients with CRKP infection and 948 with carbapenem-susceptible K. pneumoniae (CSKP) infection from March to July 2017. Binary logistic regression was used to identify risk factors for CRKP infection. The subgroups of CRKP respiratory infection, intra-abdominal infection, and bloodstream infection were also evaluated. Patients were followed up for 28 days. Independent risk factors for 28-day crude mortality of CRKP infection were analysed using Cox proportional hazards regression models.

RESULTS

Longer stay of hospitalization, stay in the ICU, previous exposure to antibacterial agents (especially carbapenems, quinolones, aminoglycosides, and tigecycline), invasive procedures, intravascular catheter use, tracheotomy, or admission to ICU in the preceding 90 days were risk factors for CRKP infection. Carbapenem exposure was the only common predictor of different types of CRKP infection. The 28-day mortality of CRKP infection was 13.1% and was independently associated with sex, admitted unit, and types of infection.

CONCLUSIONS

Strict policies for antibiotic use, cautious decisions regarding the implementation of invasive procedures, and careful management of patients with catheters, especially intravascular catheters, are necessary to handle CRKP infection.

Colistin resistance increases 28-day mortality in bloodstream infections due to carbapenem-resistant Klebsiella pneumoniae

Mortality due to K. pneumoniae bacteremia is on rise, particularly in regions with high rates of carbapenem and colistin resistance. We aimed to define risk factors for colistin resistance and its impact on mortality. Patients diagnosed with "carbapenem-resistant K. pneumoniae (CRKp)" bacteremia between 2014 and 2018 were divided into two groups as "colistin susceptible (ColS)" and "colistin resistant (ColR)" based on broth microdilution method. Retrospective case-control study was conducted to compare characteristics and outcomes. Multiple logistic regression model was used to define independent risk factors for acquired colistin resistance and Cox proportional hazard model for 28-day mortality. A total of 82 patients (39 ColS and 43 ColR) were included. Mean age was 61.5 years, and 50 (61%) were male. Colistin resistance was significantly increased with duration of hospital stay (p = 0.007) and prior colistin use (p = 0.007). Overall, the 28-day mortality rate was 66%. Age (p = 0.014) and colistin resistance significantly increased 28-day (p = 0.009) mortality. Microbiological response to treatment within 7 days favors survival. PFGE analysis revealed an outbreak with K. pneumoniae ST78 and ST45 clones. Patients treated with combined antimicrobials had significantly lower 28-day mortality (p = 0.045) in comparison to monotherapy. However, types of combinations did not show significant superiority on each other. Colistin resistance increases 28-day mortality in CRKp bacteremia. Although combined regimens are more effective than monotherapy, existing antibacterial combinations have no apparent superiority to each other. New treatment options are pivotal.

Tracking high-risk β-lactamase gene (bla gene) transfers in two Chinese intensive dairy farms

Extended-spectrum β-lactam antibiotics are critically important antibiotics for humans, but their use in food-animals poses a potential threat for public health. This paper addressed the occurrence of high-risk β-lactamase genes (bla genes) in intensive dairy farms, and assessed the effects of different waste treatment technologies at dairies on the propagation and dissemination of bla genes. Results showed that ESBL genes (bla_TEM-1, bla_OXA-1), ampC β-lactamase genes (bla_ampC) and carbapenemase genes (bla_GES-1, bla_NDM) were prevalent in dairy cow waste, and even prevailed through each processing stage of solid manure and dairy wastewater. Significant levels of bla genes were present in the final lagoon (from 10⁴ to 10⁶ copies/mL, representing from 10% to 151%, of raw influent levels), raising the possibility of dissemination to the receiving environment. This concern was validated by the investigation on farmland that had long-term undergone wastewater irrigation, where causing an increase in bla gene levels in soils (approximately 1-3 orders of magnitude). More troublesomely, considerable levels of certain bla genes were still observed in the bedding material (up to 10⁵ and 10⁷ copies/g), which would directly threaten the dairy cow health. Otherwise, correlation analysis showed that both bacterial community and environmental factors played important roles in the bla genes abundances in dairy farms. This study demonstrated the prevalence of high-risk bla genes in dairy farms, and also underscored that dairy waste was a non-ignored great source of multidrug resistance for their surroundings.

Emergence of carbapenemase-producing and colistin resistant Klebsiella pneumoniae ST101 high-risk clone in Turkey

Carbapenemase-producing and colistin resistant Klebsiella pneumoniae has become a worldwide healthcare problem. This study describes molecular characterization of carbapenemase-producing and colistin resistant clinical K. pneumoniae isolates.A total of 93 non-replicate carbapenem and colistin resistant K. pneumoniae were recovered from clinical specimens in a university hospital during 2017-2019. Detection of blaOXA-48, blaKPC, blaNDM-1, blaIMP, blaVIM-1 and mcr-1, -2, -3, -4, -5, -6, -7, and -8 genes was performed by PCR. The bacterial isolates were assigned to clonal lineages by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).All isolates harbored blaOXA-48 and only two isolates harbored blaOXA-48, and blaNDM-1 genes together. In colistin resistant K. pneumoniae, mcr-1 was detected in two (2.1%) isolates. Ninety three isolates of K. pneumoniae were categorized into three clusters and five pulsotypes. MLST revealed two different sequence types, ST101 (89/93) and ST147 (4/93).In our study ST101 was found to be a significantly dominant clone carrying blaOXA-48 and among our strains a low frequency of mcr-1 gene was determined. The emergence of colistin resistance was observed in K. pneumoniae ST101 isolates. ST101 may become a global threat in the dissemination of carbapenem and colistin resistance.

Prekallikrein - an emerging therapeutic target for Klebsiella pneumoniae infection?†

Klebsiella pneumoniae is a Gram-negative bacterium that is increasingly difficult to treat due to the emergence of multidrug resistant strains. In a recent article, Ding et al demonstrate that prekallikrein depletion in mice followed by intranasal instillation of K. pneumoniae leads to a reduced bacterial burden and prolonged host survival, together with evidence of reduced distant organ damage. These effects are apparently independent of the role of prekallikrein in the contact system, and are associated with transcriptional changes relevant to innate immunity in the lung, established prior to infection. This study highlights the importance of further investigating the role of prekallikrein and other contact cascade components in host defence to counter K. pneumoniae (and perhaps other pathogens), with an overall aim of identifying potential therapeutic targets relevant to pulmonary infection with such resistant pathogens. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Intra-hospital acquisition of colonization and infection by Klebsiella pneumoniae strains producing carbapenemases and carriage evolution: A longitudinal analysis in an Italian teaching hospital from January 2017 to August 2019

OBJECTIVES

We present an updated picture (1/1/2017-31/08/2019) of the frequency of carbapenemase producing Klebsiella pneumoniae (CPKP) in surveillance rectal swabs (SRS) and in clinical samples (CS) of patients admitted to a tertiary level hospital, focusing on longitudinal evolution of CPKP detected in SRS and on colistin resistant strains.

METHODS

Retrospective longitudinal analysis. Only the first positive CPKP strain isolated from each patient was included.

RESULTS

638 CPKP strains were identified (471 in SRS and 167 in CS). SRS frequency increased over time in the medical department, remained high in the surgical department (SD) and decreased in the intensive care department. Most SRS-71.3%-and 49.1% of CS had nosocomial origin; about half of the SRS were identified in the SD. Regarding SRS evolution, carriage was confirmed in 39.5% of patients, no more testing in 25.5%, clinical involvement in 24.8 %, and negative result in 10.2%. Rates of colistin resistance were 20.1% in 2017, 31.2% in 2018 and 26.9% in 2019.

CONCLUSIONS

CPKP diffusion is still an important issue despite the surveillance program. It is vital to enhance medical staff's awareness on this because most CPKP first detections in SRS occurred during hospital stay due to a nosocomial acquisition with a comparable picture over time. Colistin resistance is increasing.