KPC-producing Klebsiella pneumoniae rectal colonization is a risk factor for mortality in patients with diabetic foot infections

Risk factors for nosocomial rectal colonisation with carbapenem-resistant Gram-negative bacilli in children with haematological malignancies: a case-control study

BACKGROUND

Rectal colonisation with carbapenem-resistant Gram-negative bacilli (CR-GNB) may cause CR-GNB infection in children with haematological malignancies (HMs) haematological. To date, information on its epidemiology is limited. This study aimed to assess the the risk factors for rectal colonisation with CR-GNB in children with HMs.

METHODS

A case-control study in a tertiary children's hospital in Hangzhou City, was conducted between July 2019, and September 2021. Based on the hospitalisation date, children in the CR-GNB colonisation group and control groups were matched at a ratio of 1:2. Conditional logistic regression models were used to compute the adjusted odds ratios (aORs) and 95% confidence intervals (CIs) of the risk factors for CR-GNB rectal colonisation in children with HMs.

RESULTS

A total of 85 non-duplicated CR-GNB isolates were collected from rectal swab samples of 69 children with HMs. The 30-day mortality rates were 5.8% in the CR-GNB colonisation group and 0% in the control group (P = 0.020).colonisation In the conditional logistic regression model, the aORs were 6.84 (95% CI 1.86-25.20) for acute myeloid leukemia (AML) or acute lymphoblastic leukemia (ALL), 4.16 (95% CI 1.17-14.84) for prior concomitant infections within the last 1 month, 2.33 (95% CI 1.16-4.69) for prior carbapenems usage within the last 1 month and 7.46 (95% CI 1.81-30.67) for prior hematopoietic stem-cell transplantation (HSCT).

CONCLUSION

AML/ALL, prior concomitant infections within the last 1 month, prior carbapenems usage within the last 1 month, and prior HSCT are associated with an increased risk of rectal colonisation with CR-GNB in children with HMs.

MALDI-TOF MS Based Bacterial Antibiotics Resistance Finger Print for Diabetic Pedopathy

Diabetes mellitus has become a major global health issue. Currently, the use of antibiotics remains the best foundational strategy in the control of diabetic foot infections. However, the lack of accurate identification of pathogens and the empirical use of antibiotics at early stages of infection represents a non-targeted treatment approach with a poor curative effect that may increase the of bacterial drug resistance. Therefore, the timely identification of drug resistant bacteria is the key to increasing the efficacy of treatments for diabetic foot infections. The traditional identification method is based on bacterial morphology, cell physiology, and biochemistry. Despite the simplicity and low costs associated with this method, it is time-consuming and has limited clinical value, which delays early diagnosis and treatment. In the recent years, MALDI-TOF MS has emerged as a promising new technology in the field of clinical microbial identification. In this study, we developed a strategy for the identification of drug resistance in the diagnosis of diabetic foot infections using a combination of macro-proteomics and MALDI MS analysis. The macro-proteomics result was utilized to determine the differential proteins in the resistance group and the corresponding peptide fragments were used as the finger print in a MALDI MS analysis. This strategy was successfully used in the research of drug resistance in patients with diabetic foot infections and achieved several biomarkers that could be used as a finger print for 4 different drugs, including ceftazidime, piperacillin, levofloxacin, and tetracycline. This method can quickly confirm the drug resistance of clinical diabetic foot infections, which can help aid in the early treatment of patients.

Bacteriophage SRD2021 Recognizing Capsular Polysaccharide Shows Therapeutic Potential in Serotype K47 Klebsiella pneumoniae Infections

Klebsiella pneumoniae is an opportunistic pathogen posing an urgent threat to global public health, and the capsule is necessary for K. pneumoniae infection and virulence. Phage-derived capsule depolymerases have shown great potential as antivirulence agents in treating carbapenem-resistant K. pneumoniae (CRKP) infections. However, the therapeutic potential of phages encoding depolymerases against CRKP remains poorly understood. In this study, we identified a long-tailed phage SRD2021 specific for mucoid CRKP with capsular K47 serotype, which is the predominant infectious K-type in Asia. Genome sequencing revealed that ΦSRD2021 belonged to the Drulisvirus genus and exhibited a capsular depolymerase domain in its tail fiber protein. A transposon-insertion library of host bacteria was constructed to identify the receptor for ΦSRD2021. We found that most phage-resistant mutants converted to a nonmucoid phenotype, including the mutant in wza gene essential for capsular polysaccharides export. Further knockout and complementation experiments confirmed that the Δwza mutant avoided adsorption by ΦSRD2021, indicating that the K47 capsular polysaccharide is the necessary receptor for phage infection. ΦSRD2021 lysed the bacteria mature biofilms and showed a therapeutic effect on the prevention and treatment of CRKP infection in the Galleria mellonella model. Furthermore, ΦSRD2021 also reduced the colonized CRKP in mouse intestines significantly. By recognizing the host capsule as a receptor, our results showed that ΦSRD2021 may be used as a potential antibacterial agent for K47 serotype K. pneumoniae infections.

Distinguishing bla KPC Gene-Containing IncF Plasmids from Epidemiologically Related and Unrelated Enterobacteriaceae Based on Short- and Long-Read Sequence Data

Limited information is available on whether bla _KPC-containing plasmids from isolates in a hospital outbreak can be differentiated from epidemiologically unrelated bla _KPC-containing plasmids based on sequence data. This study aimed to evaluate the performance of three approaches to distinguish epidemiologically related from unrelated bla _KPC-containing pKpQiL-like IncFII(k2)-IncFIB(pQiL) plasmids. Epidemiologically related isolates were subjected to short- and long-read whole-genome sequencing. A hybrid assembly was performed, and plasmid sequences were extracted from the assembly graph. Epidemiologically unrelated plasmid sequences were extracted from GenBank. Pairwise comparisons of epidemiologically related and unrelated plasmids based on SNPs using snippy and of phylogenetic distance using Roary and using a similarity index that penalizes size differences between plasmids (Stoesser index) were performed. The percentage of pairwise comparisons misclassified as genetically related or as clonally unrelated was determined using different genetic thresholds for genetic relatedness. The ranges of number of SNPs, Roary phylogenetic distance, and Stoesser index overlapped between the epidemiologically related and unrelated plasmids. When a genetic similarity threshold that classified 100% of epidemiologically related plasmid pairs as genetically related was used, the percentages of plasmids misclassified as epidemiologically related ranged from 6.7% (Roary) to 20.8% (Stoesser index). Although epidemiologically related plasmids can be distinguished from unrelated plasmids based on genetic differences, bla _KPC-containing pKpQiL-like IncFII(k2)-IncFIB(pQiL) plasmids show a high degree of sequence similarity. The phylogenetic distance as determined using Roary showed the highest degree of discriminatory power between the epidemiologically related and unrelated plasmids.

A Novel KPC Variant KPC-55 in Klebsiella pneumoniae ST307 of Reinforced Meropenem-Hydrolyzing Activity

A novel Klebsiella pneumoniae carbapenemase (KPC) variant, KPC-55, produced by a K. pneumoniae ST307 strain was characterized. K. pneumoniae strain BS407 was recovered from an active surveillance rectal swab of a patient newly admitted to a general hospital in Busan, South Korea. Carbapenemase production was confirmed by the modified Hodge test, and the MICs of β-lactams were determined by the broth microdilution method. The whole genome was sequenced. Cloning and expression of the bla_KPC–55 gene in Escherichia coli and MIC determination were performed. The enzyme KPC-55 was used for kinetic assays against β-lactams and compared with the KPC-2 enzyme. The new allele of the bla_KPC gene had a T794A alteration compared to the bla_KPC–2 gene, resulting in the amino acid substitution Y264N in the middle of the β9-sheet. Compared to the KPC-2-producing strain, the KPC-55-producing strain exhibited a lower level of resistance to most β-lactam drugs tested, however, the KPC-55 enzyme catalyzed aztreonam and meropenem at an increased efficiency compared to the catalytic activity of KPC-2. KPC subtypes could have varied phenotypes due to alterations in amino acid sequences, and such an unexpected resistance phenotype emphasizes the importance of detailed characterizations for the carbapenemase-producing Enterobacterales.

Risk factors for mortality in patients with diabetic foot infections: a prospective cohort study

BACKGROUND

An increasing prevalence of diabetes mellitus has led to a high risk of diabetic foot infections (DFI) and associated morbidity. However, little is known about the relationship between DFI and mortality.

AIM

To investigate the risk of mortality and associated factors in patients with DFI in an Australian context.

METHODS

A prospective cohort study of inpatients with DFI between May 2012 and October 2016 was done at Royal Darwin Hospital, a tertiary referral hospital for the Top End of the Northern Territory. Primary outcome was 1-year mortality with Cox regression analysis undertaken to assess risk factors for mortality.

RESULTS

Four hundred and thirteen consecutive adult diabetic patients with 737 admissions were referred to the High-Risk Foot Service for DFI. Cumulative risk of mortality at 1 year was 8.9% (95% confidence interval (CI) 6.4-12.2). On univariable analysis, mortality was associated with older age (hazard ratio (HR) per year increase 1.08, 95% CI 1.06-1.11, P = 0.001), haemodialysis (HR 3.64, 1.74-7.62, P < 0.001), isolation of Pseudomonas aeruginosa (HR 2.32, 1.05-5.12, P = 0.04) and ischaemic heart disease (HR 2.05, 1.04-4.07, P = 0.04), while indigenous status (HR 0.48, 0.25-0.95, P = 0.04) and HbA1c > 7% (HR 0.45, 0.20-0.99, P < 0.05) were protective. After adjusting for confounders, independent risk factors for mortality were haemodialysis (adjusted HR 5.76, 95% CI 2.28-14.59, P < 0.001) and older age (adjusted HR 1.09, 1.06-1.13, P < 0.001). Patients on haemodialysis had a cumulative risk of mortality of 24.5% (95% CI 14.0-40.8) at 1 year.

CONCLUSION

There is a high risk of mortality associated with DFI, substantially increased in patients undergoing haemodialysis, highlighting the importance of early and dedicated interventions targeted at this high-risk group.

Health outcomes attributable to carbapenemase-producing Enterobacteriaceae infections: A systematic review and meta-analysis

BACKGROUND

Carbapenemase-producing Enterobacteriaceae (CPE) pose a significant global health threat.

OBJECTIVE

To conduct a systematic review of health outcomes and long-term sequelae attributable to CPE infection.

METHODS

We followed PRISMA reporting guidelines and published our review protocol on PROSPERO (CRD42018097357). We searched Medline, Embase, CINAHL and the Cochrane Library. We included primary studies with a carbapenem-susceptible control group in high-income countries, published in English. Quality appraisal was completed using Joanna Briggs Institute checklists. We qualitatively summarized frequently reported outcomes and conducted a meta-analysis.

RESULTS

Our systematic review identified 8,671 studies; 17 met the eligibility criteria for inclusion. All studies reported health outcomes; none reported health-related quality-of-life. Most studies were from Europe (65%), were conducted in teaching or university-affiliated hospitals (76%), and used case-control designs (53%). Mortality was the most commonly reported consequence of CPE-infections; in-hospital mortality was most often reported (62%). Our meta-analysis (n = 5 studies) estimated an absolute risk difference (ARD) for in-hospital bloodstream infection mortality of 0.25 (95% confidence interval [CI], 0.17-0.32). Duration of antibiotic therapy (range, 4-29.7 vs 1-23.6 days) and length of hospital stay (range, 21-87 vs 15-43 days) were relatively higher for CPE-infected patients than for patients infected with carbapenem-susceptible pathogens. Most studies (82%) met >80% of their respective quality appraisal criteria.

CONCLUSIONS

The risk of in-hospital mortality due to CPE bloodstream infection is considerably greater than carbapenem-susceptible bloodstream infection (ARD, 0.25; 95% CI, 0.17-0.32). Health outcome studies associated with CPE infection are focused on short-term (eg, in-hospital) outcomes; long-term sequelae and quality-of-life are not well studied.

TRIAL REGISTRATION

PROSPERO (CRD42018097357).

Risk Factors for Carbapenem-resistant Klebsiella pneumoniae Infection and Mortality of Klebsiella pneumoniae Infection

Background:

Klebsiella pneumoniae (KP) is a pathogen commonly causing nosocomial infection. Carbapenem-resistant KP (CRKP) is more resistant to multiple antimicrobial drugs than carbapenem-susceptible KP (CSKP) isolates. The aim of the present study was to identify the risk factors for CRKP infection and the predictors of mortality among KP-infected adult patients.

Methods:

Patients with CRKP and CSKP infection were categorized as the case group and control group, respectively, and we conducted a 1:1 ratio case-control study on these groups. The CRKP isolates collected were tested for antimicrobial susceptibility and presence of KP carbapenemase (KPC) gene. Clinical data were collected to identify risk factors for CRKP infection and mortality of KP infection. Risk factors were analyzed under univariable and multivariable logistic regression model.

Results:

The independent risk factors for CRKP infection were admission to Intensive Care Unit (odds ratio [OR]: 15.486, 95% confidence interval [CI]: 3.175–75.541, P < 0.001); use of β-lactams and β-lactamase inhibitor combination (OR: 4.765, 95% CI: 1.508–15.055, P = 0.008); use of cephalosporins (OR: 8.033, 95% CI: 1.623–39.763, P = 0.011); fluoroquinolones (OR: 6.090, 95% CI: 1.343–27.613, P = 0.019); and indwelling of urethral catheter (OR: 6.164, 95% CI: 1.847–20.578, P = 0.003). However, older age (OR: 1.079, 95% CI: 1.005–1.158, P = 0.036), Charlson comorbidity index (OR: 4.690, 95% CI: 2.094–10.504, P = 0.000), and aminoglycoside use (OR: 670.252, 95% CI: 6.577–68,307.730, P = 0.006) were identified as independent risk factors for patient deaths with KP infection. The mortality of CRKP group was higher than that of the CSKP group. KPC gene did not play a role in the CRKP group. CRKP mortality was high.

Conclusion:

Implementation of infection control measures and protection of the immunefunction are crucial.

Influence of multidrug resistant organisms on the outcome of diabetic foot infection

OBJECTIVES

We described the clinical outcomes of the diabetic patients who had foot infections with multidrug resistant organisms.

METHODS

We included the patients with diabetic foot infections (DFI) from 19 centers, between May 2011 and December 2015. Infection was defined according to IDSA DFI guidelines. Patients with severe infection, complicated moderate infection were hospitalized. The patients were followed-up for 6 months after discharge.

RESULTS

In total, 791 patients with DFI were included, 531(67%) were male, median age was 62 (19-90). Severe infection was diagnosed in 85 (11%) patients. Osteomyelitis was diagnosed in 291(36.8%) patients. 536 microorganisms were isolated, the most common microorganisms were S. aureus (20%), P. aeruginosa (19%) and E. coli (12%). Methicillin resistance (MR) rate among Staphylococcus aureus isolates was 31%. Multidrug resistant bacteria were detected in 21% of P. aeruginosa isolates. ESBL (+) Gram negative bacteria (GNB) was detected in 38% of E. coli and Klebsiella isolates. Sixty three patients (8%) were re-hospitalized. Of the 791 patiens, 127 (16%) had major amputation, and 24 (3%) patients died. In multivariate analysis, significant predictors for fatality were; dialysis (OR: 8.3, CI: 1.82-38.15, p=0.006), isolation of Klebsiella spp. (OR:7.7, CI: 1.24-47.96, p=0.028), and chronic heart failure (OR: 3, CI: 1.01-9.04, p=0.05). MR Staphylococcus was detected in 21% of the rehospitalized patients, as the most common microorganism (p<0.001).

CONCLUSION

Among rehospitalized patients, methicillin resistant Staphylococcus infections was detected as the most common agent, and Klebsiella spp. infections were found to be significantly associated with fatality.

Optimizing skin and skin structure infection outcomes: considerations of cost of care

INTRODUCTION

Skin and skin structure infections (SSSIs) refer to a collection of clinical infectious syndromes involving layers of skin and associated soft tissues. Although associated with less morbidity and mortality than other common skin infections, SSSIs represent a significant increasing source of healthcare expense, with a prevalence of 500 episodes per 10,000 patient-years in the United States resulting in burdening health care systems, of approximately $6 billion annually.

AREAS COVERED

Opportunities to reduce costs of care associated with SSSI are highlighted, including transitions of care and avoiding unnecessary hospital admissions. Moreover, we reviewed new antibiotics (e.g. single dose glycopeptides), and the impact of consulting specialists in the emergency department on SSSI treatment outcomes.

EXPERT COMMENTARY

New healthcare models and payment strategies combined with new therapeutics are challenging norms of care. Newer drugs to treat skin infections can move a substantive percent of patients previously admitted to hospital care to the outpatient setting. Additionally, patients can be managed with oral or one time intravenous regimens, improving the likelihood of patient adherence and satisfaction. These variables need to be weighed against added acquisition costs and the development of thoughtful algorithms is needed to direct care and optimize treatment, cost, and patient satisfaction.

The prevalence of rectal carriage of Klebsiella pneumoniae amongst diabetic patients and their clinical relevance in Taiwan: A five-year prospective study

BACKGROUND/PURPOSE

Pyogenic liver abscess (PLA) and bacteremia caused by Klebsiella pneumoniae is a common complication among patients with diabetes mellitus (DM). The aim of this study is to investigate the prevalence of rectal carriage and serotype distribution of K. pneumoniae amongst DM patients and their clinical relevance.

METHODS

We prospectively collected rectal swabs for K. pneumoniae culture in asymptomatic DM patients from March 2008 to June 2009. Seven capsular serotypes that were commonly associated with PLA were determined by capsular polysaccharide synthesis (cps) genotyping. Microbiologically confirmed bacterial infections were evaluated 1 and 5 years after initial enrolment of the patients.

RESULTS

A total of 100 male and 62 female patients (mean age, 56.6 years) were enrolled. Of these, 77 (47.5%) had rectal K. pneumoniae colonization. Colonizers were older than non-colonizers (p = 0.03). Sex, fasting blood glucose, and initial HbA1C were not statistically different (p = 0.26, 0.18, and 0.31, respectively). Among the 65 available isolates, 22 (33.8%) belonged to the seven main serotypes. During the 5-year's follow-up, 21 patients developed microbiologically documented bacterial infections but none of them developed PLA and bacteremia. Risk factors for bacterial infection within 5 years included initial glycosylated hemoglobin (HbA1C) > 10% or first-year average HbA1C > 10%.

CONCLUSION

Although nearly half of asymptomatic DM patients had rectal carriage of K. pneumoniae and one-third of them colonized by isolates belonging to the seven serotypes related to PLA, none of them subsequently developed PLA and colonized patients did not have higher risk of microbiologically confirmed bacterial infections.

A Proposed New Classification of Skin and Soft Tissue Infections Modeled on the Subset of Diabetic Foot Infection

Schemes for classifying skin and soft tissue infections (SSTIs) pose limitations for clinicians and regulatory agencies. Diabetic foot infections (DFIs) are a subset of SSTIs. We developed and are proposing a classification to harmonize current schemes for SSTIs and DFIs. Existing schemes for classifying SSTIs are limited in both their usefulness to clinicians and to regulatory agencies. The guidelines on SSTI from the Infectious Diseases Society of America (IDSA) and the guidance from the US Food and Drug Administration do not adequately address many types of wound infections. However, guidelines developed by the IDSA for DFIs provide a classification scheme that has been validated and widely used. Diabetic foot infections are similar to SSTIs in pathophysiology, microbiology, and treatment and can be seen as a subset of SSTI. Thus, based on the documents noted above, and our review of the literature, we have developed a proposed classification scheme for SSTI that harmonizes well with the DFI classification. We believe this new scheme will assist clinicians in classifying most wound infections and potentially aid regulatory agencies in testing and approving new antimicrobials for these infections.

Molecular Epidemiology of Colonizing and Infecting Isolates of Klebsiella pneumoniae

K. pneumoniae commonly infects hospitalized patients, and these infections are increasingly resistant to carbapenems, the antibiotics of last resort for life-threatening bacterial infections. To prevent and treat these infections, we must better understand how K. pneumoniae causes disease and discover new ways to predict and detect infections. This study demonstrates that colonization with K. pneumoniae in the intestinal tract is strongly linked to subsequent infection. This finding helps to identify a potential time frame and possible approach for intervention: the colonizing strain from a patient could be isolated as part of a risk assessment, and antibiotic susceptibility testing could guide empirical therapy if the patient becomes acutely ill.

Klebsiella pneumoniae is among the most common causes of hospital-acquired infections and has emerged as an urgent threat to public health due to carbapenem antimicrobial resistance. K. pneumoniae commonly colonizes hospitalized patients and causes extraintestinal infections such as urinary tract infection, bloodstream infection (septicemia), and pneumonia. If colonization is an intermediate step before infection, then detection and characterization of colonizing isolates could enable strategies to prevent or empirically treat K. pneumoniae infections in hospitalized patients. However, the strength of the association between colonization and infection is unclear. To test the hypothesis that hospitalized patients become infected with their colonizing strain, 1,765 patients were screened for rectal colonization with K. pneumoniae, and extraintestinal isolates from these same patients were collected over a 3-month period in a cohort study design. The overall colonization prevalence was 23.0%. After adjustment for other patient factors, colonization was significantly associated with subsequent infection: 21 of 406 (5.2%) colonized patients later had extraintestinal infection, compared to 18 of 1,359 (1.3%) noncolonized patients (adjusted odds ratio [OR], 4.01; 95% confidence interval, 2.08 to 7.73; P < 0.001). Despite a high diversity of colonizing isolates, 7/7 respiratory, 4/4 urinary, and 2/5 bloodstream isolates from colonized patients matched the patient corresponding rectal swab isolates, based on wzi capsular typing, multilocus sequence typing (MLST), and whole-genome sequence analysis. These results suggest that K. pneumoniae colonization is directly associated with progression to extraintestinal infection.

IMPORTANCE K. pneumoniae commonly infects hospitalized patients, and these infections are increasingly resistant to carbapenems, the antibiotics of last resort for life-threatening bacterial infections. To prevent and treat these infections, we must better understand how K. pneumoniae causes disease and discover new ways to predict and detect infections. This study demonstrates that colonization with K. pneumoniae in the intestinal tract is strongly linked to subsequent infection. This finding helps to identify a potential time frame and possible approach for intervention: the colonizing strain from a patient could be isolated as part of a risk assessment, and antibiotic susceptibility testing could guide empirical therapy if the patient becomes acutely ill.

Diabetic foot infections: Current treatment and delaying the 'post-antibiotic era'

BACKGROUND

Treatment for diabetic foot infections requires properly diagnosing infection, obtaining an appropriate specimen for culture, assessing for any needed surgical procedures and selecting an empiric antibiotic regimen. Therapy will often need to be modified based on results of culture and sensitivity testing. Because of excessive and inappropriate use of antibiotics for treating diabetic foot infections, resistance to the usually employed bacteria has been increasing to alarming levels.

REVIEW

This article reviews recommendations from evidence-based guidelines, informed by results of systematic reviews, on treating diabetic foot infections. Data from the pre-antibiotic era reported rates of mortality of about 9% and of high-level leg amputations of about 70%. Outcomes have greatly improved with appropriate antibiotic therapy. While there are now many oral and parenteral antibiotic agents that have demonstrated efficacy in treating diabetic foot infections, the rate of infection with multidrug-resistant pathogens is growing. This problem requires a multi-focal approach, including providing education to both clinicians and patients, developing robust antimicrobial stewardship programmes and using new diagnostic and therapeutic technologies. Recently, new methods have been developed to find novel antibiotic agents and to resurrect old treatments, like bacteriophages, for treating these difficult infections.

CONCLUSION

Medical and political leaders have recognized the serious global threat posed by the growing problem of antibiotic resistance. By a multipronged approach that includes exerting administrative pressure on clinicians to do the right thing, investing in new technologies and encouraging the profitable development of new antimicrobials, we may be able to stave off the coming 'post-antibiotic era'.