Klebsiella pneumoniae is a common cause of antimicrobial-resistant opportunistic infections in hospitalized patients. The species is naturally resistant to penicillins, and members of the population often carry acquired resistance to multiple antimicrobials. However, knowledge of K. pneumoniae ecology, population structure or pathogenicity is relatively limited. Over the past decade, K. pneumoniae has emerged as a major clinical and public health threat owing to increasing prevalence of healthcare-associated infections caused by multidrug-resistant strains producing extended-spectrum β-lactamases and/or carbapenemases. A parallel phenomenon of severe community-acquired infections caused by 'hypervirulent' K. pneumoniae has also emerged, associated with strains expressing acquired virulence factors. These distinct clinical concerns have stimulated renewed interest in K. pneumoniae research and particularly the application of genomics. In this Review, we discuss how genomics approaches have advanced our understanding of K. pneumoniae taxonomy, ecology and evolution as well as the diversity and distribution of clinically relevant determinants of pathogenicity and antimicrobial resistance. A deeper understanding of K. pneumoniae population structure and diversity will be important for the proper design and interpretation of experimental studies, for interpreting clinical and public health surveillance data and for the design and implementation of novel control strategies against this important pathogen.

Population genomics of Klebsiella pneumoniae.

SUMMARY β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Epidemiology of β-Lactamase-Producing Pathogens.

SUMMARY Surveillance studies have shown that OXA-48-like carbapenemases are the most common carbapenemases in Enterobacterales in certain regions of the world and are being introduced on a regular basis into regions of nonendemicity, where they are responsible for nosocomial outbreaks. OXA-48, OXA-181, OXA-232, OXA-204, OXA-162, and OXA-244, in that order, are the most common enzymes identified among the OXA-48-like carbapenemase group. OXA-48 is associated with different Tn1999 variants on IncL plasmids and is endemic in North Africa and the Middle East. OXA-162 and OXA-244 are derivatives of OXA-48 and are present in Europe. OXA-181 and OXA-232 are associated with ISEcp1, Tn2013 on ColE2, and IncX3 types of plasmids and are endemic in the Indian subcontinent (e.g., India, Bangladesh, Pakistan, and Sri Lanka) and certain sub-Saharan African countries. Overall, clonal dissemination plays a minor role in the spread of OXA-48-like carbapenemases, but certain high-risk clones (e.g., Klebsiella pneumoniae sequence type 147 [ST147], ST307, ST15, and ST14 and Escherichia coli ST38 and ST410) have been associated with the global dispersion of OXA-48, OXA-181, OXA-232, and OXA-204. Chromosomal integration of blaOXA-48 within Tn6237 occurred among E. coli ST38 isolates, especially in the United Kingdom. The detection of Enterobacterales with OXA-48-like enzymes using phenotypic methods has improved recently but remains challenging for clinical laboratories in regions of nonendemicity. Identification of the specific type of OXA-48-like enzyme requires sequencing of the corresponding genes. Bacteria (especially K. pneumoniae and E. coli) with blaOXA-48, blaOXA-181, and blaOXA-232 are emerging in different parts of the world and are most likely underreported due to problems with the laboratory detection of these enzymes. The medical community should be aware of the looming threat that is posed by bacteria with OXA-48-like carbapenemases.

The Global Ascendency of OXA-48-Type Carbapenemases.

Background In vitro data support the use of combination of aztreonam (ATM) with ceftazidime-avibactam (CAZ-AVI), but clinical studies are lacking. The aim of our study was to compare the outcome of patients with bloodstream infections (BSIs) due to metallo-β-lactamase (MBL)-producing Enterobacterales treated either with CAZ-AVI plus ATM or other active antibiotics (OAAs). Methods This was a prospective observational study including patients admitted to 3 hospitals in Italy and Greece. The primary outcome measure was 30-day all-cause mortality. Secondary outcomes were clinical failure at day 14 and length of stay after BSI diagnosis. Cox regression analysis including a propensity score (PS) for receiving CAZ-AVI + ATM was performed to evaluate primary and secondary outcomes. A PS-based matched analysis was also performed. Results We enrolled 102 patients with BSI; 82 had infections caused by NDM-producing (79 Klebsiella pneumoniae and 3 Escherichia coli) and 20 by VIM-producing (14 K. pneumoniae, 5 Enterobacter species, 1 Morganella morganii) strains. The 30-day mortality rate was 19.2% in the CAZ-AVI + ATM group vs 44% in the OAA group (P = .007). The PS-adjusted analysis showed that the use of CAZ-AVI + ATM was associated with lower 30-day mortality (hazard ratio [HR], 0.37 [95% confidence interval {CI}, .13-.74]; P = .01), lower clinical failure at day 14 (HR, 0.30 [95% CI, .14-.65]; P = .002), and shorter length of stay (subdistributional HR, 0.49 [95% CI, .30-.82]; P = .007). The PS-matched analysis confirmed these findings. Conclusions The CAZ-AVI + ATM combination offers a therapeutic advantage compared to OAAs for patients with BSI due to MBL-producing Enterobacterales. Further studies are warranted.

Efficacy of Ceftazidime-avibactam Plus Aztreonam in Patients With Bloodstream Infections Caused by Metallo-β-lactamase–Producing Enterobacterales

The Klebsiella pneumoniae complex comprises seven K. pneumoniae-related species, including K. variicola. K. variicola is a versatile bacterium capable of colonizing different hosts such as plants, ...

https://tandfonline.com/doi/pdf/10.1080/22221751.2019.1634981

Klebsiella variicola: an emerging pathogen in humans

SUMMARY New Delhi metallo-β-lactamase (NDM) is a metallo-β-lactamase able to hydrolyze almost all β-lactams. Twenty-four NDM variants have been identified in >60 species of 11 bacterial families, and several variants have enhanced carbapenemase activity. Klebsiella pneumoniae and Escherichia coli are the predominant carriers of blaNDM, with certain sequence types (STs) (for K. pneumoniae, ST11, ST14, ST15, or ST147; for E. coli, ST167, ST410, or ST617) being the most prevalent. NDM-positive strains have been identified worldwide, with the highest prevalence in the Indian subcontinent, the Middle East, and the Balkans. Most blaNDM-carrying plasmids belong to limited replicon types (IncX3, IncFII, or IncC). Commonly used phenotypic tests cannot specifically identify NDM. Lateral flow immunoassays specifically detect NDM, and molecular approaches remain the reference methods for detecting blaNDM. Polymyxins combined with other agents remain the mainstream options of antimicrobial treatment. Compounds able to inhibit NDM have been found, but none have been approved for clinical use. Outbreaks caused by NDM-positive strains have been reported worldwide, attributable to sources such as contaminated devices. Evidence-based guidelines on prevention and control of carbapenem-resistant Gram-negative bacteria are available, although none are specific for NDM-positive strains. NDM will remain a severe challenge in health care settings, and more studies on appropriate countermeasures are required.

NDM Metallo-β-Lactamases and Their Bacterial Producers in Health Care Settings.

A genome sequence-based analysis of 74 carbapenem-resistant Klebsiella pneumoniae (CRKP) from 12 hospitals in Sichuan, China, revealed that the isolates carried blaKPC-2 (n = 48), blaNDM (n = 22), or blaIMP-4 (n = 4) were identified as K. pneumoniae (n = 67), Klebsiella variicola (n = 5), and Klebsiella quasipneumoniae (n = 2) and belonged to 19 sequence types. Both inter- and intrahospital transmission of multiple ST11 strains was identified. There is an urgent need for all hospitals in a given region to coordinate actions against CRKP.

Carbapenem-resistant Isolates of the Klebsiella pneumoniae Complex in Western China: The Common ST11 and the Surprising Hospital-specific Types.

Abstract Background Understanding resident physicians’ perceptions of competency-based medical education(CBME) may help improve approaches for implementing such education in standardized resident training (SRT). We conducted surveys of residents in China to identify their perceptions of CBME and determine the degree to which such education impacts their career plans. Methods Questionnaire contained a total of 24 questions, which were answered using multiple choice or yes/no, was distributed to residents who were undergoing SRT, regardless of specialty, at 7 accredited training bases located across six provinces of China. The survey aimed to investigate residents’ reasons for participating in SRT, perceptions of CBME, interest in receiving CBME-associated courses, and attitudes towards CBME. Results Overall, 441 residents completed the questionnaire.17.7% (78/441) responded “no clear objective” before the participated in SRT. Only 3.9% (17/441) fully understood the objectives, training contents, and assessment system of the current “competency-based” standardized training program for residents in China. Residents ranked clinical skills and patient care, interpersonal communication, and professionalism, as the three most important competencies. Most were interested in the CBME residency programs. 90.7% felt that implementing CBME could help them clarify their professional direction and improve their career planning. Conclusion Residents had positive perceptions of the incorporation of CBME into SRT. Administrators, educational leaders, and clinical faculty should seek to further publicize and increase the popularity of CBME. 

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A survey of resident physicians’ perceptions of competency-based education in standardized resident training in China: a preliminary study

Objective
To investigate the concentrations of voriconazole (VCZ) in the central nervous system (CNS) of patients with cryptococcal meningitis and the relationship thereof.


Methods
We retrospectively analyzed the trough concentration of VCZ in the cerebrospinal fluid (CSF) and the blood of 25 adult patients who had cryptococcal meningitis, and who were not infected with HIV. We also examined patient-level characteristics that could contribute to the differences in CSF/plasma VCZ concentration ratio.


Results
The trough concentration of VCZ in plasma ranged from 0.38 to 8.56 mg/L, and the median (P 25, P 75) was 1.81 (1.40, 3.84) mg/L. The trough concentration of VCZ in CSF ranged from 0.17 to 3.92 mg/L, and the median (P 25, P 75) was 1.02 (0.54, 1.84) mg/L. The CSF VCZ trough concentration showed a slight negative correlation with the nucleated cell counts in CSF, but the correlation was not statistically significant ( r=-0.377, P=0.063). There was a positive correlation between VCZ concentrations in CSF and that in the plasma ( r=0.736, P<0.001), and the median (P 25, P 75) CSF/plasma ratio was 0.43 (0.34, 0.68). The CSF/plasma ratio did not statistically correlate with age, body surface area (BSA), radiology changes (hydrocephalus), or intracranial pressure.


Conclusion
There is a positive correlation between VCZ concentration in CSF and VCZ concentration in the plasma, and no influencing factors of CSF/plasma ratio were found.

[Clinical Analysis of Voriconazole Concentrations in Cerebrospinal Fluid and Blood in Patients with Ryptococcal Meningitis].

Abstract Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) currently has spread all over the world. However, the dynamic characteristics of SARS-CoV-2 infections have not previously been described in detail. Here, we report a cured patient in West China Hospital, and describe the dynamic detection of SARS-CoV-2-RNA in different specimens and viral specific IgM and IgG antibodies in blood. The findings suggest that the fecal SARS-CoV-2-RNA negativity may be considered as a new standard for de isolation. Serum IgM and IgG antibodies detection were helpful for early diagnosis of SARS-CoV-2 infection and judgment of patients in recovery stage, respectively.

https://doi.org/10.1097/id9.0000000000000040

Guangmin Tang

Papers

NDM Metallo-β-Lactamases and Their Bacterial Producers in Health Care Settings.

Carbapenem-resistant Isolates of the Klebsiella pneumoniae Complex in Western China: The Common ST11 and the Surprising Hospital-specific Types.

A survey of resident physicians’ perceptions of competency-based education in standardized resident training in China: a preliminary study

[Clinical Analysis of Voriconazole Concentrations in Cerebrospinal Fluid and Blood in Patients with Ryptococcal Meningitis].

A COVID-19 Patient Discharged According to Strict Discharge Standards: Viral Negativity in Both Nasopharynx and Feces