Dissemination of NDM-1 positive bacteria in the New Delhi environment and its implications for human health: an environmental point prevalence study

In Silico Characterization of blaNDM-Harboring Conjugative Plasmids in Acinetobacter Species

New Delhi metallo-β-lactamase (NDM)-producing clinical strains in Acinetobacter spp. have been recently reported in many countries and have received considerable attention. The vast majority of blaNDM cases occur on conjugative plasmids, which play a vital role in disseminating blaNDM. To characterize the conjugative plasmids bearing blaNDM genes in Acinetobacter spp., we analyzed the variants of blaNDM, conjugative transfer regions, genetic contexts of blaNDM, and the phylogenetic pattern of the 62 predicted blaNDM-positive plasmids, which were selected from 1,191 plasmids of Acinetobacter species from GenBank. We identified 30 conjugative plasmids from the 62 blaNDM-harboring plasmids in Acinetobacter species, with the oriT sites similar to plasmid pNDM-YR7 in our study, genes coding for relaxases of the MOBQ family, genes encoding type IV coupling proteins (T4CPs) of the TrwB/TraD subfamily, and VirB-like type IV secretion system (T4SS) gene clusters. The genome sizes of all 30 pNDM-YR7-like plasmids ranged from 39.36 kb to 49.65 kb, with a median size of 44.56 kb. The most common species of Acinetobacter containing the blaNDM-positive conjugative plasmids was A. baumannii, followed by Acinetobacter lwoffii and Acinetobacter indicus. Notably, pNDM-YR7 is the first report on a blaNDM-positive conjugative plasmid in Acinetobacter junii. Moreover, all 30 blaNDM-positive conjugative plasmids in Acinetobacter species were found to contain genetic contexts with the structure ISAba14-aph(3')-VI-ISAba125-blaNDM-ble. Our findings provide important insights into the phylogeny and evolution of blaNDM-positive plasmids of Acinetobacter species and further address their role in acquiring and spreading blaNDM genes in Acinetobacter species. IMPORTANCE Conjugative plasmids harboring the blaNDM gene play a vital role in disseminating carbapenem resistance. In this study, we first report a conjugative plasmid, pNDM-YR7, in Acinetobacter junii. Based on the genomic characteristics of the blaNDM-positive pNDM-YR7, we performed in silico typing and comparative analysis of blaNDM-positive plasmids using the 1,191 plasmids of Acinetobacter species available in the NCBI RefSeq database. We analyzed the characteristics of blaNDM-positive plasmids, including the variants of blaNDM, genetic features associated with blaNDM, conjugative transfer regions, and the phylogenetic pattern of the blaNDM-positive plasmids. All 30 blaNDM-positive conjugative plasmids were found to contain an ISAba14-aph(3')-VI-ISAba125-blaNDM-ble region. This study provides novel insights into the phylogeny and evolution of blaNDM-harboring conjugative plasmids and contributes to the repertoire of knowledge surrounding blaNDM-positive plasmids in the genus Acinetobacter.

Tandem Repeat of bla NDM-1 and Clonal Dissemination of a fosA3 and bla KPC-2 Co-Carrying IncR-F33: A-: B- Plasmid in Klebsiella pneumoniae Isolates Collected in a Southwest Hospital in China, 2010-2013

Introduction

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has been widespread in coastal cities of eastern China since 2009. However, how CRKP spreads and evolves in southwest China is unclear.

Aim

We investigated the genetic characteristics and dissemination mechanisms of carbapenemase genes in forty-one non-repetitive CRKP isolates collected from a southwest hospital, Kunming, Yunnan, during 2010-2013.

Methodology

Drug susceptibilities were analyzed by using VITEK 2 compact system. Genetic relationships were ascertained based on multilocus sequence typing (MLST) and Pulsed-field gel electrophoresis (PFGE) analysis. Genetic backgrounds of bla _KPC-2 and bla _NDM-1 were revealed by DNA walking and high-throughput sequencing.

Results

All isolates were highly resistant to common antibiotics except for tigecycline. In total, 34 bla _KPC-2, 3 bla _NDM-1, 1 bla _IMP-4 and 3 bla _IMP-26 genes were identified and KP67 plasmid 1 co-harbored bla _NDM-1 and bla _IMP-26. Five sequence types, namely ST11, ST290, ST340, ST395 and ST437, were recognized by MLST. Surprisingly, bla _KPC-2 was only detected in ST11 strains. We described a clonal dissemination of fosA3-positive IncR-IncF33:A-:B- multireplicon plasmid carrying the gene cassettes IS26-ΔTn3-ISKpn27-bla _KPC-2-ΔISKpn6-korC-klcA-ΔrepB-Tn1721 in all ST11 isolates. Three bla _NDM-1 positive isolates belonged to three different ST types and their bla _NDM-1 genetic backgrounds were also distinct. Interestingly, the flanking regions of bla _NDM-1 in KP67 and KP72 were duplicated into one to five copies in a form of tandem repeat by the transposition of IS91 like element. The bla _NDM-1 of KP82 was carried on a common IncX3 plasmid.

Conclusion

This study described the early epidemiological characteristics of bla _KPC-2/bla _NDM-1-carrying CRKP, and reported a new tandem repeat pattern of bla _NDM-1 cluster in Yunnan. These findings extend our knowledge on the carbapenemase gene evolutions.

Environmental surveillance of ESBL and carbapenemase-producing gram-negative bacteria in a Ghanaian Tertiary Hospital

Background

The burden of antibiotic resistant infection is mainly felt in low-to-middle income countries, where the rate of antimicrobial resistance is largely under-surveyed and under huge pressure from unregulated, disparate and often self-guided access to antimicrobials. Nosocomial infections from hospital environments have been shown to be a particularly prevalent source of multi-drug resistant strains, yet surveillance of hospital environmental contamination is often not investigated.

Methods

The study was prospective, observational and cross-sectional, sampling 231 high and low touch surfaces from 15th March to 13th April 2021, from five wards in the Cape Coast Teaching Hospital, Ghana. Microbial growth in the presence of vancomycin and either meropenem or cefotaxime was examined and bacterial species were identified by MALDI-TOF. The presence of common extended-spectrum β-lactamases (ESBL) and carbapenemase antimicrobial resistance genes (ARG) were identified through PCR screening, which were confirmed by phenotypic antimicrobial susceptibility determination. Isolates positive for carbapenem resistance genes were sequenced using a multi-platform approach.

Results

We recovered microbial growth from 99% of swabs (n = 229/231) plated on agar in the absence of antimicrobials. Multiple sites were found to be colonised with resistant bacteria throughout the hospital setting. Bacteria with multi-drug resistance and ARG of concern were isolated from high and low touch points with evidence of strain dissemination throughout the environment. A total of 21 differing species of bacteria carrying ARG were isolated. The high prevalence of Acinetobacter baumannii carrying bla_NDM-1 observed was further characterised by whole genome sequencing and phylogenetic analysis to determine the relationship between resistant strains found in different wards.

Conclusion

Evidence of multiple clonal incursions of MDR bacteria of high sepsis risk were found in two separate wards for a regional hospital in Ghana. The prevalence of multiple bla_NDM carrying species in combination with combinations of ESBLs was particularly concerning and unexpected in Africa. We also identify strains carrying tet(X3), bla_VIM-5 or bla_DIM-1 showing a high diversity of carbapenamases present as a reservoir in a hospital setting. Findings of multi-drug resistant bacteria from multiple environmental sites throughout the hospital will inform future IPC practices and aid research prioritisation for AMR in Ghana.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13756-022-01090-2.

Air temperature and incidence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae

BACKGROUND

Higher outdoor temperature may be related to an increase in antibiotic resistant bacteria. We investigated the association between local outdoor air temperature and the incidence of extended-spectrum betalactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) correcting for known drivers of antibiotic resistance.

METHODS

We performed a time-series regression study using prospectively collected weekly surveillance data on all ESBL-PE isolated from in- and outpatients of the University Hospital Basel, a tertiary care center in Switzerland, between 01/2008-12/2017. Temperature was measured hourly at the meteorological institute of the University Basel next to our institution over this time period. A time-series approach using a Poisson regression model and different lag terms for delayed exposure effects was performed to assess associations between minimal, mean and maximal weekly temperature and the number of ESBL-PE recovered.

RESULTS

Over 10 years, recovery of ESBL-PE increased (annual incidence rate ratio [IRR] 1.14, 95%CI 1.13-1.16), while mean weekly temperature measures remained stable. In multivariable analyses, increasing temperature was associated with higher recovery rates of ESBL-PE after three to four weeks, correcting for potential confounders, such as the number of admissions, proportion of long-term nursing facility- and ICU-admissions, age, Charlson comorbidity index and consumption of antimicrobials (IRRs per 10 °C ranging from 1.14 to 1.22, 95%CIs 1.07-1.33). These trends remained when analyzing correlations between temperature with the proportion of extended spectrum cephalosporin resistance of all recovered Enterobacteriaceae.

CONCLUSIONS

Higher outdoor temperature may be associated with an increase of ESBL-PE-incidence, independent of important confounders, such as antimicrobial consumption and thus should be considered for future resistance-trajectories.

Effect of temperature on Escherichia coli bloodstream infection in a nationwide population-based study of incidence and resistance

BACKGROUND

The incidence of Escherichia coli bloodstream infections (BSI) is high and increasing. We aimed to describe the effect of season and temperature on the incidence of E. coli BSI and antibiotic-resistant E. coli BSI and to determine differences by place of BSI onset.

METHODS

All E. coli BSI in adult Israeli residents between January 1, 2018 and December 19, 2019 were included. We used the national database of mandatory BSI reports and outdoor temperature data. Monthly incidence and resistance were studied using multivariable negative binomial regressions with season (July-October vs. other) and temperature as covariates.

RESULTS

We included 10,583 events, 9012 (85%) community onset (CO) and 1571 (15%) hospital onset (HO). For CO events, for each average monthly temperature increase of 5.5 °C, the monthly number of events increased by 6.2% (95% CI 1.6-11.1%, p = 0.008) and the monthly number of multidrug-resistant events increased by 4.9% (95% CI 0.3-9.7%, p = 0.04). The effect of season was not significant. For HO events, incidence of BSI and resistant BSI were not associated with temperature or season.

CONCLUSION

Temperature increases the incidence of CO E. coli BSI and CO antibiotic-resistant E. coli BSI. Global warming threatens to increase the incidence of E. coli BSI.

Pathogenic bacteria significantly increased under oxygen depletion in coastal waters: A continuous observation in the central Bohai Sea

The spread of pathogenic bacteria in coastal waters endangers the health of the local people and jeopardizes the safety of the marine environment. However, their dynamics during seasonal hypoxia in the Bohai Sea (BHS) have not been studied. Here, pathogenic bacteria were detected from the 16S rRNA gene sequencing database and were used to explore their dynamics and driving factors with the progressively deoxygenating in the BHS. Our results showed that pathogenic bacteria were detected in all samples, accounting for 0.13 to 24.65% of the total number of prokaryotic sequences in each sample. Pathogenic Proteobacteria was dominated in all samples, followed by Firmicutes, Actinobacteria, Tenericutes, and Bacteroidetes, etc. β-diversity analysis showed that pathogenic bacteria are highly temporally heterogeneous and regulated by environmental factors. According to RDA analysis, these variations may be influenced by salinity, ammonia, DO, phosphate, silicate, and Chl a. Additionally, pathogenic bacteria in surface water and hypoxia zone were found to be significantly separated in August. The vertical distribution of pathogenic bacterial communities is influenced by several variables, including DO and nutrition. It is noteworthy that the hypoxia zones increase the abundance of certain pathogenic genera, especially Vibrio and Arcobacter, and the stability of the pathogenic bacterial community increased from May to August. These phenomena indicate that the central Bohai Sea is threatened by an increasingly serious pathogenic community from May to August. And the developing hypoxia zone in the future may intensify this phenomenon and pose a more serious threat to human health. This study provides new insight into the changes of pathogenic bacteria in aquatic ecosystems and may help to make effective policies to control the spread of pathogenic bacteria.

Antimicrobial resistance in fish and poultry: Public health implications for animal source food production in Nigeria, Egypt, and South Africa

Antimicrobial resistance (AMR) is a significant threat to global public health. Specifically, excessive usage of antimicrobials in food animal production is one significant reason for AMR development in humans. Therefore, it is essential to identify the trends of AMR in fish and poultry and develop better surveillance strategies for the future. Despite this imperative need, such information is not well documented, especially in Africa. This study used a systematic review to assess AMR trend, spatial distribution, and incidence in fish and poultry research in Nigeria, Egypt, and South Africa. A literature assessment was conducted for published studies on AMR between 1989 and 2021 using the Scopus and Web of Science databases. One hundred and seventy-three relevant articles were obtained from the database search. Egypt was the leading exponent of antimicrobial resistance research (43.35%, 75 studies), followed by Nigeria (39.31%, 68 studies), then South Africa (17.34%, 30 studies). The majority of the antimicrobial resistance studies were on poultry in Egypt (81%, 61 studies), Nigeria (87%, 59 studies), and South Africa (80%, 24 studies). Studies on fish were 17% (13 studies), 9% (6 studies), and 10% (3 studies) in Egypt, Nigeria, and South Africa, respectively. Antimicrobial resistance patterns showed multiple drug resistance and variations in resistant genes. AMR research focused on sulfamethoxazole groups, chloramphenicol, trimethoprim, tetracycline, erythromycin, and ampicillin. Most studies employed the disk diffusion method for antimicrobial susceptibility tests. Among the four mechanisms of AMR, limiting drug uptake was the most reported in this study (both in fish and poultry). The findings reveal public and environmental health threats and suggest that it would be useful to promote and advance AMR research, particularly for countries on the global hotspot for antimicrobial use.

One Health approaches adapted in low resource settings to address antimicrobial resistance

Inter-disciplinary collaborations are now considered as key factors for integrated health system strengthening. Its application in the domain of One Health needs more milestones to achieve. Other than the human health sector, the antimicrobials are used in food animals and aquaculture for therapy, prophylaxis and growth promotion which significantly contributes to the development of antimicrobial resistance. It is the high time to develop a sustainable collaboration between the concerned sectors of One Health for a resilient health system. The domain of One Health not only mitigates the emergence of antimicrobial resistance but also helps in realizing the surveillance and epidemiology of zoonotic diseases, and the control of public health emergencies such as COVID-19. The review identified the key One Health strategies adapted by India, the exemplary low resource settings, to address antimicrobial resistance and zoonosis.

Clinically Relevant β-Lactam Resistance Genes in Wastewater Treatment Plants

Antimicrobial resistance (AMR) is one of the largest global concerns due to its influence in multiple areas, which is consistent with One Health's concept of close interconnections between people, animals, plants, and their shared environments. Antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) circulate constantly in various niches, sediments, water sources, soil, and wastes of the animal and plant sectors, and is linked to human activities. Sewage of different origins gets to the wastewater treatment plants (WWTPs), where ARB and ARG removal efficiency is still insufficient, leading to their transmission to discharge points and further dissemination. Thus, WWTPs are believed to be reservoirs of ARGs and the source of spreading AMR. According to a World Health Organization report, the most critical pathogens for public health include Gram-negative bacteria resistant to third-generation cephalosporins and carbapenems (last-choice drugs), which represent β-lactams, the most widely used antibiotics. Therefore, this paper aimed to present the available research data for ARGs in WWTPs that confer resistance to β-lactam antibiotics, with a particular emphasis on clinically important life-threatening mechanisms of resistance, including extended-spectrum β-lactamases (ESBLs) and carbapenemases (KPC, NDM).

A Cephalosporin-Tripodalamine Conjugate Inhibits Metallo-β-Lactamase with High Efficacy and Low Toxicity

The wide spread of metallo-β-lactamase (MBL)-expressing bacteria has greatly threatened human health, and there is an urgent need for inhibitors against MBLs. Herein, we present a cephalosporin-tripodalamine conjugate (DPASC) as a potent MBL inhibitor with a block-release design. The cephalosporin tag blocks the ligand binding site to reduce toxicity and is cleaved by MBLs to release active ligands to inhibit MBLs in situ. The screening of MBL-expressing pathogenic strains with 16 μg/mL DPASC showed a decrease of the minimum inhibitory concentration of meropenem (MEM) by 16 to 512-fold, and its toxicity was minimal to human HepG2 cells, with an IC₅₀ exceeding 512 μg/mL. An in vivo infection model with Galleria mellonella larvae showed an increased 3-day survival rate of 87% with the coadministration of DPASC and MEM, compared to 50% with MEM alone and no toxicity at a dose of 256 mg/kg of DPASC. Our findings with DPASC demonstrate that it is an effective MBL inhibitor and that the block-release strategy could be useful for the development of new MBL inhibitors.

Efficacy of Five Disinfectant Products Commonly Used in Pig Herds against a Panel of Bacteria Sensitive and Resistant to Selected Antimicrobials

The growing threat of antimicrobial resistance worldwide has led to an increasing concern in the human, veterinary, and environmental fields, highlighting the need for strategies to effectively control bacterial contamination. Correct biosecurity practices, including the appropriate use of disinfectants, play a crucial role in controlling bacterial contamination. This study aimed to verify whether the recommended concentrations defined according to the Defra General Orders concentration (GO, published by the UK Department for Environment, Food and Rural Affairs' disinfectant-approval scheme) of five commercial disinfectant preparations (peroxygen-based, phenol-based, two halogen-releasing agents, and glutaraldehyde/quaternary ammonium compound-based; disinfectants A to E, respectively) were sufficient to inhibit growth and inactivate selected bacterial strains, including some that carry known phenotypic patterns of multidrug resistance. The effectiveness of each disinfectant was expressed as the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values, determined by the broth-microdilution method. The results indicate that the type of disinfectant and its concentration influence the inhibitory and bactericidal efficacy. The glutaraldehyde/quaternary ammonium compound-based (disinfectant D) and chlorocresol-based products (disinfectant B) were the most effective, and the GO concentration was bactericidal in all the strains tested. The efficacy of the other compounds varied, depending on the bacterial species tested. The GO concentrations were at least able to inhibit the bacterial growth in all the products and bacterial strains tested. A greater tolerance to the compounds was observed in the strains of E. coli with multidrug-resistance profiles compared to the strains that were sensitive to the same antimicrobials.

Studies toward synthesis of the core skeleton of spiroaspertrione A

Bioassay-guided isolation of spiroaspertrione A from cultures of Aspergillus sp. TJ23 in 2017 demonstrated potent resensitization of oxacillin against methicillin-resistant Staphylococcus aureus by lowering the oxacillin minimal inhibitory concentration up to 32-fold. To construct this unique spiro[bicyclo[3.2.2]nonane-2,1′-cyclohexane] system, a protocol for ceric ammonium nitrate-induced intramolecular cross-coupling of silyl enolate is disclosed.

Diversity and abundance of antibiotic resistance genes and their relationship with nutrients and land use of the inflow rivers of Taihu Lake

Taihu Lake is the third largest freshwater lake in China and an important source for drinking water, flood protection, aquaculture, agriculture, and other activities. This lake is connected to many principal and small rivers with inflow from west and outflow on the eastern side of the lake and these inflow rivers are believed to significantly contribute to the water pollution of the lake. This study was aimed at assessing the diversity and abundance of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs), and their relationship with water quality parameters and land use patterns. Water samples were collected from 10 major inflow rivers and the source water protection area of the Taihu Lake in spring and summer 2019. High-throughput profiling was used to detect and quantify 384 ARGs and MGEs and in addition, 11 water quality parameters were analyzed. The results showed that the number of ARGs/MGEs detected in each inflow river ranged from 105 to 185 in spring and 107 to 180 in summer. The aminoglycoside resistance genes were the most dominant types ARGs detected followed by beta-lactam resistance, multidrug resistance, macrolide-lincosamide-streptogramin B (MLSB) resistance genes, which contributed to 65% of the ARGs. The water quality parameters showed significant correlation with absolute abundance of ARGs. Furthermore, significant correlation between ARGs and MGEs were also observed which demonstrates potential gene transfer among organisms through horizontal gene transfer via MGEs. ARGs showed strong positive correlation with cultivated and industrial lands whereas, negative correlation was observed with river, lake, forest, land for green buffer, and land for port and harbor. The overall results indicate that the inflow rivers of Taihu Lake are polluted by various sources including multiple nutrients and high abundance of ARGs, which needs attention for better management of the inflow rivers of this lake.

Novel Megaplasmid Driving NDM-1-Mediated Carbapenem Resistance in Klebsiella pneumoniae ST1588 in South America

Carbapenem-resistant Enterobacterales (CRE) is a critical public health problem in South America, where the prevalence of NDM metallo-betalactamases has increased substantially in recent years. In this study, we used whole genome sequencing to characterize a multidrug-resistant (MDR) Klebsiella pneumoniae (UCO-361 strain) clinical isolate from a teaching hospital in Chile. Using long-read (Nanopore) and short-read (Illumina) sequence data, we identified a novel un-typeable megaplasmid (314,976 kb, pNDM-1_UCO-361) carrying the bla_NDM-1 carbapenem resistance gene within a Tn3000 transposon. Strikingly, conjugal transfer of pNDM-1_UCO-361 plasmid only occurs at low temperatures with a high frequency of 4.3 × 10⁻⁶ transconjugants/receptors at 27 °C. UCO-361 belonged to the ST1588 clone, previously identified in Latin America, and harbored aminoglycoside, extended-spectrum β-lactamases (ESBLs), carbapenem, and quinolone-resistance determinants. These findings suggest that bla_NDM-1-bearing megaplasmids can be adapted to carriage by some K. pneumoniae lineages, whereas its conjugation at low temperatures could contribute to rapid dissemination at the human–environmental interface.

The antimicrobial peptide LI14 combats multidrug-resistant bacterial infections

The prevalence of multidrug-resistant (MDR) pathogens raises public fears of untreatable infections and represents a huge health risk. There is an urgent need to exploit novel antimicrobial agents. Due to the unique mechanisms, antimicrobial peptides (AMPs) with a low probability to achieve resistance are regarded as potential antibiotic alternatives to address this issue. Herein, we develop a panel of synthetic peptide compounds with novel structures based on the database filters technology (DFT), and the lead peptide LI14 shows potent antibacterial activity against all tested drug-resistant bacteria. LI14 exhibits rapid bactericidal activity and excellent anti-biofilm and -persisters activity, simultaneously showing a low propensity to induce resistance. Moreover, LI14 shows tolerance against pH, temperatures, and pepsin treatment, and no detectable toxicity both in vitro and in vivo. Mechanistic studies revealed that LI14 induces membrane damage by targeting bacterial-specific membrane components and dissipates the proton motive force (PMF), thereby resulting in metabolic perturbations and the accumulation of toxic metabolic products. Furthermore, LI14 sensitizes clinically relevant antibiotics against MDR bacteria. In animal models of infection, LI14 or combined with antibiotics are effective against drug-resistant pathogens. These findings suggest that LI14 is a promising antibiotic candidate to tackle MDR bacterial infections.

A synthetic peptide LI14 demonstrates potent antibacterial activity against drug-resistant bacteria in vitro and in vivo by inducing membrane damage and disrupting membrane potential leading to metabolic perturbation.

Multidrug-Resistant Bacteria: Their Mechanism of Action and Prophylaxis

In the present scenario, resistance to antibiotics is one of the crucial issues related to public health. Earlier, such resistance to antibiotics was limited to nosocomial infections, but it has now become a common phenomenon. Several factors, like extensive development, overexploitation of antibiotics, excessive application of broad-spectrum drugs, and a shortage of target-oriented antimicrobial drugs, could be attributed to this condition. Nowadays, there is a rise in the occurrence of these drug-resistant pathogens due to the availability of a small number of effective antimicrobial agents. It has been estimated that if new novel drugs are not discovered or formulated, there would be no effective antibiotic available to treat these deadly resistant pathogens by 2050. For this reason, we have to look for the formulation of some new novel drugs or other options or substitutes to treat such multidrug-resistant microorganisms (MDR). The current review focuses on the evolution of the most common multidrug-resistant bacteria and discusses how these bacteria escape the effects of targeted antibiotics and become multidrug resistant. In addition, we also discuss some alternative mechanisms to prevent their infection as well.

Sub-lethal photocatalysis promotes horizontal transfer of antibiotic resistance genes by conjugation and transformability

The spread of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in water is increasingly becoming a worldwide problem due to frequent recent major public health events. Herein, the horizontal ARG transfer mechanisms were studied under sub-lethal photocatalysis. The results show that ARGs had at most a 3- to 6-fold increase in the conjugative transfer frequency when only donor bacteria were induced with sub-lethal photocatalysis, while the frequency exhibited a trend toward inhibition when only the recipient bacteria were induced. However, when the donor or recipient bacteria were induced beforehand for a specific time, the frequency increased by a maximum of 10- to 22-fold. Moreover, the horizontal transfer frequency and its mechanism were related to the oxidative stress systems, ATP systems and the expression of related genes. Furthermore, the transformability of extracellular plasmids of the ARB and the contribution in horizontal transfer were also studied. Results show that the transformation frequency accounted for up to 50% of the total number of transconjugants, indicating that transformation might be a primary mode of horizontal ARG transfer by ARB in water. All of the above results demonstrate that sub-lethal photocatalysis will increase the frequency of horizontal gene transfer of ARGs through both conjugative transfer and the transformation pathway, which increases the risk of ARB in aquatic environments.

A case–control study of infections caused by Klebsiella pneumoniae producing New Delhi metallo-beta-lactamase-1: Predictors and outcomes

Introduction

Infections caused by antimicrobial-resistant bacteria are a significant cause of death worldwide, and carbapenemase-producing bacteria are the principal agents. New Delhi metallo-beta-lactamase-1 producing Klebsiella pneumoniae (KP-NDM-1) is an extensively drug-resistant bacterium that has been previously reported in Mexico. Our aim was to conduct a case–control study to describe the risk factors associated with nosocomial infections caused by K. pneumoniae producing NDM-1 in a tertiary-care hospital in Mexico.

Methods

A retrospective case–control study with patients hospitalized from January 2012 to February 2018 at the Hospital Civil de Guadalajara “Fray Antonio Alcalde” was designed. During this period, 139 patients with a culture that was positive for K. pneumoniae NDM-1 (cases) and 486 patients hospitalized in the same department and on the same date as the cases (controls) were included. Data were analyzed using SPSS v. 24, and logistic regression analysis was conducted to calculate the risk factors for KP-NDM-1 infection.

Results

One hundred and thirty-nine case patients with a KP-NDM-1 isolate and 486 control patients were analyzed. In the case group, acute renal failure was a significant comorbidity, hospitalization days were extended, and significantly more deaths occurred. In a multivariate analysis of risk factors, the independent variables included the previous use of antibiotics (odds ratio, OR = 12.252), the use of a urinary catheter (OR = 5.985), the use of a central venous catheter (OR = 5.518), the use of mechanical ventilation (OR = 3.459), and the length of intensive care unit (ICU) stay (OR = 2.334) as predictors of infection with NDM-1 K. pneumoniae.

Conclusion

In this study, the previous use of antibiotics, the use of a urinary catheter, the use of a central venous catheter, the use of mechanical ventilation, and ICU stay were shown to be predictors of infection with NDM-1 K. pneumoniae and were independent risk factors for infection with NDM-1 K. pneumoniae.

The Spread of Antibiotic Resistance Genes In Vivo Model

Infections caused by antibiotic-resistant bacteria are a major public health threat. The emergence and spread of antibiotic resistance genes (ARGs) in the environment or clinical setting pose a serious threat to human and animal health worldwide. Horizontal gene transfer (HGT) of ARGs is one of the main reasons for the dissemination of antibiotic resistance in vitro and in vivo environments. There is a consensus on the role of mobile genetic elements (MGEs) in the spread of bacterial resistance. Most drug resistance genes are located on plasmids, and the spread of drug resistance genes among microorganisms through plasmid-mediated conjugation transfer is the most common and effective way for the spread of multidrug resistance. Experimental studies of the processes driving the spread of antibiotic resistance have focused on simple in vitro model systems, but the current in vitro protocols might not correctly reflect the HGT of antibiotic resistance genes in realistic conditions. This calls for better models of how resistance genes transfer and disseminate in vivo. The in vivo model can better mimic the situation that occurs in patients, helping study the situation in more detail. This is crucial to develop innovative strategies to curtail the spread of antibiotic resistance genes in the future. This review aims to give an overview of the mechanisms of the spread of antibiotic resistance genes and then demonstrate the spread of antibiotic resistance genes in the in vivo model. Finally, we discuss the challenges in controlling the spread of antibiotic resistance genes and their potential solutions.

Characterization of structurally related peptide impurities using HPLC-QTOF-MS/MS: application to Cbf-14, a novel antimicrobial peptide

Cbf-14 (RLLRKFFRKLKKSV), a designed antimicrobial peptide derived from the cathelicidin family, is effective against drug-resistant bacteria. Structurally related peptide impurities in peptide medicines probably have side effects or even toxicity, thus impurity profiling research during the entire production process is indispensable. In this study, a simple liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method using a quadrupole time-of-flight (Q-TOF) mass spectrometer was developed for separation, identification, and characterization of structurally related peptide impurities in Cbf-14. A total of one process-related impurity and thirty-two degradation products were identified, and seven of them have been synthesized and confirmed. These impurities have not been declared in custom synthetic peptides. The degradation products were divided into five categories: fifteen Cbf-14 hydrolysates, five Cbf-14 isomers, four acetyl-Cbf-14 isomers, two aldimine derivatives, and six oxidized impurities. Combined with the peptide synthesis and the stress-testing studies, the origins and the formation mechanisms of these impurities were elucidated, which provides a unique insight for the follow-up quality study of Cbf-14 and other peptide products.

Epidemiology and clinical characteristics of infection/colonization due to carbapenemase-producing Enterobacterales in neonatal patients

Background

The aim of this study was to elucidate the epidemiological features of carbapenemase-producing Enterobacterales (CPE) in the pediatric and neonatal patients, to describe clinical characteristics of neonatal patients with CPE infections, and to assess risk factors for neonatal rectal colonization with CPE.

Results

A total of 439 carbapenem-resistant Enterobacterales (CRE) isolates recovered from 367 infant patients were characterised, including 397 isolates of Klebsiella pneumoniae (KP) and 42 isolates of Escherichia coli (EC). Carbapenemase gene blaNDM-1 was the most commonly detected, accounting for 86.56% (n = 380), followed by blaKPC-2 (9.11%, 40) and blaIMP-4 (4.33%, 19). MLST analysis showed 17 different STs detected within CPKP isolates, with ST20, ST2068, ST36 and ST17 being the most frequently isolated types. Eleven STs were identified within CPEC isolates, with ST325 being the dominant types. Eight isolates of NDM-1 producing KP, belonging to ST23, were identified as having hypervirulent traits. The main infections caused by CPE were pneumonia (n = 90) and sepsis (n = 16). All infected patients received monotherapy, with meropenem and ciprofloxacin being the most commonly used antibiotics. All pneumonia patients were cured or improved after treatment. Of the 16 patients with sepsis, 9 were cured or improved, 3 died, and 4 abandoned treatment without any clinical improvement. The rectal prevalences of CPE in the 0–3 days old (DO), the 4–28 DO, and the 29 DO-1 year old groups were decreased from 15.31%, 27.37% and 14.29% in the first stool screening period to 11.78%, 19.59% and 4.07% in the second stool screening period, respectively. Multivariate analysis showed that cesarean section, acidosis, respiration failure, gastric lavage and enema were independent risk factors for rectal colonization in the 0–3 DO group, whereas cesarean section, cephalosporins, gastric lavage and residence in rural area were independently associated with rectal colonization in the 4–28 DO group. The implementation of a series of evidence-based control measures eventually contained the CPE transmission.

Conclusions

Continued vigilance, epidemiological studies, and multimodal infection prevention strategies are urgently needed due to frequent importations.

Dissemination of carbapenemase-producing Enterobacterales in the community of Rawalpindi, Pakistan

Carbapenems are considered last-line beta-lactams for the treatment of infections caused by multidrug-resistant Gram-negative bacteria. However, their activity is compromised by the rising prevalence of carbapenemase-producing Enterobacterales (CPE), which are especially marked in the Indian subcontinent. In Pakistan, previous reports have warned about the possible spread of CPE in the community, but data are still partial. This study was carried out to analyse the prevalence of CPE, the genetic characterisation, and phylogenetic links among the spreading CPE in the community. In this cohort study, we collected 306 rectal swabs from patients visiting Benazir Bhutto hospital, Rawalpindi. CPEs were screened by using ertapenem-supplemented MacConkey agar. Identification was performed by using conventional biochemical tests, and genomes were sequenced using Illumina chemistry. Antibiotic resistance genes, plasmid incompatibility groups, and Escherichia coli phylogroups were determined in silico. Sequence types were determined by using MLST tool. The prevalence of CPE carriage observed was 14.4% (44/306 samples). The most common carbapenemase-encoding gene was bla-_NDM-5 (n = 58) followed by bla_NDM-1 (n = 7), bla_NDM (non-assigned variant, n = 4), bla_OXA-181 (n = 3), bla_OXA-232 (n = 3) and bla_NDM-7 (n = 1). Most of the CPE were E. coli (55/64, 86%), and the genomic analysis revealed a pauciclonal diffusion of E. coli with ST167 (n = 14), 405 (n = 10), 940 (n = 8), 648 (n = 6) and 617 (n = 5). We obtained a second sample from 94 patients during their hospital stay in whom carriage was negative at admission and found that 7 (7.4%) acquired a CPE. Our results indicate that the prevalence of CPE carriage in the Pakistani urban community was high and driven by the dissemination of some E. coli clones, with ST167 being the most frequent. The high CPE carriage in the community poses a serious public health threat and calls for implementation of adequate preventive measures.

Genomic Surveillance of Clinical Pseudomonas aeruginosa Isolates Reveals an Additive Effect of Carbapenemase Production on Carbapenem Resistance

Carbapenem resistance in Pseudomonas aeruginosa is increasing globally, and surveillance to define the mechanisms of such resistance in low- and middle-income countries is limited. This study establishes the genotypic mechanisms of β-lactam resistance by whole-genome sequencing (WGS) in 142 P. aeruginosa clinical isolates recovered from three hospitals in Islamabad and Rawalpindi, Pakistan between 2016 and 2017. Isolates were subjected to antimicrobial susceptibility testing (AST) by Kirby-Bauer disk diffusion, and their genomes were assembled from Illumina sequencing data. β-lactam resistance was high, with 46% of isolates resistant to piperacillin-tazobactam, 42% to cefepime, 48% to ceftolozane-tazobactam, and 65% to at least one carbapenem. Twenty-two percent of isolates were resistant to all β-lactams tested. WGS revealed that carbapenem resistance was associated with the acquisition of metallo-β-lactamases (MBLs) or extended-spectrum β-lactamases (ESBLs) in the blaGES, blaVIM, and blaNDM families, and mutations in the porin gene oprD. These resistance determinants were found in globally distributed lineages, including ST235 and ST664, as well as multiple novel STs which have been described in a separate investigation. Analysis of AST results revealed that acquisition of MBLs/ESBLs on top of porin mutations had an additive effect on imipenem resistance, suggesting that there is a selective benefit for clinical isolates to encode multiple resistance determinants to the same drugs. The strong association of these resistance determinants with phylogenetic background displays the utility of WGS for monitoring carbapenem resistance in P. aeruginosa, while the presence of these determinants throughout the phylogenetic tree shows that knowledge of the local epidemiology is crucial for guiding potential treatment of multidrug-resistant P. aeruginosa infections. IMPORTANCE Pseudomonas aeruginosa is associated with serious infections, and treatment can be challenging. Because of this, carbapenems and β-lactam/β-lactamase inhibitor combinations have become critical tools in treating multidrug-resistant (MDR) P. aeruginosa infections, but increasing resistance threatens their efficacy. Here, we used WGS to study the genotypic and phylogenomic patterns of 142 P. aeruginosa isolates from the Potohar region of Pakistan. We sequenced both MDR and antimicrobial susceptible isolates and found that while genotypic and phenotypic patterns of antibiotic resistance correlated with phylogenomic background, populations of MDR P. aeruginosa were found in all major phylogroups. We also found that isolates possessing multiple resistance mechanisms had significantly higher levels of imipenem resistance compared to the isolates with a single resistance mechanism. This study demonstrates the utility of WGS for monitoring patterns of antibiotic resistance in P. aeruginosa and potentially guiding treatment choices based on the local spread of β-lactamase genes.

Association of Carbapenemase-Producing Enterobacterales Detected in Stream and Clinical Samples

Background

The spread of carbapenem-resistant Enterobacterales (CRE) strains has caused treatment failure and is a worldwide threat to public health. However, there are limited reports on the prevalence of carbapenemase-producing Enterobacterales (CPE) in aquatic environments and its association with clinical isolates. This study aimed to investigate the prevalence of CPE in a stream environment and its genetic relationship with clinical isolates in Korea.

Methods

A total of 4,582 water samples were collected from 94 streams. Multiplex PCR and sequencing were used to detect and identify six carbapenemase genes. Multi-locus sequence typing (MLST) was performed to investigate the genetic relatedness between the environmental strains and clinical isolates.

Results

A total of 133 CRE strains were isolated from the streams. Klebsiella pneumoniae was the most common CRE (45.9%), followed by Enterobacter cloacae complex (29.3%), Escherichia coli (13.5%), Raoultella ornithinolytica (5.3%), and Citrobacter freundii (2.3%). Ninety (67.7%) isolates carried carbapenemase genes. K. pneumoniae carbapenemase-2 (36.7%) and New Delhi metallo-β-lactamase-5 (32.2%) were the common carbapenemases detected. Sequence type (ST)307 and ST11 K. pneumoniae strains harboring the bla_KPC-2 gene were the most prevalent in stream and patient samples.

Conclusion

CPE was highly prevalent in streams and closely related to the isolates obtained from patients. Therefore, continuous monitoring of stream environments is required to control the spread of carbapenem resistance.

Otilonium bromide boosts antimicrobial activities of colistin against Gram-negative pathogens and their persisters

Colistin is the last-line antibiotic against Gram-negative pathogens. Here we identify an FDA-approved drug, Otilonium bromide (Ob), which restores the activity of colistin against colistin-resistant Gram-negative bacteria in vitro and in a mouse infection model. Ob also reduces the colistin dosage required for effective treatment of infections caused by colistin-susceptible bacteria, thereby reducing the toxicity of the drug regimen. Furthermore, Ob acts synergistically with colistin in eradicating multidrug-tolerant persisters of Gram-negative bacteria in vitro. Functional studies and microscopy assays confirm that the synergistic antimicrobial effect exhibited by the Ob and colistin involves permeabilizing the bacterial cell membrane, dissipating proton motive force and suppressing efflux pumps, resulting in membrane damages, cytosol leakage and eventually bacterial cell death. Our findings suggest that Ob is a colistin adjuvant which can restore the clinical value of colistin in combating life-threatening, multidrug resistant Gram-negative pathogens.

The drug otilonium bromide restores the activity of colistin against colistinresistant Gram-negative bacteria in vitro and in a mouse infection model, suggesting that this combination may restore the value of colistin in treatment of antibiotic resistant disease.

Co-transfer of mcr-8 with blaNDM-1 or tmexCD1-toprJ1 by plasmid hybridisation

Carbapenems, tigecycline and colistin are three important antimicrobial agents for the treatment of clinical infections caused by multidrug-resistant Enterobacteriaceae. Here we characterised the formation of hybrid plasmids containing mcr-8 and bla_NDM-1 or tmexCD1-toprJ1 that could confer resistance to colistin and carbapenems or tigecycline. More specifically, these clinically important genes could be co-transferred through IS26- and ltrA-mediated plasmid fusion to clinical isolates during conjugation under single drug (colistin) selection, following which the recipient strains became carbapenem- or tigecycline-resistant. The transferability and stability of these hybrid multidrug resistance (MDR) plasmids depend on the bacterial host and the presence of antibiotics. Further evolution and adaptation of these hybrid plasmids may facilitate their emergence and spread, which is of great concern for clinical therapy.

Prevalence of faecal carriage of Carbapenemase Producing Enterobacteriaceae in healthy Indian subjects from the community

PURPOSE

Faecal carriage of carbapenemase-producing Enterobacterales (CPE) has been extensively investigated in hospitalized patients, but limited data is available on the carriage rate in healthy individuals in India.

METHODS

A total of 1000 stool samples were screened for CPE from healthy individuals in Chennai (n ​= ​50), Hyderabad (n ​= ​184) and Mumbai (n ​= ​766). Diluted stool samples were cultured on chromID CARBA SMART plates. Growing colonies were screened for CPE by RAPIDEC® CARBA NP Test and minimum inhibitory concentration (MIC) of imipenem by E-Test. PCR was performed for confirmation of CPE genes.

RESULTS

Out of the 1000 stool samples tested, 6.1% were positive for CPE. A total of 64 carbapenem resistant isolates (56 ​E.coli, 4 Klebsiella pneumoniae, 3 Enterobacter cloacae and 1 Citrobacter freundii) were recovered from ChromID CARBA SMART biplate. Carbapenemase production was identified in 57/64 isolates by RAPIDEC® CARBA NP test. PCR analysis showed 28 bla_NDM-1 and 33 bla_OXA48. Three remaining isolates (2 ​E.coli, 1 ​K.pneumoniae) were negative for the tested carbapenemase genes. Interestingly, out of these 61 PCR positive isolates, 49.1% displayed imipenem MIC within the susceptibility range on the basis of CLSI interpretative criteria.

CONCLUSIONS

Faecal carriage of CPE among healthy individuals was 6.1%. Comprehensive measures to improve the sanitation scenario and implementation of National AMR action plan are needed to prevent further generation and dissemination of carbapenem resistant Enterobacterales (CRE).

Worldwide Prevalence of mcr-mediated Colistin-Resistance Escherichia coli in Isolates of Clinical Samples, Healthy Humans, and Livestock-A Systematic Review and Meta-Analysis

Background: Antimicrobial resistance is a serious public-health problem throughout the world. Escherichia coli, the most common Gram-negative microorganism, has developed different resistance mechanisms, making treating infections difficult. Colistin is considered a last-resort drug in the treatment of infections caused by E. coli. Plasmid-mediated mobile-colistin-resistant (mcr) genes in E. coli, now disseminated globally, are considered a major public-health threat. Humans, chickens, and pigs are the main reservoirs for E. coli and the sources of antibiotic resistance. Hence, an up-to-date and precise estimate of the global prevalence of mcr resistance genes in these reservoirs is necessary to understand more precisely the worldwide spread and to more effectively implement control and prevention strategies. Methodology: Publications were identified in the PubMed database on the basis of the PRISMA guidelines. English full-text articles were selected from December 2014 to March 2021. Descriptive statistics and a meta-analysis were performed in Excel and R software, respectively. Colistin resistance was defined as the molecular-genetic detection of the mcr genes. The crude and estimated prevalence were calculated for each host and continent. The studies were divided into two groups; community-based when they involved isolates from healthy humans, chickens, or pigs, and clinical studies when they involved only hospital, outpatient, or laboratory isolates. Results: A total of 1278 studies were identified and 218 were included in this systematic review and meta-analysis, divided into community studies (159 studies) and clinical studies (59 studies). The general prevalence of mcr-mediated colistin-resistant E. coli (mcrMCRE) was 6.51% (n = 11,583/177,720), reported in 54 countries and on five continents; Asia with 119 studies followed by Europe with 61 studies registered the most articles. Asia reported the major diversity of mcr-variants (eight of nine, except mcr-2). Worldwide, chickens and pigs proved to be the principal reservoir of mcr with an estimated prevalence of 15.8% and 14.9%, respectively. Healthy humans and clinical isolates showed a lower prevalence with 7.4% and 4.2% respectively. Conclusions: In this systematic review and meta-analysis, the worldwide prevalence of mcr in E. coli isolated from healthy humans, chickens, and pigs was investigated. A wide prevalence and distribution of mcr genes was demonstrated on all continents in E. coli isolates from the selected reservoirs. Understanding the epidemiology and occurrence in the reservoirs of mcr in E. coli on different continents of the world facilitates tracing how mcr genes are transmitted and determining the infection risks for humans. This knowledge can be used to reduce the incidence of zoonotic transmission by implementing the appropriate control programs.

Molecular Epidemiology, Microbial Virulence, and Resistance of Carbapenem-Resistant Enterobacterales Isolates in a Teaching Hospital in Guangzhou, China

Infection caused by carbapenem-resistant Enterobacterales (CRE) is a global public health problem. We performed whole-genome sequencing to investigate the molecular epidemiological characteristics of local CRE infections and understand the prevalence of hypervirulent carbapenem-resistant Klebsiella pneumoniae (CRKP). Analysis of multiLocus sequence typing (MLST), antibiotic resistance genes, plasmid replicons, virulence genes, and the genetic environment was also performed. Klebsiella pneumoniae (89, 60.95%) was the most common CRE species, primarily prevalent in the intensive care unit (36, 40.45%). Most CRE strains showed a high resistance rate to multiple antibiotics, especially cephalosporins and carbapenems. However, most of these isolates were susceptible to tigecycline (81.7%). Notably, the predominant sequence type (ST) of CRKP isolates was ST11 (80.90%, 72/89), with 93.05% as Klebsiella pneumoniae carbapenemase (KPC)-ST11. In Escherichia coli isolates, ST410 (21.43%, 6/28) was the predominant type, with approximately half carrying bla_NDM-5, and importantly, the ST167 carbapenem-resistant Escherichia coli (CRECO) harbors both New Delhi metallo-β-lactamase (NDM)-5 and KPC-2. In Enterobacter cloacae isolates, three cases of ST88 were carrying the bla_NDM-1 gene, and the ST594 carbapenem-resistant Enterobacter cloacae (CRECC) carrying NDM-1 and KPC-2 has also been identified. In addition, we found three novel STs, ST5386-ST5388. The IncFII (pHN7A8) (98.41%, 62/63) was the most common plasmid replicon type in KPC-2-producing CRKP strains, and the predominant plasmid ST of IncF was [f33:A-:B-] (n = 73). Two CRKP isolates were found to carry 4 virulence genes (iutA, iroB, rmpA, and rmpA2). As concluded, among CRKP strains, ST11 was the predominant ST with bla_KPC-2, and a large proportion of CRKP strains co-harbor bla_KPC-2, bla_SHV, bla_CTX-M, bla_TEB-1B, and fosA. The predominant carbapenemase genes carried by CRECO and CRECC were bla_NDM-1 and bla_CTX-M, respectively.

Metagenomics highlights the impact of climate and human activities on antibiotic resistance genes in China's estuaries

Estuarine environments faced with contaminations from coastal zones and the inland are vital sinks of antibiotic resistance genes (ARGs). However, little is known about the temporal-spatial pattern of ARGs and its predominant constraints in estuarine environments. Here, we leveraged metagenomics to investigate ARG profiles from 16 China's estuaries across 6 climate zones in dry and wet seasons, and disentangled their relationships with environmental constraints. Our results revealed that ARG abundance, richness, and diversity in dry season were higher than those in wet season, and ARG abundance exhibited an increasing trend with latitude. The prevalence of ARGs was significantly driven by human activities, mobile gene elements, microbial communities, antibiotic residuals, physicochemical properties, and climatic variables. Among which, climatic variables and human activities ranked the most important factors, contributing 44% and 36% of the total variance of observed ARGs, respectively. The most important climatic variable shaping ARGs is temperature, where increasing temperature is associated with decreased ARGs. Our results highlight that the prevalence of ARGs in estuarine environments would be co-driven by anthropogenic activities and climate, and suggest the dynamics of ARGs under future changing climate and socioeconomic development.

Descriptive Analysis of Circulating Antimicrobial Resistance Genes in Vancomycin-Resistant Enterococcus (VRE) during the COVID-19 Pandemic

COVID-19 offers ideal premises for bacteria to develop antimicrobial resistance. In this study, we evaluated the presence of several antimicrobial resistance genes (ARG) in vancomycin-resistant Enterococcus (VRE) isolated from rectal swabs from patients at a hospital in Cluj-Napoca, Romania. Rectal swabs were cultivated on CHROMID^® VRE (bioMérieux, Marcy—l’ Étoile, France) and positive isolates were identified using MALDI-TOF Mass Spectrometry (Bruker Daltonics, Bremen, Germany) and further analyzed using the PCR technique for the presence of the following ARGs: van A, van B, tet(M), tet(L), ermB, msrA, mefA, aac(6′)-Im, aph(2)-Ib, ant(4′)-Ia, sul1, sul2, sul3, and NDM1. We isolated and identified 68 isolates of Enterococcus faecium and 11 isolates of Enterococcus faecalis. The molecular analysis showed 66 isolates positive for the vanA gene and eight positive for vanB. The most frequent association of ARG in VRE was vanA-tet(M)-ermB. There was no statistically significant difference between Enterococcus faecium and Enterococcus faecalis regarding ARGs. Our work proves that during the COVID-19 pandemic, highly resistant isolates of Enterococcus were present in patients in the intensive care unit; thus, better healthcare policies should be implemented for the management and control of these highly resistant isolates in the future.

Increase of Macrolide-Resistance in Streptococcus pneumoniae Strains After the Introduction of the 13-Valent Pneumococcal Conjugate Vaccine in Lima, Peru

Streptococcus pneumoniae upper respiratory infections and pneumonia are often treated with macrolides, but recently macrolide resistance is becoming an increasingly important problem. The 13-valent pneumococcal conjugate vaccine (PCV13) was introduced in the National Immunization Program of Peru in 2015. This study aimed to evaluate the temporal evolution of macrolide resistance in S. pneumoniae isolates collected in five cross-sectional studies conducted before and after this vaccine introduction, from 2006 to 2019 in Lima, Peru. A total of 521 and 242 S. pneumoniae isolates recovered from nasopharyngeal swabs from healthy carrier children < 2 years old (2 carriage studies) and samples from normally sterile body areas from pediatric patients with invasive pneumococcal disease (IPD) (3 IPD studies), respectively, were included in this study. Phenotypic macrolide resistance was detected using the Kirby-Bauer method and/or MIC test. We found a significant increase in macrolide resistance over time, from 33.5% to 50.0% in carriage studies, and from 24.8% to 37.5% and 70.8% in IPD studies. Macrolide resistance genes [erm(B) and mef(A/E)] were screened using PCR. In carriage studies, we detected a significant decrease in the frequency of mef(A/E) genes among macrolide-resistant S. pneumoniae strains (from 66.7% to 50.0%) after introduction of PCV13. The most common mechanism of macrolide-resistant among IPD strains was the presence of erm(B) (96.0%, 95.2% and 85.1% in the 3 IPD studies respectively). Macrolide resistance was more common in serotype 19A strains (80% and 90% among carriage and IPD strains, respectively) vs. non-serotype 19A (35.5% and 34.4% among carriage and IPD strains, respectively). In conclusion, S. pneumoniae macrolide resistance rates are very high among Peruvian children. Future studies are needed in order to evaluate macrolide resistance trends among pneumococcal strains, especially now after the COVID-19 pandemic, since azithromycin was vastly used as empiric treatment of COVID-19 in Peru.

Dissemination of blaNDM-5 in Escherichia coli through the IncX3 Plasmid from Different Regions in China

The spread of NDM-5-producing Escherichia coli has become a severe challenge in clinical therapy, which necessitates reliable detection and surveillance methods. However, limited information is available regarding the prevalence and dissemination of the bla_NDM-5 gene in E. coli in China. Therefore, we investigated the dissemination of the bla_NDM-5 gene in carbapenem-resistant E. coli isolates from different regions. A total of 1,180 carbapenem-resistant enterobacteriaceae strains were obtained from patients admitted to the 20 sentinel hospitals in 8 cities. Strains positive for bla_NDM-5 were detected using the Vitek 2 compact system, 16S ribosomal RNA (rRNA) gene sequencing, polymerase chain reaction, the S1 pulsed-field gel electrophoresis assay, and Southern blot hybridization. The horizontal-transfer capability of the bla_NDM gene was assessed by filter mating with a standard E. coli J53 azide-resistant strain as the recipient. Genotyping, susceptibility testing, and whole genome sequencing were performed. Seven strains of bla_NDM-5-positive E. coli were detected in 1,180 clinical strains from different regions in China. The bla_NDM-5-carrying strains showed resistance to multiple tested antibiotics and belonged to two widespread sequence types, sequence type (ST)167 and ST405. Antimicrobial resistance genes, including bla_CTX-M, bla_OXA, bla_CMY, and two novel bla_TEM variants (bla_TEM-230 and bla_TEM-231) were also identified. Southern blotting located the bla_NDM-5 gene on 46 kb IncX3 plasmids in all isolates, which showed only two single nucleotide differences between EJN003 and the other strains. This study further confirms the increasing occurrence of bla_NDM-5-carrying IncX3 plasmids and the dissemination of carbapenem resistance in E. coli isolates using the plasmid from different parts in China, which warrants stringent surveillance and control measures.

Tracking Klebsiella pneumoniae carbapenemase gene as an indicator of antimicrobial resistance dissemination from a hospital to surface water via a municipal wastewater treatment plant

Antibiotic-resistant bacteria originating from hospitals are ultimately discharged to municipal wastewater treatment plants (WWTP), which may serve as important reservoirs for the spread of antibiotic resistant genes. This study traced and quantified the presence of a rare but clinically relevant antimicrobial resistance gene; Klebsiella pneumoniae carbapenamase (KPC)-and the viable organisms (KPCO) which carried this gene in hospital, non-hospital wastewater discharges, various compartments within a municipal WWTP, receiving water and sediment samples. High concentration of the gene, blaKPC harbored in viable and multispecies KPCO was detected in the hospital wastewater and in the forepart stages of the WWTP, but was not detected in the final effluent following UV disinfection. KPCO were not detected in multiple non-hospital sources of wastewater discharges tested. The treatment train used in the sampled WWTP was found to help remove and reduce KPCO load. Using whole-genome sequencing, a KPC-producing Klebsiella oxytoca strain identical to strains seen in the patients and hospital environment was isolated from the downstream receiving water on one sampling event. KPCO were also found to persist in the biosolids throughout the WWTP, but were not detected in the processed compost-products made from WWTP-biosolids. This study systematically demonstrates dissemination of KPCO from hospital point source to environment via municipal WWTP. Understanding hospitals as the origin and source of spread of some of the most clinically urgent antimicrobial-resistant organisms may help direct interventions that target rate at which antibiotic resistant bacteria evolve and spread via enhancement of wastewater treatment and mitigation of dissemination at source.

Multidrug resistance from a one health perspective in Ethiopia: A systematic review and meta-analysis of literature (2015–2020)

Purpose

The emergence of antimicrobial resistance is a major global health challenge and becoming an urgent priority for policymakers. There is a paucity of scientific studies presenting the multidrug resistance pattern from one health perspective in Ethiopia. Therefore, a systematic review and meta-analysis aimed to determine the pooled prevalence of multidrug resistance in bacteria from human, animal, food, and environmental sources.

Methods

In this systematic review and meta-analysis, an electronic search was made in PubMed & Google scholar using different keywords. The studies conducted in all areas of Ethiopia, published from 2015 to 2020 in peer-reviewed journals, English full-length papers were included. The meta-analysis was done on STATA version 14. The pooled prevalence of multidrug resistance for each bacterium was analysed using the random-effects model; Cochran Q statistics and the I² statistic was used to analyse heterogeneity and considered significant at p < 0.01.

Results

81 studies were included in the systematic review and meta-analysis; 53 human studies, eight animal studies, and 16 environments/food studies. The meta-analysis included six species from gram-positive bacteria and 13 from gram-negative bacteria. S. aureus 53% (95%CI: 42–64%), Coagulase negative Staphylococci 68%(95%CI:53–82), Pseudomonas spp. 73%(95%CI:48–93%), E. coli 70% (95%CI:61–78%), Citrobacter spp. 71%(95%CI:54–87%), Klebsiella spp. 68% (54–80%), Enterobacter spp. 67% (48–83%) and Salmonella spp. 65% (95%CI:48–81%) were the common multidrug-resistant species of bacteria from two or more sources.

Conclusion

In Ethiopia, the pooled prevalence of MDR is high in most bacterial species from humans, animals, food, and environmental sources. Staphylococcus, most members of the Enterobacteriaceae and Pseudomonas, are the standard MDR bacterial population involving all sources. Therefore, integrated policy and intervention measures should be implemented to reduce the emergence and spread of MDR bacteria for better animal and human health outcomes.

Clonal spread of carbapenemase-producing Enterobacteriaceae in a region, China

Background

The increasing number of carbapenemase-producing Enterobacterales (CPE) has become a serious problem globally. This study aimed to elucidate their geographically epidemiological characteristics.

Methods

Resistance genes were identified by polymerase chain reaction (PCR) and sequencing. Bacterial genotyping was studied using multilocus sequence typing (MLST) and wzi typing. The transferability of carbapenemase genes was determined by a broth mating method. The relationships between the rates of antimicrobial consumption and the prevalence of CRE were performed by Pearson's or Spearman's correlation analyses.

Results

A total of 930 phenotypically confirmed carbapenem-resistant Enterobacterales (CRE) isolates collected from 19 hospitals were genotypically characterized. K. pneumoniae (KP) and E. coli isolates were 785 (85.14%) and 96 (10.41%) among 922 CPE isolates. Two major carbapenemase genes blaKPC-2 and blaNDM in CPE isolates accounted for 84.6% (n = 780) and 13.77% (n = 127). ST11 comprised 86.83% (633/729) of KPC-2 KP isolates. Different combinations of extended spectrum-β-lactamase (ESBL) genes of blaSHV, blaCTX, and blaTEM were found in KPC-2 producing KP isolates, and blaCTM-M-14/15, blaSHV-11/12 and blaTEM-1 were common ESBL genotypes. The wzi typing method could further subdivide ST11 KP group into at least five subgroups, among which wzi209 (69.83%, 442/633) was the most frequently isolated, followed by wzi141 (25.28%, 160/633). Conjugation assays showed that high conjugation rates were observed in CPE (15.24%, 32/210) for NDM plasmids, but relatively low (8.1%, 17/210) for KPC-2 plasmids. Different STs, different wzis and temperature could influence plasmid conjugation efficiency. No associations between the rates of antibiotics consumption and CPE prevalence were observed. The number of intra-hospital and inter-hospital transfers of CPE patients increased gradually from 18 (17.82%, 101) and 12 (11.88%, 101) in 2015 to 63 (30.73%, 205) and 51 (24.88%, 205) in 2018 (p = 0.016 and p = 0.008), respectively. Evidence-based measures could effectively reduce the prevalence of ST11-wzi209 clone but failed to control the dissemination of ST11-wzi141 KP clone.

Conclusions

Clonal spread of CPE, especially KPC-2 ST11 KP was the key factor contributing to the CPE increase in the region. Continued vigilance for the importations should be maintained. Coordinated regional interventions are urgently needed to reduce CPE threat.

Characteristics changes on Applications of Antibiotics and Current Approaches to Enhance Productivity with Soil Microbiome

The contamination of environmental sully with antibiotics is regarded as a major problem today and predictable to attain more recognition in near future. However, human intervention resulting in antibiotic consumption is being enhancing all around the world. Our review of literature revealed the role of microbiome in sully and how antibiotic resistant genes raised. The structure of antibiotics basically influenced by natural components such as biotic and abiotic push which shifts based on different soils. Therefore, management of microbiome in soil and their expression studies were distinctively revealed. The assessment of antibiotic resistance genes with help of next generation sequencing provided a clear comprehension on genome and transcriptome of the bacterial genes. Thus, interaction of microbiome with soil can also be well understood. The current findings in our study will guide every researcher to follow logical protocol in analyzing microbiota composition is covered as well and also to understand its metagenomic and sequenced with next-generation sequencer which helps to comprehend the diverse micro-flora present in soil and its operation. Finally, later progresses in bioinformatics computer program, flow of work, and applications for analyzing metagenomic information are put in a nutshell.

Quantitative Risk Assessment for the Introduction of Carbapenem-Resistant Enterobacteriaceae (CPE) into Dutch Livestock Farms

Early detection of emerging carbapenem-resistant Enterobacteriaceae (CPE) in food-producing animals is essential to control the spread of CPE. We assessed the risk of CPE introduction from imported livestock, livestock feed, companion animals, hospital patients, and returning travelers into livestock farms in The Netherlands, including (1) broiler, (2) broiler breeder, (3) fattening pig, (4) breeding pig, (5) farrow-to-finish pig, and (6) veal calf farms. The expected annual number of introductions was calculated from the number of farms exposed to each CPE source and the probability that at least one animal in an exposed farm is colonized. The total number of farms with CPE colonization was estimated to be the highest for fattening pig farms, whereas the probability of introduction for an individual farm was the highest for broiler farms. Livestock feed and imported livestock are the most likely sources of CPE introduction into Dutch livestock farms. Sensitivity analysis indicated that the number of fattening pig farms determined the number of high introductions in fattening pigs from feed, and that uncertainty on CPE prevalence impacted the absolute risk estimate for all farm types. The results of this study can be used to inform risk-based surveillance for CPE in livestock farms.

A multivariable analysis of the contribution of socioeconomic and environmental factors to blood culture Escherichia Coli resistant to fluoroquinolones in high- and middle-income countries

BACKGROUND

Antimicrobial resistance (AMR) is a public health concern. We wanted to determine if various environmental and socioeconomic variables as well as markers of antimicrobial use impacted on the level of AMR in countries of different income levels.

METHODS

We performed cross-national univariate and multivariable analyses using the national proportion of quinolone-resistant Escherichia coli (QREC) in blood culture as the dependent variable. Access to safe water and sanitation, other socioeconomic variables, and human and animal antimicrobial consumption were analysed.

RESULTS

In middle-income countries, unsafely managed sanitation, corruption and healthcare access and quality were significantly associated with the national proportion of blood culture QREC (%) in univariate analyses, whereas no variables remained significant in the multivariable models. For the multivariable high-income country model, corruption and healthcare access and quality were significantly associated with blood culture QREC (%) levels. For the model including all countries, human fluoroquinolone use, corruption level, livestock and crop production index were significantly associated with blood culture QREC (%) levels in the univariate analyses.

CONCLUSION

Corruption is a strong predictor of AMR, likely reflecting a multitude of socioeconomic factors. Sanitation quality contributed to increased blood culture QREC (%) levels in middle-income countries, although was not an independent factor, highlighting the need to also focus on infrastructure such as sanitation services in the context of AMR.

Grassland ecology system: A critical reservoir and dissemination medium of antibiotic resistance in Xilingol Pasture, Inner Mongolia

Antibiotic resistance is a major threat to human health. It is necessary to explore all the potential sources and comprehend the pathways that antibiotic resistance genes (ARGs) are transmitted. In this study, by applying high-throughput quantitative PCR and high-throughput sequencing, ARGs and microbial community structure were determined, to understand the reservoirs and spread of ARGs in the Xilingol grassland system. A total of 151,140 and 138 different ARGs were observed in manure, soil, and water samples, respectively. Only 12 ARGs were shared in all environmental and animal manure samples. Multidrug defense system, such as efflux pump, was the most dominant factor in manure and soil samples, followed by antibiotic deactivation processes. These genes coffering resistance to major classes of antibiotics including β_Lactamase (bla_SFO, fox5, bla_CTX-M-04, bla_OXY), vancomycin (vanC-03, vanXD), MLSB (vatE-01, mphA-01), aminoglycoside (aadA2-01), Multidrug (oprJ) and others (oprD, qacEdelta1-02), except sulfonamide and tetracycline. The 12 ARGs were significantly enriched in water samples compared to manure and soil samples (p < 0.01) and demonstrated that the water environment was an important transmission source of ARGs in the grassland. The highest enrichment was up to 324.5-fold. Moreover, the 12 shared ARGs were positively correlated with the mobile genetic elements (p < 0.01). The nonrandom co-occurrence network patterns between ARGs and microbial community suggested that a total of three bacterial phyla were viewed as the potential ARGs hosts. These findings indicate that ARGs were highly enriched in water samples, demonstrating that the water environment was a critical source and sink of ARGs in the grassland system. It may illuminate the mechanism stressing the effects of human activity on the occurrence and transmission of ARGs in the grassland system.

Long-term spatiotemporal variation of antimicrobial resistance genes within the Serratia marcescens population and transmission of S. marcescens revealed by public whole-genome datasets

The development of antimicrobial resistance (AMR) is accelerated by the selective pressure exerted by the widespread use of antimicrobial drugs, posing an increasing danger to public health. However, long-term spatiotemporal variation in AMR genes in microorganisms, particularly in bacterial pathogens in response to antibiotic consumption, is not fully understood. Here, we used the NCBI RefSeq database to collect 478 whole-genome sequences for Serratia marcescens ranging from 1961 up to 2019, to document global long-term AMR trends in S. marcescens populations. In total, 100 AMR gene subtypes (16 AMR gene types) were detected in the genomes of S. marcescens populations. We identified 3 core resistance genes in S. marcescens genomes, and a high diversity of AMR genes was observed in S. marcescens genomes after corresponding antibiotics were discovered and introduced into clinical practice, suggesting the adaptation of S. marcescens populations to challenges with therapeutic antibiotics. Our findings indicate spatiotemporal variation of AMR genes in S. marcescens populations in relation to antibiotic consumption and suggest the potential transmission of S. marcescens isolates harboring AMR genes among countries and between the environment and the clinic, representing a public health threat that necessitates international solidarity to overcome.

Persistence and Dissemination Capacities of a BlaNDM-5-Harboring IncX-3 Plasmid in Escherichia coli Isolated from an Urban River in Montpellier, France

To investigate the capacities of persistence and dissemination of bla_NDM-5 within Escherichia coli and in aquatic environment, we characterized E. coli (sequence type 636) strains B26 and B28 isolated one month apart from the same urban river in Montpellier, France. The two isolates carried a pTsB26 plasmid, which sized 45,495 Kb, harbored bla_NDM-5 gene and belonged to IncX-3 incompatibility group. pTsB26 was conjugative in vitro at high frequency, it was highly stable after 400 generations and it exerted no fitness cost on its host. bla_NDM-5harboring plasmids are widely dispersed in E. coli all around the world, with no lineage specialization. The genomic comparison between B26 and B28 stated that the two isolates probably originated from the same clone, suggesting the persistence of pTsB26 in an E. coli host in aquatic environment.

Ancient Oriental Wisdom still Works: Removing ARGs in Drinking Water by Boiling as compared to Chlorination

Antibiotic resistance genes (ARGs) in municipal drinking water may not be effectively removed during centralized treatment. To reduce potential health risks, water disinfection at the point-of-use scale is warranted. This study investigated the performance of boiling, a prevalent household water disinfection means, in response to ARGs contamination. We found that boiling was more efficient in inactivating both Escherichia coli and environmental bacteria compared to chlorination and pasteurization. Boiling of environmental bacteria suspension removed a much broader spectrum of ARGs and mobile genetic elements (up to 141 genes) than chlorination (up to 13 genes), such better performance was largely attributed to a stronger inactivation of chlorine-tolerant bacteria including Acinetobacter and Bacillus. Accumulation of extracellular ARGs was found during low-temperature heating (≤ 80°C) and in the initial stage of chlorination (first 3 min when initial chlorine was 5 mg/L and first 12 min when initial chlorine was 1 mg/L). These extracellular ARGs as well as the intracellular ARGs got removed as the heating temperature increased or the chlorination time prolonged. Under the same treatment time (30 min), high-temperature heating (≥ 90.1°C) damaged the DNA structure more thoroughly than chlorination (5 mg/L). Taking into account the low transferability of ARGs after DNA melting, boiling may provide an effective point-of-use approach to attenuating bacterial ARGs in drinking water and is still worth promoting in the future.

Overcoming the rising incidence and evolving mechanisms of antibiotic resistance by novel drug delivery approaches - An overview

Antimicrobial resistance is a normal evolutionary process for microorganisms. Antibiotics exerted accelerated selective pressure that hasten bacterial resistance through mutation, and acquisition external genes. These genes often carry multiple antibiotic resistant determinants allowing the recipient microbe an instant "super-bug" status. The extent of Antimicrobial Resistance (AMR) has reached a level of global crisis, existing antimicrobials are no long effective in treating infections caused by AMR pathogens. The great majority of clinically available antimicrobial agents are administered through oral and intra-venous routes. Overcoming antibacterial resistance by novel drug delivery approach offered new hopes, particularly in the treatment of AMR pathogens in sites less assessible through systemic circulation such as the lung and skin. In the current review, we will revisit the mechanism and incidence of important AMR pathogens. Finally, we will discuss novel drug delivery approaches including novel local antibiotic delivery systems, hybrid antibiotics, and nanoparticle-based antibiotic delivery systems.

Effects and relevant mechanisms of non-antibiotic factors on the horizontal transfer of antibiotic resistance genes in water environments: A review

Antibiotic resistance has created obstacles in the treatment of infectious diseases with antibiotics. The horizontal transfer of antibiotic resistance genes (ARGs) can exacerbate the dissemination of antibiotic resistance in water environments. In addition to antibiotic selective pressure, multiple non-antibiotic factors can affect the horizontal transfer of ARGs. Herein, we seek to comprehensively review the effects and relevant mechanisms of non-antibiotic factors on the horizontal transfer of ARGs in water environments, especially contaminants from human activities and water treatment processes. Four pathways have been identified to accomplish horizontal gene transfer (HGT), i.e., conjugation, transformation, transduction, and vesiduction. Changes in conjugative frequencies by non-antibiotic factors are mainly related to their concentrations, which conform to hormesis. Relevant mechanisms involve the alteration in cell membrane permeability, reactive oxygen species, SOS response, pilus, and mRNA expression of relevant genes. Transformation induced by extracellular DNA may be more vulnerable to non-antibiotic factors than other pathways. Except bacteriophage infection, the effects of non-antibiotic factors on transduction exhibit many similarities with that of conjugation. Given the secretion of membrane vesicles stimulated by non-antibiotic factors, their effects on vesiduction can be inferred. Furthermore, contaminants from human activities at sub-inhibitory or environmentally relevant concentrations usually promote HGT, resulting in further dissemination of antibiotic resistance. The horizontal transfer of ARGs is difficult to be inhibited by individual water treatment processes (e.g., chlorination, UV treatment, and photocatalysis) unless they attain sufficient intensity. Accordingly, the synergistic application containing two or more water treatment processes is recommended. Overall, we believe this review can elucidate the significance for risk assessments of contaminants from human activities and provide insights into the development of environment-friendly and cost-efficient water treatment processes to inhibit the horizontal transfer of ARGs.

Mobile genetic elements-mediated Enterobacterales-associated carbapenemase antibiotic resistance genes propagation between the environment and humans: A One Health South African study

We, (1) studied carbapenem-resistant Enterobacterales (CRE) in the environment, humans, and animals, within the same geographical area and, (2) delineated the isolates' resistome, mobilome, virulome, and phylogeny. Following ethical approval, 587 samples (humans = 230, pigs = 345, and water = 12) were collected and cultured on CRE selective media. Confirmatory identification and antibiotic susceptibility testing were performed using the VITEK 2 automated platform. The resistomes, virulomes, mobilomes, and phylogenies were ascertained by whole genome sequencing. Nineteen (3.2%), i.e., 15/19 humans and 4/19 environmental, but no pig, CRE were obtained. CREs included Klebsiella pneumoniae 9/19 (47%), Enterobacter hormaechei 6/19 (32%), Klebsiella quasipneumoniae 2/19 (11%), a novel ST498 Citrobacter freundii 1/19 (5%) and Serratia marcescens 1/19 (5%). Eleven isolates were extensively drug-resistant; eight were multidrug-resistant. Sixteen CRE harbored the bla_OXA-181, bla_OXA-48, bla_OXA-484, bla_NDM-1, and bla_GES-5 genes. Multiple species/clones carried bla_OXA-48 and bla_NDM-1 carbapenemase-encoding genes with respective mobile genetic elements (MGEs). The IncFIB(K) plasmid replicon was found in most human K. pneumoniae strains (7/9) and all environmental K. quasipneumoniae isolates; most K. pneumoniae produced OXA-181 (5/9). The (Col440I) plasmid replicon, identified in 11 (26.82%) isolates, mainly E. hormaechei (n = 6), predominated both sectors. Most β-lactamase-encoding genes were associated with class 1 integrons IntI1, insertion sequences (IS) (IS91, IS5075, IS30, IS3000, IS3, IS19, ISKpn19, IS5075) and transposons (Tn3). The IncL/M(pMU407) and IncL/M(pOXA48) plasmid replicons were found exclusively in K. pneumoniae; all but one of these strains produced OXA-181. Also, the Klebsiella spp. harbored 80 virulence genes. Phylogenomic clustered identified isolates with other carbapenemase-producing K. pneumoniae, E. hormaechei, S. marcescens, and C. freundii from different South African sources (animals, environment, and humans). We delineated the resistome, mobilome, virulome, and phylogeny of carbapenemase-producing Enterobacterales in humans and environment, highlighting antibiotic resistance genes propagation via MGEs across sectors, emphasizing a One Health approach to AMR.

Metformin Reverses tmexCD1-toprJ1- and tet(A)-Mediated High-Level Tigecycline Resistance in K. pneumoniae

Tigecycline (TIG) is one of the last effective options against multidrug resistance bacteria. Recently, the RND (resistance–nodulation–division) efflux pump gene cluster, tmexCD1-toprJ1, and the tetracycline-efflux pump tet(A) mutation were reported to mediate high level resistance to TIG in clinically important pathogens, weakening the efficacy of TIG. In this study, we report the potent synergistic effect of the antidiabetic drug metformin in combination with TIG against tet(A) mutant and tmexCD1-toprJ1 positive K. pneumoniae. The fractional inhibitory concentration index (FICI) of TIG and metformin were less than 0.05 for all the tested isolates. The time–kill curve assay showed that the combination of TIG and metformin exhibited much better antimicrobial effect than TIG alone. The synergistic effect was also confirmed in vivo using a well-studied Galleria mellonella larvae model. Mechanistic studies demonstrated that metformin disrupted the important component of proton motive force, the electric potential (Δψ) and the function of efflux pump, thereby increasing the intracellular concentration of TIG. This finding revealed that metformin might be a possible adjuvant of TIG for combating with superbugs carrying the tet(A) mutant and tmexCD1-toprJ1 genes.

Climate Change and Infections on the Move in North America

Climate change is increasingly recognized for its impacts on human health, including how biotic and abiotic factors are driving shifts in infectious disease. Changes in ecological conditions and processes due to temperature and precipitation fluctuations and intensified disturbance regimes are affecting infectious pathogen transmission, habitat, hosts, and the characteristics of pathogens themselves. Understanding the relationships between climate change and infectious diseases can help clinicians broaden the scope of differential diagnoses when interviewing, diagnosing, and treating patients presenting with infections lacking obvious agents or transmission pathways. Here, we highlight key examples of how the mechanisms of climate change affect infectious diseases associated with water, fire, land, insects, and human transmission pathways in the hope of expanding the analytical framework for infectious disease diagnoses. Increased awareness of these relationships can help prepare both clinical physicians and epidemiologists for continued impacts of climate change on infectious disease in the future.

Environmental spreading of clinically relevant carbapenem-resistant gram-negative bacilli: the occurrence of blaKPC-or-NDM strains relates to local hospital activities

Background

Aquatic matrices impacted by sewage may shelter carbapenem-resistant (CR) Gram-negative bacilli (GNB) harboring resistance genes of public health concern. In this study, sewage treatment plants (STPs) servicing well-defined catchment areas were surveyed for the presence of CR-GNB bearing carbapenemase genes (bla_KPC or bla_NDM).

Results

A total of 325 CR-GNB were recovered from raw (RS) and treated (TS) sewage samples as well as from water body spots upstream (UW) and downstream (DW) from STPs. Klebsiella-Enterobacter (KE) group amounted to 116 isolates (35.7%). CR-KE isolates were recovered from TS, DW (35.7%) and RS samples (44.2%) (p = 0.001); but not from UW samples. KE isolates represented 65.8% of all bla_KPC or bla_NDM positive strains. The frequency of bla_KPC-or-NDM strains was positively associated with the occurrence of district hospitals located near STPs, as well as with the number of hospitalizations and of sewer connections serviced by the STPs. bla_KPC-or-NDM strains were recovered from ST samples in 7 out of 14 STPs, including four tertiary-level STPs; and from 6 out of 13 DW spots whose RS samples also had bla_KPC-or-NDM strains.

Conclusions

Clinically relevant GNB bearing bla_KPC-or-NDM resist sewage treatments and spread into environmental aquatic matrices mainly from STPs impacted by hospital activities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02400-1.