Extended spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae: critical tools for antibiotic resistance pattern

Inhibitory Potential of Bifidobacterium longum FB1-1 Cell-Free Supernatant against Carbapenem-Resistant Klebsiella pneumoniae Drug Resistance Spread

The widespread dissemination of carbapenem-resistant Klebsiella pneumoniae (CRKP) and its drug resistance transfer poses a global public health threat. While previous studies outlined CRKP's drug resistance mechanism, there is limited research on strategies inhibiting CRKP drug resistance spread. This study investigates the potential of Bifidobacterium longum (B. longum) FB1-1, a probiotic, in curbing the spread of drug resistance among CRKP by evaluating its cell-free supernatant (CFS) for antibacterial activity. Evaluating the inhibitory effect of FB1-1 CFS on CRKP drug resistance spread involved analyzing its impact on drug resistance and virulence gene expression; drug resistance plasmid transfer FB1-1 CFS exhibited an MIC range of 125 μL/mL against CRKP. After eight hours of co-culture, CFS achieved a 96% and 100% sterilization rate at two and four times the MIC, respectively. At sub-inhibitory concentrations (1/2× MIC), FB1-1 CFS reduced the expression of the bla_KPC gene, which is pivotal for carbapenem resistance, by up to 62.13% across different CRKP strains. Additionally, it markedly suppressed the expression of the uge gene, a key virulence factor, by up to 91%, and the fim_H gene, essential for bacterial adhesion, by up to 53.4%. Our study primarily focuses on determining the inhibitory effect of FB1-1 CFS on CRKP strains harboring the bla_KPC gene, which is a critical resistance determinant in CRKP. Furthermore, FB1-1 CFS demonstrated the ability to inhibit the transfer of drug resistance plasmids among CRKP strains, thus limiting the horizontal spread of resistance genes. This study highlights FB1-1 CFS's inhibitory effect on CRKP drug resistance spread, particularly in strains carrying the bla_KPC gene, thus offering a novel idea and theoretical foundation for developing antibacterial drugs targeting CRKP resistance.

Proteome analysis, genetic characterization, and antibiotic resistance patterns of Klebsiella pneumoniae clinical isolates

Klebsiella pneumoniae (K. pneumoniae) is a member of the ESKAPE group and is responsible for severe community and healthcare-associated infections. Certain Klebsiella species have very similar phenotypes, which presents a challenge in identifying K. pneumoniae. Multidrug-resistant K. pneumoniae is also a serious global problem that needs to be addressed. A total of 190 isolates were isolated from urine (n = 69), respiratory (n = 52), wound (n = 48) and blood (n = 21) samples collected from various hospitals in the Al-Qassim, Saudi Arabia, between March 2021 and October 2022. Our study aimed to rapidly and accurately detect K. pneumoniae using the Peptide Mass Fingerprinting (PMF) technique, confirmed by real-time PCR. Additionally, screening for antibiotic susceptibility and resistance was conducted. The primary methods for identifying K. pneumoniae isolates were culture, Gram staining, and the Vitek® 2 ID Compact system. An automated MALDI Biotyper (MBT) instrument was used for proteome identification, which was subsequently confirmed using SYBR green real-time polymerase chain reaction (real-time PCR) and microfluidic electrophoresis assays. Vitek® 2 AST-GN66 cards were utilized to evaluate the antimicrobial sensitivity of K. pneumoniae isolates. According to our results, Vitek® 2 Compact accurately identified 178 out of 190 (93.68%) K. pneumoniae isolates, while the PMF technique correctly detected 188 out of 190 (98.95%) isolates with a score value of 2.00 or higher. Principal component analysis was conducted using MBT Compass software to classify K. pneumoniae isolates based on their structure. Based on the analysis of the single peak intensities generated by MBT, the highest peak values were found at 3444, 5022, 5525, 6847, and 7537 m/z. K. pneumoniae gene testing confirmed the PMF results, with 90.53% detecting entrobactin, 70% detecting 16 S rRNA, and 32.63% detecting ferric iron uptake. The resistance of the K. pneumoniae isolates to antibiotics was as follows: 64.75% for cefazolin, 62.63% for trimethoprim/sulfamethoxazole, 59.45% for ampicillin, 58.42% for cefoxitin, 57.37% for ceftriaxone, 53.68% for cefepime, 52.11% for ampicillin-sulbactam, 50.53% for ceftazidime, 52.11% for ertapenem, and 49.47% for imipenem. Based on the results of the double-disk synergy test, 93 out of 190 (48.95%) K. pneumoniae isolates were extended-spectrum beta-lactamase. In conclusion, PMF is a powerful analytical technique used to identify K. pneumoniae isolates from clinical samples based on their proteomic characteristics. K. pneumoniae isolates have shown increasing resistance to antibiotics from different classes, including carbapenem, which poses a significant threat to human health as these infections may become difficult to treat.

Contribution of genetic factors towards cefotaxime and ciprofloxacin resistance development among Extended spectrum beta-lactamase producing-Quinolone resistant pathogenic Enterobacteriaceae

β-lactams and quinolones are widely utilised to treat pathogenic Enterobacterial isolates worldwide. Due to improper use of these antibiotics, both ESBL producing and quinolone resistant (ESBL-QR) pathogenic bacteria have emerged. Nature of contribution of beta-lactamase (bla)/quinolone resistant (QR) genes, efflux pumps (AcrAB-TolC) over-expression and outer membrane proteins (OMPs) /porin loss/reduction and their combinations towards development of this phenotype were explored in this study. Kirby-Bauer disc diffusion method was used for phenotypic characterization of these bacteria and minimum inhibitory concentration of cefotaxime and ciprofloxacin was determined by broth micro dilution assay. Presence of bla, QR, gyrA/B genes was examined by PCR; acrB upregulation by real-time quantitative PCR and porin loss/reduction by SDS-PAGE. Based on antibiogram, phenotypic categorization of 715 non-duplicate clinical isolates was: ESBL+QR+ (n = 265), ESBL+QR- (n = 6), ESBL-QR+ (n = 346) and ESBL-QR-(n = 11). Increased OmpF/K35 and OmpC/K36 reduction, acrB up-regulation, prevalence of bla, QR genes and gyrA/B mutation was observed among the groups in following order: ESBL+QR+> ESBL-QR+> ESBL+QR-> ESBL-QR-. Presence of bla gene alone or combined porin loss and efflux pump upregulation or their combination contributed most for development of a highest level of cefotaxime resistance of ESBL+QR+ isolates. Similarly, combined presence of QR genes, porin loss/reduction, efflux pump upregulation and gyrA/B mutation contributed towards highest ciprofloxacin resistance development of these isolates.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Prevalence of gram-negative bacteria and their antibiotic resistance in neonatal sepsis in Iran: a systematic review and meta-analysis

BACKGROUND

Neonatal sepsis, particularly gram-negative (GN) bacteria-induced, is a significant cause of morbidity and mortality in newborns. Healthcare professionals find this issue challenging because of antibiotic resistance. This study aims to combine findings to identify the prevalence of GN bacteria and their antibiotic resistance in Iranian neonates with sepsis.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). The literature search was performed through international databases, including (PubMed/MEDLINE, EMBASE, Scopus, and Web of Science), Iranian local databases (Magiran, Iranmedex, Irandoc, Scimed, and SID), and the first 100 records of Google Scholar. Analytical cross-sectional study checklist from the Joanna Briggs Institute (JBI) was used for the quality assessment of included studies. Comprehensive Meta-Analysis Software Version 2 was used to conduct the meta-analysis. The between-study heterogeneity was investigated by I2 statistics.

RESULTS

The prevalence of GN bacteria was estimated to be 53.6% [95% CI: 45.9- 61.1: P = 0.362] in Iranian neonates with sepsis, based on 31 studies with a sample size of 104,566. klebsiella pneumoniae (K.pneumonia) (23.2% [95% CI: 17.5-30.0, P < 0.001]) followed by Escherichia coli (E.coli) (13.5% [95% CI: 9.4-18.9, P < 0.001]) were more prevalent among GN bacteria. The highest resistance in K.pneumoniae was observed in Cefixime (80.6%, [95% CI: 56.3-93.1, P = 0.018]). E.coli showed greater resistance to Ampicillin (61.8%, [95% CI: 44.2-76.5, P = 0.188]. The prevalence of GN bacteria in Iranian neonates with sepsis has a decreasing trend based on the year, as shown by a meta-regression model (P < 0.0004).

CONCLUSION

GN pathogens, particularly K.pneumoniae, and E.coli, are the leading cause of neonatal sepsis in Iran. GN bacteria showed the highest resistance to Third-generation cephalosporin and Aminoglycosides.

Investigating the evolution and predicting the future outlook of antimicrobial resistance in sub-saharan Africa using phenotypic data for Klebsiella pneumoniae: a 12-year analysis

BACKGROUND

Antimicrobial resistance (AMR) is a major public health challenge, particularly in sub-Saharan Africa (SSA). This study aimed to investigate the evolution and predict the future outlook of AMR in SSA over a 12-year period. By analysing the trends and patterns of AMR, the study sought to enhance our understanding of this pressing issue in the region and provide valuable insights for effective interventions and control measures to mitigate the impact of AMR on public health in SSA.

RESULTS

The study found that general medicine patients had the highest proportion of samples with AMR. Different types of samples showed varying levels of AMR. Across the studied locations, the highest resistance was consistently observed against ceftaroline (ranging from 68 to 84%), while the lowest resistance was consistently observed against ceftazidime avibactam, imipenem, meropenem, and meropenem vaborbactam (ranging from 92 to 93%). Notably, the predictive analysis showed a significant increasing trend in resistance to amoxicillin-clavulanate, cefepime, ceftazidime, ceftaroline, imipenem, meropenem, piperacillin-tazobactam, and aztreonam over time.

CONCLUSIONS

These findings suggest the need for coordinated efforts and interventions to control and prevent the spread of AMR in SSA. Targeted surveillance based on local resistance patterns, sample types, and patient populations is crucial for effective monitoring and control of AMR. The study also highlights the urgent need for action, including judicious use of antibiotics and the development of alternative treatment options to combat the growing problem of AMR in SSA.

Herbal Products and Their Active Constituents Used Alone and in Combination with Antibiotics against Multidrug-Resistant Bacteria

The purpose of this review is to summarize the current knowledge acquired on herbal products and their active constituents with antimicrobial activity used alone and in combination with antibiotics against multidrug-resistant bacteria. The most promising herbal products and active constituents used alone against multidrug-resistant bacteria are Piper betle (methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, extended-spectrum beta-lactamase, Acinetobacter baumannii, Pseudomonas aeruginosa), Glycyrrhiza glabra (methicillin-resistant S. aureus, vancomycin-resistant Enterococcus, P. aeruginosa), and berberine (methicillin-resistant S. aureus, A. baumannii, P. aeruginosa), respectively. The synergistic effect of the combination of herbal products and their active constituents with antibiotics against multidrug-resistant bacteria are also described. These natural antibacterial agents can be promising sources of inhibitors, which can modulate antibiotic activity against multidrug-resistant bacteria, especially as efflux pump inhibitors. Other possible mechanisms of action of herbal therapy against multidrug-resistant bacteria including modification of the bacterial cell wall and/or membrane, inhibition of the cell division protein filamenting temperature sensitive Z-ring, and inhibition of protein synthesis and gene expression, all of which will also be discussed. Our review suggests that combination herbal therapy and antibiotics can be effectively used to expand the spectrum of their antimicrobial action. Therefore, combination therapy against multidrug-resistant bacteria may enable new choices for the treatment of infectious diseases and represents a potential area for future research.

Invited review: Antimicrobial resistance in bovine mastitis pathogens: A review of genetic determinants and prevalence of resistance in European countries

Antimicrobial resistance is an urgent and growing problem worldwide, both for human and animal health. In the animal health sector actions have been taken as concerns grow regarding the development and spread of antimicrobial resistance. Mastitis is the most common infection in dairy cattle. We aimed to summarize the genetic determinants found in staphylococci, streptococci, and Enterobacteriaceae isolated from mastitic milk samples and provide a comparison of percentage resistance to a variety of antimicrobials in European countries.

Magnitude and Molecular Characterization of Extended-Spectrum β-Lactamase Genes among Klebsiella pneumoniae Isolates in a Large Tertiary Hospital in Ethiopia

Background Extended-spectrum β-lactamases (ESBLs)-producing Klebsiella pneumoniae is reported worldwide increasingly. However, studies on ESBLs are still scarce in Ethiopia. Therefore, the current study aimed to determine the magnitude and resistance patterns of ESBL-producing K. pneumoniae as well as the frequency of ESBL-encoding genes.Methods A cross-sectional study was conducted from September 2018 to February 2019 at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia among a total of 132 non-duplicate K. pneumoniae isolates. Phenotypic detection of ESBL production was done using Combined Disc Test. ESBL-encoding genes of bla_CTX-M, bla_TEM, and bla_SHV were detected through multiplex PCR.Results The magnitude of ESBL production was 102/132 (77.3%). ESBL positive isolates were 100% resistant to ceftriaxone, cefotaxime, and cefuroxime. Co-resistance of ESBL-positive isolates to other non β-lactam antimicrobials was high to trimethoprim-sulfamethoxazole (96.1%) followed by tetracycline (75.5%) and gentamicin (73.5%). However, these isolates showed high susceptibility to amikacin (96.1%) and meropenem (89.2%). From the total ESBL-positive isolates, 82.6%, 73.5%, and 75% carried bla_CTX-M, bla_TEM, and bla_SHV genes, respectively. The majority 78/102 (76.5%) of ESBL-positive isolates harbored all three types of ESBL genes simultaneously.Conclusions The magnitude of ESBL-producing K. pneumoniae isolates was very alarming in the study area. The co-occurrence of bla_CTX-M, bla_TEM, and bla_SHV genes is high, demanding large-scale studies to evaluate the presence of antimicrobial resistance super-clones. ESBL-producing isolates showed high resistance to most of the antimicrobials, needing phenotypic detection of ESBL regularly for better management of patients.

Electrospun Polyacrylonitrile Silver(I,III) Oxide Nanoparticle Nanocomposites as Alternative Antimicrobial Materials

Infectious microbial diseases can easily be transferred from person to person in the air or via high contact surfaces. As a result, researchers must aspire to create materials that can be implemented in surface contact applications to disrupt pathogen growth and transmission. This study examines the antimicrobial properties of polyacrylonitrile (PAN) nanofibers coated with silver nanoparticles (AgNPs) and silver(I,III) oxide. PAN was homogenized with varied weight concentrations of silver nitrate (AgNO₃) in N,N-dimethylformamide solution, a common organic solvent that serves as both an electrospinning solvent and as a reducing agent that forms AgNPs. The subsequent colloids were electrospun into nanofibers, which were then characterized via various analysis techniques, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, dynamic light scattering, and X-ray photoelectron spectroscopy. A total of 10 microbes, including 7 strains of Gram-positive bacteria, 2 strains of Gram-negative bacteria, and Candida albicans, were incubated with cutouts of various PAN-AgNP nanocomposites using disk diffusion methods to test for the nanocomposites' antimicrobial efficiency. We report that our electrospun PAN-AgNP nanocomposites contain 100% AgO, a rare, mixed oxidation state of silver(I,III) oxide that is a better sterilizing agent than conventional nanosilver. PAN-AgNP nanocomposites also retain a certain degree of antimicrobial longevity; samples stored for approximately 90 days demonstrate a similar antimicrobial activity against Escherichia coli (E. coli) and Lactobacillus crispatus (L. crispatus) when compared to their newly electrospun counterparts. Moreover, our results indicate that PAN-AgNP nanocomposites successfully display antimicrobial activity against various bacteria and fungi strains regardless of their resistance to conventional antibiotics. Our study demonstrates that PAN-AgNP nanocomposites, a novel polymer material with long-term universal antimicrobial stability, can potentially be applied as a universal antimicrobial on surfaces at risk of contracting microbial infections and alleviate issues related to antibiotic overuse and microbial mutability.

Molecular epidemiology and mechanism of Klebsiella pneumoniae resistance to ertapenem but not to other carbapenems in China

Resistance to only ertapenem is an unusual phenotype of carbapenem-resistant Klebsiella pneumoniae (CRKP). This study aimed to investigate the molecular epidemiology and underlying mechanism involved in ertapenem resistance of K. pneumoniae strains that are susceptible to meropenem and imipenem. Among the 697 K. pneumoniae strains isolated from 11 grade A hospitals in China, 245 were CRKP strains, of which 18 strains resistant only to ertapenem were isolated. The genotypes, phenotypes, drug resistance homology, and drug sensitivity were analyzed; moreover, the expressions of efflux pump components and outer membrane proteins were assessed. The whole genomes of these 18 strains were sequenced and analyzed for mutations leading to drug resistance. The results revealed that ertapenem resistance may be related to ramR mutation. The function of ramR was confirmed using gene complementation to the original strain to determine the mechanism underlying ertapenem resistance of K. pneumoniae strains. In total, 7.4% of the tested CRKP strains were resistant only to ertapenem. None of these strains contained carbapenemase genes. Of the 18 ertapenem-resistant strains, 17 expressed the efflux pump, and outer membrane protein expression was reduced or absent in 4 strains. Whole-genome sequencing revealed the presence of mutations that introduced premature ramR codons stop in 14 strains (77.78%). When a functional copy of ramR was restored in the 14 strains, the minimum inhibitory concentration of ertapenem decreased, inhibition of efflux pumps was not detected, and the expression of outer membrane protein OmpK35 was either increased or was restored. These findings reveal the existence of ertapenem-resistant K. pneumoniae exhibiting no clonal transmission between strains. Mutations in ramR were demonstrated to cause efflux pump inhibition and over-expression of outer membrane protein OmpK35 in some strains, which is implicated in ertapenem resistance only in K. pneumoniae.

Screening for Escherichia coli in Chopping Board Meat Samples and Survey for Sanitary and Hygienic Practices in Retail Meat Shops of Bharatpur Metropolitan City, Nepal

In this study, chopping board meat samples collected from meat shops of Bharatpur Metropolitan City, Nepal, were screened for the presence of Escherichia coli (E. coli), with a special emphasis on the identification of extended-spectrum β-lactamase (ESBL)-producing strains. Representatives from the meat shops were also interviewed to understand the sanitary status and hygienic practices. E. coli bacteria were detected in one third (33/99) of the meat samples, while none of the samples had ESBL-producing strains. While 60.6% (60/99) of the meat shop personnel wore protective clothing, 15.15% (15/99) used gloves, and only 5.05% (5/99) had separate equipment for cleaning the viscera of animals. This study highlights the need for the regular screening of meat samples to identify pathogenic bacteria such as E. coli and for improvements in the sanitary status and hygienic practices of retail meat shops in Bharatpur Metropolitan City, Nepal.

Development of a hematite nanotube and tyramine-based drug carrier against drug-resistant bacteria Klebsiella pneumoniae

In this study, hematite nanotube (HNT) and tyramine-based advanced nano-drug carriers were developed for inhibiting the growth of Klebsiella pneumoniae (K. pneumoniae). The HNT was synthesized by following the Teflon line autoclaved assisted hydrothermal process and tyramine was incorporated on the surface of the HNT to fabricate the formulated nano-drug. The nano-drug was prepared by conjugating meropenem (MP) on the surface of Tyramine-HNT and characterized using different techniques, such as scanning electron microscopy (SEM), attenuated total reflection Fourier transform infrared (ATR-FTIR), etc. Furthermore, the drug-loading efficiency and loading capacity were measured using a UV-vis spectrometer. The pH, amount of Tyr, and HNT required for drug loading were optimized. A controlled and gradual manner of pH-sensitive release profiles was found after investigating the release profile of MP from the carrier drug. The antibacterial activity of MP@Tyramine-HNT and MP was compared through the agar disc diffusion method which indicates that antibacterial properties of antibiotics are enhanced after conjugating. Surprisingly, the MP@Tyramine-HNT exhibits a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of K. pneumoniae lower than MP itself. These results indicate the nanocarrier can reduce the amount of MP dosed to eradicate K. pneumoniae.

The Combination of Amoxicillin and 1,8-Cineole Improves the Bioavailability and the Therapeutic Effect of Amoxicillin in a Rabbit Model

In this study, the effectiveness of the combination therapy of 1,8-cineole with amoxicillin (AMX) and clavulanic acid (Clav) was investigated. For this, the pharmacokinetic behaviors of AMX in rabbits were studied after a single oral dose. The animals were divided randomly into two groups: the reference group (received AMX/Clav (50/12.5 mg/kg)) and the test group (received AMX/Clav/1,8-cineole (50/12.5/10 mg/kg)). Blood samples were collected prior to administration and after T1h, T2h, T3h, and T6h post-administration. Plasma concentrations of AMX were quantified using a validated HPLC method. The antibacterial activity of plasma and cerebrospinal fluid (CSF) of treated rabbits was tested against Escherichia coli ESBL-producing a strain by microdilution method. The obtained results showed significant differences in pharmacokinetic parameters between the two groups. The resulting AUC_0–6h and C_max mean values of the AMX reference group were 14.74 µg.h/mL and 3.49 µg/mL, respectively. However, those of the AMX test group were 22.30 µg.h/mL and 5.79 µg/mL, respectively. The results showed that the antibacterial activity of the plasma and CSF test group was significantly higher than that of the reference group. The effectiveness of this combination (Olipen: AMX/Clav/1,8-cineole) was demonstrated by increasing the level of the antibiotic and by improving the bioavailability.

Pathogen Distribution and Antimicrobial Resistance of Early Onset Sepsis in Very Premature Infants: A Real-World Study

INTRODUCTION

Early onset sepsis (EOS) remains a potentially fatal newborn condition, especially in very preterm infants. Data on the pathogen distribution and antibiotic susceptibility patterns of EOS among very preterm infants are scarce but essential for the choice of empirical antibiotic administration. We sought to assess the epidemiologic characteristics and antibiotic susceptibility patterns of pathogens causing EOS among a cohort of very preterm infants in China.

METHODS

This prospective, observational study included a cohort of infants born at a gestational age (GA) less than 32 weeks of 32 newborn intensive care units (NICUs) in China between January 1, 2018 and December 31, 2020. EOS was defined by isolation of pathogenic species from blood culture within 72 h of birth.

RESULTS

A total of 108 EOS cases (18.4 per 1000 admissions) were identified among 5865 very preterm infants. Incidence of EOS increased with the decrease of GA and birthweight. Escherichia coli (n = 44, 40.7%) was the most common pathogen, followed by Klebsiella spp. (n = 10, 9.3%). The distribution and proportion of pathogenic bacteria varied significantly by GA. E. coli and Klebsiella spp. showed high resistance to ampicillin and third-generation cephalosporins, while they showed good susceptibility to carbapenem antibiotics and piperacillin-tazobactam.

CONCLUSION

Our data demonstrated that pathogens causing neonatal EOS showed high rates of resistance to ampicillin and third-generation cephalosporins. This raised questions about the best empirical antibiotic choice for preterm infants suspected of having EOS in low- and middle-income countries (LMICs).

Innovative Insights into In Vitro Activity of Colloidal Platinum Nanoparticles against ESBL-Producing Strains of Escherichia coli and Klebsiella pneumoniae

Growing morbidity and mortality rates due to increase in the number of infections caused by MDR (multi-drug resistant) microorganisms are becoming some of the foremost global health issues. Thus, the need to search for and find novel approaches to fight AMR (antimicrobial resistance) has become obligatory. This study aimed to determine the antimicrobial properties of commercially purchased colloidal platinum nanoparticles by examining the existence and potency of their antibacterial effects and investigating the mechanisms by means of which they express these activities. Antimicrobial properties were investigated with respect to standard laboratory ATCC (American Type Cell Culture) and clinical extended-spectrum beta-lactamase (ESBL)-producing strains of Escherichia (E.) coli and Klebsiella (K.) pneumoniae. Standard microbiological methods of serial microdilution, modulation of microbial cell death kinetics (“time–kill” assays), and biofilm inhibition were used. Bacterial cell wall damage and ROS (reactive oxygen species) levels were assessed in order to explore the mechanisms of platinum nanoparticles’ antibacterial activities. Platinum nanoparticles showed strong antibacterial effects against all tested bacterial strains, though their antibacterial effects were found to succumb to time kinetics. Antibiofilm activity was modest overall and significantly effective only against E. coli strains. By measuring extracellular DNA/RNA and protein concentrations, induced bacterial cell wall damage could be assumed. The determination of ROS levels induced by platinum nanoparticles revealed their possible implication in antibacterial activity. We conclude that platinum nanoparticles exhibit potent antibacterial effects against standard laboratory and resistant strains of E. coli and K. pneumoniae. Both, cell wall damage and ROS induction could have important role as mechanisms of antibacterial activity, and, require further investigation.

Pandemic Clones of CTX-M-15 Producing Klebsiella pneumoniae ST15, ST147, and ST307 in Companion Parrots

Psittacine birds are commonly kept as companion birds and the maintenance of these birds in captivity may represent a zoonotic risk and contribute to the propagation of multidrug-resistant and β-lactamase extended-spectrum (ESBLs)-producing pathogens. This study aimed to identify and characterize strains of the Klebsiella pneumoniae complex isolated from diseased psittacine birds, determining virulence and resistance profiles. K. pneumoniae strains were isolated from 16 birds (16/46). All strains carried more than three virulence genes, with a high frequency of fimH and kpn (93.75%), uge (87.52%), and irp-2 (81.25%) genes. The antimicrobial susceptibility revealed that 3/16 strains were ESBL producers. Genomic analysis revealed that CTX-M-15-positive strains belonged to sequence types (STs) ST15, ST147, and ST307, characterized as international clones associated with outbreaks of healthcare-associated infections (HAIs) worldwide.

Escherichia coli Mastitis in Dairy Cattle: Etiology, Diagnosis, and Treatment Challenges

Bovine mastitis is an inflammation of the udder tissue parenchyma that causes pathological changes in the glandular tissue and abnormalities in milk leading to significant economic losses to the dairy industry across the world. Mammary pathogenic Escherichia (E.) coli (MPEC) is one of the main etiologic agents of acute clinical mastitis in dairy cattle. MPEC strains have virulence attributes to resist the host innate defenses and thrive in the mammary gland environment. The association between specific virulence factors of MPEC with the severity of mastitis in cattle is not fully understood. Furthermore, the indiscriminate use of antibiotics to treat mastitis has resulted in antimicrobial resistance to all major antibiotic classes in MPEC. A thorough understanding of MPEC’s pathogenesis and antimicrobial susceptibility pattern is required to develop better interventions to reduce mastitis incidence and prevalence in cattle and the environment. This review compiles important information on mastitis caused by MPEC (e.g., types of mastitis, host immune response, diagnosis, treatment, and control of the disease) as well as the current knowledge on MPEC virulence factors, antimicrobial resistance, and the dilemma of MPEC as a new pathotype. The information provided in this review is critical to identifying gaps in knowledge that will guide future studies to better design diagnostic, prevent, and develop therapeutic interventions for this significant dairy disease.

Prevalence of colistin resistance of Klebsiella pneumoniae isolates in Iran: a systematic review and meta-analysis

Objective

Klebsiella pneumoniae is a gram-negative pathogen common cause of nosocomial infections. Colistin is a last resort antibiotic to treat infections caused by K. pneumoniae. In recent years, the resistance rate to colistin has increased in K. pneumoniae. This study evaluated the prevalence of colistin resistance of K. pneumoniae isolates in Iran using a systematic review and meta-analysis.

Method

A systematic search was performed for relevant articles until August 2021 in the following database: PubMed, Scopus, SID and Google Scholar. The pooled prevalence of colistin resistance in clinical K. pneumoniae isolates analyzed using Comprehensive Meta-Analysis Software (CMA).

Results

Finally, 19 articles with appropriate criteria were included in the meta-analysis. Our results showed 6.9% of the pooled prevalence of colistin resistance in clinical K. pneumoniae isolates in Iran. The results of subgroup analysis demonstrated increase resistance of colistin from 4.8%; (95% CI 1.5–13.9%) in 2013–2018 to 8.2%; (95% CI 3.4–18.6%), in 2019–2021. Also, the results of our study showed a strong association between the carbapenem producing K. pneumoniae and increased resistance to colistin.

Conclusions

This study showed a high prevalence of colistin resistance in K. pneumoniae isolates. It is recommended that regular evaluation be performed to control colistin resistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-022-00520-8.

Ceftazidime-Avibactam for the Treatment of Multidrug-Resistant Pathogens: A Retrospective, Single Center Study

Background: Ceftazidime/avibactam is a new cephalosporin/beta-lactamase inhibitor combination approved in 2015 by the FDA for the treatment of complicated intra-abdominal and urinary tract infection, hospital-acquired pneumoniae and Gram-negative infections with limited treatment options. Methods: In this retrospective study, we evaluate the efficacy of ceftazidime/avibactam treatment in 81 patients with Gram-negative infection treated in our center from January 2018 to December 2019. The outcome evaluated was 30-days survival or relapse of infection after the first positive blood culture. Results: the majority of patients were 56 male (69%), with median age of 67. Charlson’s Comorbidity Index was >3 in 58 patients. In total, 46% of the patients were admitted into the medical unit, 41% in the ICU, and 14% in the surgical ward. Of the patients, 78% had nosocomial infections, and 22% had healthcare-related infections. The clinical failure rate was 35%: 13 patients died within 30 days from the onset of infection. The outcome was influenced by the clinical condition of the patients: solid organ transplantation (p = 0.003) emerged as an independent predictor of mortality; non-survival patients most frequently had pneumonia (p = 0.009) or mechanical ventilation (p = 0.049). Conclusion: Ceftazidime−avibactam showed high efficacy in infections caused by MDR Gram-negative pathogens with limited therapeutic options.

Antibiotic-resistance genes in E. coli strains in GCC countries: A meta-analysis

Background:

Antimicrobial resistance (AMR) in Escherichia coli is an alarming issue worldwide, including in the Gulf Cooperation Council (GCC) countries, yet the prevailing gene patterns have not recently been reviewed. This study was conducted to determine and report on the dominant E. coli antimicrobial resistant gene patterns in GCC countries.

Method:

A scoping review identified the predominant AMR genes in GCC countries: CTX M, TEM, SHV, NDM, OXA, and VIM genes. For the systematic review, two authors independently searched Scopus, PubMed, Google Scholar, Science Direct, and Web of Science for interventional, clinical, or observational studies on the chosen AMR-conferring genes in E. coli published from GCC countries between January 2013 and June 2019, when the last search was carried out. The search strategy followed the PRISMA guidelines. The risk of bias was assessed using a 6-item standardized checklist. Random-effects modeling was used for all analyses.

Results:

A total 32 studies were included in the final synthesis of evidence. Overall, CTX-M (53.8%) was the most prevalent gene in the region followed TEM (40.6%), NDM-1 (28.4%), OXA (24.3%), VIM (8.5%), and SHV (7.8%). Most included studies were from Saudi Arabia: CTX-M was again most common with a prevalence of 46.8% from 5442 isolates.

Conclusion:

The risk of bias analysis showed a mean quality score of 4.25 ± 0.75, indicating high-quality in studies included in this meta-analysis. This review found that CTX-M gene is the most common AMR-conferring gene in E. coli strains from most GCC countries.

Surging bloodstream infections and antimicrobial resistance during the first wave of COVID-19: a study in a large multihospital institution in the Paris region

Objectives

This study measured the impact of the first wave of COVID-19 pandemic (COVID-19) (March–April 2020) on the incidence of bloodstream infections (BSIs) at Assistance Publique – Hôpitaux de Paris (APHP), the largest multisite public healthcare institution in France.

Methods

The number of patient admission blood cultures (BCs) collected, number of positive BCs, and antibiotic resistance and consumption were analysed retrospectively for the first quarter of 2020, and also for the first quarter of 2019 for comparison, in 25 APHP hospitals (ca. 14 000 beds).

Results

Up to a fourth of patients admitted in March–April 2020 in these hospitals had COVID-19. The BSI rate per 100 admissions increased overall by 24% in March 2020 and 115% in April 2020, and separately for the major pathogens (Escherichia coli, Klebsiella pneumoniae, enterococci, Staphylococcus aureus, Pseudomonas aeruginosa, yeasts). A sharp increase in the rate of BSIs caused by microorganisms resistant to third-generation cephalosporins (3GC) was also observed in March–April 2020, particularly in K. pneumoniae, enterobacterial species naturally producing inducible AmpC (Enterobacter cloacae...), and P. aeruginosa. A concomitant increase in 3GC consumption occurred.

Conclusions

The COVID-19 pandemic had a strong impact on hospital management and also unfavourable effects on severe infections, antimicrobial resistance, and laboratory work diagnostics.

The Action of Efflux Pump Genes in Conferring Drug Resistance to Klebsiella Species and Their Inhibition

Nosocomial infections caused by Klebsiella species are characterized by high rates of morbidity and mortality. The emergence of the multidrug-resistant (MDR) and extensive drug-resistant (XDR) Gram-negative bacteria reduces the antibiotic efficacy in the treatment of infections caused by the microorganisms. Management of these infections is often difficult, due to the high frequency of strains resistant to multiple antimicrobial agents. Multidrug efflux pumps play a major role as a mechanism of antimicrobial resistance in Gram-negative pathogens. Efflux systems are significant in conferring intrinsic and acquired resistance to the bacteria. The emergence of increasing drug resistance among Klebsiella pneumoniae nosocomial isolates has limited the therapeutic options for treatment of these infections and hence there is a constant quest for an alternative. In this review, we discuss various resistance mechanisms, focusing on efflux pumps and related genes in conferring resistance to Klebsiella. The role of various efflux pump inhibitors (EPIs) in restoring the antibacterial activity has also been discussed. In specific, antisense oligonucleotides as alternative therapeutics in combatting efflux-mediated resistance in Klebsiella species have focused upon.

Development of Drug-Resistant Klebsiella pneumoniae Vaccine via Novel Vesicle Production Technology

Drug resistance of Klebsiella pneumoniae severely threatens human health. Overcoming the mechanisms of K. pneumoniae resistance to develop novel vaccines against drug-resistant K. pneumoniae is highly desired. Here, we report a technology platform that uses high pressure to drive drug-resistant K. pneumoniae to pass through a gap, inducing the formation of stable artificial bacterial biomimetic vesicles (BBVs). These BBVs had little to no bacterial intracellular protein or nucleic acid and had high yields. BBVs were efficiently taken up by dendritic cells to stimulate their maturation. BBVs as K. pneumoniae vaccines had the dual functions of inducing bacteria-specific humoral and cellular immune responses to increase animals' survival rate and reduce pulmonary inflammation and bacterial loads. We believe that BBVs are new-generation technology for bacterial vesicle preparation. Establishment of this BBV vaccine platform can maximally expand preparation technology for vaccines against drug-resistant K. pneumoniae.

Heterogeneity of Antibiotics Multidrug-Resistance Profile of Uropathogens in Romanian Population

Urinary tract infections (UTIs) are a leading cause of morbidity for both males and females. The overconsumption of antibiotics in general medicine, veterinary, or agriculture has led to a spike in drug-resistant microorganisms; obtaining standardized results is imposed by standard definitions for various categories of drug-resistant bacteria—such as multiple-drug resistant (MDR), extensive drug-resistant (XDR), and pan drug-resistant (PDR). This retrospective study conducted in three university teaching hospitals in Romania has analyzed urine probes from 15,231 patients, of which 698 (4.58%) presented multidrug-resistant strains. Escherichia coli was the leading uropathogen 283 (40.54%), presenting the highest resistance to quinolones (R = 72.08%) and penicillin (R = 66.78%) with the most important patterns of resistance for penicillin, sulfonamides, and quinolones (12.01%) and aminoglycosides, aztreonam, cephalosporins, and quinolones (9.89%). Klebsiella spp. followed—260 (37.24%) with the highest resistance to amoxicillin-clavulanate (R = 94.61%) and cephalosporins (R = 94.23%); the leading patterns were observed for aminoglycosides, aminopenicillins + β-lactams inhibitor, sulfonamides, and cephalosporins (12.69%) and aminoglycosides, aztreonam, cephalosporins, quinolones (9.23%). The insufficient research of MDR strains on the Romanian population is promoting these findings as an important tool for any clinician treating MDR-UTIs.

Antimicrobial Resistance in Escherichia coli Strains Isolated from Humans and Pet Animals

Throughout scientific literature, we can find evidence that antimicrobial resistance has become a big problem in the recent years on a global scale. Public healthcare systems all over the world are faced with a great challenge in this respect. Obviously, there are many bacteria that can cause infections in humans and animals alike, but somehow it seems that the greatest threat nowadays comes from the Enterobacteriaceae members, especially Escherichia coli. Namely, we are witnesses to the fact that the systems that these bacteria developed to fight off antibiotics are the strongest and most diverse in Enterobacteriaceae. Our great advantage is in understanding the systems that bacteria developed to fight off antibiotics, so these can help us understand the connection between these microorganisms and the occurrence of antibiotic-resistance both in humans and their pets. Furthermore, unfavorable conditions related to the ease of E. coli transmission via the fecal-oral route among humans, environmental sources, and animals only add to the problem. For all the above stated reasons, it is evident that the epidemiology of E. coli strains and resistance mechanisms they have developed over time are extremely significant topics and all scientific findings in this area will be of vital importance in the fight against infections caused by these bacteria.

Inhibition of biofilm formation and quorum sensing mediated virulence in Pseudomonas aeruginosa by marine sponge symbiont Brevibacterium casei strain Alu 1

The alternative antimicrobial strategies that mitigate the threat of antibiotic resistance is the quorum-sensing inhibition (QSI) mechanism, which targets autoinducer dependent virulence gene expression in bacterial pathogens. N-acyl homoserine lactone (AHL) acts as a key regulator in the production of virulence factors and biofilm formation in Pseudomonas aeruginosa PAO1 and violacein pigment production in Chromobacterium violaceum ATCC 12472. In the present study, the marine sponge Haliclona fibulata symbiont Brevibacterium casei strain Alu 1 showed potential QSI activity in a concentration-dependent manner (0.5-2% v/v) against the N-acyl homoserine lactone (AHL)-mediated violacein production in C. violaceum (75-95%), and biofilm formation (53-96%), protease (27-82%), pyocyanin (82-95%) and pyoverdin (29-38%) productions in P. aeruginosa. Further, the microscopic analyses validated the antibiofilm activity of the cell-free culture supernatant (CFCS) of B. casei against P. aeruginosa. Subsequently, the biofilm and pyoverdin inhibitory efficacy of the ethyl acetate extract of B. casei CFCS was assessed against P. aeruginosa. Further, the gas chromatography-mass spectrometry (GC-MS) analysis revealed the presence of variety of components in which diethyl phthalate was found to be a major active component. This phthalate ester, known as diethyl ester of phthalic acid, could act as a potential therapeutic agent for preventing bacterial biofilm and virulence associated infectious diseases.

Synthesis and characterization of an NH4CL-induced Eskanbil activated carbon (EAC) for the removal of penicillin G from contaminated water

Penicillin G (PG) is one of the most widely used antibiotics around the world. The release of PG in an aqueous solution leads to contamination of water resources. This study aimed to determine the efficiency of modified Eskanbil activated carbon for the removal of PG from aqueous solutions. The NH4Cl-induced activated carbon was synthesized by a simple method and used for the degradation of PG in contaminated water. Activated carbon was characterized by Fourier transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The four main reaction parameters optimized in this study were pH, time, the concentration of the EAC (Eskanbil Activated Carbon), and initial PG concentration. The synthesized carbon was characterized and the results showed it as a mesoporous material with the BET specific surface area of 1473 m²/g and pore volume of 0.81 cm³/g. The maximum PG adsorption onto EAC was observed at the pH of 6. The PG removal of 33% at an EAC concentration of 0.1 g/L increased to 99.98% at an activated carbon concentration of 0.5 g/L. The isotherm and kinetic studies of PG removal by EAC showed that the Freundlich model (R² > 0.995) and the pseudo-second-order (R² > 0.983) equation represented the best fit with the adsorption data. EAC is recommended as a suitable and cost-efficient adsorbent for removing poisons, pharmaceuticals, and other emerging contaminants from water resources.

Strategic Moves of "Superbugs" Against Available Chemical Scaffolds: Signaling, Regulation, and Challenges

Superbugs' resistivity against available natural products has become an alarming global threat, causing a rapid deterioration in public health and claiming tens of thousands of lives yearly. Although the rapid discovery of small molecules from plant and microbial origin with enhanced bioactivity has provided us with some hope, a rapid hike in the resistivity of superbugs has proven to be the biggest therapeutic hurdle of all times. Moreover, several distinct mechanisms endowed by these notorious superbugs make them immune to these antibiotics subsequently causing our antibiotic wardrobe to be obsolete. In this unfortunate situation, though the time frame for discovering novel "hit molecules" down the line remains largely unknown, our small hope and untiring efforts injected in hunting novel chemical scaffolds with unique molecular targets using high-throughput technologies may safeguard us against these life-threatening challenges to some extent. Amid this crisis, the current comprehensive review highlights the present status of knowledge, our search for bacteria Achilles' heel, distinct molecular signaling that an opportunistic pathogen bestows to trespass the toxicity of antibiotics, and facile strategies and appealing therapeutic targets of novel drugs. Herein, we also discuss multidimensional strategies to combat antimicrobial resistance.

Distinct Skin Microbiome and Skin Physiological Functions Between Bedridden Older Patients and Healthy People: A Single-Center Study in Japan

With the increase in the older populations, the number of bedridden older patients is becoming a matter of concern. Skin microbiome and skin physiological functions are known to change according to lifestyle and community; however, such changes in case of movement- and cleaning-restricted bedridden older patients have not yet been revealed. To address this issue, we analyzed skin microbiome and skin physiological functions, including pH, hydration, sebum level, and transepidermal water loss (TEWL), of bedridden older patients, compared with those of ambulatory older and young individuals. For this analysis, we enrolled 19 healthy young and 18 ambulatory older individuals from the community and 31 bedridden older patients from a single, long-term care hospital in Japan. The area of interest was set to the sacral (lower back) skin, where pressure injuries (PIs) and subsequent infection frequently occurs in bedridden older patients. We observed a higher number of gut-related bacteria, fewer commensals, higher skin pH, and lower TEWL on the sacral skin of bedridden older patients than on that of young or ambulatory older individuals. In addition, we observed that 4 of the 31 bedridden older patients developed PIs during the research period; a higher abundance of pathogenic skin bacteria were also observed inside the PI wounds. These findings imply distinct skin microbiome and skin physiological functions in bedridden older patients in comparison with healthy individuals and may suggest the need for more stringent cleaning of the skin of bedridden older patients in light of the closeness of skin and wound microbiome.

Association between the rate of third generation cephalosporin-resistant Escherichia coli and Klebsiella pneumoniae and antibiotic consumption based on 143 Chinese tertiary hospitals data in 2014

This study sought to discuss the correlation between the third-generation cephalosporins (3GC)-resistant Escherichia coli and Klebsiella pneumoniae and antibiotic consumption intensity from 143 Chinese tertiary hospitals in 2014. With a retrospective design, the correlation between antibiotic consumption and 3GC-resistant E. coli and K. pneumoniae were performed. 3GC-resistant E. coli was significantly correlated with the consumption of all antibiotics (r = 0.252, p < 0.01), β-Lactams antibiotics (r = 0.313, p < 0.01), β-Lactams excluding combinations with β-lactamase inhibitors (r = 0.365, p < 0.01), cephalosporin (r = 0.398, p < 0.01), cephalosporins excluding combinations with β-lactamase inhibitors (r = 0.374, p < 0.01), 3GC (r = 0.321, p < 0.01), and 3GC excluding combinations with β-lactamase inhibitors (r = 0.343, p < 0.01). 3GC-resistant K. pneumoniae was significantly correlated with the consumption of all antibiotics (r = 0.200, p < 0.05), β-Lactams antibiotics (r = 0.232, p < 0.01), cephalosporin (r = 0.215, p < 0.05), 3GC (r = 0.383, p < 0.01), 3GC excluding combinations with β-lactamase inhibitors (r = 0.245, p < 0.01), and β-lactam-β-lactamase inhibitor combinations (r = 0.218, p < 0.05). There was a significant relationship between the antibiotic consumption and the rates of 3GC-resistant E. coli and K. pneumoniae. Clinicians should grasp the indication of antibiotics use to reduce the production of drug-resistant bacteria.

A 7-year surveillance of the drug resistance in Klebsiella pneumoniae from a primary health care center

Background

The increased prevalence of Klebsiella pneumoniae infections and resistance rates are a current cause for concern. However, data for resistance rates in K. pneumoniae strains from primary hospitals and the resistance distribution among the different isolate sample sources are scarce.

Methods

All the K. pneumoniae strains were isolated from patients who visited a primary health care center located in Central Zhejiang Province from January 2011 to December 2017. The specimens included blood, sputum, cervical secretions and urine. The species were identified by the Vitek 2 Compact Bacterial Identification and Monitoring System or VITEK-MS and the extended spectrum β-lactamase (ESBL) and drug resistance profiles were identified using the AST-GN13 Gram negative susceptibility card (VITEK-2). The genotype of strains from urine sources was analyzed by detecting TEM and SHV genes. Finally, the drug resistance rates among the isolates from different sample sources were analyzed using the Chi square test with SPSS software.

Results

A total of 5319 K. pneumoniae strains were isolated in this study. Among the 20 antimicrobial drugs studied, the resistance rates of K. pneumoniae strains varied from 1.4% (ertapenem) to 23.1% (nitrofurantoin). The antibiotic resistance rates varied significantly among the isolate samples sources for all, with the highest rates for all antibiotics except for nitrofurantoin found in urine samples. In addition, the ESBL-positive rate in urine samples was 27.1%, significantly higher than that of cervical secretions (20.2%), blood (16.5%) and sputum (15.2%). Compared to the ESBL-negative strains, higher resistance rates were detected in the ESBL-positive strains. The most common genotype of isolates from urine was SHV (28%, 23/82), following by TEM (14.6%, 12/82).

Conclusion

The highest resistance rates of K. pneumoniae strains to most antibiotics found in urine samples are partly due to the ESBLs, indicating that a special attention should be paid in the treatment of urinary tract infection.

Antibiotic-resistance of Fecal Coliforms at the Bottom of the Tama River, Tokyo

We investigated the midstream bottom of the Tama River, which flows through Tokyo, to evaluate the occurrence and degree of antibiotic-resistant fecal coliforms including multidrug-resistant fecal coliforms. The genera Klebsiella and Escherichia were the major isolates among the fecal coliforms. For the genus Klebsiella, the highest antibiotic resistance was observed for ampicillin (100%) , followed by kanamycin, tetracycline, cefotaxime, and cefoxitin. The highest resistance to E. coli was found for kanamycin (44.4%) , followed by ampicillin, tetracycline, chloramphenicol, amoxicillin-clavulanate, cefotaxime, ceftazidime, and aztreonam. Multidrug resistance （MDR） was observed in three E. coli isolates. A double disc synergy test confirmed the production of extended-spectrum β-lactamases by the six-antibiotic-resistant isolate E. coli hfa7, and the strain had CTX-M-1 group gene. Assessments of antibiotic-resistant fecal coliforms at the bottom of the Tama River are important toward the goals of preventing the spread of antibiotic-resistant fecal coliforms in humans, animals, and the environment.

Preliminary survey of extended-spectrum β-lactamases (ESBLs) in nosocomial uropathogen Klebsiella pneumoniae in north-central Iran

Infections caused by extended-spectrum β-lactamases (ESBLs) producing bacteria, including Klebsiella pneumoniae have increasingly subjected to therapeutic limitations and patients with these infections are at high risk for treatment failure, long hospital stays, high health care costs, and high mortality. The aim of this study was to screen the prevalence of the bla_TEM,bla_CTX-M and bla_SHV ESBL genes in K. pneumoniae strains isolated from nosocomial urinary tract infections (UTIs). During the March 2016 to December 2017, one hundred isolates of K. pneumoniae were collected from urine specimens of patients suffering from nosocomial UTI referred to Khatam Al-Anbia hospital in Shahrud, north-central Iran. All isolates were identified by standard bacteriological tests. The pattern of antibiotic susceptibility was determined according to the CLSI guidelines. The presence of the ESBLs was investigated using the double-disc synergy test (DDST). Polymerase chain reaction technique was used to detect the bla_TEM, bla_CTX-M and bla_SHV genes in DDST positive isolates. Most isolates showed remarkable resistance to tested antibiotics with highest rate against nitrofurantoin (75%) and trimethoprim/sulfamethoxazole (65%). The imipenem was the most effective antibiotic against K. pneumoniae isolates. ESBL phenotype was detected in 50 (50%) of isolates. The prevalence of bla_TEM, bla_CTX-M and bla_SHV genes among 50 ESBLs-positive isolates was 25 (50%), 15 (30%) and 35 (70%) respectively. The bla_TEM and bla_SHV genes were seen in 25 isolates (50%) simultaneously. The findings of this study indicated the 50% frequency rate of ESBL-producing K. pneumoniae in our geographic region. Since the treatment of infections caused by this bacterium is associated with many limitations, this high prevalence is a warning sign to adopt new control policies to prevent further spread of this microorganism.

Risk factors and outcomes in non-transplant patients with extended-spectrum beta-lactamase-producing Escherichia coli bacteremia: a retrospective study from 2013 to 2016

Background

Escherichia coli is one of the most common strains of extended-spectrum β-lactam (ESBL)-producing bacteria, and the prevention and treatment of ESBL-producing E. coli infections is an ongoing challenge. The clinical characteristics and outcomes of ESBL-producing E. coli bacteremia in non-transplant patients remain to be elucidated.

Methods

This retrospective study included 491 non-transplant patients with E. coli bloodstream infections (BSIs) from January 2013 to December 2016 and was conducted to investigate the risk factors, clinical features, and outcomes of these infections.

Results

Of the 491 E. coli BSI patients, 57.6% suffered from infections with ESBL-producing strains. A multivariate analysis showed that urinary tract infection, prior use of cephalosporin, and treatment with β-lactam-β-lactamase inhibitor (BLBLI) combination antibiotics were independent risk factors for the development of ESBL-producing E. coli BSIs. The overall mortality rate in E. coli BSI patients was 14.46%, and there was no significant difference in the 28 day mortality rate between ESBL-producing E. coli and non-ESBL-producing E. coli BSI patients (14.8% vs. 14.0%, respectively; P = 0.953). Similarly, there was no difference between the community-acquired infection group and the nosocomial infection group. Hepatobiliary disease, carbapenem exposure, high APACHE II score, and hypoproteinemia were independent risk factors for death in E. coli BSI patients. Multivariate analysis showed that hypoproteinemia and severe disease were independent risk factors for death from ESBL-producing E. coli BSIs. Furthermore, there was no significant difference in the 28 day mortality between patients with ESBL-producing E. coli BSIs treated with carbapenem monotherapy versus those treated with BLBLI combination antibiotics (12.8% vs. 17.9%, respectively; P = 0.384).

Conclusions

Prior use of cephalosporin or BLBLI combination antibiotics increased the risk ratio for ESBL-producing E. coli infection. Hypoproteinemia and severe disease are independent risk factors for death in patients with E. coli BSIs. There was no significant difference in the 28 day prognosis of patients with ESBL-producing E. coli and those with non-ESBL-producing E. coli BSIs. These data do not support the conclusion that carbapenems might be more effective than BLBLI antibiotics for treatment of patients with BSIs caused by ESBL-producing E. coli.

Electronic supplementary material

The online version of this article (10.1186/s13756-019-0599-y) contains supplementary material, which is available to authorized users.

Degradable antimicrobial polycarbonates with unexpected activity and selectivity for treating multidrug-resistant Klebsiella pneumoniae lung infection in mice

Multidrug resistant (MDR) Klebsiella pneumoniae is a major cause of healthcare-associated infections around the world, with attendant high rates of morbidity and mortality. Progressive reduction in potency of antibiotics capable of treating MDR K. pneumoniae infections - including lung infection - as a consequence of escalating drug resistance provides the motivation to develop drug candidates targeting MDR K. pneumoniae. We recently reported degradable broad-spectrum antimicrobial guanidinium-functionalized polycarbonates with unique antimicrobial mechanism - membrane translocation followed by precipitation of cytosolic materials. These polymers exhibited high potency against bacteria with negligible toxicity. The polymer with ethyl spacer between the quanidinium group and the polymer backbone (pEt_20) showed excellent in vivo efficacy for treating MDR K. pneumoniae-caused peritonitis in mice. In this study, the structures of the polymers were optimized for the treatment of MDR Klebsiella pneumoniae lung infection. Specifically, in vitro antimicrobial activity and selectivity of guanidinium-functionalized polycarbonates containing the same number of guanidinium groups but of a shorter chain length and a structural analogue containing a thiouronium moiety as the pendent cationic group were evaluated. The polymers with optimal compositions and varying hydrophobicity were assessed against 25 clinically isolated K. pneumonia strains for antimicrobial activity and killing kinetics. The results showed that the polymers killed the bacteria more efficiently than clinically used antibiotics, and repeated use of the polymers did not cause drug resistance in K. pneumonia. Particularly, the polymer with butyl spacer (pBut_20) self-assembled into micelles at high concentrations, where the hydrophobic component was shielded in the micellar core, preventing interacting with mammalian cells. A subtle change in the hydrophobicity increased the antimicrobial activity while reducing in vivo toxicity. The in vivo efficacy studies showed that pBut_20 alleviated K. pneumonia lung infection without inducing damage to major organs. Taken together, pBut_20 is promising for treating MDR Klebsiella pneumoniae lung infection in vivo. STATEMENT OF SIGNIFICANCE: Multidrug resistant (MDR) Klebsiella pneumoniae is a major cause of healthcare-associated infections, with attendant high rates of morbidity and mortality. The progressive reduction in antibiotics capable of treating MDR K. pneumoniae infections - including lung infection - as a consequence of escalating drug resistance rates provides the motivation to develop drug candidates. In this study, we report a degradable guanidinium-functionalized polycarbonate with unexpected antimicrobial activity and selectivity towards MDR Klebsiella pneumoniae. A subtle change in polymer hydrophobicity increases antimicrobial activity while reducing in vivo toxicity due to self-assembly at high concentrations. The polymer with optimal composition alleviates Klebsiella pneumonia lung infection without inducing damage to major organs. The polymer is promising for treating MDR Klebsiella pneumoniae lung infection in vivo.

Carriage of carbapenemase- and extended-spectrum cephalosporinase-producing Escherichia coli and Klebsiella pneumoniae in humans and livestock in rural Cambodia; gender and age differences and detection of blaOXA-48 in humans

Objectives

This study investigates the frequency and characteristics of carbapenemase‐producing Escherichia coli/Klebsiella pneumoniae (CPE/K) and extended‐spectrum cephalosporinase‐producing E. coli/K. pneumoniae (ESCE/K) in healthy humans and livestock in rural Cambodia. Additionally, household practices as risk factors for faecal carriage of ESCE/K are identified.

Methods

Faecal samples were obtained from 307 humans and 285 livestock including large ruminants, pigs and poultry living in 100 households in rural Cambodia in 2011. Each household was interviewed, and multilevel logistic model determined associations between household practices/meat consumption and faecal carriage of ESCE/K. CPE and ESCE/K were detected and further screened for colistin resistance genes.

Results

CPE/K isolates harbouring bla_OXA‐48 were identified in two humans. The community carriage of ESCE/K was 20% in humans and 23% in livestock. The same ESBL genes: bla_CTX‐M‐15, bla_CTX‐M‐14, bla_CTX‐M‐27, bla_CTX‐M‐55, bla_SHV‐2, bla_SHV‐12, bla_SHV‐28; AmpC genes: bla_CMY‐2, bla_CMY‐42,bla_DHA‐1; and colistin resistance genes: mcr‐1‐like and mcr‐3‐like were detected in humans and livestock. ESCE/K was frequently detected in women, young children, pigs and poultry, which are groups in close contact. The practice of burning or burying meat waste and not collecting animal manure indoors and outdoors daily were identified as risk factors for faecal carriage of ESCE/K.

Conclusions

Faecal carriage of E. coli and K. pneumoniae harbouring extended‐spectrum cephalosporinase genes are common in the Cambodian community, especially in women and young children. Exposure to animal manure and slaughter products are risk factors for intestinal colonization of ESCE/K in humans.

Prevalence of Plasmid-Mediated Quinolone Resistance in Multidrug-Resistant Gram Negative Bacilli in Egypt

Resistance to quinolone has increased significantly and one of the most reasons is plasmid-mediated quinolone resistance (PMQR). The aim of this study is to detect the prevalence of PMQR in multidrug-resistant (MDR) Gram negative bacilli and to characterize these resistance genes. A total of 420 Gram negative bacilli clinical isolates were collected from patients attending Misr children hospital. Isolates were identified by biochemical reactions, while antimicrobial susceptibility testingwas done by Kirby-Bauer disk diffusion method. Minimum inhibitory concentrations (MIC) of ciprofloxacin were detected by E-test, whereas combined test method was used to detect extended-spectrum β-lactamase (ESBL) production. QnrA, qnrB, and qnrS genes were determined by multiplex polymerase chain reaction (PCR). MDRGram negative bacilli represented 68% (268/420); most of them were recovered from blood culture specimens (21%).Among these MDR isolates21%(60/268) were ciprofloxacin resistant; with MICs >32µg/ml in 95% of the isolates.ESBL production was detected in 11.7% of the studied isolates. The qnr genes were detected in 60%. QnrS and qnrB were the detected genes in 77.8% and 16.7% of the isolates respectively. Both qnrB and qnrS genes were determined simultaneously in 5.5%.QnrB gene was found alone in only one isolate (14.3%) that was ESBL-producer. The most MDR isolates were recovered from blood culture; this confirms the occurrence of these superbugs and their ability to cause life threatening infections. The prevalence of quinolone resistant Gram negative bacilli clinical isolates is high. The mostly prevalent PMQR gene is qnrS followed by qnrB.

Antimicrobial polymers as therapeutics for treatment of multidrug-resistant Klebsiella pneumoniae lung infection

Klebsiella pneumoniae (K. pneumoniae) is one of the most common pathogens in hospital-acquired infections. It is often resistant to multiple antibiotics (including carbapenems), and can cause severe pneumonia. In search of effective antimicrobials, we recently developed polyionenes that were demonstrated to be potent against a broad-spectrum of microbes in vitro. In this study, polyionenes containing rigid amide bonds were synthesized to treat multidrug-resistant (MDR) K. pneumoniae lung infection. The polyionene exhibited broad-spectrum activity against clinically-isolated MDR bacteria with low minimum inhibitory concentrations (MICs). It also demonstrated stronger antimicrobial activity against 20 clinical strains of K. pneumoniae and more rapid killing kinetics than imipenem and other commonly used antibiotics. Multiple treatments with imipenem and gentamycin led to drug resistance in K. pneumoniae, while repeated use of the polymer did not cause resistance development due to its membrane-disruption antimicrobial mechanism. Additionally, the polymer showed potent anti-biofilm activity. In a MDR K. pneumoniae lung infection mouse model, the polymer demonstrated lower effective dose than imipenem with negligible systemic toxicity. The polymer treatment significantly alleviated lung injury, markedly reduced K. pneumoniae counts in the blood and major organs, and decreased mortality. Given its potent in vivo antimicrobial activity, negligible toxicity and ability of mitigating resistance development, the polyionene may be used to treat MDR K. pneumoniae lung infection.

STATEMENT OF SIGNIFICANCE

Klebsiella pneumoniae (K. pneumoniae) is one of the most common pathogens in hospital-acquired infections, is often resistant to multiple antibiotics including carbapenems and can cause severe pneumonia. In this study, we report synthesis of antimicrobial polymers (polyionenes) and their use as antimicrobial agents for treatment of K. pneumoniae-caused pneumonia. The polymers have broad spectrum antibacterial activity against clinically isolated MDR bacteria, and eliminate MDR K. pneumoniae more effectively and rapidly than clinically used antibiotics. The polymer treatment also provides higher survival rate and faster bacterial removal from the major organs and the blood than the antibiotics. Repeated use of the polymer does not lead to resistance development. More importantly, at the therapeutic dose, the polymer treatment does not cause acute toxicity. Given its in vivo efficacy and negligible toxicity, the polymer is a promising candidate for the treatment of MDR K. pneumoniae-caused pneumonia.

The relationship between phylogenetic classification, virulence and antibiotic resistance of extraintestinal pathogenic Escherichia coli in İzmir province, Turkey

Background

Extraintestinal pathogenic Escherichia coli (ExPEC) is an important bacterium and responsible for many bloodstream infections, including urinary tract infections and even fatal bacteremia. The aim of this research was to investigate whether ExPEC strains isolated from Turkish blood cultures have a relationship between 16S rRNA based phylogenetic clusters and antibiotic resistance profiles, virulence factors or clonal lineages.

Methods

Phenotypically identified ExPEC blood culture isolates (n = 104) were included in this study. The 16S rRNA partial sequence analysis was performed for genotypic identification of ExPEC isolates. Antibiotic susceptibility and Extended-Spectrum β-Lactamase testing of isolates were performed. Phylogenetic classification (A, B1, B2 and D), Multi Locus Sequence Typing analysis and virulence-associated genes were investigated.

Results

Based on 16S rRNA partial sequence analysis, 97 out of 104 (93.26%) ExPEC isolates were confirmed as E. coli. Ampicillin (74.22%) and cefuroxime axetil (65.97%) resistances had the highest frequencies among the ExPEC isolates. In terms of phylogenetic classification of ExPEC, D (38.14%, 37/97) was the most prevalent group after A (29.89%, 29/97), B2 (20.61%, 20/97), and B1 (11.34%, 11/97). The sequence types of the 20 ExPEC isolates belonging to the B2 phylogenetic group were analyzed by Multi Locus Sequence Typing. Ten isolates out of 20 (50.0%) were identified as ST131. The other STs were ST95 (n = 1), ST14 (n = 1), ST10 (n = 1), ST69 (n = 1), ST1722 (n = 2), ST141 (n = 1), ST88 (n = 1), ST80 (n = 1), and ST998 (n = 1). Of the ST131 strains, six (60%, 6/10) represented serogroup O25. The most common virulence factor genes were serum resistance factor gene, traT (55.7%) aerobactin siderophore receptor and yersiniabactin encoding genes iutA (45.3%) and fyuA (50.5%), respectively. In addition, PAI (41.2%), iroN (23.7%), hlyA (15.4%), kpsII (13.4%), ompT (13.4%), papG (12.4%), iss (9.3%), cnf1 (7.2%), ibeA (2.06%), and sfaS (2.06%) genes were present in the ExPEC isolates.

Conclusion

The 16S rRNA-based phylogenetic relationship tree analysis showed that a large cluster was present among 97 ExPEC isolates along with related reference strains. There were 21 main clusters with 32 closely related subclusters. Based on our findings, different clonal lineages of ExPEC can display different antibiotic susceptibilities and virulence properties. We also concluded that virulence factors were not distributed depending on phylogenetic groups (A, B1, B2, and D). The ExPEC isolates belonging to the same phylogenetic group and sequence type could display different resistance and virulence characteristics.

Identification and antimicrobial resistance of pathogens in neonatal septicemia in China-A meta-analysis

OBJECTIVES

The purpose of this study was to analyze the distribution and antimicrobial resistance of common bacterial pathogens causing neonatal septicemia based on a systematic review of published studies in China.

METHODS

Articles on neonatal sepsis published in the Chinese literature from 2009 to 2014 were identified according to the inclusion and exclusion criteria. Data were extracted and analyzed using Comprehensive Meta-Analysis software.

RESULTS

A total of 71 studies were included, in which a total of 8080 bacterial species were isolated from culture-positive blood samples. The pooled distribution rates of common bacterial pathogens were as follows: Staphylococcus 67.1% (95% confidence interval (CI) 63.3-70.6%), Enterococcus 4.1% (95% CI 3.5-4.8%), Streptococcus 2.3% (95% CI 1.6-3.2%), Escherichia coli 7.4% (95% CI 6.4-8.7%), Klebsiella 6.5% (95% CI 5.2-8.2%), Enterobacterium 2.3% (95% CI 1.9-2.8%), Acinetobacter 1.6% (95% CI 1.3-2.0%), Pseudomonas 1.7% (95% CI 1.3-2.2%). Among the Staphylococcus aureus strains isolated, more than 60% were methicillin-resistant (MRSA). In addition, over 50% of the Gram-negative isolates, including Escherichia and Klebsiella, were resistant to the commonly used third-generation cephalosporins. Most of the Gram-positive and Gram-negative bacteria isolated were sensitive to aminoglycosides, especially amikacin.

CONCLUSIONS

It is concluded that Staphylococcus, especially coagulase-negative Staphylococcus, continues to be the principal organism responsible for neonatal septicemia in China; Enterobacteriaceae are common among the Gram-negative isolates. Significant numbers of MRSA and multidrug-resistant Gram-negative bacteria are being isolated as pathogens responsible for neonatal septicemia in China.

Case Report: Carbapenemase-Producing Enterobacteriaceae in an Asylum Seeker with Multidrug-Resistant Tuberculosis

A Syrian asylum seeker with multidrug-resistant tuberculosis (TB) developed a bronchopleural fistula after pneumonectomy. Although screening tests were negative on admission, carbapenemase-producing Enterobacteriaceae were cultured after a few months of TB treatment. Prevalence of multidrug-resistant organisms is reported to be increased in asylum seekers compared with the general Dutch population. Arduous conditions during transit and interrupted health care delivery in our patient led to multiple-resistant microorganisms that complicated treatment.