Nosocomial infection and its molecular mechanisms of antibiotic resistance

Perspectives on the use of ceftolozane/tazobactam: a review of clinical trial data and real-world evidence

Hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) are common healthcare-associated infections linked to high morbidity and mortality. Gram-negative pathogens, such as Pseudomonas aeruginosa, exhibit multidrug resistance and are recognized as major public health concerns, particularly among critically ill patients with HABP/VABP. Ceftolozane/tazobactam is a novel combination antibacterial agent comprising ceftolozane (a potent antipseudomonal cephalosporin) and tazobactam (a β-lactamase inhibitor). Phase III trials have demonstrated non-inferiority of ceftolozane/tazobactam to comparators, leading to the approval of ceftolozane/tazobactam for the treatment of complicated urinary tract infections, complicated intra-abdominal infections, and nosocomial pneumonia. In this article, we review the clinical trial evidence and key real-world effectiveness data of ceftolozane/tazobactam for the treatment of serious healthcare-associated Gram-negative infections, focusing on patients with HABP/VABP.

Importance of lactate/albumin ratio in pediatric nosocomial infection and mortality at different times

Aim: To evaluate the lactate/albumin ratio and its relation to mortality in children with nosocomial infections. Materials & methods: One hundred six children were included in this study. Blood gas and albumin levels were analyzed at the first, 24th and 48th h. Results: The types of detected microbial agents, signs of sepsis, development of septic shock and mortality rates were different. The first-, 24th- and 48th h lactate levels of the children who died were higher than those of the living children, but the albumin levels were lower. The highest area under the curve value for the lactate/albumin ratio was detected at the 24th h. Conclusion: Lactate/albumin ratio can be used to predict mortality in children with nosocomial infections.

A computational investigation of potential plant-based bioactive compounds against drug-resistant Staphylococcus aureus of multiple target proteins

Drug-resistant Staphylococcus aureus (DRSA) poses a significant global health threat, like bacteremia, endocarditis, skin, soft tissue, bone, and joint infections. Nowadays, the resistance against conventional drugs has been a prompt and focused medical concern. The present study aimed to explore the inhibitory potential of plant-based bioactive compounds (PBBCs) against effective target proteins using a computational approach. We retrieved and verified 22 target proteins associated with DRSA and conducted a screening process that involved testing 87 PBBCs. Molecular docking was performed between screened PBBCs and reference drugs with selected target proteins via AutoDock. Subsequently, we filtered the target proteins and top PBBCs based on their binding affinity scores. Furthermore, molecular dynamic simulation was carried out through GROMACS for a duration of 100 ns, and the binding free energy was calculated using the gmx_MMPBSA. The result showed consistent hydrogen bonding interactions among the amino acid residues Ser 149, Arg 151, Thr 165, Thr 216, Glu 239, Ser 240, Ile 14, as well as Asn 18, Gln 19, Lys 45, Thr 46, Tyr 109, with their respective target proteins of the penicillin-binding protein and dihydrofolate reductase complex. Additionally, we assessed the pharmacokinetic properties of screened PBBCs via SwissADME and AdmetSAR. The findings suggest that β-amyrin, oleanolic acid, kaempferol, quercetin, and friedelin have the potential to inhibit the selected target proteins. In future research, both in vitro and in vivo, experiments will be needed to establish these PBBCs as potent antimicrobial drugs for DRSA.Communicated by Ramaswamy H. Sarma.

Metal nanoparticles as inhibitors of enzymes and toxins of multidrug-resistant Staphylococcus aureus

Staphylococcus aureus is an aerobic Gram-positive spherical bacterium known to cause a broad range of infections worldwide. It is a major cause of infective skin and soft infections and severe and life-threatening conditions, such as pneumonia, bloodstream infections, and endocarditis. The emergence of drug-resistant strains of S aureus, particularly methicillin-resistant S aureus (MRSA), has become a significant concern in the healthcare community. Antibiotic-resistant S aureus is commonly acquired in hospitals and long-term care facilities. It often affects patients with weakened immune systems, those undergoing invasive medical procedures, or those who have been hospitalized for extended periods. In the US, S aureus is known to cause potentially fatal illnesses, such as toxic shock syndrome (TSS) and acute-onset toxic shock syndrome (TSS), which are characterized by fever and hypotension. It develops resistance to antibiotics through several mechanisms, such as the production of enzymes that inactivate antibiotics, target site modification, efflux pumps, and plasmid-mediated resistance. Therefore, preventing the spread of drug-resistant S aureus is needed, and there is an urgent need to explore novel approaches in the development of anti-staphylococcal agents. This article reviews the principal infections caused by S aureus, major virulence factors, mechanisms of resistance development, and nanotechnology-based solutions for the control of drug-resistant S aureus.

Antibiotic resistance in patients with liver cirrhosis: Prevalence and current approach to tackle

Regardless of etiology, complications with bacterial infection in patients with cirrhosis are reported in the range of 25%-46% according to the most recent data. Due to frequent episodes of bacterial infection and repetitive antibiotic treatment, most often with broad-spectrum gram negative coverage, patients with cirrhosis are at increased risk of encountering multidrug resistant bacteria, and this raises concern. In such patients, extended-spectrum beta-lactamase and AmpC-producing Enterobacterales, methicillin- or vancomycin-resistant Staphylococcus aureus, vancomycin-resistant Enterococci, carbapenem-resistant Pseudomonas aeruginosa, and Acinetobacter baumannii, all of which are difficult to treat, are the most common. That is why novel approaches to the prophylaxis and treatment of bacterial infections to avoid antibiotic resistance have recently been developed. At the same time, our knowledge of resistance mechanisms is constantly updated. This review summarizes the current situation regarding the burden of antibiotic resistance, including the prevalence and mechanisms of intrinsic and acquired resistance in bacterial species that most frequently cause complications in patients with liver cirrhosis and recent developments on how to deal with multidrug resistant bacteria.

Nosocomial infections in the surgical intensive care unit: an observational retrospective study from a large tertiary hospital in Palestine

BACKGROUND

Nosocomial infections or hospital-acquired infections are a growing public health threat that increases patient morbidity and mortality. Patients at the highest risk are those in intensive care units. Therefore, our objective was to provide a pattern analysis of nosocomial infections that occurred in an adult surgical intensive care unit (ICU).

METHODS

This study was a retrospective observational study conducted in a 6-bed surgical intensive care unit (SICU) at An-Najah National University Hospital (NNUH) to detect the incidence of nosocomial infections from January 2020 until December 2021. The study group included 157 patients who received antibiotics during their stay in the SICU.

RESULTS

The incidence of nosocomial infections, either suspected or confirmed, in the SICU was 26.9% (95 out of 352 admitted patients). Pneumonia (36.8%) followed by skin and soft tissue infections (35.8%) were the most common causes. The most common causative microorganisms were in the following order: Pseudomonas aeruginosa (26.3%), Acinetobacter baumannii (25.3%), extended-spectrum beta lactamase (ESBL)-Escherichia coli (23.2%) and Klebsiella pneumonia (15.8%). The average hospital stay of patients with nosocomial infections in the SICU was 18.5 days.

CONCLUSIONS

The incidence of nosocomial infections is progressively increasing despite the current infection control measures, which accounts for an increased mortality rate among critically ill patients. The findings of this study may be beneficial in raising awareness to implement new strategies for the surveillance and prevention of hospital-acquired infections in Palestinian hospitals and health care centers.

Abundance and prevalence of ESBL coding genes in patients undergoing first line eradication therapy for Helicobacter pylori

The spread of extended-spectrum beta-lactamases (ESBLs) in nosocomial and community-acquired enterobacteria is an important challenge for clinicians due to the limited therapeutic options for infections that are caused by these organisms. Here, we developed a panel of ESBL coding genes, evaluated the abundance and prevalence of ESBL encoding genes in patients undergoing H. pylori eradication therapy, and summarized the effects of eradication therapy on functional profiles of the gut microbiome. To assess the repertoire of known beta lactamase (BL) genes, they were divided into clusters according to their evolutionary relation. Primers were designed for amplification of cluster marker regions, and the efficiency of this amplification panel was assessed in 120 fecal samples acquired from 60 patients undergoing H. pylori eradication therapy. In addition, fecal samples from an additional 30 patients were used to validate the detection efficiency of the developed ESBL panel. The presence for majority of targeted clusters was confirmed by NGS of amplification products. Metagenomic sequencing revealed that the abundance of ESBL genes within the pool of microorganisms was very low. The global relative abundances of the ESBL-coding gene clusters did not differ significantly among treatment states. However, at the level of each cluster, classical ESBL producers such as Klebsiella sp. for blaOXY (p = 0.0076), Acinetobacter sp. for blaADC (p = 0.02297) and others, differed significantly with a tendency to decrease compared to the pre- and post-eradication states. Only 13 clusters were common across all three datasets, suggesting a patient-specific distribution profile of ESBL-coding genes. The number of AMR genes detected in the post-eradication state was higher than that in the pre-eradication state, which could be attributed, at least in part, to the therapy. This study demonstrated that the ESBL screening panel was effective in targeting ESBL-coding gene clusters from bacterial DNA and that minor differences exist in the abundance and prevalence of ESBL-coding gene levels before and after eradication therapy.

The Current Progress of Tetrahedral DNA Nanostructure for Antibacterial Application and Bone Tissue Regeneration

Recently, programmable assembly technologies have enabled the application of DNA in the creation of new nanomaterials with unprecedented functionality. One of the most common DNA nanostructures is the tetrahedral DNA nanostructure (TDN), which has attracted great interest worldwide due to its high stability, simple assembly procedure, high predictability, perfect programmability, and excellent biocompatibility. The unique spatial structure of TDN allows it to penetrate cell membranes in abundance and regulate cellular biological properties as a natural genetic material. Previous studies have demonstrated that TDNs can regulate various cellular biological properties, including promoting cells proliferation, migration and differentiation, inhibiting cells apoptosis, as well as possessing anti-inflammation and immunomodulatory capabilities. Furthermore, functional molecules can be easily modified at the vertices of DNA tetrahedron, DNA double helix structure, DNA tetrahedral arms or DNA tetrahedral cage structure, enabling TDN to be used as a nanocarrier for a variety of biological applications, including targeted therapies, molecular diagnosis, biosensing, antibacterial treatment, antitumor strategies, and tissue regeneration. In this review, we mainly focus on the current progress of TDN-based nanomaterials for antimicrobial applications, bone and cartilage tissue repair and regeneration. The synthesis and characterization of TDN, as well as the biological merits are introduced. In addition, the challenges and prospects of TDN-based nanomaterials are also discussed.

Metagenomic analysis reveals the short-term influences on conjugation of blaNDM-1 and microbiome in hospital wastewater by silver nanoparticles at environmental-related concentration

Hospital wastewater contains large amounts of antibiotic-resistant bacteria and serves as an important reservoir for horizontal gene transfer (HGT). However, the response of the microbiome in hospital wastewater to silver remains unclear. In this study, the short-term impacts of silver on the microbiome in hospital wastewater were investigated by metagenome next-generation sequencing. The influence of silver on the conjugation of plasmid carrying bla_NDM-1 was further examined. Our results showed that in hospital wastewater, high abundances of antibiotic resistance genes (ARGs) were detected. The distribution tendencies of certain ARG types on chromosomes or plasmids were different. Clinically important ARGs were identified in phage-like contigs, indicating potential transmission via transduction. Pseudomonadales, Enterobacterales, and Bacteroidales were the major ARG hosts. Mobile genetic elements were mainly detected in plasmids and associated with various types of ARGs. The binning approach identified 29 bins that were assigned to three phyla. Various ARGs and virulence factors were identified in 14 and 11 bins, respectively. MetaCHIP identified 49 HGT events. The transferred genes were annotated as ARGs, mobile genetic elements, and functional genes, and they mainly originated from donors belonging to Bacteroides and Pseudomonadales. In addition, 20 nm AgNPs reduced microbial diversity and enhanced the relative abundance of Acinetobacter. The changes induced by 20 nm AgNPs included increases in the abundances of ARGs and genes involved lipid metabolism pathway. Conjugation experiments showed that Ag⁺ and 20 nm AgNPs caused 2.38-, 3.31-, 4.72-, and 4.57-fold and 1.46-, 1.61-, 3.86-, and 2.16-fold increases in conjugation frequencies of plasmid with bla_NDM-1 at 0.1, 1, 10, and 100 μg/L, respectively. Our findings provide insight into the response of the microbiome in hospital wastewater to silver, emphasize the adaptation capability of Acinetobacter inhabiting hospitals against adverse environments, and highlight the promotion of silver for antibiotic resistance.

Naringenin: A flavanone with anti-inflammatory and anti-infective properties

Although a growing body of research has recently shown how crucial inflammation and infection are to all major diseases, several of the medications currently available on the market have various unfavourable side effects, necessitating the development of alternative therapeutic choices. Researchers are increasingly interested in alternative medications or active components derived from natural sources. Naringenin is a commonly consumed flavonoid found in many plants, and since it was discovered to have nutritional benefits, it has been utilized to treat inflammation and infections caused by particular bacteria or viruses. However, the absence of adequate clinical data and naringenin's poor solubility and stability severely restrict its usage as a medicinal agent. In this article, we discuss naringenin's effects and mechanisms of action on autoimmune-induced inflammation, bacterial infections, and viral infections based on recent research. We also present a few suggestions for enhancing naringenin's solubility, stability, and bioavailability. This paper emphasizes the potential use of naringenin as an anti-inflammatory and anti-infective agent and the next prophylactic substance for the treatment of various inflammatory and infectious diseases, even though some mechanisms of action are still unclear, and offers some theoretical support for its clinical application.

Antibiotic susceptibility pattern, risk factors, and prediction of carbapenem-resistant Pseudomonas aeruginosa in patients with nosocomial pneumonia

Objectives

This study was aimed at describing antibiotic susceptibility patterns and developing a predictive model by assessing risk factors for carbapenem-resistant Pseudomonas aeruginosa (CRPA).

Methods

A retrospective case-control study was conducted at a teaching hospital in China from May 2019 to July 2021. Patients were divided into the carbapenem-susceptible P. aeruginosa (CSPA) group and the CRPA group. Medical records were reviewed to find an antibiotic susceptibility pattern. Multivariate analysis results were used to identify risk factors and build a predictive model.

Results

A total of 61 among 292 patients with nosocomial pneumonia were infected with CRPA. In the CSPA and CRPA groups, amikacin was identified as the most effective antibiotic, with susceptibility of 89.7%. The CRPA group showed considerably higher rates of resistance to the tested antibiotics. Based on the results of mCIM and eCIM, 28 (45.9%) of 61 isolates might be carbapenemase producers. Independent risk factors related to CRPA nosocomial pneumonia were craniocerebral injury, pulmonary fungus infection, prior use of carbapenems, prior use of cefoperazone-sulbactam, and time at risk (≥15 d). In the predictive model, a score >1 point indicated the best predictive ability.

Conclusions

CRPA nosocomial pneumonia could be predicted by risk factor assessment particularly based on the underlying disease, antimicrobial exposure, and time at risk, which could help prevent nosocomial pneumonia.

Anti-plasmodial potential of selected medicinal plants and a compound Atropine isolated from Eucalyptus obliqua

The present research study was aimed to investigate the efficiency of selected medicinal plants against Plasmodium vivax. Crude methanolic extracts from the seeds of leaves of Datura stramonium, Parthenium hysterophorus, Calotropis procera, and Dodonaea viscosa were prepared. In addition, Atropine was also isolated from alkaloid components of Eucalyptus obliqua to evaluate their in vitro anti-plasmodial effects. It was observed that proguanil (positive control) and Atropine displayed strong anti-plasmodial activity (94.04 and 68.02%, respectively) against P. vivax at 0.1 mg/mL concentration while the leaf extracts of other medicinal plants did not exhibit any notable anti-plasmodial activity. It was concluded that alkaloids of E. obliqua plant’s extracts were rich in anti-plasmodial compound Atropine, which exhibit a remarkable anti-plasmodial activity against P. vivax. Anti-plasmodial action of medicinal plants are attributed to these phytochemicals. In vitro studies using medicinal plant’s extracts and standardized methods will help to make more powerful and cost-effective anti-plasmodial compounds.

The Impact of Harsh Stratospheric Conditions on Survival and Antibiotic Resistance Profile of Non-Spore Forming Multidrug Resistant Human Pathogenic Bacteria Causing Hospital-Associated Infections

Bacteria are constantly being lifted to the stratosphere due to air movements caused by weather phenomena, volcanic eruptions, or human activity. In the upper parts of the atmosphere, they are exposed to extremely harsh and mutagenic conditions such as UV and space radiation or ozone. Most bacteria cannot withstand that stress, but for a fraction of them, it can act as a trigger for selective pressure and rapid evolution. We assessed the impact of stratospheric conditions on the survival and antibiotic resistance profile of common non-spore-forming human pathogenic bacteria, both sensitive and extremely dangerous multidrug-resistant variants, with plasmid-mediated mechanisms of resistance. Pseudomonas aeruginosa did not survive the exposure. In the case of strains that were recovered alive, the survival was extremely low: From 0.00001% of Klebsiella pneumoniae carrying the ndm-1 gene and methicillin-resistant Staphylococcus aureus mecA-positive with reduced susceptibility to vancomycin (MRSA/VISA), to a maximum of 0.001% of K. pneumoniae sensitive to all common antibiotics and S. aureus sensitive to vancomycin (MRSA/VSSA). We noticed a tendency towards increased antibiotic susceptibility after the stratospheric flight. Antimicrobial resistance is a current real, global, and increasing problem, and our results can inform current understandings of antibiotic resistance mechanisms and development in bacteria.

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.

Inflammatory and pathological changes in Escherichia coli infected mice

Purpose

Understanding the inflammation and histopathological changes in vivo caused by Escherichia coli infection is of great significance for scientific research and clinical diagnosis.

Methods

Mice were randomly divided into 6 groups (N = 10) after adaptive feeding, and it challenged by intraperitoneal injection with different concentrations of E. coli ATCC25922. The survival situation within 7 days was recorded, and the half-lethal dose (LD₅₀) was calculated by Karber's method. After the end, the blood, heart, liver, spleen, lung, and kidney of the mice were collected. We detected the concentration of inflammatory cytokines (IL-6, IL-β, and TNF-α) and inducible nitric oxide synthase (iNOS) in serum by ELSIA. Organs were observed by histopathological staining and electron microscope observation.

Results

The LD₅₀ of mice infected with E. coli was 1.371∗10⁶ CFU/kg. The concentrations of IL-6, IL-β, and TNF-α increased with time after infection in mice, reaching the highest concentration on the 7th day. iNOS was significantly increased on the 1st day of infection, and then decreased over time (P < 0.01). Within a week after infection, the colony counts of the heart, liver, spleen, lung and kidney showed a first decrease, and then reached a surge on the 7th day. Pathological results showed that a small amount of mitochondrial swelling and autophagy were seen in the spleen, lung and kidney tissues of the infected group; and a small amount of secondary lysosomes and autophagy were also seen; but no pathological changes were found in the liver and heart.

Conclusion

Escherichia coli can cause inflammation and oxidative stress in mice, causing different degrees of damage to the spleen, lung, and kidney tissues, which provides theoretical support for inflammatory and pathological changes caused by Escherichia coli infection in vivo.

A Systematic Review of Antibiotic Resistance Trends and Treatment Options for Hospital-Acquired Multidrug-Resistant Infections

Antimicrobial resistance is a major public health challenge described by the World Health Organization as one of the top 10 public health challenges worldwide. Drug-resistant microbes contribute significantly to morbidity and mortality in the hospital, especially in the critical care unit. The primary etiology of increasing antibiotic resistance is inappropriate and excessive use of antibiotics. The alarming rise of drug-resistant microbes worldwide threatens to erode our ability to treat infections with our current armamentarium of antibiotics.

Unfortunately, the pace of development of new antibiotics by the pharmaceutical industry has not kept up with rising resistance to expand our options to treat microbial infections. The costs of antibiotic resistance include death and disability, extended hospital stays due to prolonged sickness, need for expensive therapies, rising healthcare expenditure, reduced productivity from time out of the workforce, and rising penury. This review sums up the common mechanisms, trends, and treatment options for hospital-acquired multidrug-resistant microbes.

Interactions between Jumbo Phage SA1 and Staphylococcus: A Global Transcriptomic Analysis

Staphylococcus aureus (S. aureus) is an important zoonotic pathogen that poses a serious health concern to humans and cattle worldwide. Although it has been proven that lytic phages may successfully kill S. aureus, the interaction between the host and the phage has yet to be thoroughly investigated, which will likely limit the clinical application of phage. Here, RNA sequencing (RNA-seq) was used to examine the transcriptomics of jumbo phage SA1 and Staphylococcus JTB1-3 during a high multiplicity of infection (MOI) and RT-qPCR was used to confirm the results. The RNA-seq analysis revealed that phage SA1 took over the transcriptional resources of the host cells and that the genes were categorized as early, middle, and late, based on the expression levels during infection. A minor portion of the resources of the host was employed to enable phage replication after infection because only 35.73% (997/2790) of the host genes were identified as differentially expressed genes (DEGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses showed that the phage infection mainly affected the nucleotide metabolism, protein metabolism, and energy-related metabolism of the host. Moreover, the expression of the host genes involved in anti-phage systems, virulence, and drug resistance significantly changed during infection. This research gives a fresh understanding of the relationship between jumbo phages and their Gram-positive bacteria hosts and provides a reference for studying phage treatment and antibiotics.

Perception of Professionals from Different Healthcare Units Regarding the Use of Spray Technology for the Instantaneous Decontamination of Personal Protective Equipment during the Coronavirus Disease Pandemic: A Short Analysis

Within the context of the coronavirus disease (COVID-19) pandemic, different disinfection technologies have been developed to efficiently exercise microbial control, especially to minimize the potential risks that are associated with transmission and infection among healthcare professionals. Thus, the aim of this work was to evaluate the perception of professionals regarding the use of a new technology (chamber) for the instantaneous decontamination of personal protective equipment before the doffing stage. This was a cross-sectional descriptive study where the study data were obtained by using a questionnaire with qualitative questions. In total, 245 professionals participated in the study in three hospitals. Healthcare professionals represented 72.24% (n = 177) of the investigated sample. Approximately 69% of the professionals considered the disinfection chamber as a safe technology, and 75.10% considered it as an important and effective protective barrier for healthcare professionals in view of its application before the doffing process. The results found in this study demonstrate that the use of spray technology in the stage prior to the doffing process is acceptable to professionals, and that it can be an important tool for ensuring the additional protection of the professionals who work directly with patients who are diagnosed with COVID-19.

Macromolecular Structure Assembly as a Novel Antibiotic Target

This review discusses the inhibition of macromolecular structure formation as a novel and under-investigated drug target. The disruption of cell wall structures by penicillin-binding protein interactions is one potential target. Inhibition of DNA polymerase III assembly by novel drugs is a second target that should be investigated. RNA polymerase protein structural interactions are a third potential target. Finally, disruption of ribosomal subunit biogenesis represents a fourth important target that can be further investigated. Methods to examine these possibilities are discussed.

Chemical Barrier Proteins in Human Body Fluids

Chemical barriers are composed of those sites of the human body where potential pathogens can contact the host cells. A chemical barrier is made up by different proteins that are part of the antimicrobial and immunomodulatory protein/peptide (AMP) family. Proteins of the AMP family exert antibacterial, antiviral, and/or antifungal activity and can modulate the immune system. Besides these proteins, a wide range of proteases and protease inhibitors can also be found in the chemical barriers maintaining a proteolytic balance in the host and/or the pathogens. In this review, we aimed to identify the chemical barrier components in nine human body fluids. The interaction networks of the chemical barrier proteins in each examined body fluid were generated as well.

Evidence of cross-contamination of waste workers and transmission of antimicrobial resistance genes by coagulase-negative Staphylococcus isolated from dental solid waste: an intriguing study

The aim of this study was to phenotypically and genotypically identify coagulase-negative Staphylococcus (CoNS) recovered from the nostrils of waste workers and from dental waste; 135 strains were recovered and S. epidermidis was the prevailing species. Genetic similarity (100%) was observed between the two S. epidermidis isolated from different employees on the same shift and 85% similarity between the S. epidermidis recovered from an employee's nostril and from waste. The mecA gene was found in 20 CoNS, and 20% were also found to possess the vanA gene. The blaZ gene was detected in 46.7%, and the icaA (34.8%), B and C genes (11.8% each). Our findings emphasized the biological risk to which waste workers are exposed and unprecedently confirms that it was possible to recover genetically identical bacterial species from waste and from workers' nostrils. It is important to highlight that this risk is raised by the detection of relevant antimicrobial resistance genes. The results also suggest that effective measures to correctly manage waste and promote the rational use of antimicrobials should be adopted.

Clinical Perspective of Antimicrobial Resistance in Bacteria

Antimicrobial resistance (AMR) has become a global clinical problem in recent years. With the discovery of antibiotics, infections were not a deadly problem for clinicians as they used to be. However, worldwide AMR comes with the overuse/misuse of antibiotics and the spread of resistance is deteriorated by a multitude of mobile genetic elements and relevant resistant genes. This review provides an overview of the current situation, mechanism, epidemiology, detection methods and clinical treatment for antimicrobial resistant genes in clinical important bacteria including methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), penicillin-resistant Streptococcus pneumoniae (PRSP), extended-spectrum β-lactamase-producing Enterobacteriaceae, acquired AmpC β-lactamase-producing Enterobacteriaceae, carbapenemase-producing Enterobacteriaceae (CPE), multidrug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa.

The Gram-Negative Bacilli Isolated from Caves-Sphingomonas paucimobilis and Hafnia alvei and a Review of Their Involvement in Human Infections

The opportunistic infections with Gram-negative bacilli are frequently reported. The clinical studies are focused on the course of human infectious and very often the source of infection remain unclear. We aim to see if the Gram-negative bacilli isolated from a non-contaminated environment—the caves—are reported in human infections. Eleven samples were collected from six Romanian caves. We used the standard procedure used in our clinical laboratory for bacterial identification and for antibiotic susceptibility testing of the cave isolates. Out of the 14 bacterial strains, three isolates are Gram-negative bacilli—one isolate belong to Hafnia alvei and two strains belong to Sphingomonas paucimobilis. We screened for the published studies—full-text original articles or review articles—that reported human infections with S. paucimobilis and H. alvei. Data sources—PubMed and Cochrane library. We retrieved 447 cases from 49 references—262 cases (58.61%) are S. paucimobilis infections and 185 cases (41.39%) are H. alvei infections. The types of infections are diverse but there are some infections more frequent; there are 116 cases (44.27%) and many infections of the bloodstream with S. paucimobilius (116 cases) and 121 cases (65.41%) are urinary tract infections with H. alvei. The acquired source of the bloodstream infections is reported for 93 of S. paucimobilis bloodstream infections—50 cases (43%) are hospital-acquired, and 40 cases (37%) are community-acquired. Most of the infections are reported in patients with different underlying conditions. There are 80 cases (17.9%) are reported of previously healthy persons. Out of the 72 cases of pediatric infections, 62 cases (86.11%) are caused by S. paucimobilis. There are ten death casualties—three are H. alvei infections, and seven are S. paucimobilis infections.

Analysis of the Occurrence of Antibiotic Resistant Bacteria in the Hospital’s Effluent and its Receiving Environment

The use of antibiotics on a regular and excessive basis is a major factor in the spread of antibiotic-resistant bacteria. Patients discharge un-metabolized or relatively low doses of non-metabolized antibiotics through urine and stool, which might enter into the environment through sewage disposal and promote the emergence of antibiotic resistant bacteria. This study is designed to investigate how excessive use of antibiotics in the hospital sector and their release into hospital wastes contribute to the spread of antibiotic-resistant bacteria in different environmental settings. In this study, liquid hospital waste was collected from the sewage of Chittagong Medical College Hospital (CMCH), Bangladesh as well as from its distribution position in Chittagong city, Bangladesh. A total of 5 samples were collected from different positions in Chittagong city, including CMCH liquid waste. After collection, total bacteria and total cefixime resistant bacteria were counted by the total viable count (TVC) method. The result of bacteriological enumeration showed that a high magnitude of cefixime-resistant bacteria were available in all the hospital’s associated waste samples. The highest proportion of cefixime resistant bacteria (23.35%) was found in sample 2, whereas 17.4%, 7.6%, 5%, and 1.32% were found in samples 1, 3, 4, and 5, respectively. The total number of cefixime-resistant bacteria decreased with the increase in distance between the sample collection site and the hospital drain. This means that resistant bacteria developed in the hospital effluent are transferred to the environmental distribution sites.

Isolation of Elizabethkingia anophelis From COVID-19 Swab Kits

Purpose: To investigate and characterize the putative Elizabethkingia anophelis contaminant isolated from throat and anal swab samples of patients from three fever epidemic clusters, which were not COVID-19 related, in Shenzhen, China, during COVID-19 pandemic. Methods: Bacteria were cultured from throat (n = 28) and anal (n = 3) swab samples from 28 fever adolescent patients. The isolated bacterial strains were identified using matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF/MS) and the VITEK2 automated identification system. Nucleic acids were extracted from the patient samples (n = 31), unopened virus collection kits from the same manufacturer as the patient samples (n = 35, blank samples) and from unopened throat swab collection kits of two other manufacturers (n = 22, control samples). Metagenomic sequencing and quantitative real-time PCR (qPCR) detection were performed. Blood serum collected from patients (n = 13) was assessed for the presence of antibodies to E. anophelis. The genomic characteristics, antibiotic susceptibility, and heat resistance of E. anophelis isolates (n = 31) were analyzed. Results: The isolates were identified by MALDI-TOF/MS and VITEK2 as Elizabethkingia meningoseptica. DNA sequence analysis confirmed isolates to be E. anophelis. The patients' samples and blank samples were positive for E. anophelis. Control samples were negative for E. anophelis. The sera from a sub-sample of 13 patients were antibody-negative for isolated E. anophelis. Most of the isolates were highly homologous and carried multiple β-lactamase genes (bla _B, bla _GOB, and bla _CME). The isolates displayed resistance to nitrofurans, penicillins, and most β-lactam drugs. The bacteria survived heating at 56°C for 30 min. Conclusion: The unopened commercial virus collection kits from the same manufacturer as those used to swab patients were contaminated with E. anophelis. Patients were not infected with E. anophelis and the causative agent for the fevers remains unidentified. The relevant authorities were swiftly notified of this discovery and subsequent collection kits were not contaminated. DNA sequence-based techniques are the definitive method for Elizabethkingia species identification. The E. anophelis isolates were multidrug-resistant, with partial heat resistance, making them difficult to eradicate from contaminated surfaces. Such resistance indicates that more attention should be paid to disinfection protocols, especially in hospitals, to avoid outbreaks of E. anophelis infection.

Efflux Pump Mediated Antimicrobial Resistance by Staphylococci in Health-Related Environments: Challenges and the Quest for Inhibition

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

The Utility of Prolonged Prophylactic Systemic Antibiotics (PPSA) for Subfascial Drains After Degenerative Spine Surgery

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

The aim of the current investigation was to evaluate the impact of prolonged prophylactic systemic antibiotics (PPSA) on the development of surgical site infection rate (SSIR) in degenerative spine surgery.

SUMMARY OF BACKGROUND DATA

Surgical drains are utilized postoperatively in posterior spine surgery to help minimize the risk of seroma formation. Prophylactic antibiotics while drains are in place are frequently used to reduce SSIR, though the practice remains controversial.

METHODS

We performed a single center, retrospective review of all patients that underwent posterior spinal surgery for cervical and lumbar degenerative pathology over a 3.5 year period (January 2016-July 2019). Patients underwent a traditional open posterior midline procedure with postoperative placement of a subfascial surgical drain. Antibiotics were administered for the duration of the drain (PPSA group) or for 24 hours postoperatively (non-PPSA group). The number of surgical site infections, organism, and Clostridium difficile infections was recorded.

RESULTS

Three hundred thirty six patients were identified, 168 patients in the PPSA group and 168 in the non-PPSA groups. The overall SSIR was 5.36% (18/336). The SSIR for the non-PPSA and PPSA groups were 7.14% (12/168) and 3.57% (6/168), respectively (P = 0.146). While difference of SSIR between the groups was two-fold, it was not statistically significant. For the non-PPSA and PPSA groups, the SSIR for cervical (5.95% [5/84] vs. 2.38% [2/84], P = 0.443) and lumbar (8.33% [7/84], vs. 4.76% [4/84], P = 0.535) regions were not significantly different. C. difficile cases in the PPSA and non-PPSA groups were 1/168 and 0/168 respectively (P = 1.00).

CONCLUSION

Our series demonstrate a two-fold reduction of SSI with implementation of PPSA regimen. This benefit was demonstrated separately for both cervical and lumbar regions. Randomized trials and increase in sample size are warranted to elucidate the significance of PPSA in posterior spinal surgery.Level of Evidence: 3.

Is the Antibacterial Activity of Multi-Walled Carbon Nanotubes (MWCNTs) Related to Antibiotic Resistance? An Assessment in Clinical Isolates

Antimicrobial resistance has spread globally, compromising the treatment of common infections. This feature is particularly harmful for nosocomial pathogens that can survive on hospital surfaces. Research studies have been conducted to evaluate new materials that are able to counteract the microbial growth and the colonization of the hospital environment. In this context, nanotechnologies have showed encouraging applications. We investigated the antibacterial activity of multi-walled carbon nanotubes (MWCNTs), both pristine (p) and functionalized (f), at concentrations of 50 and 100 μg mL⁻¹, against bacterial strains isolated from hospital-acquired infections, and this activity was correlated with the antibiotic susceptibility of the strains. The inhibiting effect of MWCNTs occurred for both types and doses tested. Moreover, f-MWCNTs exerted a greater inhibiting effect, with growth decreases greater than 10% at 24 h and 20% at 48 h compared to p-MWCNTs. Moreover, a lower inhibitory effect of MWCNTs, which was more lasting in Gram-positives resistant to cell wall antibiotics, or temporary in Gram-negatives resistant to nucleic acid and protein synthesis inhibitors, was observed, highlighting the strong relation between antibiotic resistance and MWCNT effect. In conclusion, an antimicrobial activity was observed especially for f-MWCNTs that could therefore be loaded with bioactive antimicrobial molecules. However, this potential application of CNTs presupposes the absence of toxicity and therefore total safety for patients.

Highlights Regarding the Use of Metallic Nanoparticles against Pathogens Considered a Priority by the World Health Organization

The indiscriminate use of antibiotics has facilitated the growing resistance of bacteria, and this has become a serious public health problem worldwide. Several microorganisms are still resistant to multiple antibiotics and are particularly dangerous in the hospital and nursing home environment, and to patients whose care requires devices, such as ventilators and intravenous catheters. A list of twelve pathogenic genera, which especially included bacteria that were not affected by different antibiotics, was released by the World Health Organization (WHO) in 2017, and the research and development of new antibiotics against these genera has been considered a priority. The nanotechnology is a tool that offers an effective platform for altering the physicalchemical properties of different materials, thereby enabling the development of several biomedical applications. Owing to their large surface area and high reactivity, metallic particles on the nanometric scale have remarkable physical, chemical, and biological properties. Nanoparticles with sizes between 1 and 100 nm have several applications, mainly as new antimicrobial agents for the control of microorganisms. In the present review, more than 200 reports of various metallic nanoparticles, especially those containing copper, gold, platinum, silver, titanium, and zinc were analyzed with regard to their anti-bacterial activity. However, of these 200 studies, only 42 reported about trials conducted against the resistant bacteria considered a priority by the WHO. All studies are in the initial stage, and none are in the clinical phase of research.

Spatial Patterns in Hospital-Acquired Infections in Portugal (2014-2017)

BACKGROUND

Hospital-Acquired Infections (HAIs) represent the most frequent adverse event associated with healthcare delivery and result in prolonged hospital stays and deaths worldwide.

AIM

To analyze the spatial patterns of HAI incidence from 2014 to 2017 in Portugal.

METHODS

Data from the Portuguese Discharge Hospital Register were used. We selected episodes of patients with no infection on admission and with any of the following HAI diagnoses: catheter-related bloodstream infections, intestinal infections by Clostridium difficile, nosocomial pneumonia, surgical site infections, and urinary tract infections. We calculated age-standardized hospitalization rates (ASHR) by place of patient residence. We used empirical Bayes estimators to smooth the ASHR. The Moran Index and Local Index of Spatial Autocorrelation (LISA) were calculated to identify spatial clusters.

RESULTS

A total of 318,218 HAIs were registered, with men accounting for 49.8% cases. The median length of stay (LOS) was 9.0 days, and 15.7% of patients died during the hospitalization. The peak of HAIs (n = 81,690) occurred in 2015, representing 9.4% of the total hospital admissions. Substantial spatial inequalities were observed, with the center region presenting three times the ASHR of the north. A slight decrease in ASHR was observed after 2015. Pneumonia was the most frequent HAI in all age groups.

CONCLUSION

The incidence of HAI is not randomly distributed in the space; clusters of high risk in the central region were seen over the entire study period. These findings may be useful to support healthcare policymakers and to promote a revision of infection control policies, providing insights for improved implementation.

The microbial diversity following antibiotic treatment of Clostridioides difficile infection

Background

Clostridioides difficile (C. difficile) is a major nosocomial pathogen that infects the human gut and can cause diarrheal disease. A dominant risk factor is antibiotic treatment that disrupts the normal gut microbiota. The aim of the study was to examine the correlation between antibiotic treatment received prior to C. difficile infection (CDI) onset and patient gut microbiota.

Methods

Stool samples were collected from patients with CDI, presenting at the Baruch Padeh Medical Center Poriya, Israel. Demographic and clinical information, including previous antibiotic treatments, was collected from patient charts, and CDI severity score was calculated. Bacteria were isolated from stool samples, and gut microbiome was analyzed by sequencing the 16S rRNA gene using the Illumina MiSeq platform and QIIME2.

Results

In total, 84 patients with CDI were enrolled in the study; all had received antibiotics prior to disease onset. Due to comorbidities, 46 patients (55%) had received more than one class of antibiotics. The most common class of antibiotics used was cephalosporins (n = 44 cases). The intestinal microbiota of the patients was not uniform and was mainly dominated by Proteobacteria. Differences in intestinal microbiome were influenced by the different combinations of antibiotics that the patients had received (p = 0.022)

Conclusions

The number of different antibiotics administered has a major impact on the CDI patients gut microbiome, mainly on bacterial richness.

Rapid Identification of Plasmid Replicon Type and Coexisting Plasmid-Borne Antimicrobial Resistance Genes by S1-Pulsed-Field Gel Electrophoresis-Droplet Digital Polymerase Chain Reaction

Bacterial drug resistance is a significant food safety problem and public health threat. Plasmids carrying drug resistance genes may result in the rapid spread of resistance among different bacteria, hosts, and environments; therefore, antibiotic resistance monitoring and continuing research into the mechanisms of drug resistance are urgently needed. Southern blotting with probes for antibiotic resistance genes and even next-generation sequencing have been used previously to detect plasmid-borne resistance genes, but these approaches are complex and time-consuming. The next-generation sequencing requires strict laboratory conditions and bioinformatics analysis ability. In this study, we developed a simplified and sensitive method to detect plasmid-borne antimicrobial resistance genes and plasmid replicon types. Salmonella strains carrying plasmids of three different replicon types that contained mcr-1 and two ESBL-producing genes were used to verify the new method. The plasmids harbored by the Salmonella strains were separated by S1 nuclease treatment and pulsed-field gel electrophoresis (PFGE), then recovered and used as the templates for droplet digital polymerase chain reaction (ddPCR) to identify target genes. The target genes were present in significantly higher copy numbers on the plasmids than the background noise. These results were consistent with the plasmid sequencing results. This S1-PFGE-ddPCR method was less time-consuming to perform than Southern blot and complete plasmid sequencing. Therefore, this method represents a time-saving alternative for detecting plasmid-borne genes, and is likely to be a valuable tool for detecting coexisting plasmid-borne drug resistance genes.

Review of therapeutic options for infections with carbapenem-resistant Klebsiella pneumoniae

Infections with multi-drug resistant (MDR) bacteria including carbapenem-resistant Klebsiella pneumoniae are emerging worldwide but are difficult to treat with the currently available antibiotic compounds and therefore constitute serious threats to human health. This prompted us to perform a literature survey applying the MEDLINE database and Cochrane Register of Controlled Trials including clinical trials comparing different treatment regimens for infections caused by carbapenem-resistant K. pneumoniae. Our survey revealed that a combined application of antibiotic compounds such as meropenem plus vaborbactam, meropenem plus colistin and carbapenem plus carbapenem, resulted in significantly increased clinical cure and decreased mortality rates as compared to respective control treatment. However, further research on novel antibiotic compounds, but also on antibiotic-independent molecules providing synergistic or at least resistance-modifying properties needs to be undertaken in vitro as well as in large clinical trials to provide future options in the combat of emerging life-threatening infections caused by MDR bacteria.

Salt coatings functionalize inert membranes into high-performing filters against infectious respiratory diseases

Respiratory protection is key in infection prevention of airborne diseases, as highlighted by the COVID-19 pandemic for instance. Conventional technologies have several drawbacks (i.e., cross-infection risk, filtration efficiency improvements limited by difficulty in breathing, and no safe reusability), which have yet to be addressed in a single device. Here, we report the development of a filter overcoming the major technical challenges of respiratory protective devices. Large-pore membranes, offering high breathability but low bacteria capture, were functionalized to have a uniform salt layer on the fibers. The salt-functionalized membranes achieved high filtration efficiency as opposed to the bare membrane, with differences of up to 48%, while maintaining high breathability (> 60% increase compared to commercial surgical masks even for the thickest salt filters tested). The salt-functionalized filters quickly killed Gram-positive and Gram-negative bacteria aerosols in vitro, with CFU reductions observed as early as within 5 min, and in vivo by causing structural damage due to salt recrystallization. The salt coatings retained the pathogen inactivation capability at harsh environmental conditions (37 °C and a relative humidity of 70%, 80% and 90%). Combination of these properties in one filter will lead to the production of an effective device, comprehensibly mitigating infection transmission globally.

Profile of Enterobacteria Resistant to Beta-Lactams

A serious emerging problem worldwide is increased antimicrobial resistance. Acquisition of coding genes for evasion methods of antimicrobial drug mechanisms characterizes acquired resistance. This phenomenon has been observed in Enterobacteriaceae family. Treatment for bacterial infections is performed with antibiotics, of which the most used are beta-lactams. The aim of this study was to correlate antimicrobial resistance profiles in Enterobacteriaceae by phenotypic methods and molecular identification of 14 beta-lactamase coding genes. In this study, 70 exclusive isolates from Brazil were used, half of which were collected in veterinary clinics or hospitals Phenotypic methodologies were used and real-time PCR was the molecular methodology used, through the Sybr Green system. Regargding the results found in the tests it was observed that 74.28% were resistant to ampicillin, 62.85% were resistant to amoxicillin associated with clavalunate. The mechanism of resistance that presented the highest expression was ESBL (17.14%). The genes studied that were detected in a greater number of species were blaGIM and blaSIM (66.66% of the samples) and the one that was amplified in a smaller number of samples was blaVIM (16.66%). Therefore, high and worrying levels of antimicrobial resistance have been found in enterobacteria, and a way to minimize the accelerated emergence of their resistance includes developing or improving techniques that generate diagnoses with high efficiency and speed.

Antibiotics targeting bacterial ribosomal subunit biogenesis

This article describes 20 years of research that investigated a second novel target for ribosomal antibiotics, the biogenesis of the two subunits. Over that period, we have examined the effect of 52 different antibiotics on ribosomal subunit formation in six different microorganisms. Most of the antimicrobials we have studied are specific, preventing the formation of only the subunit to which they bind. A few interesting exceptions have also been observed. Forty-one research publications and a book chapter have resulted from this investigation. This review will describe the methodology we used and the fit of our results to a hypothetical model. The model predicts that inhibition of subunit assembly and translation are equivalent targets for most of the antibiotics we have investigated.

Molecular Interactions between Pathogens and the Circadian Clock

The daily periodicity of the Earth's rotation around the Sun, referred to as circadian (Latin "circa" = about, and "diem" = day), is also mirrored in the behavior and metabolism of living beings. The discovery that dedicated cellular genes control various aspects of this periodicity has led to studies of the molecular mechanism of the circadian response at the cellular level. It is now established that the circadian genes impact on a large network of hormonal, metabolic, and immunological pathways, affecting multiple aspects of biology. Recent studies have extended the role of the circadian system to the regulation of infection, host-pathogen interaction, and the resultant disease outcome. This critical review summarizes our current knowledge of circadian-pathogen interaction at both systemic and cellular levels, but with emphasis on the molecular aspects of the regulation. Wherever applicable, the potential of a direct interaction between circadian factors and pathogenic macromolecules is also explored. Finally, this review offers new directions and guidelines for future research in this area, which should facilitate progress.

Prevention of urinary catheter-associated infections by coating antimicrobial peptides from crowberry endophytes

Urinary catheters are extensively used in hospitals, being responsible for about 75% of hospital-acquired infections. In this work, a de novo designed antimicrobial peptide (AMP) Chain201D was studied in the context of urinary catheter-associated infections. Chain201D showed excellent antimicrobial activity against relevant ATCC strains and clinical isolates of bacteria and yeast and demonstrated high stability in a wide range of temperatures, pH and salt concentrations. Moreover, the bactericidal activity of Chain201D immobilized on a model surface was studied against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), some of the most prevalent strains found in urinary catheter-associated infections. Chain201D was successfully tethered to ((1-mercapto-11-undecyl)-(tetra(ethylene glycol) (EG4)) terminated self-assembled monolayers (SAMs), (EG4-SAMs), activated by 1,1'-Carbonyldiimidazole (CDI) at different concentrations. Chain201D surfaces can bind and kill by contact a high percentage of adherent bacteria. These achievements are obtained without any peptide modification (for chemoselective conjugation) and without the use of a spacer. Moreover, increased amounts of immobilized AMP lead to higher numbers of adhered/dead bacteria, revealing a concentration-dependent behaviour and demonstrating that Chain201D has excellent potential for developing antimicrobial urinary catheters.

Can Biofilm Be Reversed Through Quorum Sensing in Pseudomonas aeruginosa?

Pseudomonas aeruginosa is a Gram-negative bacterium causing diseases in plants, animals, and humans, and its drug resistance is a major concern in medical care. Biofilms play an important role in P. aeruginosa drug resistance. Three factors are most important to induce biofilm: quorum sensing (QS), bis-(3′-5′)-cyclic diguanosine monophosphate (c-di-GMP), and small RNAs (sRNAs). P. aeruginosa has its own specific QS system (PQS) besides two common QS systems, LasI–LasR and RhlI–RhlR, in bacteria. PQS is interesting not only because there is a negative regulation from RhlR to pqsR but also because the null mutation in PQS leads to a reduced biofilm formation. Furthermore, P. aeruginosa dispersed cells have physiological features that are distinct between the planktonic cells and biofilm cells. In response to a low concentration of c-di-GMP, P. aeruginosa cells can disperse from the biofilms to become planktonic cells. These raise an interesting hypothesis of whether biofilm can be reversed through the QS mechanism in P. aeruginosa. Although a single factor is certainly not sufficient to prevent the biofilm formation, it necessarily explores such possibility. In this hypothesis, the literature is analyzed to determine the negative regulation pathways, and then the transcriptomic data are analyzed to determine whether this hypothesis is workable or not. Unexpectedly, the transcriptomic data reveal a negative regulation between lasI and psqR. Also, the individual cases from transcriptomic data demonstrate the negative regulations of PQS with laslI, laslR, rhlI, and rhlR under different experiments. Based on our analyses, possible strategies to reverse biofilm formation are proposed and their clinic implications are addressed.

MexXY Multidrug Efflux System Is More Frequently Overexpressed in Ciprofloxacin Resistant French Clinical Isolates Compared to Hospital Environment Ones

Modulation of the membrane permeability through a decrease in porin-mediated antibiotic entry and/or an increase in antibiotic efflux is one of the resistance mechanisms to antibiotics evolved by Gram-negative bacteria. To assess whether the outer membrane porin OprD and Resistance-Nodulation-Division (RND) efflux pumps were similarly expressed in 33 ciprofloxacin-resistant clinical strains of Pseudomonas aeruginosa and in 30 non-clinical strains originating from the hospital environment (mainly waterborne Pseudomonas aeruginosa), the expression of oprD, mexB, mexF, and mexY genes was investigated. Overall, the expression of oprD was not detected by RT-qPCR in 14 (22%) strains and underexpressed in 35 (56%) more. No significant difference in oprD expression was detected between clinical and non-clinical strains. As for efflux pumps, 23 (70%) of the clinical strains overexpressed at least one of the tested RND genes. Overexpression of mexB, mexF and mexY was detected in 27, 12, and 45% of the clinical strains, respectively. In the 30 non-clinical strains, no overexpression could be found for mexB, mexF, or mexY. On the contrary, a global underexpression of the tested efflux pump genes was recorded. In both clinical and environmental strains, a positive correlation was found between the expressions of oprD and mexB. Similarly, the expressions of oprD and mexF were positively correlated. This result contrasts with the inverse correlation between both MexAB-OprM/MexEF-OprN and OprD previously described in carbapenem-resistant P. aeruginosa strains. The only positive correlation between phenotypic ciprofloxacin minimum inhibitory concentrations (MICs) and the expression of efflux pump gene was witnessed with mexY (analysis on pooled results for clinical and environmental strains). However, in clinical strains, no statistically significant link could be found between the degree of reduction in ciprofloxacin MICs witnessed with Phenylalanine-Arginine β-naphthylamide (PAβN) and the expression of any of the 3 RND genes tested.

Change in the antimicrobial resistance profile of Pseudomonas aeruginosa from soil after exposure to herbicides

The extensive use of pesticides represents a risk to human health and to the environment. This study aimed to investigate if the exposure to atrazine and diuron, two herbicides widely used in Brazil, could induce changes in the susceptibility profile to aztreonam, colistin and polymyxin B antimicrobials in isolates of P. aeruginosa obtained from soil samples by using the determination of minimum inhibitory concentration (MIC) test. Three isolates had an increase of MIC to aztreonam after exposure to both herbicides and one isolate did not show any MIC change. The MexAB-OprM efflux pump has already been upregulated in these isolates and the herbicides atrazine and diuron did not increase MexAB-OprM overexpression. Therefore, the decrease in aztreonam susceptibility was not directly related to this pump, suggesting that probably other mechanisms should be involved.

The Structure of ampG Gene in Pseudomonas aeruginosa and Its Effect on Drug Resistance

In order to study the relationship between the structure and function of AmpG, structure, site-specific mutation, and gene complementary experiments have been performed against the clinical isolates of Pseudomonas aeruginosa. We found that there are 51 nucleotide variations at 34 loci over the ampG genes from 24 of 35 P. aeruginosa strains detected, of which 7 nucleotide variations resulted in amino acid change. The ampG variants with the changed nucleotides (amino acids) could complement the function of ampG deleted PA01 (PA01ΔG). The ampicillin minimum inhibitory concentration (MIC) of PA01ΔG complemented with 32 ampG variants was up to 512 μg/ml, similar to the original PA01 (P. aeruginosa PA01). Furthermore, site-directed mutation of two conservative amino acids (I53 and W90) showed that when I53 was mutated to 53S or 53T (I53S or I53T), the ampicillin MIC level dropped drastically, and the activity of AmpC β-lactamase decreased as well. By contrast, the ampicillin MIC and the activity of AmpC β-lactamase remained unchanged for W90R and W90S mutants. Our studies demonstrated that although nucleotide variations occurred in most of the ampG genes, the structure of AmpG protein in clinical isolates is stable, and conservative amino acid is necessary to maintain normal function of AmpG.

Characteristics and Outcomes of Acinetobacter baumannii Infections in Patients with HIV: A Matched Case-Control Study

Acinetobacter baumannii (AB) infection is an increasing global threaten to hospitalized patients, especially those with impaired immune function. Still, few studies addressed the disease burdens and outcomes of AB infection in HIV patients. We aimed to describe characteristics and outcomes of AB infections in patients with HIV, measure the impact of AB infection on 28-day mortality in HIV patients, as well as assess the predictors of 28-day survival among HIV patients with AB pneumonia. A retrospective study with HIV/AB co-infected patients was conducted at Shanghai Public Health Clinical Center (SPHCC), China. Patients with AB pneumonia were further analyzed for predictors of mortality, as well as an additional 1:1 case-control study to determine the fatality of AB pneumonia compared with pneumonia of other pathogens. We found the incidence of AB infection was 17.4 cases per 100 person-years among all hospitalized HIV patients. Hospital mortality rate was 37.5% (21/56). There was a higher 28-day mortality rate in HIV patients with pneumonia due to AB than other pathogens (34% vs 16%, P = 0.03). APACHE II score was independently associated with 28-day survival by multivariate logistic regression (P = 0.031). Our findings indicate that AB infection is incident and can be fatal in HIV seropositive population. AB infection is an independent risk factor of mortality in patients with HIV and pneumonia. A lower APACHE II score on admission predicts a higher 28-day survival rate among HIV/AB co-infected patients.

Efficacy of sodium hypochlorite against multidrug-resistant Gram-negative bacteria

BACKGROUND

Increased antimicrobial resistance has been observed among many bacteria leading to treatment failures in human and veterinary medicine. Disinfection is a prerequisite for infection control and prevention in healthcare settings. Chlorine compounds are cost-effective and accessible worldwide.

AIM

To determine the efficacy of sodium hypochlorite (NaOCl) against multidrug-resistant Gram-negative bacteria (MDR-GNB).

METHODS

Minimum inhibitory concentrations (MICs) were determined using broth macro-dilution. Bactericidal efficacy was measured by qualitative and quantitative suspension tests followed by practical tests without mechanical action on stainless steel carriers. The guidelines of the German Association for Applied Hygiene were followed.

FINDINGS

Results varied remarkably depending on the method. MICs were 0.1% or 0.2% NaOCl. Qualitative suspension tests revealed up to 500-fold lower bactericidal concentrations. Pseudomonas aeruginosa (P = 0.0025) was significantly less susceptible in these tests whereas quantitative suspension tests revealed no significant differences between strains (P > 0.05). Practical tests determined bactericidal concentrations of 0.8-0.32% NaOCl at 1 min of contact and even lower concentrations for longer contact times. At 1 min, five Klebsiella were significantly less susceptible (P = 0.0124), whereas the lower susceptibility of P. aeruginosa was not confirmed. Organic load inhibited bactericidal activity significantly, whereas contact time had a marginal effect. Differing test results underline that MIC determination and qualitative suspension tests may be insufficient approaches to evaluate bacterial susceptibility or resistance.

CONCLUSION

NaOCl efficiently reduced Pseudomonas aeruginosa, Acinetobacter spp., and Klebsiella spp., most notably in the absence of organic matter. Strain- and species-specific differences in susceptibility were noticed, but in general MDR-GNB revealed no higher tolerance to NaOCl.

Investigation on outcomes and bacterial distributions of liver cirrhosis patients with gram-negative bacterial bloodstream infection

Objective

The study aimed at analyzing the epidemiology and outcomes of liver cirrhosis patients undergoing gram-negative bacterial bloodstream infection.

Results

Totally 508 eligible patients were collected, with 25.79% 30-day mortality, and 58.86% patients were confirmed as nosocomial infection. The most common isolates were Escherichia coli (48.29%) and Klebsiella pneumoniae (19.29%), and multidrug-resistant isolates accounted for 36.61%. The bacterial distributions were similar between survivors and non-survivors (P>0.05), but showed close association with acquisition sites of infection (P<0.05). Nosocomial infection (HR=1.589, 95% CI=1.004-2.517), Child-Pugh grade (HR=2.471, 95% CI=1.279-4.772), septic shock (HR=1.966, 95% CI=1.228-3.146), complications (HR=3.529, 95% CI=2.140-5.818), and WBC (HR=1.065, 95% CI=1.018-1.114) were independent indicators for 30-day mortality. β-lactamase inhibitor antibiotics exerted a high antibacterial activity.

Methods

The inpatients with liver cirrhosis developed gram-negative bacterial bloodstream infection were collected. The clinical characteristics, bacterial distribution and drug sensitivity results of patients were compared according to their 30-day survival status and acquisition sites of infections. Cox regression model was applied to evaluate the risk factors for 30-day mortality.

Conclusion

Escherichia coli and Klebsiella pneumoniae are frequently isolated from gram-negative bacterial bloodstream infection episodes in cirrhosis patients. Acquisition site of infection can influence clinical characteristics and etiological distribution. β-lactamase inhibitor antibiotics may be the first choice for empirical treatments.

Virulence and transcriptome profile of multidrug-resistant Escherichia coli from chicken

Numerous studies have examined the prevalence of pathogenic Escherichia coli in poultry and poultry products; however, limited data are available regarding their resistance- and virulence-associated gene expression profiles. This study was designed to examine the resistance and virulence of poultry E. coli strains in vitro and in vivo via antibiotic susceptibility, biofilm formation and adhesion, and invasion and intracellular survivability assays in Caco-2 and Raw 264.7 cell lines as well as the determination of the median lethal dose in two-day old chickens. A clinical pathogenic multidrug-resistant isolate, E. coli 381, isolated from broilers, was found to be highly virulent in cell culture and 1000-fold more virulent in a chicken model than other strains; accordingly, the isolate was subsequently selected for transcriptome analysis. The comparative gene expression profile of MDR E. coli 381 and the reference human strain E. coli ATCC 25922 was completed with Illumina HiSeq. 2500 transcriptome analysis. Differential gene expression analysis indicates that there are multiple pathways involved in the resistance and virulence of this highly virulent strain. The results garnered from this study provide critical information about the highly virulent MDR E. coli strain of poultry origin and warrant further investigation due to its significant threat to public health.