High Level Of Intrinsic Resistance Research Articles

Preliminary Data on Escherichia coli, Yersinia enterocolitica, and Other Bacteria, as Well as Absent African Swine Fever Virus in the Gut Microbiota of Wild Mice and Voles from Bulgaria

Small mammals are bioindicator organisms, and, through their gut microbiota (GM), could be carriers of pathogens and resistant bacteria. Also, wild GM composition has been suggested to have large implications for conservation efforts. Seventeen bacterial species were obtained from intestinal samples of Bulgarian yellow-necked mice (Apodemus flavicollis) and bank voles (Myodes glareolus) via classic microbiological cultivation and biochemical identification. Twelve Gram-negative—Escherichia coli, Yersinia enterocolitica, Yersinia kristensenii, Hafnia alvei, Serratia liquefaciens, Serratia marcescens, Serratia proteamaculans, Pseudescherichia vulneris, Klebsiella pneumoniae ssp. ozaenae, Enterobacter cloacea, Pantoea agglomerans, Pseudomonas fluorescens group—and five Gram-positive bacteria, Enterococcus faecium, Enterococcus faecalis, Enterococcus hirae, Bacillus thuringiensis, and Lysinibacillus sphaericus, were discovered. Enterobacteriaceae was the most abundant family. The isolates belonged to one of the major reported taxa in rodents, Firmicutes (the Gram-positive species) and to the less abundant, but still among the first, phyla, Proteobacteria (the Gram-negative strains). We did not find any members of the other major phylum, Bacteroidetes, likely due to lack of metagenomic techniques. E. coli and Y. enterocolitica were confirmed with polymerase chain reaction. Almost all strains had pathogenic potential, but the good condition of the test animals suggests their commensal role. The Y. enterocolitica strains did not have the ail pathogenicity gene. There was high prevalence of multi-drug resistance (MDR), but for the expected species with high level of intrinsic resistance, such as the enterococci and S. marcescens. E. coli and some other species had very low antimicrobial resistance (AMR), in line with other studies of wild rodents. Many of the strains had biotechnological potential; e.g., B. thuringiensis is the most used biological insecticide, with its proteins incorporated into the Bt genetically modified maize. The GM of the tested wild mice and voles from Bulgaria proved to be a source of bacterial diversity; many of the strains were promising in terms of biotechnology, and, in addition, the samples did not contain the African swine fever virus.

Trimethoprim/Sulfamethoxazole vs Minocycline for the Treatment of Nonurinary Monomicrobial Stenotrophomonas maltophilia Infections in Hospitalized Patients.

Stenotrophomonas maltophilia is an opportunistic, gram-negative bacillus with few therapeutic options due to a high level of intrinsic resistance. Trimethoprim/sulfamethoxazole (SXT) is recommended as the first-line treatment; however, minocycline (MIN) has been shown to have similar clinical outcomes in treating S. maltophilia and addresses concern for increasing resistance to SXT. The objective of this study is to evaluate the efficacy and safety outcomes of nonurinary, monomicrobial infections due to S. maltophilia in hospitalized patients treated with MIN or SXT. This was a retrospective study of hospitalized adult patients receiving MIN or SXT for nonurinary monomicrobial S. maltophilia infection from April 1, 2018 to March 31, 2020. The primary outcome was clinical disposition classified as rates of clinical failure, clinical improvement, or clinical success. Eighty-two patients (88.2%) received MIN and 11 patients (11.8%) received SXT initially. Clinical failure occurred in 16 (19.5%) patients in the MIN group and in 4 (36.4%) patients in the SXT group (P = 0.242). Clinical improvement occurred in 11 (13.4%) patients in the MIN group and in 1 (9.1%) patient in the SXT group (P = 1.0). Clinical success occurred in 55 (67.1%) patients in the MIN group and in 6 (54.5%) patients in the SXT group (P = 0.503). Total duration of antimicrobial therapy (P = 0.3198), in-hospital mortality (P = 1.0), hospital length of stay (P = 0.9668), intensive care unit (ICU) length of stay (P = 0.1384), and 30-day readmission (P = 0.686) were similar between groups. Rates of clinical failure, clinical improvement, or clinical success were similar between MIN and SXT for nonurinary monomicrobial S. maltophilia infections.

Drug Repurposing for the Treatment of Mycobacterium abscessus Infections

Abstract With the ever-increasing burden of antimicrobial resistance, the demand to introduce countermeasures becomes increasingly critical. The urgency of this need is intensified by the void in antibiotic discovery, with the identification of novel compounds declining with time. Of increasing concern is Mycobacterium abscessus, which displays high levels of intrinsic resistance that lead to poor success rates, even after lengthy drug regimens. Research tackling these issues is now focused on the repurposing of preexisting drugs for antimycobacterial use, facilitating the discovery of antimicrobial compounds amidst a crisis where novel antibiotics are sparse. Part of this includes the use of combination treatments, whereby coadministration of synergistic compounds can reduce dose requirements and slow the progression of antimicrobial resistance in the long term. In this review, we will introduce the current therapeutic options for M. abscessus and provide insight into why treatment is so burdensome. We will also compile the current updates within drug repurposing for this pathogen, including the use of unconventional agents such as antimalarial drugs, the repositioning of antituberculosis candidates and the repurposing of preexisting antibiotics, including the application of combination regimens. In addition, the in vitro drug screening platforms used in their discovery will be appraised, with the view of highlighting potential future perspectives that may help increase physiological relevance. This review provides a timely appraisal of the future of M. abscessus treatment.

S4.3b Candida glabrata-host interactions

S4.3 Emergent species of the Candida genus, September 22, 2022, 10:30 AM - 12:00 PM Candida glabrata is among the most common pathogenic yeasts of humans. Yet, this fungus is phylogenetically, genetically, and phenotypically very different from other clinically relevant Candida species. This includes an unusual high level of intrinsic resistance to antifungals such as azoles. Furthermore, in contrast to the rather aggressive pathogenicity mechanisms of the dominant Candida species, C. albicans, C. glabrata seems to have evolved strategies that are based on stealth, evasion and persistence, without causing severe host cell damage during infection. For example, C. glabrata is unable to invade epithelial cells in vitro and causes only low levels of damage in standard in vitro infection models. However, the addition of a single common host protein, albumin, strongly enhances the damage potential to vaginal epithelial cells. Similar to other Candida species, the potential of C. glabrata to survive in human blood is low. However, C. glabrata can survive within macrophages for long periods without causing host cell damage and responses. This intracellular stage requires the acquisition of nutrients, such as biotin, facilitated by defined biotin up-take systems. Survival in macrophages is further supported by transient mitochondria dysfunction: C. glabrata is able to switch into a petite phenotype upon interaction with human phagocytes. The petite phenotype significantly differs from non-petite cells in its growth behavior, its interactions with the immune system, and even its resistance to antifungal drugs. Effectively, the interaction with phagocytes can render C. glabrata mostly resistant to commonly used azole drugs, and vice versa (‘cross resistance’), providing a principle mechanism by which intrinsic antifungal resistance may have evolved.SourcesSeider et al. (2011) The facultative intracellular pathogen Candida glabrata subverts macrophage cytokine production and phagolysosome maturation. J Immunol. 187(6):3072-86.Brunke and Hube. (2013) Two unlike cousins: Candida albicans and C. glabrata infection strategies. Cell Microbiol. 15(5):701-8.Kämmer et al. (2020) Survival strategies of pathogenic Candida species in human blood show independent and specific adaptations. mBio 11(5):e02435-20.Sprenger et al. (2020) Fungal biotin homeostasis is essential for immune evasion after macrophage phagocytosis and virulence. Cell Microbiol. 22(7):e13197.Pekmezovic et al. (2021) Candida pathogens induce protective mitochondria-associated type I interferon signalling and a damage-driven response in vaginal epithelial cells. Nat Microbiol. 6(5):643-657.Pekmezovic et al. (2021) Human albumin enhances the pathogenic potential of Candida glabrata on vaginal epithelial cells. PLoS Pathog. 17(10):e1010037.Siscar-Lewin et al. (2021) Transient mitochondria dysfunction confers fungal cross-resistance against phagocytic killing and fluconazole. mBio 12(3):e0112821.

The Rising Threat of Drug Resistant Pseudomonas aeruginosa- A Nightmare for Intensive Care Unit Patients

Introduction: Multidrug Resistant (MDR), Extensively Drug Resistant (XDR) and Pan Drug Resistant (PDR) variants manifest a high level of intrinsic resistance to antimicrobial drugs by the help of efflux pump, biofilm formation and aminoglycoside modifying enzymes. The potentiality of Pseudomonas spp. to produce variety of drug resistance mechanism has led to evolution of drug resistant phenotypes this poses a challenge for clinicians in the treatment of severe infection among Intensive Care Unit (ICU) patients. Aim: To determine the phenotypic profiling of b-lactamases and burden of MDR, XDR and PDR Pseudomonas aeruginosa (P. aeruginosa) in ICU patients. Materials and Methods: The present cross-sectional prospective study was carried in the Department of Microbiology, Santosh Medical College and Hospital, Ghaziabad, Uttar Pradesh, India, after permission from Institutional Ethics Committee (IEC). A total of 115 isolates of P. aeruginosa were isolated from 502 human clinical samples from January 2019 to February 2021 and all the clinical samples were non duplicate. Antimicrobial Susceptibility Testing (AST) was performed for all isolates by standard Kirby- Bauer disc diffusion method on Mueller Hinton Agar (MHA). Phenotypic profiling of Extended Spectrum b-Lactamase (ESBL), Metallo b-Lactamase (MBL) and Ampicillinase C (AmpC) was performed by disc potentiation test; Imipenemase (IMP) - Ethylenediamine Tetraacetic Acid (EDTA) combined disc test and Cefoxitin Cloxacillin Double Disc Synergy Test (CC-DDST), respectively. The obtained results were statistically analysed in numbers and percentages using MS Excel 2013 version. Results: Out of 502 total human clinical samples, 115 isolates were P. aeruginosa giving the prevalence rate of 23%. Among 115 Pseudomonas isolates, 60 (52%) were MDR phenotypes, 8 (7%) were XDR phenotypes and there was no PDR phenotypes isolated in present study as all isolates were sensitive to Ticarcillin/Clavulanic acid, Colistin and Polymyxin B. Out of 115 isolates, 59 (51%) were ESBL producers, 26 (23%) were MBL producers, and 6 (5%) were AmpC producers. Conclusion: Strict antibiotic policies and regular surveillance programme of antimicrobial resistance must be tailored to fend off the emergence of drug resistant Pseudomonas aeruginosa.

Natural killer cells kill Burkholderia cepacia complex via a contact-dependent and cytolytic mechanism.

Burkholderia cepacia complex (Bcc), which includes B. cenocepacia and B. multivorans, pose a life-threatening risk to patients with cystic fibrosis. Eradication of Bcc is difficult due to the high level of intrinsic resistance to antibiotics, and failure of many innate immune cells to control the infection. Because of the pathogenesis of Bcc infections, we wondered if a novel mechanism of microbial host defense involving direct antibacterial activity by natural killer (NK) cells might play a role in the control of Bcc. We demonstrate that NK cells bound Burkholderia, resulting in Src family kinase activation as measured by protein tyrosine phosphorylation, granule release of effector proteins such as perforin and contact-dependent killing of the bacteria. These studies provide a means by which NK cells could play a role in host defense against Bcc infection.

Preclinical therapeutic targets in diffuse midline glioma.

Diffuse midline gliomas (DMG) are rapidly fatal tumors of the midbrain in children, characterized by a diffuse growing pattern and high levels of intrinsic resistance to therapy. The location of these tumors, residing behind the blood-brain barrier (BBB), and the limited knowledge about the biology of these tumors, has hindered the development of effective treatment strategies. However, the introduction of diagnostic biopsies and the implementation of autopsy protocols in several large centers world-wide has allowed for a detailed characterization of these rare tumors. This has resulted in the identification of novel therapeutic targets, as well as major advances in understanding the biology of DMG in relation to therapy resistance. We here provide an overview of the cellular pathways and tumor-specific aberrations that have been targeted in preclinical DMG research, and discuss the advantages and limitations of these therapeutic strategies in relation to therapy resistance and BBB-penetration. Therewith, we aim to provide researchers with a framework for successful preclinical therapy development.

Antibiotic Resistance of Lactobacillus spp. and Streptococcus thermophilus Isolated from Chinese Fermented Milk Products.

The aim of the present study was to investigate the phenotypic and genotypic antimicrobial resistance and the transferability of resistance markers in 87 lactic acid bacterial strains recovered from fermented milk products obtained from different areas of China. The isolates were identified as 21 Lactobacillus bulgaricus, 8 Lactobacillus casei, 6 Lactobacillus rhamnosus, 3 Lactobacillus paracasei, 2 Lactobacillus acidophilus, and 47 Streptococcus thermophilus strains. High levels of intrinsic resistance were revealed among the tested species. The following resistance genes were detected in strains isolated from fermented milk products: tet(M) in two L. bulgaricus and two S. thermophilus isolates, strA and strB in nine and seven S. thermophilus isolates, respectively; sul1 in six L. bulgaricus and seven S. thermophilus isolates, sul2 in one S. thermophilus isolate, aac(6')-aph(2″) in two L. bulgaricus isolates, and aph(3″)-II and aph(3″)-III in one S. thermophilus and two L. bulgaricus isolates, respectively. Transfer of the monitored antibiotic resistance genes was not observed in the filter mating assays of this study. To our knowledge, the strA, strB, sul1, sul2, and aph(3″)-II genes in S. thermophilus, and the sul1 and aac(6')-aph(2″) genes in L. bulgaricus were identified for the first time. These results indicate the potential risks posed by lactic acid bacteria (LAB) in fermented milk products in expanding the antibiotic resistance gene reservoir and transferring antibiotic resistance genes among bacteria. Further investigations are required to identify the potential sources of contamination and the dissemination routes of antibiotic resistance genes among LAB in fermented milk products.

Presence of β-Lactamase Encoding Genes in Burkholderia cepacia Complex Isolated from Soil.

Burkholderia cepacia complex has emerged as an important opportunistic bacteria group for immunocompromised patients, and it has a high level of intrinsic resistance for different antibiotic classes. Hydrolysis of β-lactam antibiotics by β-lactamases is the most common resistance mechanism in Gram-negative bacteria, and the presence of such enzymes complicates the selection of appropriate therapy. This study aimed at investigating the antimicrobial resistance profile and the presence of β-lactamase encoding genes in B. cepacia complex isolated from Brazilian soils. High-level ceftazidime resistance and several β-lactamase encoding genes were found, including the first report of blaKPC genes in bacteria isolated from soil.

Burkholderia cepacia Complex Regulation of Virulence Gene Expression: A Review.

Burkholderia cepacia complex (Bcc) bacteria emerged as opportunistic pathogens in cystic fibrosis and immunocompromised patients. Their eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. Bcc bacteria have large and complex genomes, composed of two to four replicons, with variable numbers of insertion sequences. The complexity of Bcc genomes confers a high genomic plasticity to these bacteria, allowing their adaptation and survival to diverse habitats, including the human host. In this work, we review results from recent studies using omics approaches to elucidate in vivo adaptive strategies and virulence gene regulation expression of Bcc bacteria when infecting the human host or subject to conditions mimicking the stressful environment of the cystic fibrosis lung.

Antibiotic resistance among Ureaplasma spp. isolates: cause for concern?

There is growing global concern regarding the rise of antibiotic-resistant organisms. Many of these reports have focused on various Gram-positive and Gram-negative pathogens, with little attention to the genus Ureaplasma. Ureaplasma spp. are associated with numerous infectious diseases affecting pregnant women, neonates and the immunocompromised. Treatment options are extremely limited due to high levels of intrinsic resistance resulting from the unique physiology of these organisms and further restricted in cases of the developing fetus or neonate, often limiting therapeutic options to predominantly macrolides or rarely fluoroquinolones. The increasing presence of macrolide- and fluoroquinolone-resistant strains among neonatal infections may result in pan-drug resistance and potentially untreatable conditions. Here, we review the requirements for accurate measurement of antimicrobial susceptibility, provide a comprehensive review of the antimicrobial resistance (AMR) for Ureaplasma species in the literature and contextualize these results relative to some investigators' reliance on commercial kits that are not CLSI compliant when determining AMR. The dramatic variation in the resistance patterns and impact of high levels of AMR amongst neonatal populations suggests the need for continued surveillance. Commercial kits represent an excellent tool for initial antibiotic susceptibility determination and screening. However, AMR reporting must utilize internationally standardized methods, as high-titre samples, or Mycoplasma hominis-contaminated samples routinely give false AMR results. Furthermore, there is a requirement for future reports to determine the underlying AMR mechanisms and determine whether expanding AMR is due to spontaneous mutation, transmission of resistance genes on mobile elements or selection and expansion of resistant clones.

A Mini Review on the Antimicrobial Treatment, Mechanisms and Patterns of Resistance among Clinical, Veterinary and Environmental isolates of Burkholderia pseudomallei

The causative agent of human and animal melioidosis, Burkholderia pseudomallei is a saprophytic organism that is widely distributed in various environmental niches such as soil and water in endemic regions. Infection results from exposure to environments containing B. pseudomallei through direct skin inoculation or contamination of wounds, and inhalation of aerosolised bacteria. The infection is usually treatable with antibiotics but the treatments are becoming difficult, because these bacteria demonstrate a high level of intrinsic resistance against most common clinically relevant antibiotics. There are various mechanisms involved in B. pseudomallei antimicrobial resistance, four among which have been established; expression of multiple drug efflux pumps of the resistance-nodulation-cell division (RND) superfamily, production of hydrolytic enzymes, β-lactamases, deletion of antibiotic target and reduced drug uptake due to outer membrane protein (Omp), BpsOmp38. Most of these mechanisms were established among clinical strains of B. pseudomallei such information among the veterinary and environmental isolates is limited. However there appears to be no distinction between antimicrobial susceptibility and resistance pattern amongst the strains isolated from human and those isolated from animal or environmental sources. The emergence of resistance particularly to ceftazidime, carbapenems, Trimethoprim/sulfamethoxazole and amoxicillin/clavulanic acid, has serious clinical implications, for therapeutic efficacy of both initial and eradication phase drugs are compromised. There is need for more investigation into clinical, veterinary and environmental isolates of B. pseudomallei to determine the antibiotic susceptibility and resistance pattern and characterization of the various antimicrobial resistance genes recognized in the B. pseudomallei genome to elucidate their role in conferring resistance to antimicrobial agents. The information about the resistance mechanisms is imperative in future efforts in design of antimicrobial agents targeting these mechanisms.

Differential roles of RND efflux pumps in antimicrobial drug resistance of sessile and planktonic Burkholderia cenocepacia cells.

Burkholderia cenocepacia is notorious for causing respiratory tract infections in people with cystic fibrosis. Infections with this organism are particularly difficult to treat due to its high level of intrinsic resistance to most antibiotics. Multidrug resistance in B. cenocepacia can be ascribed to different mechanisms, including the activity of efflux pumps and biofilm formation. In the present study, the effects of deletion of the 16 operons encoding resistance-nodulation-cell division (RND)-type efflux pumps in B. cenocepacia strain J2315 were investigated by determining the MICs of various antibiotics and by investigating the antibiofilm effect of these antibiotics. Finally, the expression levels of selected RND genes in treated and untreated cultures were investigated using reverse transcriptase quantitative PCR (RT-qPCR). Our data indicate that the RND-3 and RND-4 efflux pumps are important for resistance to various antimicrobial drugs (including tobramycin and ciprofloxacin) in planktonic B. cenocepacia J2315 populations, while the RND-3, RND-8, and RND-9 efflux systems protect biofilm-grown cells against tobramycin. The RND-8 and RND-9 efflux pumps are not involved in ciprofloxacin resistance. Results from the RT-qPCR experiments on the wild-type strain B. cenocepacia J2315 suggest that there is little regulation at the level of mRNA expression for these efflux pumps under the conditions tested.

Trimethoprim–Sulfamethoxazole for Treatment of Stenotrophomonas maltophilia Pneumonia in a Neonate

Neonates are susceptible to numerous infections. Factors that predispose these patients to nosocomial infections include very low birth weight, small size for gestational age, immunologic immaturity, and exposure to invasive procedures, including insertion of intravascular catheters and assisted ventilation. Stenotrophomonas maltophilia is an opportunistic, gram-negative aerobic bacillus with a high level of intrinsic resistance that is known to cause nosocomial infections. This organism may cause infections of many different systems, including bloodstream infections, urinary tract infections, meningitis, and (most commonly) pneumonia. Since neonatal patients are immunocompromised, infections with S. maltophilia are considered life-threatening in this population. There is very little evidence in the literature indicating the appropriate doses of trimethoprim–sulfamethoxazole required to treat S. maltophilia infections in neonates. This article describes a case in which trimethoprim–sulfamethoxazole was used to treat such an infection, with escalating doses used and tolerated.

OmpA Is the Principal Nonspecific Slow Porin of Acinetobacter baumannii

Acinetobacter species show high levels of intrinsic resistance to many antibiotics. The major protein species in the outer membrane of Acinetobacter baumannii does not belong to the high-permeability trimeric porin family, which includes Escherichia coli OmpF/OmpC, and instead is a close homolog of E. coli OmpA and Pseudomonas aeruginosa OprF. We characterized the pore-forming function of this OmpA homolog, OmpA(Ab), by a reconstitution assay. OmpA(Ab) produced very low pore-forming activity, about 70-fold lower than that of OmpF and an activity similar to that of E. coli OmpA and P. aeruginosa OprF. The pore size of the OmpA(Ab) channel was similar to that of OprF, i.e., about 2 nm in diameter. The low permeability of OmpA(Ab) is not due to the inactivation of this protein during purification, because the permeability of the whole A. baumannii outer membrane was also very low. Furthermore, the outer membrane permeability to cephalothin and cephaloridine, measured in intact cells, was about 100-fold lower than that of E. coli K-12. The permeability of cephalothin and cephaloridine in A. baumannii was decreased 2- to 3-fold when the ompA(Ab) gene was deleted. These results show that OmpA(Ab) is the major nonspecific channel in A. baumannii. The low permeability of this porin, together with the presence of constitutive β-lactamases and multidrug efflux pumps, such as AdeABC and AdeIJK, appears to be essential for the high levels of intrinsic resistance to a number of antibiotics.

Molecular approaches to pathogenesis study of Burkholderia cenocepacia, an important cystic fibrosis opportunistic bacterium

Burkholderia cenocepacia is a Gram-negative opportunistic pathogen belonging to the Burkholderia cepacia complex (Bcc). It is spread in a wide range of ecological niches, and in cystic fibrosis patients, it is responsible for serious infections. Its eradication is very difficult due to the high level of intrinsic resistance to clinically relevant antibiotics. One of the main resistance mechanisms in clinical isolates is represented by efflux systems that are able to extrude a variety of molecules, such as antibiotics, out of the cell. Resistance-Nodulation-Cell Division (RND) efflux pumps are known to be mediators of multidrug resistance in Gram-negative bacteria. Since now, the significance of the RND efflux systems in B. cenocepacia has been partially determined. However, the analysis of the completely sequenced genome of B. cenocepacia J2315 allowed the identification of 16 operons coding for these transporters. We focused our attention on the role of these pumps through the construction of several deletion mutants. Since manipulating B. cenocepacia J2315 genome is difficult, we used a peculiar inactivation system, which enables different deletions in the same strain. The characterization of our mutants through transcriptome and phenotype microarray analysis suggested that RND efflux pumps can be involved not only in drug resistance but also in pathways important for the pathogenesis of this microorganism. The aim of this review is an updated overview on host-pathogen interactions and drug resistance, particularly focused on RND-mediated efflux mechanisms, highlighting the importance of molecular techniques in the study of B. cenocepacia.

Stenotrophomonas maltophilia: Significant contemporary hospital pathogen — review

Stenotrophomonas maltophilia (Sm) plays an important role as an opportunistic pathogen in immunocompromised individuals. The growing detection rates of this bacterium in hospitalized patients are associated with the invasiveness of therapeutic and diagnostic procedures and the selection pressure of antibiotic therapy. A broad range of infections that can be caused by Sm is frequently bound to biofilm. The high level of intrinsic resistance to many unrelated antibiotics and increasing acquired resistance to the drug of choice, trimethoprim-sulfamethoxazole pose a threat for the near future when our treatment options may become depleted. Prevention of colonization and infection consists in consequent implementation of the rules governing nosocomial infection control, rational use of antibiotics including the optimization of selection and testing of antimicrobial agents suitable for the treatment of stenotrophomonad infections.

Caracterização fenotípica e genotípica de Serratia marcescens provenientes de Unidade Neonatal de Referência em Belém, Pará

Serratia marcescens has been reported as an important agent of health care-related infections and has been highlighted for presenting a high level of intrinsic resistance to antimicrobials used in neonatology, besides persisting in hospital environments for long periods. In this work, S. marcescens was recovered from colonies in the gastrointestinal tract or late sepsis in newborn infants hospitalized in a Neonatal Unit in Belem. The identification of S. marcescens and the sensitivity test was carried out using a Vitek (BioMerieux) automated system; susceptibility to ertapenem was assessed using e-test strips (Oxoid). Genotyping was executed by ERIC-PCR using the primers ERIC1 (5’-TGAATCCCCAGGAGCTTACAT-3’) and ERIC2 (5’-AAGTAAGTGACTGGGGTGAGCG-3’). Twenty-two strains of S. marcescens were recovered: 15 from hemocultures and seven from surveillance (rectal swab culture). All presented resistance to ampicillin, ampicillinsulbactam, gentamicin and cephalothin. There were no indications of resistance to ciprofloxacin, imipenem, meropenem or ertapenem. The susceptibility profiles varied for other antibiotics. Eleven amplification patterns by ERIC-PCR were obtained, and two were shared by 14 isolates. It was possible to observe a characteristic polymorphic pattern in the strains from gastrointestinal colonization, except for two cases, which presented genotypic patterns related to cases of sepsis. The data obtained in this work confirm the high level of resistance of S. marcescens against antimicrobials; however, all isolates displayed sensitivity to ciprofloxacin and carbapenemics. Antibiogram and ERIC-PCR typing suggest a dispersion of clones associated with colonization or sepsis among the wards of the Neonatal Unit in the surveyed hospital.

Assessment of three Resistance-Nodulation-Cell Division drug efflux transporters of Burkholderia cenocepacia in intrinsic antibiotic resistance

BackgroundBurkholderia cenocepacia are opportunistic Gram-negative bacteria that can cause chronic pulmonary infections in patients with cystic fibrosis. These bacteria demonstrate a high-level of intrinsic antibiotic resistance to most clinically useful antibiotics complicating treatment. We previously identified 14 genes encoding putative Resistance-Nodulation-Cell Division (RND) efflux pumps in the genome of B. cenocepacia J2315, but the contribution of these pumps to the intrinsic drug resistance of this bacterium remains unclear.ResultsTo investigate the contribution of efflux pumps to intrinsic drug resistance of B. cenocepacia J2315, we deleted 3 operons encoding the putative RND transporters RND-1, RND-3, and RND-4 containing the genes BCAS0591-BCAS0593, BCAL1674-BCAL1676, and BCAL2822-BCAL2820. Each deletion included the genes encoding the RND transporter itself and those encoding predicted periplasmic proteins and outer membrane pores. In addition, the deletion of rnd-3 also included BCAL1672, encoding a putative TetR regulator. The B. cenocepacia rnd-3 and rnd-4 mutants demonstrated increased sensitivity to inhibitory compounds, suggesting an involvement of these proteins in drug resistance. Moreover, the rnd-3 and rnd-4 mutants demonstrated reduced accumulation of N-acyl homoserine lactones in the growth medium. In contrast, deletion of the rnd-1 operon had no detectable phenotypes under the conditions assayed.ConclusionTwo of the three inactivated RND efflux pumps in B. cenocepacia J2315 contribute to the high level of intrinsic resistance of this strain to some antibiotics and other inhibitory compounds. Furthermore, these efflux systems also mediate accumulation in the growth medium of quorum sensing molecules that have been shown to contribute to infection. A systematic study of RND efflux systems in B. cenocepacia is required to provide a full picture of intrinsic antibiotic resistance in this opportunistic bacterium.

Resistance of potential probiotic lactic acid bacteria and bifidobacteria of African and European origin to antimicrobials: Determination and transferability of the resistance genes to other bacteria

Probiotic bacteria and starter cultures of Lactobacillus, Weissella and Bifidobacterium of African and European origins were studied and compared for their susceptibility to antimicrobials. The study included, for all isolates, determination of MICs (Minimal Inhibitory Concentration) for 24 antimicrobials, detection of resistance genes by PCR reactions using specific primers and sequencing of positive amplicons. The ability of Lb. reuteri from Africa to transfer the erythromycin resistance gene erm(B) to closely related bacteria was investigated by conjugation. Variations were observed and high levels of intrinsic resistance were found among the tested species. Positive amplicons were obtained for resistance genes encoding aminoglycoside ( aph(3′) -III, aadA, aadE) and tetracycline ( tet(S)) from isolates from Europe and macrolide ( erm(B)) from an isolate from Africa. However, only the erm(B) gene found in Lb. reuteri L4: 12002 from Africa contained a homologous sequence to previously published sequences. This gene could be transferred in vitro to enterococci. Higher prevalence of phenotypic resistance for aminoglycoside was found in isolates from Europe.