جستجوی مقالات مرتبط با کلیدواژه « Gram-negative bacteria » در نشریات گروه « پزشکی »

The Tol/Pal system is a group of complex proteins found in Gram-negative bacteria that has a crucial function in bacterial outer membrane development and safety. It is a promising target for potential antibacterial therapy. Initially, this Tol/Pal system was thought to be associated with the uptake of toxins such as colicins by Escherichia coli. However, the latest research has revealed that this system has much broader features beyond that. The system has been extensively studied, and this article discusses some of the conclusions drawn from those studies. Most significantly, the Tol/Pal system is a prerequisite for the pathogenicity of many Gramnegative bacteria, indicating that it has a remarkable role in how these bacteria cause diseases. Moreover, this system plays a vital role in the growth and overall fitness of specific pathogens. This indicates that it may be a promising target for growing antimicrobial therapies. Significantly, one of the proteins in this system, called Pal, is highly recognizable through the immune system and may trigger each of the adaptive and innate immune responses. A lot of these features make the Tol/Pal system an exciting area of research for the development of antibacterial therapies, in particular for dealing with stubborn infections caused by gram-negative pathogens, which are resistant to a couple of drugs. This paper offers an outline of the mechanisms of the Tol/ Pal system within the context of bacterial disease development and its potential utilization as a vaccine to counter respective bacterial infections.

Ox-bile has been recommended as a natural remedy with several therapeutic potentials in traditional Persian medicine. It has had efficacy against inflammation and infection according to traditional medicine. Evidence revealed that bile disrupts bacterial cell membrane and degrades DNA structure, so it has anti-bacterial effects. However, there is no evidence of any approved medication composed of ox-bile in Iran.

The aim of this study was to evaluate the in vitro anti-bacterial effects of ox-bile.

Ox-bile was obtained under aseptic conditions and sterilized with a 0.22 msyringe filter, then examined for their sterility status through culture on different media. Following incubation under aerobic cultures for 48 hours and the anaerobic cultures for one week. Two different kinds of antimicrobial susceptibility tests, including well-diffusion method and serial dilution test were employed to characterize the inhibitory effect of ox-bile extraction on Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Propionibacterium acnes.

Based on our study, no anti-bacterial effect of ox-bile was observed against selected gram-positive and gram-negative bacteria.

No in-vitro evidence of inhibitory effect was observed against studied gram-positive and gram-negative bacteria. Though further evaluation of the anti-bacterial effects of different preparations of ox-bile seems is still required.

A new series of derivatives of N, 2-diphenylquinazolin-4-amine (3a-g) was synthesized through nucleophilic substitution. The structures of compounds were characterized by FTIR, 1H-NMR, and 13C-NMR spectroscopy. All synthesized compounds were evaluated for their antimicrobial activities against Gram-positive (Staphylococcus aureus, Bacillus subtilis, Lactobacillus rhamnosus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria and also for antifungal activities, against Candida albicans, using broth microdilution method to determine their minimum inhibitory concentrations (MIC). Most of the compounds have shown moderate to good antibacterial activities, significantly compound 3g at 0.0625 mg/mL concentration had the highest activity against P. aeruginosa. Also, the MIC of compound 3f was 0.0078 mg/mL against S. aureus. Furthermore, the tested compounds exhibited remarkable antifungal activities against C. albicans, significantly compounds 3c and 3g showed the least MIC (equal to 0.0625 mg/mL). Also, a docking study into DNA gyrase has been made for these compounds. The synthesized compounds showed dock score values between -3.05 and -6.13kcal/mol. The highest dock score among them was -6.13 kcal/mol, found for compound 3c.

Extended-spectrum β-lactamase (ESβL) or metallo-β-lactamase (MβL) production by gram-negative bacteria in immunocompromised patients poses a serious therapeutic challenge for infection control and is associated with infections with a higher morbidity/mortality, especially in developing countries. This study aimed to phenotypically evaluate the production of ESβL as well as MβL in 75 gram-negative bacterial isolates from clinical samples of the human immunodeficiency virus (HIV) positive individuals.

Bacterial identification was by chromogenic media, analytical profile index 20 E, and 20 NE kits, and ESβL production was tested by double-disc synergy test (DDST) and combination disc method, while MβL production was screened with imipenem ethylene diamine tetra-acetic acid (EDTA) combined disc and EDTA-disc potentiation with ceftazidime.

Altogether, 57 isolates (76.0%) produced ESβL either with DDST (6), combination disc method (49), or both (2). DDST detected the ESβL enzyme in 10.7% of the tested isolates which were all Pseudomonas aeruginosa. None of the bacterial isolates revealed MβL production with the imipenem/imipenem-EDTA method, whereas 26.7% of tested isolates produced MβL with EDTA-disc potentiation using ceftazidime out of which 65.0% were P. aeruginosa. Moreover, ESβL/MβL co-production was evident in 22.7% of the tested bacterial isolates with P. aeruginosa constituting 64.7%.

ESβL and MβL co-production among the studied isolates indicates a heightened resistance to β-lactam antibiotics, suggesting grave health consequences, especially in immunocompromised individuals with already limiting therapeutic options in the region. The study revealed higher ESβL production compared to MβL production in isolates, with the predominating producing specie being P. aeruginosa, and higher ESβL and MβL detection by the combination disc method and EDTA-disc potentiation using ceftazidime, respectively.

 One of the leading causes of neonatal mortality in low- and middle-income countries (LMICs) is neonatal sepsis caused by carbapenem-resistant gram-negative bacteria.

 This study aimed to determine the frequency, bacterial profile, and outcome of carbapenem-resistant Gram-negative neonatal sepsis in southwest Iran.

 This 15-month retrospective cross-sectional descriptive study was conducted at a level 3 referral training hospital. The study included all neonates hospitalized from birth who had positive blood cultures for Gram-negative bacteria. Patients were divided into carbapenem-resistant and carbapenem-sensitive groups.

 During the study, Gram-negative bacteria were isolated from the blood cultures of 113 neonates. Positive Gram-negative bacteria blood cultures and carbapenem-resistant cases were 2.38% and 1.52%, respectively. In these cases, 66 (58.4%) of the infants were males, 100 (88.4%) were preterm, and 74 (65.4%) required mechanical ventilation within the first three days of life. The study found 45 (39.8%) infants with early-onset sepsis. Acinetobacter was the most common isolated organism, while Enterobacter had the lowest isolation rate. Carbapenem resistance was discovered in 72 (63.7%) positive blood cultures. Acinetobacter had the highest prevalence of carbapenem resistance, while Pseudomonas had the lowest. Mortality rates in infants infected with carbapenem resistance bacteria (CRB) were 89.3% compared to 10.7% in those infected with carbapenem-sensitive bacteria (CSB).

 The frequency of carbapenem-resistant Gram-negative sepsis in our ward was 1.52 percent of all admissions, and Acinetobacter bacteria was the most common cause of this type of neonatal sepsis. Infants infected with CRB had a higher mortality rate than those infected with CSB, 89.3% versus 10.7%.

Microorganisms producing Metallo-Beta-Lactamase (MBL) are a threat and cause of concern as they have become one of the most feared resistance mechanisms. This study was designed to explore the prevalence of MBL production in clinical isolates of Gram negative bacteria using phenotypic MBL detection.

A total of 248 isolates were collected from various clinical samples and were evaluated for car- bapenem resistance and MBL production. All strains were screened for MBL production using Double Disk Confirmatory Test (DDCT).

The results of screening for MBL production using phenotypic disk diffusion method showed that in the 85 isolates were carbapenemase positive; including, 10 (16.1%) Klebsiella pneumoniae, 9 (14.5%) Escherichia coli, 58 (93.6%) Acine- tobacter baumannii, and 8 (12.9%) Pseudomonas aeruginosa isolates. Also, 83 (97.6) Carbapenemase-producing isolates were resistant to at least four classes of antimicrobials (MDR).

A. baumannii was the most common carbapenem resistant bacterium in medical centers in Kermanshah. Signif- icant multiple drug resistance (MDR) incidence was observed compared to different classes of antibiotics.

Urinary tract infection (UTI) is the most prevalent infection among the community and hospitalized patients.

This study aimed to investigate the current antimicrobial susceptibility patterns among UTI agents in Tehran, Iran.

This retrospective study analyzed 9836 urine samples collected from hospitalized patients within 2019 - 2020. The antibiotic susceptibility for commonly-used antibiotics was tested according to Clinical and Laboratory Standards Institute guidelines.

Based on the findings, Escherichia coli was the most prevalent etiological agent of UTIs (72.3%), followed by Klebsiella spp. (13.4%), Pseudomonas aeruginosa (4.8%), Acinetobacter spp. (2.8%), and other species (6.7%). Of isolated microorganisms, 943 cases (97%) belonged to gram-negative bacilli; however, 32 cases (3.05 %) were gram-positive cocci. The susceptibility rates of E. coli to amikacin, nitrofurantoin, gentamicin, imipenem, and cefoperazone were 88.4%, 87.5%, 68.3%, 65.9%, and 62.6%, respectively. The sensitivity rates of Klebsiella spp. isolates for amikacin, nitrofurantoin, and imipenem were 87.6%, 71.5%, and 68.9%, respectively.

The results of the present study characterized the misuse of antibiotics in Iran. Iranian surveillance studies will assist clinicians in choosing the most appropriate empirical treatment and preventing infections caused by resistant organisms.

Bacterial infections are the most common complication in cancer patients. Infection with multi-drug resistant bacteria has recently become a worrying phenomenon in cancer patients. This study focused on Gram-negative bacteria isolated from clinical samples of cancer patients. The purpose of this study was to evaluate the presence and prevalence of drug resistance genes, including metallobetalactamase (blaIMP and blaVIM) and carbapenemase (blaKPC and blaGES) genes, in the main bacteria agents of nosocomial infections in cancer patients, such as Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli.

Common biochemical methods were used to identify bacterial isolates. Antimicrobial susceptibility testing was performed according to the standard method recommended by the Clinical and Laboratory Standards Institute (2019). Polymerase chain reaction (PCR) method was also used to check the presence and prevalence of resistance genes.

During six months, from May to November 2020, 250 clinical samples were collected from cancer patients in Ayatollah Khansari hospital in Arak city, Iran. From which 80 Gram-negative bacilli were isolated, including 33 (41.2%) E. coli, 15 (18.7%) A. baumannii complex, 12 (15%) P. aeruginosa, eight (10%) K. pneumoniae, seven (8.7%) Citrobacter freundii, and five (6.2%) Enterobacter aerogenes isolates. The frequency of blaKPC, blaGES, blaIMP, and blaVIM genes was 39.95, 21.25, 16.25, and 17.45%, respectively.

The present study emphasizes the importance of identifying Gram negative rods and their resistance genes (metallobetalactamase and carbapenemase genes) in cancer patients, carrying out preventive instructions to prevent the transmission of resistance genes, and reducing mortality in these patients.

 Gram-negative pathogens are considered the common cause of wound infections associated with increased mortality and morbidity rates. Antibiotics combination has been used to overcome this problem. In this study, we identify Gram-negative pathogens found in wound infections and assess the in-vitro efficacy of a combination of amikacin and imipenem against the resistant isolated pathogens.

 One hundered fifty gram-negative bacteria were collected from two hundered patients suffering from different wound infections. Patients attended Minia University Hospitals,Egypt at period from January 2019- January 2020 and they were  followed up periodically as a routine work in the hospitals. Swabs streaked on various media as Nutrient agar, MacConkey agar, Eosin methylene blue agar and cetrimide agar. The antimicrobial susceptibility of the identified pathogens was tested using the Kirby-Bauer method. Conventional PCR was used to detect the prevalence of bla-IMP and AAC (6’)-Ib genes. The effect of the tested combination was assessed by checkerboard technique and time-killing assay.

Escherichia coli 38.6% was the most common isolated pathogen, followed by Proteus spp 30%, P. aeruginosa 21.4%, Klebsiella spp. 5.7%, and Acinetobacter baumannii 4.3%. The isolates were completely resistant to Ampicillin/sulbactam, Amoxicillin/clavulanic, Cephalothin, Cefadroxil, Ciprofloxacin, Ceftazidime and Ofloxacin. Bla-IMP was detected in all Klebsiella spp., E. coli (85.2%), A. baumannii (66.7%), Proteus spp. (38.1%) and P. aeruginosa (33.35%). aac(6’)-Ib was detected among E. coli, P. aeruginosa and Proteus spp. The Checkerboard test showed a significant decrease in bacterial count in the presence of combination indicating a synergistic effect with FICIs ≤0.5. Time-kill assay showed a significant decrease in the bacterial count after 12h.

 The studied combinations of antibiotics showed synergistic effects against the tested Gram-negative bacteria which can help in the control and treatment of serious wound infections.

 Carbapenem-resistant Enterobacteriaceae (CRE) are rapidly growing, which makes it vital to detect antibacterial activity. However, the carbapenem family does not have an automated antimicrobial susceptibility testing card. So the aim of this study was to identify the prevalence of carbapenemase-producing strains of Gram-negative bacteria and determine their antibiotic susceptibility pattern in Tehran, Iran.

 In this cross-sectional study, between 2019 and 2020, 1600 samples were taken from the Masih Daneshvari hospital's laboratory in Iran. Utilizing standard biochemical methods, all isolated bacteria were identified. The common Kirby-Bauer Disc diffusion method was used for antimicrobial susceptibility testing. A real-time polymerase chain reaction was used to evaluate the molecular detection of genes producing carbapenemase.

Of 1502 (94.7) Gram-negative bacilli, 37.3% isolates were Pseudomonas aeruginosa, 30.6% Acinetobacter baumannii, 16.5% Klebsiella, 9.3% Escherichia coli, 0.6% Pseudomonas multophila, 0.4% Neisseria1105 (73.5%) isolates were carbapenem-sensitive, while the remaining 397 (26.5%) isolates were carbapenem-resistant. Molecular testing of this sample showed that 80% of tested isolates had resistance genes to at least one antibiotic resistance gene. The following carbapenemase genes were most frequently detected among resistant strains: blaimp (35%), blavim (20%), blakpc (15%), blaoxa -48 (10%), blandm (10%), and blages (10%).

 From this study authors can conclude that carbapenemase-producing Enterobacteriaceae is increasing in Iran and the use of phenotypic methods for detection of CPEs showed good sensitivity. Before prescribing antibiotics to patients, this test should be performed.

 Nosocomial infections caused by gram-negative bacteria are among the most important health-threatening challenges of the current century, particularly following the emergence and spreading of antibiotic-resistance strains. Extended-spectrum beta-lactamase (ESBL), one of the most important antibiotic resistance mechanisms, is spreading worldwide. Surveillance and gathering data on the prevalence of antibiotic resistance and their associated encoding genes could assist in selecting treatment strategies and policies. This systematic review and meta-analysis was designed to assess the prevalence of ESBL-positive bacteria and their resistance genes in medical centers of Kermanshah city, west of Iran.

 All studies published as original articles were retrieved by searching in EMBASE, Scopus, PubMed/Medline, Google Scholar, and Persian databases of SID and Magiran, using appropriate keywords All published studies in the field were included without time restriction until 30-Mar-2022. Comprehensive Meta-Analysis software was used to analyze the data.

The prevalence of ESBL-positive and multidrug resistance (MDR) bacteria in Kermanshah medical centers were 34.8% and 56.1%, respectively. The highest and lowest prevalence of ESBL-positive bacteria was observed for Enterobacter cloacae (59.14%) and Pseudomonas aeruginosa (4.55%), respectively. The highest and lowest prevalence of the resistance genes were observed for blaOXA-51 (99.3%) and blaKPC (0.6%), respectively. The highest resistance was estimated to mezlocillin antibiotic (92.2%).

 This study showed that the prevalence of ESBL-positive and MDR bacteria is high in Kermanshah medical centers, and it provides significant information to health policymakers to implement appropriate strategies to reduce the prevalence of resistant bacteria.

Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods.

Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB).

Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-encoding genes, including blaNDM-1, blaVIM-2, and blaOXA-48. This study described the first emergence of NDM-1 producing Klebsiella oxytoca in Egyptian ICUs.

High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiotics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

Colistin is a common antibiotic used to treat urinary tract infections (UTIs) caused by gram-negative bacteria. In recent years, due to the increasing resistance, consumption of colistin alone could lead to treatment failures. This study aimed to compare the effectiveness of colistin alone with colistin and meropenem to treat patients with urinary tract infections.

In this randomized, open-label, parallel groups controlledtrial, hospitalized patients with urinary tract infections were included. Patients were randomly allocated to the control group (n=35) that received colistin (1 mIU every 12 hours) and the intervention group (n=35) that received colistin (1 mIU every 12 hours) with meropenem (1gr every 8 hours). An infectious diseasespecialist evaluated the therapeutic responses 48-72 hours after admission. Cessation of fever, improvement of symptoms and signs, and negative urine culture within 48 hours wereconsidered successful therapeutic responses.

The mean length of hospitalization was longer in the control group (4.74±0.78 days) compared with the intervention group (4.26±0.56 days) (P=0.004). The prevalence of fever cessation had no significant difference between the two groups at any time (P>0.05). Also, there was no significant difference between the two groups at any time, considering vital signs, irritative urinary symptoms, nausea and vomiting, and flank pain (P>0.05).

The administration of colistin and meropenem to treat UTIs was associated with a shorter length of hospital stay. However, regarding response to treatment, it did not matter if they were treated with colistin alone or with combination therapy (colistin and meropenem).

Global growing infections by multi-drug resistance (MDR) or extensively drug-resistant (XDR) bacteria are a serious public health problem which can increase the rate of mortality and morbidity even in children. Carbapenem is the last choice therapy in case of antibiotic-resistant bacteria presence.

This study aimed to evaluate the easy to use method to identify carbapenemase producing bacteria which include in CLSI.

In this descriptive study, 125 carbapenem-resistant and 97 carbapenem-susceptible gram-negative bacteria were included. PCR was used to identify carbapenemase enzymes include VIM, IMP, KPC, NDM-1, SPM-1, OXA-48 as a gold standard method. The modified carbapenem inactivation method (mCIM) was employed to phenotypically identify carbapenemase-producing bacteria. Some modifications were made to the CLSI proposed mCIM to ensure more accurate results in contrast of PCR.

The OXA-48 is the most prevalent detected carbapenemase and SPM-1 was not detected in any of strain. The results of the mCIM according to CLSI guide line demonstrated 100% sensitivity to define carbapenemase-producing bacteria. However, in the cases of non-carbapenemase-producing bacteria, only 4% of mCIM test results were consistent with the outcome of PCR. Decrease of the incubation time and the consider 15mm as a break point could increase the accuracy of mCIM against PCR.

The results of this study endorse that mCIM test is a valuable method to detect carbapenemase producing bacteria if the three hours consider instead of 4 hours with 15mm break point.

Colistin relates to the polymyxin group of antibiotics. This antibiotic is still used to destroy gram-negative bacteria as a last resort. However, resistance to this antibiotic has been reported and is appearing day by day. Not much information is available on the exact mechanisms of resistance to this antibiotic. Also, not enough information about pharmacokinetics and pharmacodynamics is available, so the optimal dose should be determined to use these antibiotics to prevent the toxic effects of this antibiotic. In current study, additionally to their pharmacokinetics and pharmacodynamics, we have presented current knowledge about the genes and two-component systems that may cause such resistance to polymyxin and colistin.

Fetal abortion is one of the critical and controversial issues in most societies’ scientific, social, and academic ceremonies due to known and unknown reasons. Furthermore, updating our knowledge about isolated bacteria, their antibiotic resistance pattern, and related factors is essential for designing and implementing appropriate interventions.

The current study was conducted to determine the prevalence of bacteria among fetal abortion cases and demonstrate the antimicrobial susceptibility among isolated bacteria.

For this, 153 blood samples were collected percutaneously from the heart blood of aborted fetuses 1 - 15 hours after birth; subsequently, the identification of bacteria and evaluation of antimicrobial susceptibility testing were performed.

Generally, 82 out of 153 test cultures were positive, comprising 66 and 26 Gram-negative and Gram-positive bacteria, respectively. The most isolated bacteria among Gram-negative isolates were Acinetobacter spp. (34/82) and Escherichia coli (17/82). Likewise, the highest antibiotic resistance was detected for Acinetobacter spp. against cefixime, amikacin, gentamycin, and ciprofloxacin (24/34). On the other hand, Staphylococcus spp. was the predominant Gram-positive cocci (10/82). Also, the highest resistance for Staphylococcus spp. was against cefoxitin and ciprofloxacin (100%).

It seems more focus on following the general hygiene of pregnant mothers is essential. However, further evidence of a clinical correlation between aborted fetuses and their mothers is required.

Curative misuse of medicinal plants are worrisome with the paucity of histological information. This led to the investigation of Ipomoea asarifolia in Swiss albino rats infected with Pseudomonas aeruginosa and Staphylococcus aureus.

Extraction was done using the cold maceration method. The minimum inhibitory concentrations (MIC) of the extracts were determined using the micro-dilution method. Swiss albino rats of 6 sub-groups with 6 animals each (36 animals/organism) were administered with 0.3 ml single oral dose of P. aeruginosa and S. aureus respectively. The animals received treatment for 5 days as follows: 0.5 ml of 5% dimethyl sulphoxide (DMSO) (negative control), 250 mg/kg of amoxicillin (positive control), 2 mg/kg of whole plant extract, 4 mg/kg of whole plant extract, 2 mg/kg of leaf extract, and 4 mg/kg of leaf extract, respectively. The packed cell volume (PCV) and white blood count (WBC) of the animals were determined before and after treatment with histology examination of vital organs.

MIC for S. aureus was 2 mg/mL; the mortality in S. aureus group at 2 mg/kg was 66.7%. The PCV values (50.5±0.5, 45.0±1.0, and 50.5±1.5) decreased after infection, and a corresponding increase in the PCV was observed after treatment with the extracts. Also, a significant increase in the WBC values (3.40±0.35, 4.10±0.15, and 3.30±0.40) following infection and a corresponding decrease after treatment were observed. Congestion of vessels in the kidney was also observed.

I. asarifolia has a dose-dependent antibacterial and curative activity, and could enhance innate immunity.

This study aimed to determine the biological activity test of the alcoholic extract of the leaves of Catharanthus roseus.

Catharanthus roseus was used in the implementation of the experiment and it included three factors: the first factor is watering the plants with three concentrations of sodium chloride salt (0, 50, and 100mmol) of sodium chloride, the second factor is three concentrations of nitrogen (urea) (0, 100 and 200mg.L-1) and the third factor three concentrations of selenium (Na2SeO4; 0,25 and 50mg.L-1), then tested the biological activity of plant leaf extracts from all treatments against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria through Measure the diameters of the areas of inhibition of bacterial growth.

The results of the laboratory experiment showed that the extract of the leaves of triple combination plants (100mmol NaCl+200mg.L-1 N+50mg.L-1 Se) achieved the largest inhibition area for the growth of E. coli reaching 27.50mm compared to the control, which is 4.20mm, and plant leaf extract in the combination (100mmol NaCl+100mg.L-1 N+50mg.L-1 Se) recorded the largest inhibition area in S. aureus reached 50.27mm compared to the control which recorded 9.10mm.

The plant leaf extract had an important role in inhibiting the growth of the bacteria studied, and the highest inhibition was observed in the interaction between the three factors salt, nitrogen, and selenium.