Resistant Gram-negative Bacilli Research Articles

Impact of Gram-negative bacilli Resistance Rates on Risk of Death in Septic Shock and Pneumonia

Abstract Background Sepsis is a major cause of morbidity and mortality worldwide. When selecting empiric antibiotics for sepsis, clinicians are encouraged to use local resistance rates, but their impact on individual outcomes is unknown. Improved methods to predict outcomes are needed to optimize treatment selection and improve antibiotic stewardship. Methods We expanded on a previously developed theoretical model to estimate the excess risk of death in GNB sepsis due to discordant antibiotics using three factors: the prevalence of GNB in sepsis, the rate of antibiotic resistance in GNB, the mortality difference between discordant and concordant antibiotic treatments. We focused on ceftriaxone, cefepime, and meropenem as the anti-GNB treatment backbone in sepsis, pneumonia, and urinary infections. We analyzed both publicly available data and data from a large urban hospital. Results Publicly available data were weighted toward culture-positive cases. Excess risk of death with discordant antibiotics was highest in septic shock and pneumonia. In septic shock, excess risk of death was 4.53% (95%CI,4.04-5.01%), 0.6% (95%CI,0.55-0.66%), and 0.19% (95%CI,0.16-0.21) when considering resistance to ceftriaxone, cefepime, and meropenem, respectively. Results were similar in pneumonia. Local data included culture-negative cases, found excess risk of death in septic shock was 0.75% (95%CI,0.57-0.93) for treatment with discordant antibiotics in ceftriaxone-resistant infections and 0.18% (95%CI,0.16-0.21) for cefepime-resistant infections. Conclusions Estimating the excess risk of death for specific sepsis phenotypes in the context of local resistance rates, rather than relying on population resistance data, may be more informative in deciding empiric antibiotics in GNB infections.

The Clinical Efficacy of Adding Ceftazidime/Avibactam to Standard Therapy in Treating Infections Caused by Carbapenem-Resistant Klebsiella pneumonia with blaOXA-48-like Genes.

Ceftazidime/avibactam (CAZ-AVI) is FDA-approved for managing infections caused by resistant gram-negative bacilli, particularly infections via carbapenem-resistant Enterobacterales pathogens. The clinical data are still limited, particularly those in Saudi Arabia. The present study is a retrospective cohort study that was carried out at the Armed Forces Hospital in the southern region of Saudi Arabia to compare the clinical and microbiological outcomes for CAZ-AVI-treated patients as monotherapy and as an add-on to standard therapy for carbapenem-resistant Klebsiella pneumonia (CRKP) OXA-48 infections to those treated with standard drugs. The study included CRKP OXA-48-like infected patients who were administered antibiotics for more than seven days from 1 August 2018 to May 2023. Patients' baseline characteristics and demography were extracted from the clinical records, and their clinical/microbiology efficiencies were assessed as per the corresponding definitions. Univariate and multivariate logistic regressions were conducted to identify the potential independent variable for CAZ-AVI efficiency. A total of 114 patient files were included for the evaluation. Among these patients, 64 used CAZ-AVI combined with standard therapy and were included in the intervention group, and 50 of them used standard therapy and were included in the comparative group. Following analysis, CAZ-AVI's clinical success was 42.2% (p = 0.028), while the intervention versus comparative groups showed decreased 30-day all-cause mortality (50.0% versus 70.0%; p = 0.036) and infection recurrence (7.8% versus 24.0%; p = 0.019), as well as substantially increased rates of microbial eradication (68.8% versus 42.0%; p = 0.007). CAZ-AVI add-on therapy rather than monotherapy showed statistically significant favored clinical and microbial outcomes over the standard therapy. Furthermore, sex (female %), ICU admission, and fever were negatively associated with patients' 30-day all-cause mortality, serving as independent negative factors. Only fever, CRP bio levels, inotropes, and ICU admissions were significant predictors influencing the CAZ-AVI's clinical efficiency. The duration of CAZ-AVI therapy positively influenced CAZ-AVI's microbial eradication, while both WBC counts and fever experiences were negative predictors. This study shows the effective usage of CAZ-AVI against CRKP OXA-48-like infections. The influencing independent variables depicted here should recommend that clinicians individualize the CAZ-AVI dose based on co-existing risk factors to achieve optimal survival and efficacy. Prospective multicenter and randomized control studies are recommended, with individualized CAZ-AVI precision administration implemented based on patients' characteristics.

Prevalence of Extended-spectrum Beta-lactamase (ESBL), Metallo Beta-lactamase (MBL) and Carbapenemase Producing Acinetobacter Species Isolated from Various Clinical Samples in Tertiary Care Hospital

Acinetobacter is an important nosocomial pathogen causing health care associated infections. It is highly antibiotic resistant gram-negative bacilli. The study was done to determine the prevalence of Acinetobacter species isolated from various clinical samples with their antibiotic susceptibility pattern. To determine the antimicrobial susceptibility pattern of the isolated Acinetobacter species and also the multidrug resistant mechanisms by phenotypic characterization. The retrospective study was carried out in patients diagnosed with Acinetobacter infection in the Microbiology Department, Krishna Institute of Medical Sciences, Krishna Vishwa Vidyapeeth, Deemed To Be University, Karad, a tertiary care hospital, including the clinical departments, during the period of two years from November 2020 till November 2022. Organism identification, biochemical test, antibiotic resistance pattern and phenotypic tests such as ESBL, MBL and Carbapenemase production were performed as per the Clinical and Laboratory Standards Institute (CLSI). The Modified Hodge test (MHT) was performed for Carbapenemase production detection in Acinetobacter species. A total of 150 Acinetobacter species were isolated from clinical samples. Acinetobacter baumannii was the most prevalent species 138 (92%), followed by Acinetobacter lwoffii 10 (7%) and Acinetobacter hemolyticus 2 (1%). The isolates showed highest resistance to Ampicillin 130 (87%) and sensitive to Colistin 113 (75.3%). Most of the isolates of of Acinetobacter baumannii showed maximum ESBL 21(14%) and MBL 75 (93%) production. Modified Hodge test showed positive results in Acinetobacter baumannii, only 11 (7%). The study showed that Acinetobacter baumannii was the most prevalent species showing drug resistance by phenotypic detection methods. At present Acinetobacter is a frequent pathogen in hospital acquired infections in critically ill patients admitted to ICU. The isolates of Acinetobacter species in our study showed resistant to most commonly used antibiotics. The study showed that ESBL production in Acinetobacter was 22 (15%) and MBL 80 (53%). Most Acinetobacter isolates were Multi Drug Resistant (MDR). MDR Acinetobacter is widely increasing due to inappropriate use of antibiotics in healthcare hospital. In our study, detection of carbapenemase by Modified Hodge test was positive in 11 (7%) isolates.

Real-world experience with meropenem/vaborbactam for the treatment of infections caused by ESBL-producing Enterobacterales and carbapenem-resistant Klebsiella pneumoniae.

Real-world experience with meropenem/vaborbactam (M/V) is limited. Our aim is to report a clinical experience of M/V in the treatment of resistant Gram-negative bacilli. This is a prospective observational study including patients hospitalized in the University Hospital of Pisa (March 2021-Jan 2023) with infections by both extended-spectrum β-lactamases (ESBL)-producing Enterobacterales and carbapenem-resistant Klebsiella pneumoniae (Kp) treated with M/V. The primary outcome measure was clinical success, defined as a composite of survival, resolution of signs and symptoms and absence of microbiological failure at day 30 from infection onset. A multivariable regression analysis was performed to identify factors associated with clinical failure. Odds ratio (OR) with 95% confidence intervals (CI) was calculated. A total of 104 patients who received M/V were included: 24/104 (23.1%) infections were caused by ESBL non-hypervirulent Enterobacterales, 17/104 (16.3%) by ESBL-producing hypervirulent Klebsiella pneumoniae (hvKp) and 63/104 (60.6%) by CRE. The most common infections were bloodstream infections, followed by urinary tract infections, hospital-acquired pneumonia, intra-abdominal infections and others. Septic shock occurred in 16/104 (15.4%) patients. Clinical success was achieved in 77% of patients, and 30-day mortality rate was 15.4%. In patients with KPC-producing Kp infections, clinical success and 30-day mortality rates were 82% and 11.5%, respectively. On multivariable analysis, SOFA score (OR 1.32, 95% CI 1.02-1.7, p=0.032) was independently associated with clinical failure, while source control (OR 0.16, 95% CI 0.03-0.89, p=0.036) was protective. M/V is a promising therapeutic option against infections caused by difficult-to-treat ESBL-producing Enterobacterales and CR-Kp.

Assessment of BlaTEM, BlaSHV, and BlaCTX-M genes of antibiotic resistance in Gram-negative bacilli causing urinary tract infections in Khartoum State: a cross-sectional study

BackgroundGram-negative bacilli are the most common etiological agents responsible for urinary tract infections. The prevalence of antibiotic resistance in Gram-negative bacilli is increasing at a rapid pace globally, which is constraining the available choices for UTI treatment. The objectives of this study are to identify the most common causal organisms of urinary tract infections (UTIs), and to determine their drug resistance patterns.Materials and methodsThis was a cross-sectional hospital-based study conducted at El-Amal Hospital, Bahri Teaching Hospital, and Al-Baraha Hospital, Khartoum State, from March to October 2022. Urine samples from patients suspected to have UTI were collected, and patients with confirmed UTI by laboratory investigations and yielded culture growth were enrolled. Antibiotic sensitivity testing and PCR testing of the blaTEM, blaSHV, and blaCTX-M genes were done.ResultsThis study included 50 patients with UTI out of 229 suspected patients (21.8%). The most prominent group of patients was older than 60 years (40%); the majority were females (70%). Escherichia coli was the most prevalent isolated organism (50%), followed by Klebsiella oxytoca (24%), Klebsiella pneumoniae (20%), Pseudomonas aeruginosa (4%), and Citrobacter freundii (2%). A small percentage of organisms were resistant to colistin (17%). However, 77% were resistant to amikacin, 97.6% to cefotaxime, 96.8% to ceftazidime, 97.6% to ceftriaxone, 96.8% to cefixime, 87.6% to ciprofloxacin, 88.4% to gentamycin, 62% to imipenem, 67.6% to meropenem, 87.6% to norfloxacin, and 95.6% to trimethoprim. The overall resistance of isolated gram-negative organisms was 81%. The most prevalent gene for the resistance was blaTEM (100%), followed by blaCTX-M (94%), and then blaSHV (84%).ConclusionEscherichia coli and Klebsiella species were the most commonly isolated uropathogens in this study, and the majority were highly resistant to most of the antimicrobial agents tested. Resistance genes blaTEM, blaCTX-M, and blaSHV are very common in uropathogens.

Comparative study of colistin Methanesulfonate and colistin Sulfate/polymyxin B in the treatment of ceftazidime-avibactam resistant Gram-negative bacilli infections

Comparative study of colistin Methanesulfonate and colistin Sulfate/polymyxin B in the treatment of ceftazidime-avibactam resistant Gram-negative bacilli infections

Detection of Carbapenemase Genes by Molecular Method among Gram-Negative Bacilli Isolates from Tertiary Care Hospital in Dhaka, Bangladesh

Background: Imipenem resistance in Gram-negative bacilli is a global epidemic that is increasing day by day.To warn this global epidemic, identification and ongoing surveillance of carbapenem-resistant genes among Gram-negative bacilli needed.Objectives: This cross-sectional study was performed todetect the imipenem resistant genes among Gram-negative bacilli isolated from different samples in Dhaka medical college hospital.Methods: About 300 samples (wound swab, urine, endotracheal aspirate, blood, and sputum) were collected from July 2015 to June 2016. Among them, 204 isolates were Gram negative bacilli. Eighty imipenem resistant Gram-negative bacilli were isolated by disc diffusion method. Among them, carbapenem resistant genes (blaNDM-1, blaKPC, VIM, IMP) were detected by PCR.Results: A total 300 samples were analyzed. Out of 204 Gram negative bacilli,80 (39.21%) imipenem resistance was detected by the Disc Diffusion method. Out of 80 imipenem resistant organisms, 42 (52.5%) were positive for blaNDM-1, 6 (7.34%) were positive for blaKPC, 29 (36.25%) were positive for VIM, 13 (16.25%) were positive for IMP.Conclusion: This study illustrates the emergence of carbapenemase genes producing Gram negative bacilli isolates from patients. Close surveillance across all hospitals in Bangladesh is required. J Shaheed Suhrawardy Med Coll 2022; 14(1): 3-7

Distribution and antimicrobial resistance analysis of gram-negative bacilli isolated from a tertiary hospital in Central China: a 10-year retrospective study from 2012 to 2021.

Gram-negative bacilli are one of the most common causes of various infections in clinical. The emergence and global spread of multi-drug resistant gram-negative bacilli has become a major challenge in the global public health field. A total of 51,189 non-repetitive strains of gram-negative bacilli were isolated in clinical settings. The antimicrobial susceptibility testing was conducted by using the automated VITEK 2 compact system and the matched AST susceptibility test card, complemented by the disk diffusion method. The antimicrobial susceptibility results were interpreted by CLSI. Rates of MDR and XDR in Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa were investigated. Used the chi-square test to determine whether the antimicrobial resistance rates of four major gram-negative bacilli isolated from ICU and non-ICU department have statistical differences. Escherichia coli (31.4%), Klebsiella spp. (21.2%), Acinetobacter spp. (13.8%), and P. aeruginosa (11.0%) were the most frequently isolated gram-negative bacilli. Escherichia coli was the top one organism isolated from urinary tract (68.4%), bloodstream (39.9%), body fluid (33.2%), wound and pus (37%), except for respiratory tract (8.8%). Whereas Acinetobacter baumannii and K. pneumoniae were the major isolated organisms from respiratory tract. Acinetobacter baumannii showed high resistance to fluoroquinolones, β-lactam/β-lactamase inhibitor combinations class, ceftazidime, cefepime, imipenem, and meropenem, the resistance rates reached more than 70%. Ceftazidime showed a lower resistance rate to E. coli than ceftriaxone. For E. coli, fluoroquinolones showed a high resistance rate (ciprofloxacin 61.36% and levofloxacin 53.97%), whereas amikacin, carbapenems exhibited a lower resistance rate fluctuating at 2%. Acinetobacter baumannii and K. pneumoniae showed rapid increases in carbapenem resistance whereas E. coli had the lowest resistance rate and remain stable at 2%. Acinetobacter baumannii exhibited the highest rate of MDR and XDR, reaching 60-80 and 45-55%, respectively. Compared to non-ICU departments, the resistance rates of four major gram-negative bacilli in the ICU department were much higher and the differences were statistically significant (p < 0.05). Amikacin, carbapenems, and piperacillin/tazobactam exhibited relatively high sensitivity, whereas fluoroquinolones showed high resistance rate whether they can be the first-line antimicrobials for empirical treatment of UTI should take more consideration. The gram-negative bacilli in ICU were more resistance than that in non-ICU. These findings are helpful for clinicians using antimicrobials reasonably.

High oral carriage of multidrug resistant Gram-negative bacilli in adolescents: the SOPKARD-Junior study.

The colonization of the oral cavity by potentially pathogenic antimicrobial-resistant bacteria in adolescents and its consequences is very poorly understood. The present study focused on the occurrence of oral colonization by Gram-negative bacilli (GNB) and their multidrug resistance, including the production of extended-spectrum β-lactamases (ESBLs) and carbapenemases, among healthy adolescents and risk factors associated with GNB colonization. This study was conducted as part of "A program for the early detection of risk factors for lifestyle diseases SOPKARD-Junior" (SOPKARD-Junior). Oral samples were collected from 182 adolescents from four public elementary schools in Sopot, Poland, aged 13-14 years. Bacterial strains were identified by the MALDI-TOF MS method. Screening of antimicrobial resistance was performed using a disk diffusion method. The NG-Test® CARBA-5 was used to detect and differentiate the five most widely distributed carbapenemases. Demographic and clinical data were collected and statistical analysis of risk factors was performed. A total of 68 out of 182 (37.4%) healthy adolescents was documented oral colonization with Gram-negative bacilli, including 50/182 (27.5%) multidrug resistant (MDR-GNB) strains. Over 60% of oral carriage concerned three main genera Enterobacter spp., Pseudomonas spp., and Serratia spp., which were detected in 22.1%, 19.1%, and 19.1% of participants, respectively. Citrobacter spp., Escherichia coli, Klebsiella spp., Hafnia spp., Aeromonas spp., Acinetobacter spp., and Stenotrophomonas spp. were also isolated. The antimicrobial resistance to ampicillin (100%), ceftazidime (69.1%), meropenem (60.3%), gentamycin (60.3%), piperacillin/tazobactam (52.9%), and piperacillin (45.6%) were the most common. Among 73.5% GNB strains multidrug resistance was observed, including all Pseudomonas spp. strains. Among MDR-GNB, 30.4% were resistant to four groups of antibiotics, half of the MDR Pseudomonas spp. strains were resistant to 10 groups of antibiotics. Extended-spectrum β-lactamases were produced by Enterobacter cloacae, Klebsiella spp., and Serratia spp. (7.4%). Colonization by ESBLs-positive GNB strains was significantly associated with recurrent respiratory infections, nasal congestion, and bronchitis (p<0.05). Our study revealed high oral carriage of multi-drug resistant Gram-negative bacilli in healthy adolescents and the association of ESBL-producing strains with respiratory infections. Further studies on oral colonization with GNB are necessary due to the possibility of distinct infections and the acquisition of antibiotic resistance by resident microbiota.

Optimization of oil yield of Pelargonium graveolens L'Hér using Box-Behnken design in relation to its antimicrobial activity and in silico study

Pelargonium graveolens L'Hér is an important species of genus Pelargonium with an economic value. The unique rose scent of its oil is used in perfume and cosmetic industry. The oil is characterized by the presence of citronellol, geraniol and rose oxide. Fresh aerial parts of P. graveolens at GC–MS analysis of four seasons revealed that autumn constituted the highest yield of the oil. For the first time, optimization of the yield of extracted oil of P. graveolens was performed employing 3-level Box-Behnken design using 3-factors. The GC–MS analysis of the essential oil was performed for the 17-runs. The optimized extraction of the oil was performed employing numerical optimization and studied for antimicrobial, Minimum Inhibitory Concentration (MIC) and biofilm inhibitory activities. The 3 factors followed rank (plant material amount > water volume > NaCl percent in water), in their magnitude of effect on increasing yield of the oil. Increasing the plant material amount increased the yield of the oil by 6-folds compared to NaCl percent in water. The optimized yield of oil (4 ml) was obtained from extraction criteria (150 g of plant, 750 ml of water and 3.585% (26.85 g) of NaCl). Computational docking was performed to overcome the multi-drug resistant Gram-negative bacilli targeting undecaprenyl pyrophosphate synthase (UPPS). The optimized oil exhibited a promising inhibitory activity against Gram-negative bacteria (K. pneumonia and P. aeruginosa) with significant antibiofilm action (P < 0.05). Moreover, it exerted a synergistic effect when combined with various antibiotics (Cefoxitin, Cloxacillin, Oxacillin and Vancomycin) against MRSA clinical strains.

Novel scores relevant to antimicrobial resistance and hospital-acquired infections developed with data from a multi-hospital consortium in the Parisian region of France

Indicators for comparing and understanding differences in antimicrobial resistance (AMR) and healthcare-associated infections (HAIs) for benchmarking are essential to identify priorities for hospitals. This study measured the incidence of hospital-acquired or resistant Gram-negative bacilli bloodstream infections (GNB-BSIs) in a large public healthcare consortium in the Parisian region of France. Within each hospital, there was a strong positive correlation between the incidence of GNB-BSIs due to resistant GNB and the incidence of hospital-acquired GNB-BSIs. Two scores measuring AMR and HAI rates by combining different GNB-BSI incidence rates were developed as indicators. These scores were highly variable within the hospital consortium. On multi-variate analysis, AMR and HAI scores were significantly associated with the proportion of surgical beds, staff absenteeism and the consumption of alcohol-based hand rub, with the latter two characteristics being amenable to interventions. Carbapenem use was also linked to AMR, but this may be because carbapenems are the preferred drug for treating resistant infections. These results shed light on the incidence of HAIs and AMR in the study hospitals, and suggest possibilities for targeted interventions at healthcare facility level.

Evaluation of different methods for in vitro susceptibility testing of colistin in carbapenem resistant Gram-negative bacilli.

The increasing antibiotic resistance like the advent of carbapenem resistant Enterobactarales (CRE), Carbapenem Resistant Acinetobacter baumanii (CRAB), and Carbapenem Resistant Pseudomonas aeruginosa (CRPA) has led to to the use of toxic and older drugs like colistin for these organisms. But worldwide there is an increase in resistance even to colistin mediated both by chromosomes and plasmids. This necessitates accurate detection of resistance. This is impeded by the unavailability of a user-friendly phenotypic methods for use in routine clinical microbiology practice. The present study attempts to evaluate two different methods - colistin broth disc elution and MIC detection by Vitek two in comparison to CLSI approved broth microdilution (BMD) for colistin for Enterobactarales, Pseudomonas aeruginosa , and Acinetobacter baumanii clinical isolates. Colistin susceptibility of 6013 carbapenem resistant isolates was determined by BMD, Colistin Broth Disc Elution (CBDE), and Vitek two methods and was interpreted as per CLSI guidelines. The MIC results of CBDE, Vitek two were compared with that of BMD and essential agreement (EA), categorical agreement (CA), sensitivity, specificity, very major error (VME), major error (ME) and Cohen's kappa (CK) was calculated. The presence of any plasmid-mediated colistin resistance (mcr-1, 2, 3, 4 and 5) was evaluated in all colistin-resistant isolates by conventional polymerase chain reaction. Colistin resistance was found in 778 (12.9 %) strains among the carbapenem resistant isolates. Klebsiella pneumoniae had the highest (18.9 %) colistin resistance by the BMD method. MIC of Vitek two had sensitivity ranging from 78.2-84.8% and specificity of >92 %. There were 171 VMEs and 323 MEs by Vitek two method, much more than CLSI acceptable range. The highest percentage of errors was committed for Acinetobacter baumanii (27.8 % of VME and 7.9 % ME). On the other hand, the CBDE method performed well with EA, CA, VME and ME within acceptable range for all the organisms. The sensitivity of the CBDE method compared to gold standard BMD varied from 97.5-98.8 % for different strains with a specificity of more than 97.6 %. None of the isolated colistin resistant organisms harboured mcr plasmids. As BMD has many technical complexities, CBDE is the best viable alternative available for countries like India. A sensitive MIC reported by Vitek two needs to be carefully considered due high propensity for VMEs particularly for Klebsiella spp.

Prevalence and molecular characterization of carbapenem resistant gram-negative bacilli in a tertiary care hospital in Mumbai

Carbapenem (CR) among gram-negative bacteria is a worldwide problem. It is ranked in the highest priority category in the World Health Organization (WHO) global priority list of pathogens.It is responsible for therapeutic failure in both hospital and community-acquired infections.Identifying and monitoring the local epidemiology of the carbapenem resistant organisms, understanding specific mechanisms underlying the resistance and implementing measures to prevent their spread is the need of the hour.The aim of the study was to determine the prevalence and molecular epidemiology of Carbapenem resistant Gram negative bacilli in this hospital.: A retrospective study was carried out in the Department of Microbiology of a tertiary care Hospital in Mumbai from January to December 2022. All Gram negative bacilli from various specimens were identified and antimicrobial susceptibility was reported using the VITEK2 automated system (BioMerieux, Durham, North Carolina) and interpreted as per CLSI 2022 guidelines. The resistant genes in the isolates were detected by Xpert Carba-R assay (Cepheid, Sunnyvale, CA) on request by a consulting physician.: Out of 2,351 gram negative bacilli isolates, 624 were Carbapenem resistant (26.5%). (59.9%) was the most common CR isolate. Molecular testing was done for 190 of these 624 CR isolates. In which New Delhi Metallo beta lactamase (NDM (33.68%) was the most common resistant gene identified followed by NDM &amp; OXA-48(32.63%). With the prevalence of Carbapenem resistant isolates in the settings, adherence to infection control practices and stringent implementation of antimicrobial stewardship is crucial to curb the rate of infection.

Prevalence and pattern of multidrug resistant Gram-negative bacilli isolated from patients in the intensive care unit of a tertiary care hospital in Coastal Karnataka

Infections due to Gram negative bacilli (GNB) are the leading cause of mortality in ICU patients and are associated with higher morbidity rates, longer hospital stays and increased healthcare expenditures. Infections due to GNB in the ICU is about 2 to 5 times higher than in the general in-patient hospital population. This study aims to look at the prevalence of multi drug resistant gram-negative bacilli and proportion of ESBL producers in the MICU and to determine susceptibility patterns of GNB isolated, to various antibiotics. A total of 616 samples were collected from 396 patients admitted to the MICU during the 4-month study period. After the samples were inoculated and identified, the gram-negative isolates were subjected to Antibiotic susceptibility testing using Kirby Bauer Disc Diffusion technique with 17 different antibiotic disks. Strains showing decreased sensitivity to Ceftazidime/Cefotaxime were screened for ESBL production. Among the 616 samples tested, 149 (24.2%) samples showed growth of Gram-negative bacteria exclusively. Total number of GNB’s isolated were 173 due to some samples showing polymicrobial growth. The most common GNB found was (27.7%) which was followed by Klebsiella pneumonia at 26.0% and Acinetobacter baumannii at 18.5%. 64.2% of all GNB’s were Multi Drug Resistant which included 75% , 71.1% Klebsiella pneumoniae and 84.4% Acinetobacter baumannii. The study shows that the MDR GNB infections are on the rise in the ICU with GNBs being highly resistant to many previously effective first line antibiotics like Penicillins, newer Cephalosporins and Fluoroquinolones with susceptibility rates below 25% and even 0% for earlier generation Cephalosporins.

Oral colonization by gram-negative bacilli in patients with hematologic malignancies and solid tumors compared with healthy controls

BackgroundColonization of the oropharynx with gram-negative bacilli (GNB) is considered a negative prognostic factor in immunocompromised individuals. Hemato-oncologic patients represent a high-risk group due to their immunodeficiencies and associated treatments. This study aimed to determine the rates of oral colonization by GNB, associated factors, and clinical outcomes in patients with hematologic malignancies and solid tumors compared with healthy subjects.MethodsWe conducted a comparative study of hemato-oncologic patients and healthy subjects from August to October 2022. Swabs were taken from the oral cavity; specimens with GNB were identified and tested for antimicrobial susceptibility.ResultsWe included 206 participants (103 hemato-oncologic patients and 103 healthy subjects). Hemato-oncologic patients had higher rates of oral colonization by GNB (34% vs. 17%, P = 0.007) and GNB resistant to third-generation cephalosporins (11.6% vs. 0%, P < 0.001) compared to healthy subjects. Klebsiella spp. was the predominant genus in both groups. The factor associated with oral colonization by GNB was a Charlson index ≥ 3, while ≥ 3 dental visits per year were a protective factor. Regarding colonization by resistant GNB in oncology patients, antibiotic therapy and a Charlson index ≥ 5 were identified as associated factors, while better physical functionality (ECOG ≤ 2) was associated with less colonization. Hemato-oncologic patients colonized with GNB had more 30-day infectious complications (30.5% vs. 2.9%, P = 0.0001) than non-colonized patients.ConclusionOral colonization by GNB and resistant GNB are prevalent in cancer patients, especially those with higher scores on the severity scales. Infectious complications occurred more frequently in colonized patients. There is a knowledge gap about dental hygiene practices in hemato-oncologic patients colonized by GNB. Our results suggest that patients’ hygienic-dietary habits, especially frequent dental visits, are a protective factor against colonization.

Addition of aminoglycosides reduces recurrence of infections with multidrug-resistant Gram-negative bacilli in patients with sepsis and septic shock

Aminoglycosides and beta-lactams have been a recommended regimen in the treatment of sepsis and septic shock despite lack of mortality benefit. Previous studies have examined emergence of resistance for the same bacterial isolate using old dosing regimens and during a narrow follow up window. We hypothesized that combination regimens employing aminoglycosides will decrease the cumulative incidence of infections due to multidrug resistant (MDR) Gram-negative bacilli (GNB) compared to beta-lactams alone. All adult patients admitted to Barnes Jewish Hospital in St. Louis, MO between 2010 and 2017 with the diagnosis of sepsis or septic shock were included in this retrospective cohort study. Patients were divided into 2 treatment groups: with and without aminoglycosides. We extracted patients' demographics, severity of presentation, administered antibiotics, follow up cultures with susceptibility results for a period of 4-60 days, and mortality. After propensity score matching, a Fine-Gray sub-distribution proportional hazards model summarized the estimated incidence of subsequent infections with MDR GNB in the presence of all-cause death as a competing risk. 10212 septic patients were included with 1996 (19.5%) treated with at least 2 antimicrobials including one aminoglycoside. After propensity score matching, the cumulative incidence of MDR GNB infections between 4-60 days was lower in the combination group with an incidence of 0.073 at 60 days (95% CI [0.062, 0.085]) vs 0.116 (95% CI [0.102, 0.130]) in patients not receiving aminoglycosides. Patients younger than 65 years and with hematologic malignancies had a larger treatment effect in subgroup analyses. Addition of aminoglycosides to beta-lactams may protect against subsequent infections due to MDR GNB in patients with sepsis and septic shock.

Acquisition and carriage of genetically diverse multi-drug resistant gram-negative bacilli in hospitalised newborns in The Gambia

BackgroundThis detailed genomic study characterised multi-drug resistant-Gram negative bacilli (MDR-GNB) carriage in neonates < 2 kg and paired mothers at a low-resource African hospital.MethodsThis cross-sectional cohort study was conducted at the neonatal referral unit in The Gambia with weekly neonatal skin and peri-anal sampling and paired maternal recto-vaginal swabs. Prospective bacteriological culture used MacConkey agar with species identification by API20E and API20NE. All GNB isolates underwent whole genome sequencing on Illumina Miseq platform. Multi-Locus Sequence Typing and SNP-distance analysis identified strain type and relatedness.Results135 swabs from 34 neonates and 21 paired mothers, yielded 137 GNB isolates, of which 112 are high quality de novo assemblies. Neonatal MDR-GNB carriage prevalence is 41% (14/34) at admission with 85% (11/13) new acquisition by 7d. Multiple MDR and ESBL-GNB species are carried at different timepoints, most frequently K. pneumoniae and E. coli, with heterogeneous strain diversity and no evidence of clonality. 111 distinct antibiotic resistance genes are mostly beta lactamases (Bla-AMPH, Bla-PBP, CTX-M-15, Bla-TEM-105). 76% (16/21) and 62% (13/21) of mothers have recto-vaginal carriage of ≥1 MDR-GNB and ESBL-GNB respectively, mostly MDR-E. coli (76%, 16/21) and MDR-K. pneumoniae (24%, 5/21). Of 21 newborn-mother dyads, only one have genetically identical isolates (E. coli ST131 and K. pneumoniae ST3476).ConclusionsGambian hospitalised neonates exhibit high MDR and ESBL-GNB carriage prevalence with acquisition between birth and 7d with limited evidence supporting mother to neonate transmission. Genomic studies in similar settings are required to further understand transmission and inform targeted surveillance and infection prevention policies.

Prevalence of Carbapenem-Resistant Enterobacteriaceae and the Genes Responsible for Carbapenemase Production in a Tertiary Care Hospital in South India

Introduction: Carbapenem resistance in Gram-negative bacilli (GNB) is a major concern in the management of resistant infections. The mechanism of carbapenem resistance is most commonly mediated by carbapenemases. The five most common genes (NDM, KPC, VIM, OXA, and IMP) are responsible for carbapenemase production. Knowledge of these genes is important for the management of the disease. Objective: To estimate the prevalence of different genes responsible for carbapenemase production in GNB at a tertiary healthcare centre in South India. Method: In this retrospective study, samples were collected over 16 months. Carbapenem-resistant GNB underwent to Xpert Carba-R assay (Cepheid, Sunnyvale, California, USA) for the detection of five important genes responsible for carbapenemase production: NDM, KPC, VIM, OXA, and IMP. Results: Out of 184 carbapenem-resistant GNB, 20 samples were not included in this study. The rest of the 164 samples grew Klebsiella pneumoniae (152), Escherichia coli (10), and Enterobacter (2). OXA-48 and NDM were the most common genes responsible, with 137 (84.5%) and 95 (58.6%), respectively. Among them, 70 (43.2%) showed the presence of both genes, and 1 (0.6%) showed the presence of OXA-48, NDM, and VIM. Individually, 66 (40.7%) of OXA-48, 24 (14.8%) of NDM, and one (0.6%) of VIM. In this study, the authors did not find the presence of IMP or KPC genes. Conclusion: As a result of limited options and the higher cost of antibiotics for carbapenem-resistant infections, knowledge of these genes helps in the selection and rational use of antibiotics reduces the cost of management and will prevent mortality and morbidity from these infections.

Characterization of blaAFM-1-positive carbapenem-resistant strains isolated in Guangzhou, China

BackgroundCarbapenemase-producing makes a great contribution to carbapenem resistance in Gram-negative bacilli. BlaAFM-1 gene was first discovered by us in Alcaligenes faecalis AN70 strain isolated in Guangzhou of China and, was submitted to NCBI on 16 November 2018.MethodsAntimicrobial susceptibility testing was performed by broth microdilution assay using BD Phoenix 100. The phylogenetic tree of AFM and other B1 metallo-β-lactamases was visualized by MEGA7.0. Whole-genome sequencing technology was used to sequence carbapenem-resistant strains including the blaAFM-1 gene. Cloning and expressing of blaAFM-1 were designed to verify the function of AFM-1 to hydrolyze carbapenems and common β-lactamase substrates. Carba NP and Etest experiments were conducted to evaluate the activity of carbapenemase. Homology modeling was applied to predict the spatial structure of AFM-1. A conjugation assay was performed to test the ability of horizontal transfer of AFM-1 enzyme. The genetic context of blaAFM-1 was performed by Blast alignment.ResultsAlcaligenes faecalis strain AN70, Comamonas testosteroni strain NFYY023, Bordetella trematum strain E202, and Stenotrophomonas maltophilia strain NCTC10498 were identified as carrying the blaAFM-1 gene. All of these four strains were carbapenem-resistant strains. Phylogenetic analysis revealed that AFM-1 shares little nucleotide and amino acid identity with other class B carbapenemases (the highest identity (86%) with NDM-1 at the amino acid sequence level). The spatial structure of the AFM-1 enzyme was predicted to be αβ/βα sandwich structure, with two zinc atoms at its active site structure. Cloning and expressing of blaAFM-1 verified AFM-1 could hydrolyze carbapenems and common β-lactamase substrates. Carba NP test presented that the AFM-1 enzyme possesses carbapenemase activity. The successful transfer of pAN70-1(plasmid of AN70) to E.coli J53 suggested that the blaAFM-1 gene could be disseminated by the plasmid. The genetic context of blaAFM indicated that the downstream of the blaAFM gene was always adjacent to trpF and bleMBL. Comparative genome analysis revealed that blaAFM appeared to have been mobilized by an ISCR27-related mediated event.ConclusionsThe blaAFM-1 gene is derived from chromosome and plasmid, and the blaAFM-1 gene derived from the pAN70-1 plasmid can transfer carbapenem resistance to susceptible strains through horizontal transfer. Several blaAFM-1-positive species have been isolated from feces in Guangzhou, China.

Evolution of Antibiotic Resistance in Escherichia coli and Klebsiella pneumoniae Clinical Isolates in a Multi-Profile Hospital over 5 Years (2017-2021).

In recent years, we have witnessed a growing drug resistance among bacteria, which is associated with the use and availability of an increasing number of broad-spectrum antimicrobial agents, as well as with their irrational and excessive use. The present study aims to analyze changes in the drug resistance of Gram-negative Enterobacterales: Escherichia coli and Klebsiella pneumoniae, isolated from infections in a multi-profile hospital over five years (from 2017 to 2021). Among the practical outcomes of the evaluation of these data will be the possibility of determining changes in susceptibility to the antibiotics used in the hospital. In turn, this will help propose new therapeutic options, especially for empirical therapy that is necessary in severe infections. The analysis of the use of individual groups of antibiotics allowed for identification of the causes of the increasing resistance of Gram-negative bacilli. The highest number of infections whose etiological agent was K. pneumoniae ESBL(+) and E. coli ESBL(+) was observed in 2018. In the analyzed five-year period, the number of multi-resistant (MDR) K. pneumoniae strains increased successively, which seems to be related to the growing use, especially in the pandemic period, of broad-spectrum antibiotics, mainly penicillins with inhibitors, third-generation cephalosporins, and carbapenems.