In vitro susceptibility to fosfomycin in clinical and environmental extended-spectrum beta-lactamase producing and/or ciprofloxacin-non-susceptible Escherichia coli isolates

ABSTRACT Extended-spectrum beta-lactamase producing and ciprofloxacin-non-susceptible Escherichia coli are clinical and environmental issues. We evaluated the susceptibility profile of fosfomycin in non-susceptible E. coli isolated from urine and the environment. We measured the activity of fosfomycin against 319 and 36 E. coli strains from urine and environmental isolates, respectively, collected from rivers. Fosfomycin resistance profiles were investigated using the minimal inhibitory concentration (MIC), according to the Clinical and Laboratory Standards Institute (CLSI) and the European Committee for Antimicrobial Susceptibility Testing (EUCAST) guidelines. Antibiotic susceptibility testing revealed that 5% and 6.6% of urine samples were non-susceptible to fosfomycin according to CLSI and EUCAST guidelines, respectively. The fosfomycin MIC50/90 was 0.5/4 mg/L. Of the 36 E. coli isolates from river water, 11.1% and 13,8% were non-susceptible to fosfomycin according to CLSI and EUCAST, respectively (range ≤0.25 ≥512 mg/L). All the isolates with MIC ≥512 mg/L for fosfomycin showed the fosA3 gene. Fosfomycin resistance was more frequent in the environment than in clinical samples.

Novel antibacterial drug target against Gram-negative bacteria: lipopolysaccharide transport protein LptDE and its inhibitors / 药学学报

The outer membrane composed predominantly of lipopolysaccharide (LPS) is an essential biological barrier for most Gram-negative (G-) bacteria. Lipopolysaccharide transport protein (Lpt) complex LptDE is responsible for the critical final stage of LPS transport and outer membrane assembly. The structure and function of LptDE are highly conserved in most G- bacteria but absent in mammalian cells, and thus LptDE complex is regarded as an attractive antibacterial target. In recent 10 years, the deciphering of the three-dimensional structure of LptDE protein facilities the drug discovery based on such "non-enzyme" proteins. Murepavadin, a peptidomimetic compound, was reported to be the first compound able to target LptD, enlightening a new class of antibacterial molecules with novel mechanisms of action. This article is devoted to summarize the molecular characteristics, structure-function of LptDE protein complex and review the development of murepavadin and related peptidomimetic compounds, in order to provide references for relevant researches.

Evaluación de la formación de biopelículas en aislamientos bacterianos y fúngicos por el método semicuantitativo de microtitulación con cristal violeta y el cualitativo de agar con rojo Congo / Assessment of biofilms formation of bacterial and fungal isolates using qualitative Congo red agar and semiquantitative crystal violet microtiter methods

Introducción. El 65 % de las infecciones humanas son producidas por bacterias o levaduras, cuya capacidad de formar biopelículas las hace más resistentes a los antimicrobianos y antifúngicos. Objetivo. Determinar la capacidad de formación de biopelículas en aislamientos bacterianos y fúngicos por medio de los métodos cuantitativo de microtitulación con cristal violeta y cualitativo de cultivo en agar con rojo Congo. Materiales y métodos. Con el método cuantitativo, se utilizaron los medios de cultivo infusión cerebro-corazón, tripticasa de soya y Müeller-Hinton para aislamientos bacterianos; para levaduras, se usaron caldo infusión cerebro-corazón y Sabouraud dextrosa. Para el método cualitativo de cultivo en agar, se utilizaron los mismos medios de cultivo más una solución con 3 % de rojo Congo y 10 % de dextrosa. Cómo método de referencia, se utilizó la propuesta de Stepanovic et al. Resultados. Se evaluaron 103 aislamientos bacterianos y 108 de levaduras. No es recomendable sustituir el caldo infusión cerebro-corazón por los caldos tripticasa de soya y Müeller-Hinton en el método cuantitativo, para evaluar la formación de biopelículas en los aislamientos bacterianos. El medio Sabouraud dextrosa, en caldo y agar, puede sustituir al de infusión de cerebro-corazón para evaluar la formación de biopelículas en levaduras, tanto por el método cuantitativo como por el cualitativo. Conclusión. El estudio de las biopelículas en el laboratorio de microbiología, a partir del método cualitativo de cultivo en agar con rojo Congo, es un procedimiento sencillo, rápido y de bajo costo, que proporciona información útil para el diagnóstico y la terapéutica de infecciones persistentes causadas por bacterias y levaduras.

Introduction. Sixty-five percent of human infections are caused by bacteria or yeasts able to form biofilms. This feature makes them more resistant to antimicrobials and antifungals. Objective. To determine biofilm formation capacity of bacterial and fungal isolates by quantitative crystal violet microtiter and qualitative Congo red agar methods. Materials and methods. Brain-heart infusion, trypticase soy broth and Müeller-Hinton culture media were used in bacterial isolates for the quantitative method; brain-heart infusion broth and Sabouraud dextrose were used for yeasts. The same culture media plus 3% Congo red and 10% dextrose were used to apply the qualitative method in agar. The proposal by Stepanovic, et al. was used as a reference method. Results. We evaluated 103 bacterial isolates and 108 yeasts isolates. We did not recommend substitute brain-heart infusion broth for trypticase soy and Müeller-Hinton broths for biofilm formation assessment in bacterial isolates using the quantitative method. Sabouraud dextrose medium, both broth and agar, can replace brain-heart infusion to assess biofilm formation in yeasts, quantitatively and qualitatively. Conclusion. The study of biofilms in the microbiology laboratory, using Congo red agar qualitative method, is a simple, fast, and inexpensive procedure that provides precise information for the diagnosis and treatment of persistent infections caused by bacteria and yeasts.

Frecuencia de Bacilos Gram Negativos en la cavidad bucal de estudiantes de una Universidad de Asunción

Introducción: La cavidad bucal hospeda una gran cantidad de microorganismos, como los bacilos Gram negativos, y entre ellas, bacterias de gran importancia médica debido a su capacidad de producir enfermedades graves para el ser humano, especialmente en pacientes inmunodeprimidos. El objetivo de este trabajo fue determinar la presencia de Bacilos Gram Negativos y sus patrones de resistencia a antibióticos, en una población estudiantil de la ciudad de Asunción, en los años 2019 y 2020. Materiales y métodos: Se realizó un estudio observacional, descriptivo de corte transversal, donde se realizaron hisopados de la cavidad bucal a 35 alumnos de entre 18 a 24 años, de una universidad privada en la ciudad de Asunción. Se requirió consentimiento informado firmado por los participantes y fueron excluidos quienes tuvieron tratamientos antibióticos. Las muestras fueron obtenidas con un hisopo de algodón, posteriormente se colocaron en un medio de transporte para luego ser cultivadas en Agar MacConkey. El cultivo se realizó por 48 horas a 37° centígrados, luego se procedió a la identificación bacteriana. Por último, se realizó el antibiograma. Resultados: De los 35 alumnos se encontró una frecuencia de 48,57% de bacilos Gram negativos. Cepas de Klebsiella pneumoniae fueron las más frecuentes (35,29%). Se observó que las bacterias eran altamente resistentes a la Amoxicilina/Ácido Clavulánico. Conclusiones: La presencia de estos tipos de microorganismos puede ser peligrosa para la salud general de las personas, específicamente de los pacientes con algún tipo de inmunodepresión, debido a la gran la resistencia a antibióticos presentadas por algunas cepas.

Introduction: The oral cavity hosts a large number of microorganisms, such as Gram negative bacilli, and among them, bacteria of great medical importance due to their capacity to cause serious diseases for humans, especially in immunosuppressed patients. The objective of this work was to determine the presence of Gram Negative Bacilli and their patterns of resistance to antibiotics, in a student population of the city of Asunción, in the years 2019 and 2020. Materials and methods: An observational, descriptive cross-sectional study was carried out, where oral cavity swabs were made from 35 students between 18 and 24 years of age, from a private university in the city of Asunción. Informed consent signed by the participants was required and those who had antibiotic treatments were excluded. The samples were obtained with a cotton swab, later they were placed in a transport medium to later be cultured in MacConkey Agar. The culture was carried out for 48 hours at 37° Celsius, then the bacterial identification was carried out. Finally, the antibiogram was performed. Results: Of the 35 students, a frequency of 48,57% of Gram negative bacilli was found. Klebsiella pneumoniae strains were the most frequent (35.29%). The bacteria were found to be highly resistant to Amoxicillin/Clavulanic Acid. Conclusions: The presence of these types of microorganisms can be dangerous for the general health of people, specifically of patients with some type of immunosuppression, due to the great resistance to antibiotics presented by some strains.

Identificación y sensibilidad antibiótica directas desde el hemocultivo positivo para bacilos gram negativos. Rendimiento comparativo de los sistemas Vitek 2C y Phoenix / Direct identification and susceptibility testing from positive blood cultures. A head-to-head performance comparison between Vitek 2C and Phoenix systems / Identificação e sensibilidade antibiótica diretas a partir da hemocultura positiva para bacilos gram negativos. Desempenho comparativo dos sistemas Vitek 2C e Phoenix

Resumen El objetivo de este estudio fue comparar los resultados de las pruebas de identificación y sensibilidad antimicrobiana obtenidos por los sistemas Vitek 2C (bioMérieux, Francia) y Phoenix (Becton Dickinson, EE.UU.) directamente a partir de hemocultivos positivos. Se realizó un estudio observacional prospectivo en el Hospital Naval Pedro Mallo de Buenos Aires, Argentina, que incluyó 70 bacteriemias monomicrobianas por gram negativos. Se obtuvo una identificación correcta por Vitek® 2C y por Phoenix del 100% y 97% respectivamente [p: no significativa (NS)]. La concordancia categórica para todos los antimicrobianos fue 97,1% y 98,1% (p: NS) con Vitek 2C y con Phoenix respectivamente. El tiempo medio para obtener un resultado fue de 10,19 h y 13,8 h (p: NS), respectivamente. Vitek 2C y Phoenix son herramientas importantes, rápidas y confiables para la identificación y las pruebas de sensibilidad realizadas directamente a partir de hemocultivos positivos.

Abstract The aim of this study was to compare the results of identification and antimicrobial susceptibility tests obtained by the Vitek 2C (bioMérieux, France) and Phoenix (Becton Dickinson, USA) systems directly from positive blood cultures. A prospective observational study was performed at the Pedro Mallo Navy Hospital in Buenos Aires, Argentina, which included 70 monomicrobial bacteremias by gram negative rods. Correct identification by Vitek® 2C and Phoenix was 100% and 97%, respectively [p: not significant (NS)]. Categorical agreement for all antimicrobials was 97.1% and 98.1% (p: NS) with Vitek 2C and Phoenix, respectively. The mean time to result was 10.19 h and 13.8 h (p: NS), respectively. Vitek 2C and Phoenix are important, rapid and reliable tools for identification and susceptibility testing when performed directly from positive blood cultures.

Resumo O objetivo deste estudo foi comparar os resultados dos testes de identificação e de suscetibilidade antimicrobiana obtidos pelos sistemas Vitek 2C (bioMérieux, França) e Phoenix (Becton Dickinson, EUA) diretamente a partir de culturas de sangue positivas. Foi realizado um estudo observacional prospectivo no Hospital Naval Pedro Mallo em Buenos Aires, Argentina, incluindo 70 bacteriemias monomicrobianas devido a gram negativos. A identificação correcta por Vitek® 2C e Phoenix obtida foi de 100% e 97% respectivamente [p: não significativo (NS)]. O acordo categórico para todos os antimicrobianos foi de 97,1% e 98,1% (p: NS) com Vitek 2C e Phoenix respectivamente. O tempo médio para obter o resultado foi de 10,19 h e 13,8 h (p: NS), respectivamente. Vitek 2C e Phoenix são ferramentas importantes, rápidas e fiáveis para a identificação e testes de sensibilidade realizados diretamente a partir de hemoculturas positivas.

Phytochemical Screening and Antibacterial Activity of Chrysophyllum albidum Collected in Nsukka, South East Nigeria

Background: Chrysophyllum albidum is widely used by African people for the treatment of various types of diseases such as ear infection, sore throat, typhoid, cellulites, septicaemia, bactericemia, abscesses and tooth infections. Aim: The study was conducted to investigate the chemical components and antibacterial activity of the extract and fractions from the root bark of Chrysophyllum albidum from Nsukka, South-east Nigeria. Methodology: The fresh roots were collected, washed, cut into small pieces, air dried and pulverized to powder using mechanical grinder. Extraction and fractionation were done by cold maceration method and technique of liquid–liquid extraction respectively. The phytochemical analysis of the methanol extract and, n-hexane, butanol, aqueous and ethylacetate fractions of the plant part was carried out using standard method. The antibacterial activities were determined using cup-plate agar diffusion and agar dilution methods. Results: The phytochemical screening of the extract revealed the presence of tannins, flavonoids, saponins, terpenoids, alkaloids, reducing sugar and cardiac glycosides. The inhibition zone diameter (IZD) produced by the agents against some selected Gram positive bacteria (GPB) and Gram negative bacteria (GNB) pathogens ranged from 6 – 25 mm and 6 – 12 mm respectively. The MIC and MBC values produced by the extract and fractions of the plant’s part against the GPB ranged from 1.25 – 40 mg/ml and 5 – 80 mg/ml respectively Many of the GNB were not sensitive to the agents tested except Pseudomonas aeruginosa and Klebsiella spp that exhibited mild to moderate sensitivity to the agents. Conclusion: These agents, therefore, exhibited a potent antibacterial activity against all the GPB and a few GNB pathogens tested due to their potent phytochemicals. The results of this work have corroborated the trado-medical use of root of Chrysophyllum albidum for treating ear infection, sore throat, typhoid, cellulites, septicaemia, bactericemia, boils and tooth infection/decay.

Comamonas Testosteroni Emerging Gastrointestinal Pathogen

Comamonas testosteroni newly emerging microorganism previously known as Pseudomonas testosteroni is common environmental bacterium that is not known to be a part of the human commensal organism. Since its identification as a human pathogen in 1987, numerous reports have drizzled in, implicating this organism for various infections. Comamonas testosteroni are rare isolates in microbiology laboratories and have been infrequently reported as an infectious agent in routine clinical practice. Comamonas testosteroni has been rarely observed as an infectious agent in clinical practice. Comamonas testosteroni is rarely recognized as a human pathogen. Most of the reported cases are bloodstream infections. We report this pathogen from the stool of an immunocompromised 48-year-old male. The aim of this case report is to alert clinicians and laboratory physicians for the potential diagnosis and clinical approach of gastrointestinal infections caused by this organism.

A cross-sectional study to estimate the serum level of C-reactive protein among pediatric meningitis with bacterial etiology

Background: Bacterial meningitis is a global public health issue. C-reactive protein (CRP) has suitable diagnostic value in distinguishing between bacterial and aseptic meningitis especially in cases of negative bacterial culture of the blood and spinal fluid. Aim and Objective: The objective of this study was to estimate the serum level of CRP among pediatric meningitis cases with bacterial etiology. Materials and Methods: The hospital-based descriptive cross-sectional study was performed in a tertiary care pediatric hospital in Eastern India from June to August, 2021 with 150 samples. Patients fulfilling the inclusion criteria were selected for this study after obtaining informed consent. Cerebrospinal fluid sample was collected as per standard guidelines. Phenotypic identification of bacteria including antimicrobial susceptibility testing was done by automation (Vitek 2 compact, bioMerieux). Quantitative estimation of CRP was performed in a solid phase and sandwich-format immunometric assay using a gold antibody conjugate. Human rights, welfare, and autonomy were protected as per national ethical guidelines. Results: Median age (Inter Quartile Range) of 150 cases was 3(1–4.5) year. Escherichia coli (60.52%, 23/38) was the commonest isolate (P < 0.00000001 by Binomial test calculation) followed by Klebsiella pneumoniae (34.24%, i.e., 13/38). A total of 43/150 (28.66%) participants had higher serum CRP. Serum CRP was raised more in Gram-negative bacterial etiology (36 out of 38, 94.73%). Mean serum CRP was higher in Gram-negative cases (P < 0.05). Conclusion: Serum CRP was found significantly higher in meningitis caused by Gram-negative bacteria.

Clinicobacteriological profile and antibiotic susceptibility pattern of chronic dacryocystitis in adults

Background: Chronic dacryocystitis is a constant menace to delicate ocular structures. If left untreated, it can lead to sight as well as life-threatening complications. However, such complications may be prevented by timely intervention along with appropriate antibiotic prophylaxis. The objectives are to investigate the current bacterial community profile in adult patients with chronic dacryocystitis attending a referral eye care center in Odisha and to determine their drug susceptibility pattern to commonly used antimicrobial agents. Materials and Methods: An observational study was conducted on 70 adult patients with chronic dacryocystitis. The discharge from the punctum was collected by doing a regurgitation test or lacrimal passage irrigation and sent for microbiological analysis. Results: Out of 70 samples collected, 54 (77.1%) samples showed bacterial growth after 24–48 h of incubation. Among various isolates recovered, 68.5% were gram-positive and 27.8% were gram-negative organisms. Staphylococcus aureus was found to be the most common isolate among gram-positive, and Pseudomonas aeruginosa was most common among gram-negative organisms. Among all drugs used in the susceptibility test; amikacin, piperacilin + tazobactam, and netilmycin were found to be most sensitive and cefixime, and amoxycilin + clavulinic acid was found to be most resistant to gram-positive as well as for gram-negative organisms. Conclusion: Knowledge about the microbiological profile and the drug susceptibility pattern responsible for chronic dacryocystitis in a geographical area is important and should be kept in mind while treating these patients.

Evaluation of in-vitro susceptibility of ß-lactam-resistant Gram-negative bacilli to ceftazidime-avibactam and ceftolozane-tazobactam from clinical samples of a general hospital in southern Brazil

ABSTRACT Background: The spread of carbapenemase- and extended-spectrum β-lactamase (ESBL)-producing gram-negative bacilli (GNB) represent a global public health threat that limits therapeutic options for hospitalized patients. This study aimed to evaluate the in-vitro susceptibility of β-lactam-resistant GNB to ceftazidime-avibactam (C/A) and ceftolozane-tazobactam (C/T), and investigate the molecular determinants of resistance. Methods: Overall, 101 clinical isolates of Enterobacterales and Pseudomonas aeruginosa collected from a general hospital in Brazil were analyzed. Susceptibility to the antimicrobial agents was evaluated using an automated method, and the minimum inhibitory concentrations (MIC50/90) of C/A and C/T were determined using Etest®. The β-lactamase-encoding genes were investigated using polymerase chain reaction. Results: High susceptibility to C/A and C/T was observed among ESBL-producing Enterobacterales (100% and 97.3% for CLSI and 83.8% for BRCAST, respectively) and carbapenem-resistant P. aeruginosa (92.3% and 87.2%, respectively). Carbapenemase-producing Klebsiella pneumoniae exhibited high resistance to C/T (80%- CLSI or 100%- BRCAST) but high susceptibility to C/A (93.4%). All carbapenem-resistant K. pneumoniae isolates were susceptible to C/A, whereas only one isolate was susceptible to C/T. Both antimicrobials were inactive against metallo-β-lactamase-producing K. pneumoniae isolates. Resistance genes were concomitantly identified in 44 (44.9%) isolates, with bla CTX-M and bla SHV being the most common. Conclusions: C/A and C/T were active against microorganisms with β-lactam-resistant phenotypes, except when resistance was mediated by metallo-β-lactamases. Most C/A- and C/T-resistant isolates concomitantly carried two or more β-lactamase-encoding genes (62.5% and 77.4%, respectively).

Prevalence of bloodstream infection pathogens in hemato-oncological patients and predictors of carbapenem-resistant gram-negative bacterial infections during febrile neutropenia

ABSTRACT Background: Carbapenem-Resistant Gram-Negative (CRGN) Bloodstream Infections (BSI) represent a therapeutic challenge, especially in the context of Febrile Neutropenia (FN) in cancer patients. Methods: We characterized pathogens causing BSI in patients aged ≥18 years who had undergone systemic chemotherapy for solid or hematological cancers between 2012 and 2021 in Porto Alegre, Brazil. Predictors of CRGN were evaluated through a case-control analysis. Each case was matched to two controls from whom CRGN were not isolated and had the same sex and year of inclusion in the study. Results: From 6094 blood cultures evaluated, 1512 (24.8%) showed positive results. Gram-negative bacteria accounted for 537 (35.5%) of the isolated bacteria, of which 93 (17.3%) were carbapenem-resistant. From 105 patients included in the case-control analysis, all cases had baseline hematological malignancies (60% acute myeloid leukemia). Variables related to CRGN BSI in Cox regression analysis were the first chemotherapy session (p<0.01), chemotherapy performed in the hospital setting (p = 0.03), intensive care unit admission (p<0.01), and CRGN isolation in the previous year (p<0.01). Patients with CRGN BSI received 75% less empirical active antibiotics and had 27.2% higher 30-day mortality rates than controls. Conclusions: A CRGN risk-guided approach should be considered for empirical antibiotic therapy in patients with FN.

Efficacy and safefy of Polymyxin B treatment for neutropenic patients suffering from refractory Gram-negative bacterial bloodstream infection / 中华血液学杂志

Objective: To assess the efficacy and safety of polymyxin B in neutropenic patients with hematologic disorders who had refractory gram-negative bacterial bloodstream infection. Methods: From August 2021 to July 2022, we retrospectively analyzed neutropenic patients with refractory gram-negative bacterial bloodstream infection who were treated with polymyxin B in the Department of Hematology of the First Affiliated Hospital of the Soochow University between August 2021 to July 2022. The cumulative response rate was then computed. Results: The study included 27 neutropenic patients with refractory gram-negative bacterial bloodstream infections. Polymyxin B therapy was effective in 22 of 27 patients. The median time between the onset of fever and the delivery of polymyxin B was 3 days [interquartile range (IQR) : 2-5]. The median duration of polymyxin B treatment was 7 days (IQR: 5-11). Polymyxin B therapy had a median antipyretic time of 37 h (IQR: 32-70). The incidence of acute renal dysfunction was 14.8% (four out of 27 cases), all classified as "injury" according to RIFLE criteria. The incidence of hyperpigmentation was 59.3%. Conclusion: Polymyxin B is a viable treatment option for granulocytopenia patients with refractory gram-negative bacterial bloodstream infections.

Clinical Analysis of Colistin Sulfate in the Treatment of Hematonosis Infected by Multidrug-Resistant Gram-Negative Bacteria / 中国实验血液学杂志

OBJECTIVE@#To investigate the efficacy and safety of colistin sulfate in the treatment of hematonosis patients infected by multidrug-resistant (MDR) gram-negative bacteria (GNB), and discuss the possible factors that affect the efficacy of colistin sulfate.@*METHODS@#The clinical data of 85 hematologic patients infected with MDR GNB in the Soochow Hopes Hematonosis Hospital from April 2022 to November 2022 were collected and divided into clinically effective group with 71 cases and ineffective group with 14 cases according to the therapeutic efficacy of colistin sulfate. The age, gender, type of hematologic disease, status of hematopoietic stem cell transplantation, infection sites, type of pathogen, timing of administration, daily dose and duration of colistin sulfate, and combination with other antibacterial agents of patients in two groups were compared. Logistic regression was used to analyze on the meaningful variables to study the influencing factors of colistin sulfate. The adverse reactions of colistin sulfate were also evaluated.@*RESULTS@#There were no significant differences in age, gender, type of hematologic disease, hematopoietic stem cell transplantation status, infection sites and pathogen type between the effective group and the ineffective group (P>0.05). Compared with the medication time more than 7 days, meropenem used within 7 days in the clinical effective group, and timely replacement with colistin sulfate could obtain better efficacy, the difference was statistically significant (P=0.018). The duration of tigacycline before colistin sulfate did not affect the efficacy, and there was no significant difference in efficacy between the effective and ineffective groups. The therapeutic effect of colistin sulfate at daily dose of 500 000 U q8h was better than that of 500 000 U q12h, the difference was statistically significant (P=0.035). The time of colistin sulfate use in the clinically effective group was longer than that in the ineffective group, which had a statistical difference (P=0.003). Compared with the clinical ineffective group, the efficacy of combination regimens with colistin sulfate was better than that of colistin sulfate monotherapy, and the difference was statistically significant (P=0.013). Multivariate logistic regression analysis was performed on the indicators with statistical differences in the two groups of patients, which suggested that the use time of colistin sulfate (B: 2.358; OR: 10.573; CI: 1.567-71.361; P=0.015) and the combination of colistin sulfate (B: 1.720; OR: 5.586; CI: 1.210-25.787; P=0.028) were influential factors in the efficacy of colistin sulfate. During the treatment, the incidence of nephrotoxicity, hepatotoxicity and peripheral neurotoxicity were 5.9%, 1.2% and 1.2%, respectively.@*CONCLUSION@#The use of colistin sulfate improves the clinical efficacy of MDR GNB infections in hematological patients, and the timing of colistin sulfate administration and the combination of drugs are independent factors affecting its clinical efficacy, and the safety during treatment is high.

Evolution and development of potent monobactam sulfonate candidate IMBZ18g as a dual inhibitor against MDR Gram-negative bacteria producing ESBLs

A series of new monobactam sulfonates is continuously synthesized and evaluated for their antimicrobial efficacies against Gram-negative bacteria. Compound 33a (IMBZ18G) is highly effective in vitro and in vivo against clinically intractable multi-drug-resistant (MDR) Gram-negative strains, with a highly druglike nature. The checkerboard assay reveals its significant synergistic effect with β-lactamase inhibitor avibactam, and the MIC values against MDR enterobacteria were reduced up to 4-512 folds. X-ray co-crystal and chemoproteomic assays indicate that the anti-MDR bacteria effect of 33a results from the dual inhibition of the common PBP3 and some class A and C β-lactamases. Accordingly, preclinical studies of 33a alone and 33a‒avibactam combination as potential innovative candidates are actively going on, in the treatment of β-lactamase-producing MDR Gram-negative bacterial infections.

BRICS report of 2021: The distribution and antimicrobial resistance profile of clinical bacterial isolates from blood stream infections in China / 中华临床感染病杂志

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical bacterial isolates from bloodstream infections in China in 2021.Methods:The clinical bacterial strains isolated from blood culture from member hospitals of Blood Bacterial Resistant Investigation Collaborative System (BRICS) were collected during January 2021 to December 2021. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical Laboratory Standards Institute (CLSI). WHONET 5.6 was used to analyze data.Results:During the study period, 11 013 bacterial strains were collected from 51 hospitals, of which 2 782 (25.3%) were Gram-positive bacteria and 8 231 (74.7%) were Gram-negative bacteria. The top 10 bacterial species were Escherichia coli (37.6%), Klebsiella pneumoniae (18.9%), Staphylococcus aureus (9.8%), coagulase-negative Staphylococci (6.3%), Pseudomonas aeruginosa (3.6%), Enterococcus faecium (3.6%), Acinetobacter baumannii (2.8%), Enterococcus faecalis (2.7%), Enterobacter cloacae (2.5%) and Klebsiella spp (2.1%). The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococcus aureus were 25.3% and 76.8%, respectively. No glycopeptide- and daptomycin-resistant Staphylococci was detected; more than 95.0% of Staphylococcus aureus were sensitive to ceftobiprole. No vancomycin-resistant Enterococci strains were detected. The rates of extended spectrum B-lactamase (ESBL)-producing isolated in Escherichia coli, Klebsiella pneumoniae and Proteus mirabilis were 49.6%, 25.5% and 39.0%, respectively. The prevalence rates of carbapenem-resistance in Escherichia coli and Klebsiella pneumoniae were 2.2% and 15.8%, respectively; 7.9% of carbapenem-resistant Klebsiella pneumoniae was resistant to ceftazidime/avibactam combination. Ceftobiprole demonstrated excellent activity against non-ESBL-producing Escherichia coli and Klebsiella pneumoniae. Aztreonam/avibactam was highly active against carbapenem-resistant Escherichia coli and Klebsiella pneumoniae. The prevalence rate of carbapenem-resistance in Acinetobacter baumannii was 60.0%, while polymyxin and tigecycline showed good activity against Acinetobacter baumannii (5.5% and 4.5%). The prevalence of carbapenem-resistance in Pseudomonas aeruginosa was 18.9%. Conclusions:The BRICS surveillance results in 2021 shows that the main pathogens of blood stream infection in China are gram-negative bacteria, in which Escherichia coli is the most common. The MRSA incidence shows a further decreasing trend in China and the overall prevalence of vancomycin-resistant Enterococci is low. The prevalence of Carbapenem-resistant Klebsiella pneumoniae is still on a high level, but the trend is downwards.

Distribution and drug resistance of pathogenic bacteria of biliary tract infection in patients subjected to hepatobiliary surgery / 中国基层医药

Objective:To study the distribution and drug resistance of pathogenic bacteria of biliary tract infection in patients with hepatobiliary surgery.Methods:A total of 103 patients with biliary tract infection who received treatment in the Department of Hepatobiliary Surgery, Lanxi People's Hospital from May 2020 to October 2022 were included in this study. Their bile was cultured to analyze the distribution and drug resistance of pathogenic bacteria. The data were processed using the WHONET5.5 software system.Results:Fifty-eight pathogenic bacteria-positive samples were cultured from the bile of 103 patients with biliary tract infection, with a pathogenic bacteria-positive rate of 56.31%. Among 58 strains of pathogenic bacteria, 38 strains (65.52%) were gram-negative bacteria, mainly Escherichia coli and Klebsiella pneumonia, and 5 strains (8.62%) were fungal strains. Escherichia coli and Klebsiella pneumoniae were highly resistant to sulfamethoxazole-trimethoprim, ciprofloxacin, and other antibacterial drugs, and were completely sensitive to imipenem and meropenem. Enterococcus faecalis was mainly resistant to ampicillin and penicillin G,and it was completely sensitive to vancomycin and teicoplanin. Staphylococcus aureus was resistant to vancomycin, ciprofloxacin, cefotaxime, and other drugs. A total of 13 strains of ultrabroad-spectrum beta-lactamase bacteria were isolated from 25 strains of Escherichia coli and 7 strains of Klebsiella pneumonia, with the positive detection rate of 40.63%. Conclusion:The main pathogenic bacteria of biliary tract infection are Gram-negative bacteria, which are widely distributed and have serious drug resistance. In clinical practice, antimicrobial drugs should be reasonably selected according to the results of bile drug sensitivity tests.

Real-world study of ceftazidime-avibactam in the treatment of multidrug-resistant gram-negative bacterial infections / 中国临床药理学与治疗学

AIM: To describe and evaluate the clinical characteristics, treatment management and clinical outcomes of ceftazidime-avibactam (CZA) in the treatment of patients with multidrug-resistant gram-negative bacterial (MDR-GNB) infections. METHODS: A retrospective cohort study was performed on patients hospitalized in the Affiliated Hospital of Xuzhou Medical University from September 2019 to December 2021. Adult patients who received CZA for ≥ 72 hours consecutively were eligible for inclusion. The primary outcome was clinical failure, defined as a composite of 30-day all-cause mortality, microbiological failure and / or failure to resolve or improve signs and symptoms of infection during treatment with CZA. RESULTS: A total of 198 patients with MDR-GNB infections were described and evaluated, including 132 in the carbapenem-resistant Enterobatceriaceae (CRE) cohort and 66 in the Pseudomonas spp. cohort. The main infection sites were lung infection (92.42%), abdominal infection (10.61%), and intracranial infection (10.61%), among which 63 patients (31.82%) were positive for blood culture. Clinical failure, 30-day all-cause mortality and microbiological failure occurred in 61 (30.81%), 33(16.67%) and 11(5.56%) patients, respectively. Body mass index (BMI), acute physiology and chronic health evaluation scoring system (APACHE Ⅱ) and polymicrobial infections were positively associated with clinical outcome failureadjusted OR 1.109, 95%CI 1.017, 1.209; adjusted OR 1.071, 95%CI 1.015, 1.129; adjusted OR 2.844, 95%CI 1.391, 5.814, however, initiation of CZA within 48 hours of admission was protective (adjusted OR 0.424, 95%CI 0.205, 0.879). A total of 15 patients had adverse reactions possibly related to CZA, including 2 cases of rash, 6 cases of nausea and vomiting, and 7 cases of antibiotic-related diarrhea. CONCLUSION: CZA can be used to treat infections caused by a range of MDR-GNB, including Pseudomonas spp. and CRE.

Evaluation of tegacycline regimens in treatment of gram-negative bacterial infections with Monte Carlo simulation / 中国临床药理学与治疗学

AIM: To evaluate the dose regimens of tegacycline for treatment of hospital-acquired pneumonia, complex abdominal infection and complex skin and soft tissue infection caused by Gram-negative bacterial infections with Monte Carlo model. METHODS: The minimum inhibitory concentrations (MICs) of tegacycline against Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae were collected from the CHINET in 2018. The target probability (PTA) and cumulative response fraction (CFR) of different regimens were calculated using Monte Carlo simulation based on PK/PD theory of tegacycline. RESULTS:In the treatments of HAP caused by gram-negative bacteria, when MIC≤0.5 μg / mL, the PTA of 50 mg q12h was greater than 90%, and when MIC≥1 μg / mL, PTA and CFR of 100 mg q12h were both greater than 90%, When MIC≥2 μg/mL, 50 mg q12h, 75 mg q12h and 100 mg q12h doses of PTA were less than 90%. In the treatment of cIAI, when MIC≤0.5 μg / mL, PTA of 50 mg q12h reached the target value, and when MIC=1 μg/mL, PTA of 100 mg q12h was greater than 90%. For complex skin and soft tissue infection, when the MIC≤0.25 μg/mL, the PTA of 75 mg q12h and 100 mg q12h was greater than 90%, and the PTA of the three administration regimen was less than 90%, when the MIC≥0.5 μg/mL. CONCLUSION:The dose of 50 mg q12h is more suitable for the treatment of HAP, when MIC>0.5 μg/mL, tigecycline may need 100 mg q12h to obtain the best clinical efficacy in the treatment of cIAI. For cSSSI. when MIC≤0.25 μg/mL, tigecycline can be administered with 75 mg q12h and 100 mg q12h. For the three types of infections caused by Escherichia coli, the conventional dose of tigecycline may achieve clinical efficacy.

Distribution and drug resistance characteristics of pathogens in recipients undergoing simultaneous pancreas-kidney transplantation / 器官移植

Objective To investigate the distribution and drug resistance characteristics of pathogens in donors and recipients undergoing simultaneous pancreas-kidney transplantation (SPK). Methods Clinical data of 231 pairs of donors and recipients undergoing SPK were analyzed retrospectively. The pathogens of samples from donors and recipients were identified by VITEK-2 analyzer, and drug sensitivity test was performed by K-B method. The source distribution and composition ratio of pathogens in donor and recipient samples, distribution characteristics of multi-drug resistant organism, infection of recipients and drug resistance characteristics of pathogens were analyzed. Results A total of 395 strains of pathogens were cultured from 1 294 donor samples, and the detection rate was 30.53%. Gram-negative bacteria mainly consisted of klebsiella pneumoniae, Gram-positive bacteria mainly comprised staphylococcus aureus, and fungi primarily included candida albicans, respectively. In total, 2 690 strains of pathogens were cultured from 10 507 recipient samples, and the detection rate was 25.60%. Gram-negative bacteria mainly consisted of pseudomonas maltophilia, Gram-positive bacteria primarily comprised enterococcus faecalis, and fungi mainly included candida albicans, respectively. Among 395 pathogens of donors, 15 strains of methicillin-resistant staphylococcus aureus (MRSA), 16 strains of extended-spectrum β-lactamase (ESBL) positive drug-resistant bacteria, 8 strains of carbapenem-resistant pseudomonas aeruginosa (CR-PA), 21 strains of carbapenem-resistant acinetobacter baumannii (CR-AB), 2 strains of carbapenem-resistant enterobacteriaceae (CRE) and 1 strain of multiple-drug/pan-drug resistant pseudomonas aeruginosa (MDR/PDR-PA) were identified. Among 2 690 strains of recipient pathogens, 73 strains of ESBL positive drug-resistant bacteria, 44 strains of CR-PA, 31 strains of CR-AB and 3 strains of MDR/PDR-PA were detected. One recipient developed donor-derived infection, 69 cases of pneumonia, 52 cases of urinary tract infection, 35 cases of abdominal infection and 2 cases of hematogenous infection were reported within postoperative 1 year. Gram-negative bacteria were resistant to certain antibiotics. Gram-positive bacteria were sensitive to vancomycin. Fungi were sensitive to amphotericin B. Conclusions Gram-negative bacteria are the main pathogens of SPK recipients, which are resistant to certain antibiotics. Empirical use of antibiotics can be delivered before culture results are obtained. Subsequently, sensitive antibiotics should be chosen according to the culture results to improve the survival rate of SPK recipients.

Causative Microorganisms Isolated from Patients with Intra-Abdominal Infections and Their Drug Resistance Profiles: An 11-Year (2011-2021) Single-Center Retrospective Study / 生物医学与环境科学（英文）

OBJECTIVE@#To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections (IAIs).@*METHODS@#A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021. Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the VITEK 2 compact system and the Kirby-Bauer method. AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute.@*RESULTS@#Of the 2,926 strains identified, 49.2%, 40.8%, and 9.5% were gram-negative bacteria, gram-positive bacteria, and fungi, respectively. Escherichia coli was the most prevalent pathogen in intensive care unit (ICU) and non-ICU patients; however, a significant decrease was observed in the isolation of E. coli between 2011 and 2021. Specifically, significant decreases were observed between 2011 and 2021 in the levels of extended-spectrum β-lactamase (ESBL)-producing E. coli (from 76.9% to 14.3%) and Klebsiella pneumoniae (from 45.8% to 4.8%). Polymicrobial infections, particularly those involving co-infection with gram-positive and gram-negative bacteria, were commonly observed in IAI patients. Moreover, Candida albicans was more commonly isolated from hospital-associated IAI samples, while Staphylococcus epidermidis had a higher ratio in community-associated IAIs. Additionally, AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers, while the overall resistance rates (56.9%-76.8%) of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria. Indeed, Enterococcus faecium, Enterococcus faecalis, S. epidermidis, and S. aureus were consistently found to be susceptible to vancomycin, teicoplanin, and linezolid. Similarly, C. albicans exhibited high susceptibility to all the tested antifungal drugs.@*CONCLUSION@#The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAIs were altered between 2011 and 2021. This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections.