Minimum inhibitory concentrations of Neisseria gonorrhoeae strains in clients of the Amsterdam sexual health clinic with a Dutch versus an international sexual network.

OBJECTIVES: International travel combined with sex may contribute to dissemination of antimicrobial-resistant (AMR) Neisseria gonorrhoeae (Ng). To assess the role of travel in Ng strain susceptibility, we compared minimum inhibitory concentrations (MICs) for five antibiotics (ie, azithromycin, ceftriaxone, cefotaxime, cefixime and ciprofloxacin) in strains from clients with an exclusively Dutch sexual network and clients with an additional international sexual network. METHODS: From 2013 to 2019, we recorded recent residence of sexual partners of clients (and of their partners) with Ng at the Center for Sexual Health of Amsterdam. We categorised clients as having: (1) exclusively sexual partners residing in the Netherlands ('Dutch only') or (2) at least one partner residing outside the Netherlands. We categorised the country of residence of sexual partners by World Bank/EuroVoc regions. We analysed the difference of log-transformed MIC of Ng strains between categories using linear or hurdle regression for each antibiotic. RESULTS: We included 3367 gay and bisexual men who had sex with men (GBMSM), 516 women and 525 men who exclusively had sex with women (MSW) with Ng. Compared with GBMSM with a 'Dutch only' network, GBMSM with: (1) a Western European network had higher MICs for ceftriaxone (ß=0.19, 95% CI=0.08 to 0.29), cefotaxime (ß=0.19, 95% CI=0.08 to 0.31) and cefixime (ß=0.06, 95% CI=0.001 to 0.11); (2) a Southern European network had a higher MIC for cefixime (ß=0.10, 95% CI=0.02 to 0.17); and (3) a sub-Saharan African network had a lower MIC for ciprofloxacin (ß=-1.79, 95% CI=-2.84 to -0.74). In women and MSW, higher MICs were found for ceftriaxone in clients with a Latin American and Caribbean network (ß=0.26, 95% CI=0.02 to 0.51). CONCLUSIONS: For three cephalosporin antibiotics, we found Ng strains with slightly higher MICs in clients with partner(s) from Europe or Latin America and the Caribbean. International travel might contribute to the spread of Ng with lower susceptibility. More understanding of the emergence of AMR Ng is needed.

Novel insights into the co-selection of metal-driven antibiotic resistance in bacteria: a study of arsenic and antibiotic co-exposure.

The simultaneous development of antibiotic resistance in bacteria due to metal exposure poses a significant threat to the environment and human health. This study explored how exposure to both arsenic and antibiotics affects the ability of an arsenite oxidizer, Achromobacter xylosoxidans CAW4, to transform arsenite and its antibiotic resistance patterns. The bacterium was isolated from arsenic-contaminated groundwater in the Chandpur district of Bangladesh. We determined the minimum inhibitory concentration (MIC) of arsenite, cefotaxime, and tetracycline for A. xylosoxidans CAW4, demonstrating a multidrug resistance (MDR) trait. Following this determination, we aimed to mimic an environment where A. xylosoxidans CAW4 was exposed to both arsenite and antibiotics. We enabled the strain to grow in sub-MIC concentrations of 1 mM arsenite, 40 µg/mL cefotaxime, and 20 µg/mL tetracycline. The expression dynamics of the arsenite oxidase (aioA) gene in the presence or absence of antibiotics were analyzed. The findings indicated that simultaneous exposure to arsenite and antibiotics adversely affected the bacteria's capacity to metabolize arsenic. However, when arsenite was present in antibiotics-containing media, it promoted bacterial growth. The study observed a global downregulation of the aioA gene in arsenic-antibiotic conditions, indicating the possibility of increased susceptibility through co-resistance across the entire bacterial population of the environment. This study interprets that bacterial arsenic-metabolizing ability can rescue the bacteria from antibiotic stress, further disseminating environmental cross-resistance. Therefore, the co-selection of metal-driven antibiotic resistance in bacteria highlights the need for effective measures to address this emerging threat to human health and the environment.

Efficacy of delafloxacin alone and in combination with cefotaxime against cefotaxime non-susceptible invasive isolates of Streptococcus pneumoniae.

OBJECTIVE: We assessed the in vitro activity of delafloxacin and the synergy between cefotaxime and delafloxacin among cefotaxime non-susceptible invasive isolates of Streptococcus pneumoniae (CNSSP). METHODS: A total of 30 CNSSP (cefotaxime MIC > 0.5 mg/L) were studied. Serotyping was performed by the Pneumotest-Latex and Quellung reaction. Minimum inhibitory concentrations (MICs) of delafloxacin, levofloxacin, penicillin, cefotaxime, erythromycin and vancomycin were determined by gradient diffusion strips (GDS). Synergistic activity of delafloxacin plus cefotaxime against clinical S. pneumoniae isolates was evaluated by the GDS cross method. RESULTS: Delafloxacin showed a higher pneumococcal activity than its comparator levofloxacin (MIC50, 0.004 versus 0.75 mg/L and MIC90, 0.047 versus >32 mg/L). Resistance to delafloxacin was identified in 7/30 (23.3%) isolates, belonging to serotypes 14 and 9V. Synergy between delafloxacin and cefotaxime was detected in 2 strains (serotypes 19A and 9V). Antagonism was not observed. Addition of delafloxacin increased the activity of cefotaxime in all isolates. Delafloxacin susceptibility was restored in 5/7 (71.4%) strains. CONCLUSIONS: CNSSP showed a susceptibility to delafloxacin of 76.7%. Synergistic interactions between delafloxacin and cefotaxime were observed in vitro among CNSSP by GDS cross method.

Chlorogenic acid inhibits macrophage PANoptosis induced by cefotaxime-resistant Escherichia coli.

Antibiotics are commonly used in clinical practice to treat bacterial infections. Due to the abuse of antibiotics, the emergence of drug-resistant strains, such as cefotaxime sodium-resistant Escherichia coli (CSR-EC), has aggravated the treatment of diseases caused by bacterial infections in the clinic. Therefore, discovering new drug candidates with unique mechanisms of action is imperative. Chlorogenic acid (CGA) is an active component of Yinhua Pinggan Granule, which has antioxidant and anti-inflammatory effects. We chose the CGA to explore its effects on PANoptosis in cultured macrophages infected with CSR-EC. In this study, we explored the protective impact of CGA on macrophage cell damage generated by CSR-EC infection and the potential molecular mechanistic consequences of post-infection therapy with CGA on the PANoptosis pathway. Our findings demonstrated that during CSR-EC-induced macrophage infection, CGA dramatically increased cell survival. CGA can inhibit pro-inflammatory cytokine expression of IL-1ß, IL-18, TNF-α, and IL-6. CGA decreased ROS generation and increased Nrf-2 expression at the gene and protein levels to lessen the cell damage and death brought on by CSR-EC infection. Additionally, we discovered that the proteins Caspase-3, Caspase-7, Caspase-8, Caspase-1, GSDMD, NLRP-3, RIPK-3, and MLKL were all inhibited by CGA. In summary, our research suggests that CGA is a contender for reducing lesions brought on by CSR-EC infections and that it can work in concert with antibiotics to treat CSR-EC infections clinically. However, further research on its mechanism of action is still needed.

Identification of potential inhibitor against CTX-M-3 and CTX-M-15 proteins: an in silico and in vitro study.

Extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae infection is a serious global threat. ESBLs target 3rd generation cephalosporin antibiotics, the most commonly prescribed medicine for gram-negative bacterial infections. As bacteria are prone to develop resistance against market-available ESBL inhibitors, finding a novel and effective inhibitor has become mandatory. Among ESBL, the worldwide reported two enzymes, CTX-M-15 and CTX-M-3, are selected for the present study. CTX-M-3 protein was modeled, and two thousand phyto-compounds were virtually screened against both proteins. After filtering through docking and pharmacokinetic properties, four phyto-compounds (catechin gallate, silibinin, luteolin, uvaol) were further selected for intermolecular contact analysis and molecular dynamics (MD) simulation. MD trajectory analysis results were compared, revealing that both catechin gallate and silibinin had a stabilizing effect against both proteins. Silibinin having the lowest docking score, also displayed the lowest MIC (128 µg/mL) against the bacterial strains. Silibinin was also reported to have synergistic activity with cefotaxime and proved to have bactericidal effect. Nitrocefin assay confirmed that silibinin could inhibit beta-lactamase enzyme only in living cells, unlike clavulanic acid. Thus the present study validated the CTX-M inhibitory activity of silibinin both in silico and in vitro and suggested its promotion for further studies as a potential lead. The present study adopted a protocol through the culmination of bioinformatics and microbiological analyses, which will help future researchers identify more potential leads and design new effective drugs.Communicated by Ramaswamy H. Sarma.

The effects of switching from ceftriaxone to cefotaxime on the occurrence of third-generation cephalosporin-resistant Enterobacterales: A stepped-wedge cluster randomized trial.

OBJECTIVES: To evaluate the effects of the replacement of ceftriaxone by cefotaxime on the incidence of third-generation cephalosporin-resistant Enterobacterales (3GC-RE). PATIENTS AND METHODS: We conducted a 24-month monocentric prospective, stepped-wedge cluster randomized controlled trial. During the control phase of the study, clinicians prescribed either ceftriaxone or cefotaxime. During the intervention phase, they systematically prescribed cefotaxime. RESULTS: The cefotaxime/ceftriaxone ratio was inversely correlated with the incidence of 3GC-RE. All in all, 3GC-RE incidence was 1.05 (27/25,692) acquired cases/1000 hospitalization days during the control phase and 0.54 (11/20,419) acquired cases/1000 hospitalization days during the intervention phase (incidence rate ratio [IRR] = 0.51 [0.22-1.07], p = 0.06). In multivariable analysis, intervention phase (versus control phase) (p = 0.007), cefotaxime/ceftriaxone ratio (p = 0.003) and imported 3GC-RE (p = 0.005) were associated with the incidence of acquired cases of 3GC-RE. CONCLUSIONS: We found that replacing ceftriaxone with cefotaxime reduced the occurrence of 3GC-RE isolates. More studies are needed to confirm these results.

Clostridium neonatale antimicrobial susceptibility, genetic resistance determinants, and genotyping: a multicentre spatiotemporal retrospective analysis.

BACKGROUND: Clostridium neonatale was isolated during an outbreak of neonatal necrotizing enterocolitis (NEC) in 2002. C. neonatale was validated as a new species within the genus Clostridium sensu stricto in 2018. In the present study, we evaluated the antimicrobial susceptibility, genetic determinants of resistance, and phylogenetic relationships of a collection of clinical isolates of C. neonatale. METHODS: C. neonatale strains (n = 68) were isolated from the stools of preterm neonates who either developed NEC or were asymptomatic carriers of C. neonatale in different periods and in different hospitals. Antimicrobial susceptibility was determined by the disc diffusion method. The MICs of clindamycin, cefotaxime and tetracycline were determined. Genetic determinants of resistance were screened by PCR (n = 68) and WGS (n = 35). Genotyping of the isolates was performed by MLST. RESULTS: Antimicrobial resistance was found to clindamycin (n = 24; 35%), cefotaxime (n = 7; 10%) and tetracycline (n = 1; 1%). One clindamycin-resistant isolate carried erm(B) by PCR. In addition, one isolate carrying tet(M) was tetracycline resistant (MIC = 16 mg/L) and 44 isolates carrying either tet(O), tet(32) or tet(M) were tetracycline susceptible (MICs < 16 mg/L). MLST showed that ST2 and ST15 were significantly associated with tet(32) (P < 0.0001) and tet(O) (P < 0.0001), respectively. From WGS, we identified aph(3')-IIa and blaTEM-116 genes and a blaCBP-1-like gene. CONCLUSIONS: C. neonatale is susceptible to anti-anaerobic molecules but resistant to clindamycin, cefotaxime and tetracycline. Genes encoding tetracycline ribosomal protection, macrolide-lincosamide-streptogramin B rRNA methyltransferase, aminoglycoside 3'-phosphotransferase and ß-lactamases have been identified in genomic regions flanked by mobile genetic elements.

Contribution of genetic factors towards cefotaxime and ciprofloxacin resistance development among Extended spectrum beta-lactamase producing-Quinolone resistant pathogenic Enterobacteriaceae.

ß-lactams and quinolones are widely utilised to treat pathogenic Enterobacterial isolates worldwide. Due to improper use of these antibiotics, both ESBL producing and quinolone resistant (ESBL-QR) pathogenic bacteria have emerged. Nature of contribution of beta-lactamase (bla)/quinolone resistant (QR) genes, efflux pumps (AcrAB-TolC) over-expression and outer membrane proteins (OMPs) /porin loss/reduction and their combinations towards development of this phenotype were explored in this study. Kirby-Bauer disc diffusion method was used for phenotypic characterization of these bacteria and minimum inhibitory concentration of cefotaxime and ciprofloxacin was determined by broth micro dilution assay. Presence of bla, QR, gyrA/B genes was examined by PCR; acrB upregulation by real-time quantitative PCR and porin loss/reduction by SDS-PAGE. Based on antibiogram, phenotypic categorization of 715 non-duplicate clinical isolates was: ESBL+QR+ (n = 265), ESBL+QR- (n = 6), ESBL-QR+ (n = 346) and ESBL-QR-(n = 11). Increased OmpF/K35 and OmpC/K36 reduction, acrB up-regulation, prevalence of bla, QR genes and gyrA/B mutation was observed among the groups in following order: ESBL+QR+> ESBL-QR+> ESBL+QR-> ESBL-QR-. Presence of bla gene alone or combined porin loss and efflux pump upregulation or their combination contributed most for development of a highest level of cefotaxime resistance of ESBL+QR+ isolates. Similarly, combined presence of QR genes, porin loss/reduction, efflux pump upregulation and gyrA/B mutation contributed towards highest ciprofloxacin resistance development of these isolates.

Multidrug-resistant organisms may be associated with bed allocation and utilization efficiency in healthcare institutions, based on national monitoring data from China (2014-2020).

Analyzing the influence of the bed allocation and utilization efficiency in healthcare institutions on the isolation proportion of Multidrug-resistant organisms (MDROs) to provide data to support prevention and control of MDROs. In this study, the provincial panel data from 2014 to 2020 in China on health resource indicators, including the number of beds per 1,000 population, hospital bed utilization rate, and average hospital stay from 2014 to 2020 in China were used to analyze the relationship between bed allocation or utilization efficiency and MDROs by the panel data quantile regression model. It was shown that the number of beds per 1,000 population had a negative effect on the isolation proportion of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecalis, vancomycin-resistant Enterococcus faecium, penicillin-resistant Streptococcus pneumoniae, methicillin-resistant coagulase-negative Staphylococcus, and cefotaxime or ceftriaxone resistant Escherichia coli (regression coefficient < 0, P < 0.05). The utilization rate of hospital bed had a positive effect on the isolation proportion of methicillin-resistant Staphylococcus aureus, methicillin-resistant coagulase-negative Staphylococcus, vancomycin-resistant Enterococcus faecium, penicillin-resistant Streptococcus pneumoniae, cefotaxime or ceftriaxone resistant Escherichia coli, carbapenem-resistant Escherichia coli, cefotaxime or ceftriaxone resistant Klebsiella pneumoniae, carbapenem-resistant Klebsiella pneumoniae, carbapenem-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii (regression coefficient > 0, P < 0.05). The average hospital stay had a positive effect on the isolation proportion for several antibiotic-resistant organisms, including methicillin-resistant Staphylococcus aureus, methicillin-resistant coagulase-negative Staphylococcus, vancomycin-resistant Enterococcus faecalis, vancomycin-resistant Enterococcus faecium, penicillin-resistant Streptococcus pneumoniae, cefotaxime or ceftriaxone resistant Escherichia coli, carbapenem-resistant Escherichia coli, quinolone-resistant Escherichia coli, cefotaxime or ceftriaxone resistant Klebsiella pneumoniae, carbapenem-resistant Pseudomonas aeruginosa, and carbapenem-resistant Acinetobacter baumannii (regression coefficient > 0, P < 0.05). Bed allocation and utilization efficiency in healthcare institutions may affect the isolation proportion of MDROs in varying degrees.

[Investigation of Virulence Factors, Phylogenetic Group Features, and the Presence of ST131 Clone in Escherichia coli Isolates, a Urinary Tract Infection Agent in Children]. / Çocuklarda Üriner Sistem Enfeksiyonu Etkeni Olan Escherichia coli Izolatlarinda Virülans Faktörleri, Filogenetik Grup Özellikleri ve ST131 Klonu Varliginin Arastirilmasi.

Urinary tract infection (UTI) caused by Escherichia coli is a significant health issue in children. Today especially E.coli O25b/ST131, defined as a pandemic clone, is a serious public health problem due to its high virulence and antimicrobial resistance rates. In this study, a total of 200 (100 first and 100 recurrent UTI-causing) E.coli isolates from urine samples sent to the Ankara University School of Medicine Cebeci Training and Research Hospital Central Laboratory between January and September 2021 with the preliminary diagnosis of UTI in pediatric patients aged three to 18 years were analyzed for antimicrobial resistance rates, phylogenetic group distributions, virulence factor frequencies and whether they belong to the O25b/ST131 clone. It is aimed in this study that, the obtained data will shed light on new studies for diagnosis, treatment and prophylaxis options that can be developed for more effective UTI management by contributing to the surveillance studies in our country. Antimicrobial susceptibility of E.coli isolates identified by conventional methods was evaluated by Kirby-Bauer disc diffusion method and extended spectrum beta-lactamase (ESBL) production was evaluated by double disc synergy test. Polymerase chain reaction (PCR) was used for the investigation of phylogenetic grouping, the O25b/ST131 clone, virulence genes and the molecular level classification of the isolates detected as uropathogenic E.coli (UPEC). Pulsed-field gel electrophoresis (PFGE) was performed with the isolates collected at different times from the same patient. The highest antimicrobial resistance rates observed were against ampicillin (n= 100, 50%), cefazolin (n= 99, 49.5%), trimethoprim-sulfamethoxazole (n= 55, 27.5%), amoxicillin-clavulanic acid (n= 43, 21.5%) and cefotaxime (n= 43, 21.5%). In recurrent UTI agents, resistance rates were higher for cefotaxime (n= 29, 29%), trimethoprim-sulfamethoxazole (n= 35, 35%) and cefepime (n= 25, 25%) and in O25b/ST131 isolates (n= 67) the rates were higher for amikacin (n= 3, 4.5%), gentamicin (n= 10, 14.9%) and ciprofloxacin (n= 17, 25.4%) when compared to the first UTI agents and non-O25b/ ST131 isolates (p< 0.05). It was found that 29% (n = 58) of the isolates were multidrug resistant (MDR) and 19% (n = 38) produced ESBL.The rate of recurrent UTI agents was found to be higher among ESBL producing isolates and/or MDR isolates (n= 36, 62% and n= 27, 71%, respectively, p< 0.05). It was found that 45.5% (n= 91) of the isolates were in D, 37.5% (n= 75) in B2, 12.5% (n= 25) in A, and 4.5% (n= 9) in B1 phylogenetic groups and isolates belonging to B2 and D phylogenetic groups had higher antibiotic resistance rates and carried more virulence genes (p< 0.05). Of the isolates, 33.5% (n= 67) were found to belong to the O25b/ST131 clone, no significant difference was found between the O25b/ST131 rates among the first and recurrent UTI agents (p> 0.05). It was determined that the isolates most frequently carry virulence genes for adhesion [fimH 97% (n= 194), papA 57% (n= 114), yfcV 49.5% (n= 99)] and iron uptake systems [fyuA 85.5% (n= 171), chuA 78% (n= 156), iutA 73% (n= 146)]. All virulence factors were detected more frequently in isolates belonging to the O25b/ST131 clone (p< 0.05). Of the isolates, 97% (n= 65) belonging to the O25b/ST131 clone and 27.1% (n= 36) not belonging to this clone were defined as UPEC with molecular analysis (p< 0.0001). Thirty-three isolates belonging to 15 patients were evaluated with PFGE, and it was observed that the latter isolate and the first isolate of eight patients (53%) had the same band profile. Focusing on surveillance, diagnostic testing, treatment algorithms, and preventive measures for E.coli and especially for ST131 clone, which is frequently observed as causative agent in childhood UTIs, will help to manage challenging E.coli infections.

Carbapenem-resistant Escherichia coli in Black-headed gulls, the Danube, and human clinical samples: A One Health comparison of contemporary isolates.

OBJECTIVES: Our aim was to characterize and compare contemporary carbapenem-resistant Enterobacterales (CRE) isolates from gulls, the River Danube, and humans in Hungary, Budapest. METHODS: Multiresistant Enterobacterales were sought for in 227 gull faecal and 24 Danube water samples from 2019 to 2020. Eosin-methylene blue agar containing 2 mg/L cefotaxime and Colilert-test containing 10 mg/L cefotaxime were used for gull and water samples, respectively. Isolates were characterized by polymerase chain reactions (PCRs); acquired carbapenemase producers were further analysed by whole-genome sequencing, together with 21 Hungarian human CR Escherichia coli (CREc) isolates. RESULTS: Gull and water samples exhibited a CRE prevalence of 7.4% (9/122) and 6.7% (7/105), none and 5/12 water samples yielded CRE from 2019 and 2020, respectively; CRE were found only in samples taken downstream of Budapest. The dominant species was Escherichia coli and the most prevalent carbapenemase was blaNDM-1. High-risk CREc clones were found both in gulls (ST224, ST372, ST744) and the Danube (ST10, ST354, ST410); the closest associations were between ST410 from humans and the Danube, among ST1437 among gulls, and between ST1437 in gulls and the Danube (46, 0, and 22-24 allelic distances, respectively). Direct links between human and gull isolates were not demonstrated. CONCLUSION: The study demonstrates potential epidemiological links among humans, a river crossing a city, and urbanised birds, suggesting a local transmission network. Water bodies receiving influent wastewater, together with animals using such habitats, may serve as a local reservoir system for CRE, highlighting the importance of One Health in CRE transmission, even in a country with a low CRE prevalence in humans.

Antibacterial activity of Lagerstreomia speciosa and its active compound, corosolic acid, enhances cefotaxime inhibitory activity against Staphylococcus aureus.

AIMS: Various epidemiology studies have reported the emergence of Staphylococcus aureus and its methicillin resistance strain causing global health concerns, especially during and post-COVID-19 pandemic. This pathogen presents as a co-infection in patients with COVID-19. In addition, certain virulence factors and resistance to ß-lactam antibiotics, including cefotaxime, have been identified. We aimed to investigate the antibacterial activity of Lagerstreomia speciosa, a medicinal plant with antidiabetic activity, against S. aureus, including the strain resistant to methicillin. Furthermore, we examined whether the extract and one of its bioactive compounds, corosolic acid, can enhance the therapeutic effect of cefotaxime on antibiotic-resistant S. aureus. METHODS AND RESULTS: The minimum inhibitory concentration of each substance was determined using the standard broth microdilution test following the checkerboard dilution. The type of interactions, synergistic, additivity, indifference, or antagonism, were determined using isobolograms analysis and the dose reduction index (DRI). The evaluation of synergy and bactericidal activity of the natural products in combination with cefotaxime was performed using the time-kill kinetic assay. Corosolic acid, L. speciosa leaves extract, and bark extract alone showed antibacterial activity against all tested S. aureus ATCC 33591, S. aureus ATCC 29213, S. aureus ATCC 25923, and clinical isolated S. aureus. Corosolic acid enhanced the antibacterial activity of cefotaxime, showing a synergistic effect and greater DRI of cefotaxime against all tested S. aureus strains. Time-kill kinetic assay showed that corosolic acid has a more profound effect than L. speciosa extracts to potentiate the bactericidal activity of cefotaxime. Whereas L. speciosa leaves and bark extract showed some inhibitory effect on the growth of S. aureus after a single administration. CONCLUSIONS: Lagerstreomia speciosa leaves and bark extract and its active compound, corosolic acid, could be used as a potential anti-Staphylococcus aureus treatment to enhance the therapeutic use of cefotaxime.

Cefotaxime in Enteric Fever: Therapeutic Reappraisal.

Enteric fever is one of the most common infectious diseases in the economically developing world and this bacterial infection is the common most cause of fever in travelers to these endemic areas. Even after the availability and deployment of preventive measures like vaccination against Salmonella typhi (S. typhi) and sanitation practices; effective treatment is paramount to reduce the associated morbidity and mortality. Cephalosporins are antimicrobials belonging to the ß-lactam class with established efficacy, pharmacokinetic, and safety profile by virtue of which, they belong to the group of antibiotics most commonly utilized in clinical practice. They have a broadspectrum of activity against various gram-positive and gram-negative bacteria. Like penicillin, they belong to the ß-lactam class of drugs. Amid such a scenario of rising antimicrobial resistance, a broad-spectrum antibiotic like cefotaxime is a real bliss. Distinctive properties of cefotaxime like broad-spectrum of activity, bactericidal action, stability against the common resistance-causing mechanisms, and good safety profile make it a reliable choice in the therapy landscape of enteric fever. It delivers desired efficacy in such difficult-to-treat scenarios at a manageable tolerability profile. Cefotaxime and ceftriaxone have a comparable spectrum of antimicrobial activity, but both differ in terms of pharmacokinetics. Considering the published literature, cefotaxime seems to be a dependable option for the management of typhoid owing to its effectiveness against S. typhi bundled with an acceptable tolerability profile.

Therapeutic Switching of Rafoxanide: a New Approach To Fighting Drug-Resistant Bacteria and Fungi.

Control and management of life-threatening bacterial and fungal infections are a global health challenge. Despite advances in antimicrobial therapies, treatment failures for resistant bacterial and fungal infections continue to increase. We aimed to repurpose the anthelmintic drug rafoxanide for use with existing therapeutic drugs to increase the possibility of better managing infection and decrease treatment failures. For this purpose, we evaluated the antibacterial and antifungal potential of rafoxanide. Notably, 70% (70/100) of bacterial isolates showed multidrug resistance (MDR) patterns, with higher prevalence among human isolates (73.5% [50/68]) than animal ones (62.5% [20/32]). Moreover, 22 fungal isolates (88%) were MDR and were more prevalent among animal (88.9%) than human (87.5%) sources. We observed alarming MDR patterns among bacterial isolates, i.e., Klebsiella pneumoniae (75% [30/40; 8 animal and 22 human]) and Escherichia coli (66% [40/60; 12 animal and 28 human]), and fungal isolates, i.e., Candida albicans (86.7% [13/15; 4 animal and 9 human]) and Aspergillus fumigatus (90% [9/10; 4 animal and 5 human]), that were resistant to at least one agent in three or more different antimicrobial classes. Rafoxanide had antibacterial and antifungal activities, with minimal inhibitory concentration (MICs) ranging from 2 to 128 µg/mL. Rafoxanide at sub-MICs downregulated the mRNA expression of resistance genes, including E. coli and K. pneumoniae blaCTX-M-1, blaTEM-1, blaSHV, MOX, and DHA, C. albicans ERG11, and A. fumigatus cyp51A. We noted the improvement in the activity of ß-lactam and antifungal drugs upon combination with rafoxanide. This was apparent in the reduction in the MICs of cefotaxime and fluconazole when these drugs were combined with sub-MIC levels of rafoxanide. There was obvious synergism between rafoxanide and cefotaxime against all E. coli and K. pneumoniae isolates (fractional inhibitory concentration index [FICI] values ≤ 0.5). Accordingly, there was a shift in the patterns of resistance of 16.7% of E. coli and 22.5% of K. pneumoniae isolates to cefotaxime and those of 63.2% of C. albicans and A. fumigatus isolates to fluconazole when the isolates were treated with sub-MICs of rafoxanide. These results were confirmed by in silico and mouse protection assays. Based on the in silico study, one possible explanation for how rafoxanide reduced bacterial resistance is through its inhibitory effects on bacterial and fungal histidine kinase enzymes. In short, rafoxanide exhibited promising results in overcoming bacterial and fungal drug resistance. IMPORTANCE The drug repurposing strategy is an alternative approach to reducing drug development timelines with low cost, especially during outbreaks of disease caused by drug-resistant pathogens. Rafoxanide can disrupt the abilities of bacterial and fungal cells to adapt to stress conditions. The coadministration of antibiotics with rafoxanide can prevent the failure of treatment of both resistant bacteria and fungi, as the resistant pathogens could be made sensitive upon treatment with rafoxanide. From our findings, we anticipate that pharmaceutical companies will be able to utilize new combinations against resistant pathogens.

Antibiotic Resistance of Hemophilus influenzae Isolated from Children in Southwest China.

BACKGROUND: Hemophilus influenzae (Hi) is one of the major pediatric bacterial pneumonia pathogens that heavily threatens children's lives and global health. With widespread usage as first-line treatment, the prevalence of ß-lactam-resistant strains is increasing sharply. In order to treat Hi more effectively, a systematic study on the antibiotic resistance profiles, ß-lactamase-negative ampicillin-resistant (BLNAR) strains isolation rate, and potential BLNAR resistance mechanism in our region is needed. METHODS: This study analyzed antimicrobial susceptibility of Hi, and clinical data of Hi-infected patients retrospectively. BLNAR and ß-lactamase-positive ampicillin-clavulanate resistant strains (BLPACR) were confirmed by the Kirby-Bauer method and ß-lactamase test. ftsI gene in BLNAR was sequenced to find out whether resistance was induced by penicillin-binding protein mutation. Ampicillin susceptibility test with or without efflux pump inhibitors were done to assess efflux pump contribution in BLNAR. RT-PCR was performed to evaluate the efflux pump genes' transcription levels. RESULTS: A total of 2,561 Hi strains were isolated in our hospital from January 2016 to December 2019. Male to female ratio was 1.52:1. Median age was 10 months. Infant (< 3 years old) infection accounted for 83.72%. Hi resistance rates to sulfamethoxazole-trimethoprim, ampicillin, cefathiamidine, cefaclor, cefuroxime, cephalothin, amoxicillin-clavulanate, tetracycline, chloramphenicol, ofloxacin, cefotaxime, and rifampin were 84.28%, 78.01%, 49.80%, 41.98%, 36.58%, 33.64%, 4.55%, 4.1%, 3.37%, 1.77%, 0.99%, and 0.12%, respectively, while 1.33% were BLNAR. BLNARs were classified into four groups by mutation patterns in ftsI gene and most strains were divided to Group Ⅲ/Ⅲ-like. EmrB, ydeA and norM transcription levels in some ampicillin-resistant strains were higher than their sensitive counterparts. CONCLUSIONS: Ampicillin is not sufficiently effective as a first-line Hi infection treatment. However, ampicillin-clavulanate and cefotaxime may be a better choice. Efflux pumps, emrB, ydeA and norM play roles in the high resistance to ampicillin.

Microplastics accumulate priority antibiotic-resistant pathogens: Evidence from the riverine plastisphere.

Microplastics (MPs) might accumulate and transport antibiotic-resistant bacteria (ARB) in aquatic systems. We determined the abundance and diversity of culturable ciprofloxacin- and cefotaxime-resistant bacteria in biofilms covering MPs placed in river water, and characterized priority pathogens from these biofilms. Our results showed that the abundance of ARB colonizing MPs tends to be higher compared to sand particles. Also, higher numbers were cultivated from a mixture of polypropylene (PP), polyethylene (PE) and polyethylene terephthalate (PET), compared to PP and PET alone. Aeromonas and Pseudomonas isolates were the most frequently retrieved from MPs placed before a WWTP discharge while Enterobacteriaceae dominated the culturable plastisphere 200 m after the WWTP discharge. Ciprofloxacin- and/or cefotaxime-resistant Enterobacteriaceae (n = 54 unique isolates) were identified as Escherichia coli (n = 37), Klebsiella pneumoniae (n = 3), Citrobacter spp. (n = 9), Enterobacter spp. (n = 4) and Shigella sp. (n = 1). All isolates presented at least one of the virulence features tested (i.e. biofilm formation, haemolytic activity and production of siderophores), 70% carried the intI1 gene and 85% exhibited a multi-drug resistance phenotype. Plasmid-mediated quinolone resistance genes were detected in ciprofloxacin-resistant Enterobacteriaceae [aacA4-cr (40% of the isolates), qnrS (30%), qnrB (25%), and qnrVC (8%)], along with mutations in gyrA (70%) and parC (72%). Cefotaxime-resistant strains (n = 23) harbored blaCTX-M (70%), blaTEM (61%) and blaSHV (39%). Among CTX-M producers, high-risk clones of E. coli (e.g. ST10 or ST131) and K. pneumoniae (ST17) were identified, most of which carrying blaCTX-M-15. Ten out of 16 CTX-M producers were able to transfer blaCTX-M to a recipient strain. Our results demonstrated the occurrence of multidrug resistant Enterobacteriaceae in the riverine plastisphere, harboring ARGs of clinical concern and exhibiting virulence traits, suggesting a contribution of MPs to the dissemination of antibiotic-resistant priority pathogens. The type of MPs and especially water contamination (e.g. by WWTPs discharges) seem to determine the resistome of the riverine plastisphere.

Synergistic effect of Ru(II)-based type II photodynamic therapy with cefotaxime on clinical isolates of ESBL-producing Klebsiella pneumoniae.

Multidrug-resistant bacteria, such as ESBL producing-Klebsiella pneumoniae, have increased substantially, encouraging the development of complementary therapies such as photodynamic inactivation (PDI). PDI uses photosensitizer (PS) compounds that kill bacteria using light to produce reactive oxygen species. We test Ru-based PS to inhibit K. pneumoniae and advance in the characterization of the mode of action. The PDI activity of PSRu-L2, and PSRu-L3, was determined by serial micro dilutions exposing K. pneumoniae to 0.612 J/cm 2 of light dose. PS interaction with cefotaxime was determined on a collection of 118 clinical isolates of K. pneumoniae. To characterize the mode of action of PDI, the bacterial response to oxidative stress was measured by RT-qPCR. Also, the cytotoxicity on mammalian cells was assessed by trypan blue exclusion. Over clinical isolates, the compounds are bactericidal, at doses of 8 µg/mL PSRu-L2 and 4 µg/mL PSRu-L3, inhibit bacterial growth by 3 log10 (>99.9%) with a lethality of 30 min. A remarkable synergistic effect of the PSRu-L2 and PSRu-L3 compounds with cefotaxime increased the bactericidal effect in a subpopulation of 66 ESBL-clinical isolates to > 6 log10 with an FIC-value of 0.16 and 0.17, respectively. The bacterial transcription response suggests that the mode of action occurs through Type II oxidative stress. The upregulation of the extracytoplasmic virulence factors mrkD, magA, and rmpA accompanied this response. Also, the compounds show little or no toxicity in vitro on HEp-2 and HEK293T cells. Through the type II effect, PSs compounds are bactericidal, synergistic on K. pneumoniae, and have low cytotoxicity in mammals.

Cefotaxime/sulbactam plus gentamicin as a potential carbapenem- and amikacin-sparing first-line combination for neonatal sepsis in high ESBL prevalence settings.

BACKGROUND: Infection with ESBL-producing Enterobacteriaceae infection is ubiquitous in some neonatal ICUs and increasing levels of antibiotic resistance are a cause for urgent concern. Delineation of bacterial and viral sepsis can be challenging, often leading to patients receiving empirical antibiotics without or whilst waiting for a definitive causal diagnosis. Empirical therapy is often dependent on broad-spectrum 'Watch' antibiotics, contributing to further resistance. METHODS: ESBL-producing Enterobacteriaceae clinical isolates found to have caused neonatal sepsis and meningitis underwent a detailed in vitro screening including susceptibility testing, chequerboard combination analysis and hollow-fibre infection model dynamic analyses using combinations of cefotaxime, ampicillin and gentamicin in combination with ß-lactamase inhibitors. RESULTS: Additivity or synergy was found for all antibiotic combinations against seven Escherichia coli and three Klebsiella pneumoniae clinical isolates. Cefotaxime or ampicillin plus sulbactam combined with gentamicin was able to consistently inhibit the growth of ESBL-producing isolates at typical neonatal doses, and the combination cleared the hollow-fibre infection model system of organisms resistant to each agent alone. The combination of cefotaxime/sulbactam and gentamicin was consistently bactericidal at clinically achievable concentrations (Cmax of 180, 60 and 20 mg/L for cefotaxime, sulbactam and gentamicin, respectively). CONCLUSIONS: The addition of sulbactam to cefotaxime or ampicillin to the typical first-line empirical therapy could obviate the need for carbapenems and amikacin in settings with high ESBL-infection prevalence.

Antibiotic susceptibility of Escherichia coli isolated from neonates admitted to neonatal intensive care units across China from 2015 to 2020.

Background: Escherichia coli is one of the most common pathogens causing neonatal infections. Recently, the incidence and drug resistance of E. coli have increased, posing a major threat to neonatal health. The aim of this study was to describe and analyze the antibiotic resistance and multilocus sequence typing (MLST) characteristics of E. coli derived from infants admitted to neonatal intensive care units (NICUs) across China. Methods: In this study, 370 strains of E. coli from neonates were collected. E. coli isolated from these specimens were subjected to antimicrobial susceptibility testing (by broth microdilution method) and MLST. Results: The overall resistance rate was 82.68%, with the highest rate of methicillin/sulfamethoxazole (55.68%) followed by cefotaxime (46.22%). Multiple resistance rate was 36.74%, 132 strains (35.68%) had extended-spectrum ß-lactamase (ESBL) phenotype and 5 strains (1.35%) had insensitivity to the tested carbapenem antibiotics. The resistance of E. coli isolated from different pathogenicity and different sites of infections varied, strains derived from sputum were significantly more resistant to ß-lactams and tetracyclines. Currently, the prevalence spectrum in NICUs was dominated by ST1193, ST95, ST73, ST69 and ST131 across China. And the multidrug resistance of ST410 was the most severe. ST410 had the highest resistance rate to cefotaxime (86.67%), and its most common multidrug resistance pattern was ß-lactams + aminoglycosides + quinolones + tetracyclines + sulfonamides. Conclusions: Substantial proportions of neonatal E. coli isolates were severely resistant to commonly administered antibiotics. MLST results can suggest the prevalent characteristics of antibiotic resistance in E. coli with different ST types.

Synergistic Antibacterial Effect of Phage pB3074 in Combination with Antibiotics Targeting Cell Wall against Multidrug-Resistant Acinetobacter baumannii In Vitro and Ex Vivo.

Synergistic effects of phages in combination with antibiotics have received increasing attention. In this present study, we isolated a new phage pB3074 against clinically isolated multidrug-resistant Acinetobacter baumannii. Phage pB3074 combined with cell wall-targeting antibiotics could produce synergistic antibacterial effect in vitro bactericidal activities. Further research indicates that the bacteriophage dose is critical to synergistic antimicrobial effect of phage and antibiotic combination. Cefotaxime and meropenem were selected as the representative cell wall-targeting antibiotics for further synergistic antibacterial study. Results illustrated that phage pB3074 and cefotaxime or meropenem combination was very effective for the removal of mature biofilm and inhibition of biofilm formation. In a pig skin explant model, results also showed that phage pB3074 and cefotaxime or meropenem combination was very effective for the treatment of wound infection ex vivo. Subsequent studies showed that some extent recovery of drug sensitivity to cell wall-targeting antibiotics might be vital mechanism of synergistic antibacterial effect between bacteriophage pB3074 and these antibiotics. The existence of antibiotics could promote phage adsorption and proliferation, which might also be potential mechanism for synergistic antibacterial activities and have been observed in cefotaxime and meropenem application. In summary, results in the current study demonstrated that phage pB3074 has the potential to be developed as an antibacterial agent and combined application of phages and antibiotics might be a new choice for the treatment of current multidrug-resistant bacterial infections. IMPORTANCE Combined application of phages and antibiotics cannot only effectively inhibit the appearance of phage-resistant bacteria, but also reduce the effective use concentration of antibiotics, and even make some bacteria regain sensitivity to some resistant antibiotics. Therefore, phage-antibiotic combination (PAC) could improve the antibacterial activity of individual drug, providing a new choice for clinical treatment of multidrug-resistant bacterial infections.