Extensive Drug Resistance Research Articles

Comparison of genotypic features between two groups of antibiotic resistant Klebsiella pneumoniae clinical isolates obtained before and after the COVID-19 pandemic from Egypt

Klebsiella pneumoniae is a common pathogen capable of causing a wide range of infections. Antibiotic resistance complicates treatment of these infections significantly. We are comparing resistance levels and genotypes among two collections of K. pneumoniae clinical isolates from Alexandria Main University Hospital (AMUH). We used disc diffusion and Minimum Inhibitory Concentration (MIC) by microbroth dilution to assess resistance levels and performed whole genome sequencing (WGS) to describe multilocus sequence types (MLST) and resistance gene presence. Among a collection of 56 K. pneumoniae clinical isolates (19 from 2019 to 37 from 2021), multidrug resistance (MDR) was 33% and 10%, extended drug resistance (XDR) was 24% and 46% and pan-drug resistance (PDR) was 43% and 43%, respectively. We identified 15 MLST STs including two novel types (ST-6118 and ST-6119 ). ST-101 and ST-383 were common between the two collections; ST-101 was the most common genotype in 2019 (28.6%) and ST-147 was most common in 2021 (25%). Ampicillin/sulbactam, amikacin, cefepime, ceftriaxone and ertapenem MICs were significantly higher in 2021. Prevalence of aph(3’) – Ia, aph(3’)-VI, mphA was significantly higher in 2021. The increasing resistance levels and the persistence of some MDR/XDR genotypes is concerning. Understanding mechanisms of resistance will inform infection control and antimicrobial stewardship plans to prevent evolution and spread of XDR and PDR strains.

Resistance patterns, virulence determinants, and biofilm genes of multidrug-resistant Pseudomonas aeruginosa isolated from fish and fish handlers

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic bacterium that is widely distributed in aquatic environments and causes major economic losses in fish and public health hazards.This study aimed to identify the occurrence of P. aeruginosa in samples collected from fish and fish handlers, and to investigate the antimicrobial susceptibility, virulence determinants, and biofilm genes of P. aeruginosa isolates. A total of 276 samples were cross-sectionally collected from Nile tilapia (53), Golden grey mullet (52), Mediterranean horse mackerel (50), Striped red mullet (71), and fish handlers (50) at five different retail fish markets in Damietta Governorate, Egypt. Pseudomonas species (spp.) were biochemically identified in 57.9% of the total examined samples. Peudomonas aeruginosa were the most prevalent species isolated from the fish and human samples via PCR technique. Peudomonas aeruginosa isolates exhibited full resistance (100%) to tobramycin (TOB), gentamicin (CN), and colistin (CL), with a high level of susceptibility (88.5%) to imipenem (IPM) using the disk diffusion method. Most P. aeruginosa isolates (84.6%) exhibited drug resistance, with 61.5% were multidrug resistance (MDR) and 23.1% were extensive drug resistance (XDR). Most isolates had at least four virulence-associated genes (lasB, toxA, exoU, and oprL) and three biofilm genes (psIA, peIA, and lasR) by using uniplex PCR. The lasI, and rhlR Quorum Sensing (QS) genes were identified in 84.6% and 61.5% in the examined P. aeruginosa isolates, respectively. The highest mortality rate in Nile tilapia experimentally infected with P. aeruginosa isolate encoding most of virulent genes. Multivariate analyses revealed high heterogeneity among the examined isolates. This study revealed the emergence of virulent and drug resistant P. aeruginosa isolates in fish, poses high risks to consumers and food. Thus, strict hygienic measures should be considered when catching, handling, and storing fish, in addition to the routine application of antimicrobial susceptibility testing.

Effectiveness of new antituberculosis drugs in the treatment of children and adolescents with chemoresistant tuberculosis

BACKGROUND. There is a significant decrease the effectiveness of antituberculous (anti-TB) treatment on the background of multidrug and extensive drug resistance (MDR/XDR) of Mycobacterium tuberculosis. Therefore, in order to increase the effectiveness of treatment MDR-/XDR-TB a new antimycobacterial drugs such as bedaquiline (Bdq), delamanid (Dlm) and pretomanid have been introduced both for adults, children and adolescents in recent years. MATERIALS AND METHODS. On the basis of a retrospective cohort analysis of the data of patients' medical records the evaluation of the clinical effectiveness of chemotherapy with Bdq and Dlm was carried out. The main group: 40 children and adolescents with MDR-/XDR-TB of lungs, who received complex antimycobacterial therapy (AMBT) with Bdq and Dlm. The control group consisted of 27 patients who received complex AMBT without Bdq and Dlm. Age range – from 3 to 18 years. RESULTS AND DISCUSSION. On the background of AMBT during the first 3 months of treatment was established stopping bacterial secretion among all patients of main and control groups. However, in control group compare to main one stopping bacterial secretion was significant slowly (p<0.05). At the stage of completion of the intensive phase of AMBT, the normalization of immunological indicators occurred in 29.6±2.8 % of control group and in 43.4±4.5 % of main one. A significant difference between the groups among the immunoregulatory index CD3+CD4+/CD3+CD8+, IgM and circulating immune complexes was obtained. Among children and adolescents of the main group positive dynamic of immunological changes were observed 1.5 times more often. Among all patients of main group the resolution of the infiltration, consolidation of the focus and the absence of decay cavities were ascertained at the end of the anti-TB course. Anti-TB treatment with the formation of small residual changes into lung tissue ended in 77.5 % patients of main group. In 12.5 % cases of control group destructions persisted and bacterial excretion resumed. A large residual changes such as multiple dense foci, fibrosis and residual decay cavities in control group were observed 2.3 times more often (51.9 % vs 22.5 %), p<0.05, than in main one. Using Bdq and Dlm among children and adolescents with MDR-/XDR-TB significantly increased efficiency of complex treatment. Among main group (72.5 %) compare to control (33.3 %) one the results of treatment to be considered “cured” were 2.2 times more likely and 1.5 times less often – “completed” (27.5 % vs 51.8 % respectively). The success rate of treatment among children and adolescents who received Bdq and Dlm was 100.0 % and among patients without these new drugs – 85.2 %. CONCLUSIONS. The criteria used show that AMBT combined with Bdq and Dlm is 1.5-2.2 times more effective (according to a separate criterion) than AMBT without these drugs.

Antibiotic susceptibility of uropathogens: a 3-year retrospective study at Ho Teaching Hospital of Ghana

BackgroundUrinary tract infection (UTI) remains one of the most treated infections in primary healthcare over the last two decades. The infection is treated with antibiotics. However, there have been reported cases of increasing antibiotic resistance globally, limiting the available antibiotics for the treatment of the infection. The study aimed to determine the frequency of bacterial urinary tract infections and their antibiotic resistance pattern in Ho Teaching Hospital of Ghana from 2019–2021.MethodologyData on urine culture and susceptibility testing and patient demographics from 2019–2021 were collected from the microbiology unit archives with a designed Microsoft Excel 2019 form and later exported to IBM SPSS (v26) for statistical analysis on the uropathogens and their antibiotic resistance pattern. P-value < 0.05 was considered statistically significant.ResultsOut of 4806 records, 1005 bacterial isolates were found, with a total prevalence of 20.91%. The most prevalent group of organisms was the Enterobacteriaceae, with E. coli 409 (40.70%) being the most frequent isolate. Of the 772 isolates subjected to amikacin, 48(6.22%) and 6(0.78%) of the Gram-negative and Gram-positive bacterial organisms showed resistance to the antibiotic respectively. 58.96% (148/251) and 3.59% (9/251) of Gram-negatives and Gram-positives were resistant to cotrimoxazole. Out of the 1005 bacterial isolates, 165(16.42%), 161(16.02%) and 2(0.20%) showed multidrug resistance (MDR), extensively-drug resistance (XDR), and pandrug resistance (PDR) respectively.ConclusionThere was a high antibiotic-resistant pattern among the uropathogens reported in this current study, hence, the Standard Treatment Guidelines may need to be updated to reflect the high rates of antibiotic resistance exhibited by most prevalent isolates.

Prediction of structure of mycobacterial efflux pump protein Rv0194 and molecular dynamics simulation of the predicted structures

Tuberculosis is a major cause of morbidity and mortality primarily in developing nations. The rising number of cases of multidrug resistance and extensive drug resistance are a critical concern for the management of the condition. Even though new antibiotics are being developed, eventually there are also strains that are resistant to them. The evolution of resistance in Mycobacterium tuberculosis is significantly influenced by drug efflux caused by efflux pumps. Rv0194 is an important efflux pump associated with resistance to multiple drugs like beta lactam antibiotics like ampicillin and also erythromycin and novobiocin. The introduction of efflux inhibitors for Rv0194 could shorten the course of current therapy and improve the efficacy of second-line medications. Building a trustworthy molecular model of this efflux pump is the goal of this study. We created 3 models using different modeling tools. These models were then subjected to a 20 ns molecular dynamics simulation in a lipid bilayer. We find that the model built by Swiss Model shows the best results in molecular modeling and validation and the structure is also stable throughout the 20 ns MD simulations. Consequently, this model is reliable and can be used for further studies.

Serotype distribution and antimicrobial resistance of Streptococcus pneumoniae isolated from children in Japan, 2023

BackgroundThe prevalence of serotypes and antimicrobial resistance of Streptococcus pneumoniae was characterized among children thirteen years after the licensure of the pneumococcal conjugate vaccine (PCV) in Japan. MethodsA total of 353 pneumococcal isolates were collected from Japanese children between March and July 2023. All the isolates were serotyped using genetic methods and tested for susceptibility to 14 antimicrobial agents. ResultsAmong the 353 isolates, the prevalence rates of non-PCV13 and non-PCV20 serotypes were 96.9 % and 77.9 %, respectively, including the dominant non-PCV13/PCV20 serotypes 23A (16.1 %), 35B (15.3 %), 15A (10.5 %), 15C (9.3 %), and 34 (9.1 %), which accounted for 60.3 % of all isolates. The high non-susceptibility rates were observed for macrolides (erythromycin, azithromycin, and clarithromycin; ≥81.9 %) and tetracycline (80.7 %). Penicillin non-susceptibility and multidrug resistance (MDR) were detected in 49.9 % (6.8 % resistant and 43.1 % intermediate) and 68.3 % of the isolates, respectively. The three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B exhibited high prevalence rates of penicillin non-susceptibility (≥89.5 %) and MDR (≥81.5 %). Extensive drug resistance was observed in 10.5 % of all isolates belonging to six different serotypes (12F, 23A, 11A, 15A, 35B, and 15B) and in the non-encapsulated strains of S. pneumoniae. ConclusionsOur study revealed a higher prevalence of non-susceptibility to penicillin with MDR in the three most common non-PCV13/PCV20 serotypes 15A, 23A, and 35B, in Japan, suggesting their persistence in the PCV13 era.

Periodic phenotypic profile analysis of Acinetobacter baumannii drug resistance characteristics showing the emergence of PDR.

Acinetobacter baumannii, one of the ESKAPE pathogens, is on the World Health Organization (WHO) list of priorities needing urgent new effective antimicrobial agents due to exhibited high resistance by the bacterium to currently available antibiotics. This study examines the periodic changes of clinical A. baumannii isolates and their antimicrobial resistance patterns and types in Southeastern region of Saudi Arabia. One hundred and seventy-seven randomly selected A. baumannii isolates were used for the investigation with bacterial identities (IDs) and antimicrobial assay ascertained with Gram-negative (GN) ID cards and antimicrobial susceptibility test (AST) cards of Vitek 2 Compact Automated System according to manufacturer's guidelines. Descriptive phenotypic types of isolates were compared using comparison proportion and Fisher extraction test, while Morpheus versatile matrix visualization and analysis software was used for the dendrogram of hierarchical clustering. A significantly higher proportion of samples were from males compared to females (p = 0.025), with 33.33% of samples originating from patients aged 51-70 years. Resistance was high for imipenem (93%), meropenem (94%), levofloxacin, ciprofloxacin (99%), and aztreonam (98%). There was less percentage resistance to colistin (18%), tigecycline (23%), and minocycline (23%). Multidrug resistance (MDR)/carbapenem-resistant Acinetobacter baumannii (CRAB) was observed consistently across all years. There was no extensive drug resistance (XDR) among isolates from 2013 to 2014, but it was present in the 2016 to 2018 and 2019 to 2020 periods, while pandrug resistance was seen only in the 2019 to 2020 isolates. The study shows a clear trend of the isolates changing from MDR to XDR and then to pandrug resistance over the study period. Also, it indicates that carbapenems might no longer be a treatment choice in this study region. Although colistin exhibited less resistance, the toxicity of the drug reduces its usefulness. The development of pandrug resistance is a critical concern.

Clinical Characteristics and Molecular Insights of Carbapenem-Resistant Klebsiella pneumoniae Isolates from Patients in Intensive Care Units.

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP), a significant worldwide public health threat, is common in patients in intensive care units. Methods: A retrospective study was conducted over a period of 22 months to assess the risk factors associated with infection caused by CRKP isolates. Strain identification was performed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and antimicrobial sensitivity was assessed using the micro broth dilution method and Kirby-Bauer test. The genes blaKPC, blaOXA-48, blaNDM, blaVIM, and blaGES were amplified using polymerase chain reaction (PCR), followed by sequencing of the PCR products. The polymerase hypermucoviscosity phenotype was determined using the string test. Capsular serotypes (K1, K2) and presence of the virulence gene (rmpA) in positive isolates were investigated using phenotypic tests followed by PCR. Results: Length of hospitalization and use of carbapenems were associated with CRKP infection. CRKP isolates exhibited extensive drug resistance, but retained sensitivity to colistin and ceftazidime-avibactam (CZA). The main gene detected in 35 CRKP isolates was blaKPC-2. In addition, 11 strains were positive in the string test, and two of these strains carried rmpA. Conclusions: Prolonged hospitalization and carbapenem exposure increased the risk of CRKP infection in intensive care unit (ICU) patients. The prevalence of CRKP carrying the blaKPC-2 gene was high, and suspected hypervirulent carbapenem-resistant K. pneumoniae isolates were scattered.

Screening of the Pandemic Response Box library identified promising compound candidate drug combinations against extensively drug-resistant Acinetobacter baumannii

Infections caused by antimicrobial-resistant Acinetobacter baumannii pose a significant threat to human health, particularly in the context of hospital-acquired infections. As existing antibiotics lose efficacy against Acinetobacter isolates, there is an urgent need for the development of novel antimicrobial agents. In this study, we assessed 400 structurally diverse compounds from the Medicines for Malaria Pandemic Response Box for their activity against two clinical isolates of A. baumannii: A. baumannii 5075, known for its extensive drug resistance, and A. baumannii QS17-1084, obtained from an infected wound in a Thai patient. Among the compounds tested, seven from the Pathogen box exhibited inhibitory effects on the in vitro growth of A. baumannii isolates, with IC50s ≤ 48 µM for A. baumannii QS17-1084 and IC50s ≤ 17 µM for A. baumannii 5075. Notably, two of these compounds, MUT056399 and MMV1580854, shared chemical scaffolds resembling triclosan. Further investigations involving drug combinations identified five synergistic drug combinations, suggesting potential avenues for therapeutic development. The combination of MUT056399 and brilacidin against A. baumannii QS17-1084 and that of MUT056399 and eravacycline against A. baumannii 5075 showed bactericidal activity. These combinations significantly inhibited biofilm formation produced by both A. baumannii strains. Our findings highlight the drug combinations as promising candidates for further evaluation in murine wound infection models against multidrug-resistant A. baumannii. These compounds hold potential for addressing the critical need for effective antibiotics in the face of rising antimicrobial resistance.

GENETIC VARIABILITY AND GEOGRAPHIC DISTRIBUTION OF MYCOBACTERIUM TUBERCULOSIS LINEAGE 2

Mycobacterium tuberculosis (MTB) is a substantial threat to public health, infecting approximately 10 million individuals annually with tuberculosis. Among the genetic lineages of MTB, lineage 2 (L2), notably the Beijing family, plays a significant role in global tuberculosis epidemiology, accounting for nearly a quarter of all reported TB cases. Originating possibly in East Asia, this lineage spread globally, causing significant epidemics in Central Asia, Eastern Europe, and Eastern Africa. Geographic variability in the distribution of MTB L2 strains reveals diverse prevalence patterns among sublineages across different regions. L2.1 (proto-Beijing) is primarily composed of isolates originating from China, Thailand, and Vietnam, with a smaller number from Japan, Malaysia, and Indonesia. The ancestral sublineage, named L2.2.A, is mostly spread in China, Japan, and Thailand, while the modern sublineage, L2.2.M, is widespread, spanning almost the entire world. Moreover, the L2.2.M1 clade demonstrates a wide geographic spread, encompassing various countries across Asia and Australia, while other subclades of the L2.2.M2, L2.2.M3, and L2.2.M4 clades show more localized distributions across different regions. The L2.2.M4 clade comprises nine subclades, L2.2.M4.1 and L2.2.M4.2 are primarily found in Thailand, while L2.2.M4.3, L2.2.M4.6, and L2.2.M4.8 predominate in China. In South Africa, L2.2.M4.4 is the predominant subclade, whereas L2.2.M4.7 is associated with Nepalese isolates. In contrast, in regions such as Central Asia, Eastern Europe, and Russia, L2 strains, particularly the Modern Beijing sublineage, dominate. Notable examples include Europe/Russia W148 outbreak L2.2.M4.5 (B0W/148), Central Asia L2.2.M4.9 (CA), Central Asia outbreak L2.2.M4.9.1 (CAO), and Clade A L2.2.M4.9.2. Additionally, recent small clades like L2.2.M5 and L2.2.M6, originating from Vietnam, Thailand, and China, have emerged, with L2.2.M6 also detected in Kenya and South Africa. In Kazakhstan, we have identified such sublineages of L2 as CAO (n=69; 67.64%) L2.2.M4.9.1, CA (n=27; 26.47%) L2.2.M4.9, B0W/148 (n=5, 4.90%) L2.2.M4.5 and one isolate representative of a rare L2.2.M4 lineage (n =1; 0.98%). Strains of this lineage demonstrate the development of multidrug resistance (MDR) and extensive drug resistance (XDR), reflecting the emergence of resistance mechanisms against all available anti-tuberculosis drugs. In summary, M. tuberculosis lineage 2, especially the Beijing family, significantly impacts global tuberculosis epidemiology, with diverse prevalence patterns among sublineages across regions.

Evaluation of Antibiotic Susceptibility, Carbapenemase and Metallobetalactamase-producing Strains of Acinetobacter baumannii Isolated from Hospitalized Patients in Zahedan During 2019 - 2022

Background: Microbial resistance caused by Acinetobacter baumannii, which leads to various infectious diseases, is projected to result in ten million deaths by 2050. This is mainly due to the production of beta-lactamase enzymes, a significant concern for the World Health Organization. Objectives: This study utilized phenotypic analysis to examine isolates producing metallo-beta-lactamase and carbapenemase and to determine the pattern of antibiotic resistance in Acinetobacter baumannii. Methods: Following the isolation and identification of 372 Acinetobacter baumannii strains from clinical isolates using a variety of biochemical tests, the antibiotic resistance pattern was examined using the disc diffusion method. The production of beta-lactamase and carbapenemase was determined using the combined disc diffusion phenotypic test (CDDT) and the Modified Hodge Test (MHT), respectively. Results: Based on this study, minocycline (7.4%) exhibited the lowest resistance rate, while carbapenems (imipenem and meropenem) showed the highest resistance. All antibiotic groups demonstrated over 80% resistance, suggesting extensive drug resistance in all samples. Furthermore, 325 (94.6%) strains of Acinetobacter baumannii produced metallo-beta-lactamase, 215 (57.7%) strains strongly produced carbapenemase, and 135 (36.1%) strains weakly produced carbapenemase. Conclusions: Due to minimal resistance to colistin, minocycline, and ampicillin-sulbactam, it is advisable to use these drugs either individually or in combination for treatment.

Co-Prevalence of Quinolone Resistance and Extended-Spectrum Beta-Lactamases among Clinical Enterobacteriaceae Isolates from a Tertiary Hospital in Katsina, Nigeria

Study’s Novelty/Excerpt This study investigates the co-existence of Extended-Spectrum Beta-Lactamases (ESBLs) and quinolone resistance among clinical Enterobacteriaceae isolates, highlighting the high prevalence of multidrug resistance (MDR) and extensive drug resistance (XDR). By employing the VITEK-2 Compact automated identification system, the research demonstrates that a significant proportion of quinolone-resistant Enterobacteriaceae are also ESBL-positive, with co-resistance observed primarily in Escherichia coli and Klebsiella pneumoniae. These findings emphasize the critical need for continuous surveillance and antibiotic stewardship to mitigate the growing threat of antimicrobial resistance and align with Sustainable Development Goals (SDG) 3 for good health and well-being. Full Abstract Antimicrobial resistance (AMR) poses a major hazard to global public health. It reduces the effectiveness of many antibiotics, making infections harder to cure and raising the likelihood of disease transmission and death. Globally, beta-lactam and quinolone antibiotics are among the commonly prescribed medications. Yet, a multitude of bacteria have evolved distinct multidrug resistance (MDR) characteristics, rendering many of these important drugs worthless. This study aimed to investigate the magnitude of the simultaneous occurrence of Extended-Spectrum Beta-Lactamases (ESBLs) and Quinolone-resistance (co-existence) among clinical Enterobacteriaceae isolates. A total of 95 Enterobacteriaceae pathogens isolated from different human samples were obtained from a Tertiary Hospital in Katsina. Then, the VITEK-2 Compact automated identification system was employed for the identification and antimicrobial susceptibility testing (AST) and the ESBL screening of isolates. This study showed that out of the total 95 isolates, 67 (70.5%) were quinolone-resistant, while 53 (55.8%) were ESBL-positive. Most of the quinolone-resistant (QRE) Enterobacteriaceae were ESBL-positive, 50 (74.6%), and conversely, most of the ESBL-positive Enterobacteriaceae were quinolone-resistant (50, 94.3%). Co-resistance (quinolone-resistance and ESBL-positive) was recorded in 50 (52.63%) of the isolates, all belonging to the Escherichia coli (42, 84.0%) and Klebsiella pneumoniae (8, 16.0%). Almost all the co-resistant isolates were resistant to the tested quinolones [Ciprofloxacin (49, 98.0%) and Levofloxacin (50, 100.0%). The lowest resistance was recorded to Ertapenem(6.0%), Meropenem (6.0%), and Amikacin (2.0%), and the highest to Ampicillin, Piperacillin and Levofloxacin (100.0% each). Almost all the co-resistant isolates were multidrug-resistant (MDR), 49 (98.0%), while 33 (66.0%) were extensively drug-resistant (XDR). According to the collected samples’ demographic data, the highest prevalences were recorded among males (60.0%, based on gender), adults (50.0%, based on age), and urine (48.0%, based on sample). Continuous surveillance and stewardship are essential to achieve good health and well-being (Sustainable Development Goal 3).

A Retrospective Case Series Study of Alcaligenes faecalis Pneumonia

Background: The potentially developing human pathogen Alcaligenes faecalis is a gram-negative, nonfermenting bacterium. Treatment of A. faecalis infections is frequently difficult due to increased resistance to many antibiotics, such as β-lactam antibiotics, aminoglycosides, and quinolones. In the literature, A. faecalis pneumonia has never been documented in a case series study. Here, we provide a case series study of patients with A. faecalis pneumonia. Objectives: The aim of this study was to elucidate the clinical characteristics, management strategies, and outcomes of A. faecalis pneumonia patients. Methods: Patients with A. faecalis pneumonia between January 2014 and December 2019 were included in a retrospective investigation. We examined the clinical outcomes of patients with A. faecalis pneumonia, together with the risk factors for pneumonia, prior intravenous antibiotic use within 90 days, respiratory secretion culture results, antibiotic sensitivity test results, and other variables. Results: Observations revealed eight patients with A. faecalis pneumonia, including six males and two females. The mean age of patients was 70 years. These eight patients shared risk factors for pneumonia. Six patients were discharged, and two patients died as a result of A. faecalis pneumonia. Two patients with pneumonia caused by extensively drug-resistant A. faecalis were identified. Conclusions: Rare cases of A. faecalis pneumonia have been documented in the literature. Recently, A. faecalis has developed extensive drug resistance. To treat pneumonia caused by A. faecalis with substantial antibiotic resistance, either polymyxin B or tigecycline is needed. The clinical outcome is typically satisfactory when A. faecalis pneumonia patients receive appropriate antibiotic therapy, but cases of fatal pneumonia have been documented in the literature.

New Delhi metallo-β-lactamases among extensively drug-resistant clinical isolates from Lahore, Pakistan.

Aim: The study determines rates of carbapenem resistance (CR) and frequency of blaNDM in multidrug-resistance (MDR) or extensivedrug resistance (XDR), and evaluates the potential of phenotypic tests for detecting NDMproduction. Materials & methods: Singleplex PCR was used to detect blaNDM. Phenotypic tests, including combination disc test (CDST) and modified Hodge test (MHT), were evaluated for NDM production. Results: Among 338 CR isolates, 47.63% were MDR, whereas 52.36% were XDR with 53.25% carrying blaNDM. MHT was found to bediscriminativefor detecting NDM production, whereas no significant association was observed for CDST. Conclusion: The high incidence of CR and MDR and XDR isolates possessing blaNDM presents an impending threat in therapeutics. Limitations of phenotypic tests suggest better testing, including molecular detection of the enzyme.

Comparison of Colistin Susceptibility via Two Different Methods in Gram-Negative Extensive Drug-Resistance Isolates from ICU Patients.

To compare the susceptibility of colistin by two methods in extensive drug-resistant (XDR) Gram-negative isolates from ICU patients. Cross-sectional comparative analysis. Place and Duration of the Study: Department of Microbiology, Combined Military Hospital Karachi, Pakistan, from August 2022 to February2023. A total of 100 clinical specimens received from the intensive care unit yielded growth of extensively drug-resistant gram-negative bacteria, which were evaluated for polymyxin E susceptibility. The agar dilution method was compared with the reference broth microdilution (BMD) method. Minimum inhibitory concentration (MIC) was noted for both methods. Comparison of the MIC method by agar dilution showed a 90% correlation with the reference method of broth microdilution. With MICs within the acceptable range of the clinical and laboratory standards institute (CLSI) recommendations, 89 isolates were susceptible to colistin, whereas only 11 remained resistant. Polymyxin E's MIC 50 and MIC 90 were determined to be 1 and 2 µg/ml, respectively, with 97% susceptibility. Agar dilution susceptibility method can be used for screening purposes for the susceptibility testing of polymyxin E. This method is reliable and can easily identify the heteroresistance. Extensively drug-resistant, Broth microdilution, Multidrug-resistant, Agar dilution, Minimum inhibitory concentration, Colony forming unit.

Emergence of extensive drug resistance and high prevalence of multidrug resistance among clinical Proteus mirabilis isolates in Egypt

BackgroundProteus mirabilis is an opportunistic pathogen that has been held responsible for numerous nosocomial and community-acquired infections which are difficult to be controlled because of its diverse antimicrobial resistance mechanisms.MethodsAntimicrobial susceptibility patterns of P. mirabilis isolates collected from different clinical sources in Mansoura University Hospitals, Egypt was determined. Moreover, the underlying resistance mechanisms and genetic relatedness between isolates were investigated.ResultsAntimicrobial susceptibility testing indicated elevated levels of resistance to different classes of antimicrobials among the tested P. mirabilis clinical isolates (n = 66). ERIC-PCR showed great diversity among the tested isolates. Six isolates (9.1%) were XDR while all the remaining isolates were MDR. ESBLs and AmpCs were detected in 57.6% and 21.2% of the isolates, respectively, where blaTEM, blaSHV, blaCTX−M, blaCIT−M and blaAmpC were detected. Carbapenemases and MBLs were detected in 10.6 and 9.1% of the isolates, respectively, where blaOXA−48 and blaNDM−1 genes were detected. Quinolone resistant isolates (75.8%) harbored acc(6')-Ib-cr, qnrD, qnrA, and qnrS genes. Resistance to aminoglycosides, trimethoprim-sulfamethoxazole and chloramphenicol exceeded 80%. Fosfomycin was the most active drug against the tested isolates as only 22.7% were resistant. Class I or II integrons were detected in 86.4% of the isolates. Among class I integron positive isolates, four different gene cassette arrays (dfrA17- aadA5, aadB-aadA2, aadA2-lnuF, and dfrA14-arr-3-blaOXA−10-aadA15) and two gene cassettes (dfrA7 and aadA1) were detected. While class II integron positive isolates carried four different gene cassette arrays (dfrA1-sat1-aadA1, estXVr-sat2-aadA1, lnuF- dfrA1-aadA1, and dfrA1-sat2).ConclusionP. Mirabilis ability to acquire resistance determinants via integrons may be held responsible for the elevated rates of antimicrobial resistance and emergence of XDR or even PDR strains limiting the available therapeutic options for management of infections caused by those strains.

Synergistic effects of silver nanoparticles in combination with ineffective antibiotics against multidrug resistant Salmonella typhi.

To determine the antimicrobial activity of silver nano-particles(AgNPs) with tetracycline and ampicillin against multi-drug resistance (MDR) and extensively-drug resistance (XDR) Salmonella typhi. Cross sectional non-probability purposive study was conducted from September, 2021 to May, 2022 at Microbiology department PNS Shifa, Hospital Karachi. Blood cultures of patients suspicious of typhoid fever were collected and incubated in automated Bact/Alert system. Positive cultures were identified on blood and MacConkey and processed by API-10S, confirmed by serotyping (O9 antisera) (SSI Diagnostica's Salmonella). Antibiotic resistance was done by Kirby-Bauer disk diffusion (Sigma and Rich). MDR and XDR isolates were preserved in Brain Heart Infusion in a volume of 2ml in screw capped bottles at -70°C. Antimicrobial powders (ampicillin and tetracycline (Alfa Aesar) weighed by an electrical weighing balance (OHAUS) to take 1mg of antimicrobial drug. Absorbance spectra of serial concentrations of antibiotics (UV-Vis spectrophotometer (Mole-Qule-) AgNPs (10nm) (nanocomposix) + Antibiotic in (1:1 volume ratio). Conjugation of silver nanoparticles with tetracycline and ampicillin was done by FTIR (thermos scientificThermos ScientificNicolet 50). Out of 77 isolates, 54 were resistant to ceftriaxone (XDR) and 23 sensitive to ceftriaxone (MDR). All isolates were susceptible to azithromycin and meropenem. Comparison of zone of inhibitions of ampicillin and Amp-AgNPsas and tetracycline with Tet-AgNPs was done. Minimal inhibitory concentration was also done to determine antimicrobial activity. Significant synergistic inhibitory effects against Salmonella Typhi isolates were obtained by combination of tetracycline with silver nano-particles even at low concentration.

Molecular and bacteriological investigations for the co-existence CRISPR/Cas system and β-lactamases of types extended-spectrum and carbapenemases in Multidrug, extensive drug and Pandrug-Resistant Klebsiella pneumoniae

The recent approach towards combating the antimicrobial resistance has led to the use of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and associated sequence to overcome the challenges of antimicrobial resistance. Thus, this study aimed to detect the underlying resistance mechanisms such as ESBLs and carbapenemases and whether there is a correlation between multidrug, extensive drug and pan drug resistance and the occurrence of CRISPR loci. A total of one hundred study isolates were subjected to antimicrobial susceptibility testing using the AST card of the Vitek technique to detect resistance patterns involving ESBLs and carbapenemase (CRE). An investigation of the genes encoding CRISPR/Cas systems using PCR was achieved. Out of 81 (81.0%) resistant Klebsiella pneumoniae isolates, 71 (71%) and 21 (21.0%) produced ESBLs and carbapenemases, respectively. Also, 53 (53.0%), 19 (19.0%) and 9 (9.0%) were MDR, XDR, and PDR respectively. It was noted that Cas1, Cas3, CRISPR1, CRISPR2 and CRISPR3 were positive in 38 (38.0%) of the isolates, while CRISPR1 for incomplete CRISPR1-Cas systems alone was detected in 78 (78.0%). Further, the number of intact CRISPR1, intact CRISPR2 and intact CRISPR3 types were 7 (27.0%), 34 (34%) and 18 (18.0%) respectively. It is concluded that antibiotic resistance levels were inversely correlated with the existence of CRISPR/Cas systems. The absence of the CRISPR/Cas system increases the prevalence of MDR, XDR and PDR in ESBL and carbapenem-producing Klebsiella pneumoniae. With the increase in the degree of antibiotic resistance (MDR, XDR to PDR), the occurrence ratio of the (CRISPR)/CRISPR-associated sequence decreased.

The Impact of Urinary Catheterization on the Antibiotic Susceptibility of ESBL-Producing Enterobacterales: A Challenging Duo.

Antimicrobial resistance (AMR) is currently a growing concern among healthcare providers, underscoring the importance of describing the regional susceptibility profile for common microorganisms that are associated with urinary tract infections (UTIs). This knowledge serves as the foundation for proper empirical therapeutic recommendations tailored to local susceptibility patterns. We found a high prevalence of ESBL-producing strains (36.9%), with Escherichia coli and Klebsiella spp. being the most prevalent isolated bacteria. Among the catheterized patients, Klebsiella spp. emerged as the primary etiology, with a significant correlation between catheterization and Proteus spp. (p = 0.02) and Providencia stuartii (p < 0.0001). We observed significant correlations between urinary catheterization and older age (68.9 ± 13.7 years vs. 64.2 ± 18.1 years in non-catheterized patients, p = 0.026) and with the presence of an isolate with extensive drug resistance (p < 0.0001) or even pandrug resistance (p < 0.0001). Susceptibility rates significantly decreased for almost all the tested antibiotics during the study period. Notably, susceptibility was markedly lower among catheterized patients, with the most pronounced differences observed for carbapenems (59.6% versus 83.4%, p < 0.0001) and aminoglycosides (37.1% versus 46.9%, p = 0.0001). We conducted a retrospective study analyzing the susceptibility profiles of 724 extended-spectrum beta-lactamases (ESBL)-producing Enterobacterales isolated from urine cultures. Our focus was on highlighting susceptibility profiles among isolates associated with urinary catheterization and assessing the shifts in the susceptibility rates over time. The constant rise in AMR rates among Enterobacterales presents significant challenges in treating severe infections, particularly among urinary catheterized patients. This trend leaves clinicians with limited or no effective treatment options. Consequently, the development and implementation of personalized treatment protocols are imperative to ensure efficient empirical therapies.

Antimicrobial resistance and population genomics of emerging multidrug-resistant Salmonella 4,[5],12:i:- in Guangdong, China.

Salmonella 4,[5],12:i:-, a monophasic variant of Salmonella Typhimurium, has emerged as a global cause of multidrug-resistant salmonellosis and has become endemic in many developing and developed countries, especially in China. Here, we have sequenced 352 clinical isolates in Guangdong, China, during 2009-2019 and performed a large-scale collection of Salmonella 4,[5],12:i:- with whole genome sequencing (WGS) data across the globe, to better understand the population structure, antimicrobial resistance (AMR) genomic characterization, and transmission routes of Salmonella 4,[5],12:i:- across Guangdong. Salmonella 4,[5],12:i:- strains showed broad genetic diversity; Guangdong isolates were found to be widely distributed among the global lineages. Of note, we identified the formation of a novel Guangdong clade (Bayesian analysis of population structure lineage 1 [BAPS1]) genetically diversified from the global isolates and likely emerged around 1990s. BAPS1 exhibits unique genomic features, including large pan-genome, decreased ciprofloxacin susceptibility due to mutation in gyrA and carriage of plasmid-mediated quinolone resistance (PMQR) genes, and the multidrug-resistant IncHI2 plasmid. Furthermore, high genetic similarity was found between strains collected from Guangdong, Europe, and North America, indicating the association with multiple introductions from overseas. These results suggested that global dissemination and local clonal expansion simultaneously occurred in Guangdong, China, and horizontally acquired resistance to first-line and last-line antimicrobials at local level, underlying emergences of extensive drug and pan-drug resistance. Our findings have increased the knowledge of global and local epidemics of Salmonella 4,[5],12:i:- in Guangdong, China, and provided a comprehensive baseline data set essential for future molecular surveillance.IMPORTANCESalmonella 4,[5],12:i:- has been regarded as the predominant pandemic serotype causing diarrheal diseases globally, while multidrug resistance (MDR) constitutes great public health concerns. This study provided a detailed and comprehensive genome-scale analysis of this important Salmonella serovar in the past decade in Guangdong, China. Our results revealed the complexity of two distinct transmission modes, namely global transmission and local expansion, circulating in Guangdong over a decade. Using phylogeography models, the origin of Salmonella 4,[5],12:i:- was predicted from two aspects, year and country, that is, Salmonella 4,[5],12:i:- emerged in 1983, and was introduced from the UK, and subsequently differentiated into the local endemic lineage circa 1991. Additionally, based on the pan-genome analysis, it was found that the gene accumulation rate in local endemic BAPS 1 lineage was higher than in other lineages, and the horizontal transmission of MDR IncHI2 plasmid associated with high resistance played a major role, which showed the potential threat to public health.