Amikacin Resistance Research Articles

Acinetobacter baumannii Global Clone-Specific Resistomes Explored in Clinical Isolates Recovered from Egypt.

Acinetobacter baumannii (A. baumannii) is a highly problematic pathogen with an enormous capacity to acquire or upregulate antibiotic drug resistance determinants. The genomic epidemiology and resistome structure of 46 A. baumannii clinical isolates were studied using whole-genome sequencing. The isolates were chosen based on reduced susceptibility to at least three classes of antimicrobial compounds and were initially identified using MALDI-TOF/MS, followed by polymerase chain reaction amplification of blaOXA-51-like genes. The susceptibility profiles were determined using a broth microdilution assay. Multi-, extensive-, and pan-drug resistance was shown by 34.8%, 63.0%, and 2.2% of the isolates, respectively. These were most susceptible to colistin (95.7%), amikacin, and trimethoprim/sulfamethoxazole (32.6% each), while only 26.1% of isolates were susceptible to tigecycline. In silico multi-locus sequence typing revealed 8 Pasteur and 22 Oxford sequence types (STs) including four novel STs (STOxf 2805, 2806, 2807, and 2808). The majority of the isolates belonged to Global Clone (GC) 2 (76.4%), GC5 (19.6%), GC4 (6.5%), GC9 (4.3%), and GC7 (2.2%) lineages. An extensive resistome potentially conferring resistance to the majority of the tested antimicrobials was identified in silico. Of all known carbapenem resistance genes, blaOXA-23 was carried by most of the isolates (69.6%), followed by ISAba1-amplified blaADC (56.5%), blaNDM-1 and blaGES-11 (21.7% each), and blaGES-35 (2.2%) genes. A significant correlation was found between carbapenem resistance and carO mutations, which were evident in 35 (76.0%) isolates. A lower proportion of carbapenem resistance was noted for strains possessing both blaOXA-23- and blaGES-11. Amikacin resistance was most probably mediated by armA, aac(6')-Ib9, and aph(3')-VI, most commonly coexisting in GC2 isolates. No mutations were found in pmrABC or lpxACD operons in the colistin-resistant isolates. Tigecycline resistance was associated with adeS (N268Y) and baeS (A436T) mutations. While the lineage-specific distribution of some genes (e.g., blaADC and blaOXA-51-like alleles) was evident, some resistance genes, such as blaOXA-23 and sul1, were found in all GCs. The data generated here highlight the contribution of five GCs in A. baumannii infections in Egypt and enable the comprehensive analysis of GC-specific resistomes, thus revealing the dissemination of the carbapenem resistance gene blaOXA-23 in isolates encompassing all GCs.

Open-Label Trial of Amikacin Liposome Inhalation Suspension in Mycobacterium abscessus Lung Disease

Mycobacterium abscessus is the second most common nontuberculous mycobacterium respiratory pathogen and shows invitro resistance to nearly all oral antimicrobials. M abscessus treatment success is low in the presence of macrolide resistance. Does treatment with amikacin liposome inhalation suspension (ALIS) improve culture conversion in patients with M abscessus pulmonary disease who are treatment naive or who have treatment-refractory disease? In an open-label protocol, patients were given ALIS (590mg) added to background multidrug therapy for 12months. The primary outcome was sputum culture conversion defined as three consecutive monthly sputum cultures showing negative results. The secondary end point included development of amikacin resistance. Of 33 patients (36 isolates) who started ALIS with a mean age of 64 years (range, 14-81 years), 24 patients (73%) were female, 10 patients (30%) had cystic fibrosis, and nine patients (27%) had cavitary disease. Three patients (9%) could not be evaluated for the microbiologic end point because of early withdrawal. All pretreatment isolates were amikacin susceptible and only six isolates (17%) were macrolide susceptible. Eleven patients (33%) were given parenteral antibiotics. Twelve patients (40%) received clofazimine with or without azithromycin as companion therapy. Fifteen patients (50%) with evaluable longitudinal microbiologic data demonstrated culture conversion, and 10 patients (67%) sustained conversion through month 12. Six of the 33 patients (18%) demonstrated mutational amikacin resistance. All were patients using clofazimine or clofazimine plus azithromycin as companion medication(s). Few serious adverse events occurred for ALIS users; however, reduction of dosing to three times weekly was common (52%). In a cohort of patients primarily with macrolide-resistant M abscessus, one-half of the patients using ALIS showed sputum culture conversion to negative findings. The emergence of mutational amikacin resistance was not uncommon and occurred with the use of clofazimine monotherapy. ClinicalTrials.gov; No.: NCT03038178; URL: www. gov.

Multidrug Resistance and Plasmid Profiles of Escherichia coli Isolated from Lebanese Broiler Farms.

The present study was undertaken to determine the antimicrobial resistance patterns and plasmid fingerprints of commensal Escherichia coli isolated from Lebanese broiler chickens. To that end, a total of 30 E. coli isolates were collected from 15 semi-open broiler farms from North Lebanon and Bekaa Valley. Results showed that all the isolates were resistant to at least nine out of 18 evaluated antimicrobial agents. The best-performing antibiotic families were Carbapenems (Imipenem) and Quinolones (Ciprofloxacin and Norfloxacin) to which only 0.0 and 8.3% of the isolates were resistant, respectively. Fifteen various plasmid profiles were depicted, and all the isolates were found to possess one or multiple plasmids. The plasmid sizes varied from 1.2 to 21.0 kbp, and the most commonly detected plasmid had a size of 5.7 kbp (23.3% of the isolates). There was no significant association between the number of plasmids per isolate and resistance to a particular drug. Nevertheless, the presence of specific plasmids, namely, the 2.2 or 7.7 kbp sized ones, was strongly correlated to Quinolones or Trimethoprim resistance, respectively. Both the 7.7 and 6.8 kbp plasmids showed mild correlation to Amikacin resistance, and the 5.7 kbp plasmid was mildly correlated to Piperacillin-Tazobactam resistance. Our findings highlight the need to revise the list of antimicrobials currently used in Lebanese poultry and associate the presence of specific plasmids to antimicrobial resistance patterns in E. coli isolates. The revealed plasmid profiles could also serve any future epidemiological investigation of poultry disease outbreaks in the country.

Epidemiological, Microbiological, and Clinical Characteristics of Multi-Resistant Pseudomonas aeruginosa Isolates in King Fahad Medical City, Riyadh, Saudi Arabia

Increasing rates of serious multi-drug resistant (MDR) Pseudomonas aeruginosa infections have been reported globally, including in Saudi Arabia. This retrospective study investigates the epidemiological, microbiological, and clinical characteristics of multi-resistant P. aeruginosa (n3579 clinical isolates) in King Fahad Medical City, Riyadh, Saudi Arabia (2019-2021). Information on antimicrobial susceptibility and medical history was collected from the hospital database. P. aeruginosa infections occurred in 55.6% of males and 44.4% of females, and P. aeruginosa was more prevalent in children than in adults. Our analysis showed that P. aeruginosa had the highest sensitivity to amikacin (92.6%) and greatest resistance to aztreonam (29.8%), imipenem (29.5%), ceftazidime (26.1%), meropenem (25.6%), and cefepime (24.3%). MDR and extensively drug resistant (XDR) strains were more prevalent in male than female patients. Female patients showed higher rates of infection with pan-drug resistant (PDR) strains. Respiratory samples contained the majority of resistant isolates. Septic shock and liver disease were strongly correlated with mortality in the ICU patient group after analysing the relative risk associated with mortality. Our study emphasises the threat of multi-resistant P. aeruginosa in Saudi Arabia (and potentially the Middle East) and highlights important sources and contexts of infection that inhibit its effective control and clinical management.

Discovery of Novel Resistance Mechanisms of Vibrio parahaemolyticus Biofilm against Aminoglycoside Antibiotics.

Inappropriate use of antibiotics eventually leads to the emergence of antibiotic-resistant strains and invalidates the treatment of infectious diseases. Aminoglycoside antibiotics (AGAs) are a class of broad-spectrum cationic antibiotics widely used for the treatment of Gram-negative bacterial infections. Understanding the AGA resistance mechanism of bacteria would increase the efficacy of treating these infections. This study demonstrates a significant correlation between AGA resistance and the adaptation of biofilms by Vibrio parahaemolyticus (VP). These adaptations were the result of challenges against the aminoglycosides (amikacin and gentamicin). Confocal laser scanning microscope (CLSM) analysis revealed an enclosure type mechanism where the biological volume (BV) and average thickness (AT) of V. parahaemolyticus biofilm were significantly positively correlated with amikacin resistance (BIC) (p < 0.01). A neutralization type mechanism was mediated by anionic extracellular polymeric substances (EPSs). The biofilm minimum inhibitory concentrations of amikacin and gentamicin were reduced from 32 µg/mL to 16 µg/mL and from 16 µg/mL to 4 µg/mL, respectively, after anionic EPS treatment with DNase I and proteinase K. Here, anionic EPSs bind cationic AGAs to develop antibiotic resistance. Transcriptomic sequencing revealed a regulatory type mechanism, where antibiotic resistance associated genes were significantly upregulated in biofilm producing V. parahaemolyticus when compared with planktonic cells. The three mechanistic strategies of developing resistance demonstrate that selective and judicious use of new antibiotics are needed to win the battle against infectious disease.

Bacterial profile, antimicrobial resistance, and molecular detection of ESBL and quinolone resistance gene of uropathogens causing urinary tract infection in the southeastern part of Bangladesh.

Humans frequently contract urinary tract infections (UTIs), which can be brought on by uropathogens (UPs) that are multi-drug resistant. Treatment for UTIs brought on by pathogenic UPs that produce extended-spectrum lactamases (ESBLs) is more costly and potentially fatal. As a result, the objective of this study was to use culture, biochemical, and 16S rRNA sequencing to identify and characterize UPs isolated from outpatients in Noakhali, Bangladesh, who had symptoms of UTIs. ESBL gene identification and quinolone resistance gene typing were then performed on the isolates using polymerase chain reaction (PCR). Throughout the trial's 8-month duration, 152 (76%) of 200 urine samples were positive for the presence of UPs. The overall number of UPs recovered was 210, with 39 individuals having multiple UPs present in their samples. Among all of the isolates, Escherichia coli (45.24%, 95/210; 95% confidence interval (CI): 35.15-57.60%), Enterobacter spp. (24.76%, 52/210; CI: 19.15-35.77%), Klebsiella spp. (20.95%; 44/210; CI: 15.15-30.20%), and Providencia spp. (9.05%; 19/210; CI: 4.95-19.25%) were the four most prevalent bacteria found in the isolates. The UPs displayed a very high level of resistance to piperacillin 96.92% (126/130), ampicillin 90% (117/130), nalidixic acid 77.69% (101/130), cefazolin 70% (91/130), amoxicillin 50% (55/130), cefazolin 42.31% (55/130), nitrofurantoin 43.08% (56/130), and ciprofloxacin 33.08% (43/130), whereas resistance to netilmicin (3.85%), amikacin (4.62%), and imipenem (9.23%) was low. Individually, every species of E. coli and Providencia spp. showed greater ampicillin, amikacin, cefazolin, cefazolin, and nalidixic acid resistance than the others. The bivariate results indicate several antibiotic pairings, and isolates had meaningful associations. All MDR isolates were subjected to PCR, which revealed that blaCTX-M-15 genes predominated among the isolates, followed by the blaTEM class (37%). Isolates also had the qnrS, aac-6´-Ib-cr, and gyrA genes. The findings provide worrying indications of a major expansion of MDR isolates in the study locations, particularly the epidemiological balCTX-M 15, with the potential for the transmission of multi-drug-resistant UP strains in the population.

Molecular characterization of antibiotic resistance, aminoglycoside and PmrA genes among foodborne and clinical Acinetobacter spp.

The assessment of antibiotic resistance and related genes of foodborne Acinetobacter spp. and the analysis of whether they are genetically related to clinical infection-agent strains are crucial in terms of sustainability of food safety. The study at hand investigated antibiotic resistance, aminoglycoside-modifying enzyme (AME), and colistin resistance (PmrA) genes, clonal relationships while evaluating a possible correlation between antibiotic resistance and related genes between 27 foodborne and 50 clinical Acinetobacter spp. in Turkey. Antimicrobial susceptibilities, (AME), PmrA genes, and clonal relatedness of the strains were performed by disc diffusion, PCR, and Pulsed Field gel Electrophoresis (PFGE) methods, respectively. The aph-AI, aph-6, anth (3’’)-I, aadA1, aadB and PmrA genes were found as (24, 48%), (11, 22%), (7, 14%), (1, 2%), (2, 4%), and (46, 92%) respectively in clinical strains. This rate was found as (14, 51.9%), (16, 59.3%), (19, 70.4%), (2, 7.4%), (0, 0%), and (27, 100%) respectively in foodborne isolates. A positive correlation existed between the number of aph-AI gene positivity and trimethoprim-sulfamethoxazole and gentamycin resistance; anth (3’’)-I gene positivity, and colistin resistance; PmrA gene positivity and piperacillin-tazobactam, ceftazidime, meropenem, amikacin, and imipenem resistance in clinical strains (P

Epidemiology and source of infection in cancer patients with febrile neutropenia: an experience from a developing country

BackgroundFebrile neutropenia (FN) is a life-threatening complication that predisposes cancer patients to serious infections. This study aims to describe the epidemiology and source of infection in cancer patients with FN in a tertiary care hospital.MethodsA hospital-based retrospective study was conducted in a large tertiary care hospital from January 2020 to December 2021. Data on cancer patients with FN were collected from the hospital information system.Results150 cancer patients with FN were identified during the study period. Most patients were males (98; 65.3%), and the mean age of participants was 42.2 ± 16.0 years. Most patients (127; 84.7%) had hematologic malignancies, and acute myeloid leukemia was the most common diagnosis (42; 28%), followed by acute lymphocytic leukemia (28; 18.7%) and Hodgkin’s lymphoma (20; 13.3%). Fifty-four (36%) patients had a median Multinational Association for Supportive Care in Cancer (MASCC) scores greater than 21. Regarding the outcome, nine (6%) died, and 141(94%) were discharged. The focus of fever was unknown in most patients (108; 72%). Among the known origins of fever were colitis (12; 8%), pneumonia (8; 5.3%), cellulitis (6; 4%), bloodstream infections (7; 4.6%), perianal abscess (2; 1.3%) and others. The median duration of fever was two days, and the median duration of neutropenia was seven days. Sixty-three (42%) patients had infections: 56 (73.3%) were bacterial, four (2.6%) were viral, two (1%) were fungal and 1 (0.7%) was parasitic. Among the bacterial causes, 50 cases (89.2%) were culture-positive. Among the culture-positive cases, 34 (68%) were gram-positive and 22 (44%) were gram-negative. The most frequent gram-positive bacteria were E. faecalis (9; 18% of culture-positive cases), and the most frequent gram-negative organisms were Klebsiella pneumoniae (5; 10%). Levofloxacin was the most commonly used prophylactic antibiotic (23; 15.33%), followed by acyclovir (1610.7%) and fluconazole in 15 patients (10%). Amikacin was the most popular empiric therapy, followed by piperacillin/tazobactam (74; 49.3%), ceftazidime (70; 46.7%), and vancomycin (63; 42%). One-third of E. faecalis isolates were resistant to ampicillin. Approximately two-thirds of Klebsiella pneumoniae isolates were resistant to piperacillin/tazobactam and ceftazidime. Amikacin resistance was proven in 20% of isolates.ConclusionsThe majority of patients suffered from hematologic malignancies. Less than half of the patients had infections, and the majority were bacterial. Gram-positive bacteria comprised two-thirds of cases. Therefore, empiric therapy was appropriate and in accordance with the antibiogram of the isolated bacteria.

Molecular Detection and Antibiotic Resistance of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus from Shrimp (Penaeus monodon) and Shrimp Environments in Bangladesh

Some Vibrio species can cause food-borne diseases in humans, including cholera, vomiting, septicemia, and gastroenteritis, which are associated with the consumption of contaminated seafood products. The study was conducted to detect antimicrobial-resistant Vibrio species in shrimp and shrimp environments in Bangladesh. Samples of shrimp (n = 50), water (n = 50), and mud (n = 50) were collected aseptically from 50 different shrimp culture ponds in the Khulna region of Bangladesh. Identification of Vibrio species was based on cultural and staining characteristics, biochemical tests, and polymerase chain reaction (PCR). Antimicrobial resistance profiles were determined using a disk diffusion assay. By PCR, Vibrio isolates were found in 34% (95% CI: 26.9%–41.9%) of the samples, of which the detection rate was significantly higher in shrimp (54%), compared to mud (26%) and water (22%). Moreover, V. cholerae, V. parahaemolyticus, and V. alginolyticus were detected in 24.7%, 15.3%, and 4% of the samples, respectively. Among them, the detection rate of V. cholerae and V. alginolyticus was significantly higher in shrimp samples than in other samples. V. parahaemolyticus was also higher in the shrimp samples, but the difference was not statistically significant. Vibrio isolates showed high to moderate resistance (92.2%–15.7%) to ampicillin, amikacin, cefotaxime, tetracycline, ceftazidime, gentamicin, nalidixic acid, levofloxacin, and ciprofloxacin, and low resistance (3.9%) to imipenem, meropenem, chloramphenicol, and trimethoprim-sulfamethoxazole. Interestingly, 52.9% of the isolates were multidrug resistant, and the multiple antibiotic resistance index was up to 1.0. To our knowledge, this is the first study in Bangladesh detecting these three Vibrio species (V. parahaemolyticus, V. alginolyticus, and V. cholerae) from shrimp and shrimp environments by molecular approach in the same study. These findings reveal the alarmingly high occurrence of antimicrobial-resistant Vibrio species in shrimp and shrimp environments, which should be of concern to both the shrimp industry and public health management.

Emergence of high-level colistin resistance mediated by multiple determinants, including mcr-1.1, mcr-8.2 and crrB mutations, combined with tigecycline resistance in an ST656 Klebsiella pneumoniae.

Colistin and tigecycline are usually regarded as the last resort for multidrug-resistant Klebsiella pneumoniae infection treatment. Emergence of colistin and tigecycline resistance poses a global healthcare challenge and is associated with high mortality due to limited therapeutic options. Here, we report the ST656 extensively drug-resistant K. pneumoniae strain KP15-652, which was isolated from a patient's urine in China. Antimicrobial susceptibility testing showed it to be resistant to tigecycline, amikacin, levofloxacin, ciprofloxacin, and high-level colistin resistance (> 2048 mg/L). Whole-genome sequencing revealed that it harbors one chromosome and seven plasmids, including four plasmids carrying multiple acquired resistance genes. Transformation/conjugation tests and plasmid curing assays confirmed that mcr-1.1, mcr-8.2 and crrB mutations are responsible for the high-level colistin resistance and that a series of efflux pump genes, such as tmexCD1-toprJ1, tet(A) and tet(M), contribute to tigecycline resistance. mcr-1.1 and tet(M) are located on an IncX1 plasmid, which has conjugation transfer potential. mcr-8.2 and tet(A) are located on a multireplicon IncR/IncN plasmid but unable to be transferred via conjugation. Moreover, another conjugable and fusion plasmid carries the tmexCD1-toprJ1 gene cluster, which may have arisen due to IS26-mediated replicative transposition based on 8-bp target-site duplications. Importantly, a complex class 1 integron carrying various resistance genes was detected on this fusion plasmid. In conclusion, it is possible that the high-level of colistin resistance is caused by the accumulated effect of several factors on the chromosome and mcr-carrying plasmids, combined with many other resistances, including tigecycline. Effective surveillance should be performed to prevent further dissemination.

Species Distribution of the Aerobic Bacterial Profile in Pyoderma with Special Reference to Antibiotic Susceptibility Pattern of the Isolates at a Tertiary Care Hospital of West Bengal, India

Introduction: Pyoderma is a common health problem characterised by pyogenic infections of the skin and its appendages. Though easily treatable, the condition is known for its chronicity, recurrence and other complications. Therefore, timely recognition and prompt bacterial diagnosis with antimicrobial sensitivity is imperative for the effective management and treatment of pyoderma. It is a common bacterial skin infection accounting for nearly 25% of patients attending Dermatology Outpatient Department (OPD) in India and other tropical countries. Aim: To determine the incidence of pyoderma in relation to age, sex and socio-economic status, to isolate and identify the common aerobic microbial pathogens associated with pyoderma prevalent in the community and antibiotic susceptibility pattern. Materials and Methods: An institutional based crosssectional observational study was conducted on 148 cases in Department of Microbiology, Rampurhat Government Medical College and Hospital, Burdwan, West Bengal, India, clinical features of suspected pyoderma for a period of 12 months from March 2021 to February 2022. Lesion swabs were collected and isolates were identified; antibiotic susceptibility testing was also performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines using antibiotic discs. Descriptive data was presented as count and percentages. Results: Out of 148 samples collected 144 (97.3%) were culture positive while, rest 04 (2.7%) were culture negative. Overcrowding and low socio-economic group were closely related with pyoderma patients. Primary pyoderma (72.2%) cases were detected more than the secondary (27.8%) cases. Impetigo contagiosa (54%) were detected more among the primary pyoderma patients. High numbers (66.7%) of pyoderma were detected among children (0 to 10 years). The culture positive samples were more in male patients (68.7%) than in female patients (31.3%) and mostly detected from OPD. Out of 144 isolates, 89 (61.8%) were Staphylococcus aureus, 23 (15.9%) isolates were Coagulase Negative Staphylococci (CoNS) and 04 (2.8%) were Streptococcus pyogens. Further 06 (4.2%) isolates of Pseudomonas aeruginosa, 10 (6.9%) isolates of Escherichia coli and 08 (5.5%) isolates of Klebsiella pneumonia were found. Conclusion: The present study results suggest that the era of antibiotics has ushered in an unprecedented predominance of Staphylococcal rather than Streptococcal infections and other gram negative infections for pyoderma cases. Increasing incidence of methicillin, quinolones and amikacin resistance in Staphylococci and other gram negative isolates have limited treatment options. For this, a single infection like pyoderma is challenging in all the healthcare facility.

Urinary Tract Infections in a Tunisian Orthopedic Institute: Major Strain Microbiological Profile

Background: Urinary Tract Infection (UTI) detected in the hospital and in the community is one of the most common reasons for consultation in everyday practice; it represents a major source of antibiotic consumption. This study’s objectives were to outline the microbiological profile of Tunisian patients with UTI and assess antibiotic resistance over the course of three years at the Orthopedic Institute. Methods: All strains identified in urine samples between January 1st, 2019, and December 31st, 2021, were included. Standard laboratory procedures were used to identify the bacterium. The Microscan Walkway 40 Plus was used to do biochemical assays and antibiotic susceptibility testing. The EUCAST criteria were used to interpret the findings. Results: A total of 1313 strains were isolated. The bacteriological study showed the predominance of enterobacteria (96.8%), especially E. coli (52.2%) and K. pneumoniae (19.3%). Overall resistance rates to antimicrobial agents were as follows: for hospital, E. coli strains were in descending order amoxicillin (73.05%), trimeth/sulfamethoxazole (46.9%), ofloxacin (40.3%), amoxicillin/clavulanic acid (35.05%) and gentamicin (20.5%). Our results showed low resistance to fosfomycin for E. coli 2.6% in hospitals while ≥12.1% for K. pneumoniae. Amikacin resistance remains medium-low for E. coli being ≥20% and 10% for K. pneumonia. Nitrofuran resistance has affected 1.06% of E. coli strains in hospital settings and 21.5% of K. pneumoniae. Extended Spectrum Beta-Lactamases (ESBLs) production was present in a number of enterobacteria (19.3% of K. pneumoniae and 14.4% of E. coli). Conclusion: The prevalence of E. coli and K. pneumoniae producers ESBLs in UTI is increasing. Rigorous surveillance of resistance rate is necessary to determine appropriate empirical treatment and limit the spread of multiresistant strains.

Molecular genetic characteristics of &lt;i&gt;Vibrio cholerae&lt;/i&gt; nono1/nono139 strain, the causative agent of a new case of acute intestinal infection in Rostov-on-Don

During more than 50 years, a heterogeneous population of Vibrio cholerae non-O1/non-O139 (NAGs) exists in Rostov region of Russia, whose representatives periodically cause acute human intestinal infections; the last case was registered in 2018. In 2022, a sick child was again revealed in Rostov, from whom 2 NAG subcultures were isolated. Aim of the study: bioinformatics analysis of whole genome sequences (WGSs) of the 2022 clinical NAG isolates, genetic determinants of pathogenicity factors and relevant products. Materials and methods. Isolation, identification of cultures, as well as antibiotic sensitivity were carried out according to the MUK 4.2.3745-22. SNP analysis of WGSs obtained on the MiSeq Illumina platform were analyzed by means of designed software; BioEdit 7.2.5, Vector NTI Advance 11 package, CARD database were used to identify and analyze genes and relevant deduced products. Results. The isolated cultures with identical phenotypic features, PCR-genotypes and results of SNP analysis, were identified as a non-toxigenic NAG. The agent showed sensitivity to chloramphenicol, ceftriaxone, streptomycin, gentamicin, nalidixic acid, ciprofloxacin, ampicillin, amikacin and intermediate resistance to tetracycline, doxycycline, furazolidon and co-trimoxazole. WGSs lacked CTX and preCTX prophages, pathogenicity island VPI, thermostable and cholix toxin genes, pandemic islands VSP-I and VSP-II. The determinants of the type 6 secretion system (T6SS) were not presented completely, which evidenced in favor of the loss of its functionality. An intact T3SS cluster was revealed, which was adjacent to the nan-nag region of the VPI-2 pathogenicity island in the absence of the proximal and distal parts of the latter. Other determinants of pathogenicity factors were revealed: RTX cluster responsible for synthesis of MARTX cytotoxin, genes for hemolysin HlyA, cytotonic toxin Cef, several serine and metalloproteases. The nucleotide compositions of most determinants differed from the prototypes, but their putative products preserved characteristic active domains. The adhesive activity might be provided by mannose-insensitive MSHA-like pili, since the msh-cluster included all the genes necessary for their production, as well as flagella, as both clusters responsible for their assembling were 99% identical to the prototype. From antibiotic resistance determinants only -lactamase VarG gene was found. Conclusion. The NAG strain examined here contains a sufficient set of intact virulence-associated genetic determinants, expression of which could contribute to the development of the disease.

Evaluation of Antibiotic Resistance and adeABC, adeR, adeS Efflux Pump Genes among Foodborne and Clinical Acinetobacter spp. in Türkiye.

The adeABC efflux pump has a crucial role in the resistance of Acinetobacter baumannii strains to antimicrobial agents; it is encoded by adeABC, adeR, adeS genes. We evaluated antibiotic resistance, efflux pump genes, clonal relationships, and analyzed a probable correlation that can exist between antibiotic resistance and the aforementioned genes. We conducted this study on 27 food-originated and 50 human clinical Acinetobacter spp. in Southern Türkiye. MALDI-TOF system and disc diffusion/agar dilution (colistin) methods were used for the identification and antibiotic susceptibility. The efflux pump genes and genetic relatedness of the two groups were investigated by (PCR) and (PFGE) methods. Foodborne A. dijkshoorniae strain was multidrug- resistant (MDR), and none of them resistant to colistin. Most of the clinical isolates (92%) were Extensive-Drug Resistant (XDR); highest resistant to ceftazidime, piperacillin-tazobactam, and imipenem (47, 94%), and were lowest to colistin (7, 14%), respectively. adeABC, and adeR, adeS genes were (23, 85.2%), (9, 33.3%), (27, 100%) and (10, 37.3%), (18, 66.7%) in foodborne strains respectively. These rates were (43, 86%), (48, 96%), (50, 100%), and (34, 68%), (48, 96.7%) in clinical strains respectively. A positive correlation existed between adeA gene positivity and piperacillintazobactam, ceftazidime, gentamycin, imipenem (P=0.048), amikacin (P=0.007) and trimethoprimsulfamethoxazole (P=0.029) resistance in clinical strains. A positive correlation of trimethoprimsulfamethoxazole resistance and adeS gene positivity was seen in foodborne strains (P=0.018). Multiple-efflux pump genes rise in parallel to multidrug-resistance in clinical isolates, while susceptible to diverse antibiotics; food may be a potential provenance for the dissemination of adeABC, adeR and adeS genes.

Risk Factors for 7-Day and 21-Day Mortality in Patients with Ventilator-Associated Pneumonia Caused by Gram-Negative Multidrug Resistant Bacteria

Objective: Incidence of ventilator-associated pneumonia, caused by gram-negative multidrug resistant bacteria, is on the increase and early mortality rate is high.&#x0D; We aimed to investigate the effects of aging, comorbidities, high Charlson comobidity index score, high Acute Physiology and Chronic Health Evaluation II score, leukocytosis, high C-reactive protein level, inappropriate empirical antibiotic therapy and antibiotic resistance on mortality in ventilator-associated pneumonia caused by gram-negative multidrug-resistant bacteria.&#x0D; Methods: The study was planned as a retrospective cohort study. Patients aged 18 years and older who were hospitalized between January 01, 2015, and January 01, 2020, diagnosed with ventilator-associated pneumonia, and had Gram-negative multidrug resistant pathogen was detected in blood and/or bronchoalveolar lavage fluid specimen or quantitative endotracheal aspirate cultures were included in the study.&#x0D; Results: A total of 370 patients were included in the study. Median age of the patients was 74 (19-95) years. Most frequent bacteria was Acinetobacter baumannii (52.4%). Resistance to ceftriaxone, meropenem, and colistin was 99%, 68%, and 4%, respectively. 7-day and 21-day mortality rates were 38.3% (n=142) and 85.1% (n=315). In multivariate analysis, 7-day mortality was associated with a Charlson comorbidity index score of ≥4, and risk factors for 7-day mortality were septic shock, amikacin resistance, and white blood cell count ≥15000/mm3. Advanced age was found to be a risk factor for 21-day mortality, and a high Acute Physiology and Chronic Health Evaluation II score and a high Charlson comorbidity index score were associated with 21-day mortality. It was found that the risk of 7-day mortality in patients with tracheostomy was lower than in patients without tracheostomy.&#x0D; Conclusion:Consideration of clinical scoring systems, closer monitoring of elderly patients, following-up with tracheostomy, may provide a decrease in mortality of ventilator-associated pneumonia, caused by multidrug resistant pathogens.

1713. In Vitro Activities of Epetraborole, a Novel Bacterial Leucyl-tRNA Synthetase Inhibitor, Against Mycobacterium avium Complex Isolates

Abstract Background Epetraborole (EBO) is a boron-containing, oral inhibitor of bacterial leucyl-tRNA synthetase, an essential enzyme in protein synthesis; EBO demonstrates potent activity against nontuberculous mycobacteria. We evaluated the effects of select culture conditions on MIC determinations of EBO against isolates of M. avium complex (MAC), as well as EBO MIC90 results with Middlebrook 7H9 broth compared to those with cation-adjusted Mueller Hinton Broth (CAMHB) for 51 MAC isolates. Methods Six strains of MAC were used to test the in vitro activity of EBO in different conditions in a broth microdilution (BMD) assay. Activity was compared in Middlebrook 7H9 and CAMHB with 5% OADC from different manufacturers. The effects of glycerol, cations, oxyrase, varying pH levels, and increasing inoculum sizes were tested. Finally, EBO in vitro activity was tested for 51 MAC isolates in a BMD assay in both Middlebrook 7H9 and CAMHB with 5% OADC. Results In general, manipulation of select culture conditions caused very little variation in EBO MIC values for the 6 MAC strains except for increasing the inoculum from ∼105 to 107 CFU/mL, which caused an approximately 64x increase in the MIC. Since 1 MAC isolate out of 6 was affected by the addition of casitone, we tested 51 MAC isolates in both the minimal media Middlebrook 7H9 and the complex media CAMHB. EBO had a narrow MIC range in both broths, 0.25-8 mg/L for all isolates. The EBO modal MIC, MIC50 and MIC90 for the entire MAC panel of 51 isolates was 2 mg/L, 2 mg/L, and 8 mg/L for CAMHB and 1 mg/L, 1 mg/L, and 4 mg/L for Middlebrook 7H9, respectively (Table 1). Three clarithromycin-resistant isolates had EBO MIC values of 0.5 mg/L, 1 mg/L, and 2 mg/L suggesting that clarithromycin resistance does not affect EBO in vitro activity. In addition, amikacin resistance as determined using the Clinical Laboratory Standards Institute (CLSI) IV amikacin breakpoint (MIC ≥ 64 mg/L) had no noticeable effect on EBO MIC values. Table 1EBO In Vitro Activity Against 51 Isolates of Mycobacterium avium complex Conclusion The MIC distribution for the 51 MAC isolates tested was similar in both media types, indicating that CAMHB can be used to test EBO MAC susceptibilities per CLSI guidelines. Clarithromycin- and amikacin-resistant isolates demonstrated no cross-resistance with EBO. Disclosures Michelle S. DeStefano, n/a, AN2 Therapeutics: Grant/Research Support Carolyn M. Shoen, PhD, AN2 Therapeutics: Grant/Research Support MRK Alley, PhD, ABBOTT LABS: Stocks/Bonds|ABBVIE: Stocks/Bonds|AN2 Therapeutics: Author on epetraborole patent|AN2 Therapeutics: Salary|AN2 Therapeutics: Ownership Interest|AVANOS MED INC: Stocks/Bonds|NABRIVA THERAPEUTICS PLC: Stocks/Bonds|NOVARTIS AG: Stocks/Bonds Michael H. Cynamon, MD, AN2: Grant/Research Support|AN2: Grant/Research Support.

An Alliance of Carbapenem-Resistant Klebsiella pneumoniae with Precise Capsular Serotypes and Clinical Determinants: A Disquietude in Hospital Setting

Carbapenemase-resistant Klebsiella pneumoniae (CRKP) is a genuine burden for physicians and researchers. We aimed at carbapenemase resistance and its relation with capsular serotyping in K. pneumoniae and studied some clinical determinants, which may influence the clinical infections. Initially, 61 K. pneumoniae isolates obtained from various clinical specimens were confirmed at the molecular level and then antimicrobial susceptibility test was performed followed by capsular serotyping performed by multiplex PCR. All isolates were subjected to the detection of carbapenemase genes including bla KPC, bla NDM-1, bla OXA-48, bla VIM, and bla IMP. Clinical and demographic data of all patients were reviewed including age, gender, underlying diseases, and the treatment obtained. Multidrug-resistance was a predominant feature in 77% K. pneumoniae strains. Presence of extended-spectrum beta-lactamase was detected phenotypically in 59% K. pneumoniae strains. Carbapenem resistance was noticed phenotypically in 24.6% isolates. bla OXA-48 and bla NDM-1 were the most frequent carbapenemase genes. bla NDM-1 positive isolates correlated with gentamicin, amikacin, imipenem, and meropenem resistance (p < 0.05). The nosocomial isolates mostly harbored bla OXA-48 gene (p < 0.02). Amongst all the K. pneumoniae isolates, 59% isolates could be typed and serotype K54 had the highest prevalence followed by K20 and K5. Correlation between the carbapenemase genes, serotype and type of infection showed that bla OXA-48 positive strains had a significant association with K20 serotype and urinary tract infections (p=0.2) while, K20 serotype and bla KPC positive strains were significantly associated with wound infections (K20, p=0.3 and bla KPC, and p=0.4). Mucoid phenotype was not found related to presence of specific carbapenemase genes or serotypes except serotype K20 (p < 0.001). Patients with monotherapy had treatment failure in comparison to the combination therapy for bla KPC-associated infections. In conclusion, the present investigation exhibited the significant association between K20 serotype with bla OXA-48. The predominance of K54 reveals the possibility of endemicity in our hospital setting. K. pneumoniae isolated from wound specimens significantly harbors K20 serotype and bla KPC gene. Comprehensive clinical information and the distribution of antibiotic resistance genes, and serotypes may play important roles in the treatment process.

Increasing trends of colistin resistance in patients at high-risk of carbapenem-resistant Enterobacteriaceae

Introduction Occurrence of colistin-resistant Enterobacteriaceae in response to the unregulated use of this antibiotic has been documented. This study reports an investigation of colistin resistance rates among carbapenem-resistant enterobacterial clinical isolates. Methods A total of 196 multidrug-resistant Enterobacteriaceae isolates (Klebsiella pneumoniae (n = 100), Escherichia coli (n = 89) and Enterobacter cloacae (n = 7) were selected from Gram-negative isolates over one year. Susceptibility to antimicrobials was determined using Vitek2. Broth microdilution method was used to detect colistin antimicrobial susceptibility. Identification of ESBL and carbapenemases were both done phenotypically and by PCR. Results All the studied isolates showed multidrug-resistant phenotypes with 51.5% resistance to carbapenems (meropenem, imipenem). Very low resistance rates towards tigecycline (n = 9) 4.6% were found. Thirty-nine isolates (19.9%) showed reduced susceptibility to colistin among the MDR isolates. Sixty-four isolates (32.7%) were ESBL producers. Hundred isolates (51%) were carbapenemase producers using Carba NP test. The PCR amplification results revealed that 40 isolates (20%) harboured NDM-1 and 40 isolates contained OXA-48-like gene. Coexistence of both (NDM-1 and OXA-48-like) was observed in nine (4.59%) isolates. A Statistically significant relationship was observed between carbapenem resistance and each of the followings; OXA-48 producers (p= .009), amikacin resistance (p = .000), gentamicin resistance (p = .032), tobramycin resistance (p = .000), and tigecycline resistance (p-value ≤ .001). A statistical significance was detected between ESBL-producing isolates and carbapenem susceptible isolates ESBL producers with p = 0.000. Conclusion An alarming sign is the increasing colistin resistance rates among carbapenem-resistant isolates. Aminoglycosides are still a therapeutic option to decrease the use of colistin and avoid further development of resistance. KEY MESSAGES High rates of colistin resistance among carbapenem-resistant Enterobacteriaceae. The choice of antibiotic is significantly associated with the clinical site of infection. Aminoglycosides are offered choices for treating multiple drug-resistant Enterobacteriaceae to preserve the colistin and carbapenems.

In silico evaluation of WHO-endorsed molecular methods to detect drug resistant tuberculosis

Universal drug susceptibility testing (DST) for tuberculosis is a major goal of the END TB strategy. PCR-based molecular diagnostic tests have been instrumental in increasing DST globally and several assays have now been endorsed by the World Health Organization (WHO) for use in the diagnosis of drug resistance. These endorsed assays, however, each interrogate a limited number of mutations associated with resistance, potentially limiting their sensitivity compared to sequencing-based methods. We applied an in silico method to compare the sensitivity and specificity of WHO-endorsed molecular based diagnostics to the mutation set identified by the WHO mutations catalogue using phenotypic DST as the reference. We found that, in silico, the mutation sets used by probe-based molecular diagnostic tests to identify rifampicin, isoniazid, pyrazinamide, levofloxacin, moxifloxacin, amikacin, capreomycin and kanamycin resistance produced similar sensitivities and specificities to the WHO mutation catalogue. PCR-based diagnostic tests were most sensitive for drugs where mechanisms of resistance are well established and localised to small genetic regions or a few prevalent mutations. Approaches using sequencing technologies can provide advantages for drugs where our knowledge of resistance is limited, or where complex resistance signatures exist.

Long-Read Whole Genome Sequencing Elucidates the Mechanisms of Amikacin Resistance in Multidrug-Resistant Klebsiella pneumoniae Isolates Obtained from COVID-19 Patients

Klebsiella pneumoniae is a Gram-negative, encapsulated, non-motile bacterium, which represents a global challenge to public health as one of the major causes of healthcare-associated infections worldwide. In the recent decade, the World Health Organization (WHO) noticed a critically increasing rate of carbapenem-resistant K. pneumoniae occurrence in hospitals. The situation with extended-spectrum beta-lactamase (ESBL) producing bacteria further worsened during the COVID-19 pandemic, due to an increasing number of patients in intensive care units (ICU) and extensive, while often inappropriate, use of antibiotics including carbapenems. In order to elucidate the ways and mechanisms of antibiotic resistance spreading within the K. pneumoniae population, whole genome sequencing (WGS) seems to be a promising approach, and long-read sequencing is especially useful for the investigation of mobile genetic elements carrying antibiotic resistance genes, such as plasmids. We have performed short- and long read sequencing of three carbapenem-resistant K. pneumoniae isolates obtained from COVID-19 patients in a dedicated ICU of a multipurpose medical center, which belonged to the same clone according to cgMLST analysis, in order to understand the differences in their resistance profiles. We have revealed the presence of a small plasmid carrying aph(3′)-VIa gene providing resistance to amikacin in one of these isolates, which corresponded perfectly to its phenotypic resistance profile. We believe that the results obtained will facilitate further elucidating of antibiotic resistance mechanisms for this important pathogen, and highlight the need for continuous genomic epidemiology surveillance of clinical K. pneumoniae isolates.