Dynamic Gene Clusters Mediating Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates

Acinetobacter baumannii: A multidrug-resistant pathogen, has emerged in Saudi Arabia

A significant opportunistic pathogen, Acinetobacter baumannii (A. baumannii) has evolved mechanisms of resistance to a wide variety of antimicrobials, including carbapenems. In this article, we assessed the prevalence, risk factors, antimicrobial sensitivity, and resistance mechanisms among A. baumannii in several locations in Saudi Arabia. Hospital-acquired infections caused by A. baumannii were prevalent in the country due to a variety of reasons, such as the high number of critically ill patients, the frequency of gastrointestinal colonization, and the widespread use of antimicrobial medications. There has been an increase in the frequency of A. baumannii strains that are resistant to several antimicrobials, including carbapenems. Hospitals are a breeding ground for multidrug-resistant A. baumannii due to the widespread use of broad-spectrum antibiotics, the potential for patient-to-patient transmission of the bacteria, the high risk of infection during invasive intensive care unit procedures, and the high frequency with which diabetic and cancer patients in hospitals undergo invasive diagnostic and therapeutic procedures. Combinations of colistin and tigecycline with carbapenems or other antibiotics remain the best treatment option and are relatively safe to treat patients with multidrug resistance (MDR) A. baumannii infections, despite the rising incidence of resistance to these drugs observed in many hospitals. The prevalence of multidrug-resistant A. baumannii in Saudi hospitals calls for in-depth research into the underlying molecular mechanisms of multidrug resistance. In addition, a better understanding of A. baumannii resistance patterns and the establishment of a treatment protocol to reduce the infection burden in Saudi Arabia could benefit from the implementation of a local antibiogram database in tandem with a national antimicrobial stewardship and infection prevention program.

Phenotypic and Genotypic Investigation of Carbapenem-Resistant Acinetobacter baumannii in Maharaj Nakhon Si Thammarat Hospital, Thailand

(1) Background: Acinetobacter baumannii is well known as a causative agent of severe hospital-acquired infections, especially in intensive care units. The present study characterised the genetic traits of biofilm-forming carbapenem-resistant A. baumannii (CRAB) clinical isolates. Additionally, this study determined the prevalence of biofilm-producing A. baumannii isolates from a tertiary care hospital and investigated the association of biofilms with the distribution of biofilm-related and antibiotic resistance-associated genotypes. (2) Methods: The 995 non-duplicate A. baumannii isolates were identified, and their susceptibilities to different antibiotics were determined using the disk diffusion method. Using the modified microtiter plate assay, the CRAB isolates were investigated for their biofilm formation ability. Hemolysin and protease activities were determined. CRABs were subjected to polymerase chain reaction (PCR) assays targeting blaVIM, blaNDM, blaIMP, blaOXA-23-like, blaOXA-24-like, blaOXA-51-like, csuE and pgaB genes. Individual CRAB isolates were identified for their DNA fingerprint by repetitive element sequence-based (REP)-PCR. (3) Results: Among all A. baumannii isolates, 172 CRABs were identified. The major antibiotic resistance gene among the CRAB isolates was blaOXA-51-like (100%). Ninety-nine isolates (57.56%) were biofilm producers. The most prevalent biofilm gene was pgaB (79.65%), followed by csuE (76.74%). Evidence of virulence phenotypes revealed that all CRAB exhibited proteolytic activity; however, only four isolates (2.33%) were positive for the hemolytic-producing phenotype. REP-PCR showed that 172 CRAB isolates can be divided into 36-DNA fingerprint patterns. (4) Conclusions: The predominance of biofilm-producing CRAB isolates identified in this study is concerning. The characterisation of risk factors could aid in controlling the continual selection and spreading of the A. baumannii phenotype in hospitals, thereby improving patient care quality.

Occurrence of Multidrug-Resistant Strains of Acinetobacter spp.: An Emerging Threat for Nosocomial-Borne Infection in Najran Region, KSA

Multidrug-resistant strains are frequent causes of nosocomial infections. The majority of nosocomial infections, particularly in critical care units (ICU), have been linked to A. baumannii, which has major clinical significance. The current paper attempts to identify the potential risk and prognosis factors for acquiring an infection due to A. baumannii compared to that of other nosocomial bacteria. In our study, we employed antibiotics generally prescribed for the initial course of treatment such as colistin, meropenem, amikacin, trimethoprime-sulfamethoxazole, levofloxacin, gentamicin, ciprofloxacin, and piperacillin-tazobactam. We found that the isolated A. baumannii were resistant at a high rate to meropenem, piperacillin-tazobactam, amikacin, levofloxacin, and ciprofloxacin, while they were partially susceptible to trimethoprim-sulfamethoxazole. Our study revealed that A. baumannii was most susceptible to gentamicin and colistin at 85.8% and 92.9%, respectively, whereas the combination of colistin and trimethoprim/sulfamethoxazole was 100% active. The patients were the primary source of infection with A. baumannii, followed by inanimate objects present in the ICU and hospital premises, and then the hospital staff who were taking care of the ICU patients. Gentamicin and colistin were the most sensitive antibiotics; of the 13 tested in total, the rate of drug resistance was above 50%. The very high rate of antibiotic resistance is alarming.

Carbapenem resistance gene crisis in A. baumannii: a computational analysis

Acinetobacter baumannii (A. baumannii) is one of the members of ESKAPE bacteria which is considered multidrug resistant globally. The objective of this study is to determine the protein docking of different antibiotic resistance gene (ARGs) in A. baumannii. In silico analysis of antibiotic resistance genes against carbapenem are the blaOXA-51, blaOXA-23, blaOXA-58, blaOXA-24, blaOXA-143, NMD-1 and IMP-1 in A. baumannii. The doripenem, imipenem and meropenem were docked to blaOXA-51 and blaOXA-23 using PyRx. The top docking energy was -5.5 kcal/mol by imipenem and doripenem and meropenem showed a binding score of -5. 2 kcal/mol each and blaOXA-23 energy was -4.3 kcal/mol by imipenem and meropenem showed a binding score of -2.3 kcal/mol, while doripenem showed the binding score of -3.4 kcal/mol. Similarly, doripenem imipenem and meropenem were docked to blaOXA-58, IMP-1, Rec A and blaOXA-143, with docking energy was -8.8 kcal/mol by doripenem and meropenem each while imipenem showed a binding score of -4.2 kcal/mol and with IMP-1 demonstrated their binding energies. was -5.7 kcal/mol by meropenem and doripenem showed a binding score of -5.3 kcal/mol, while imipenem showed a binding score of -4.5 kcal/mol. And docking energy was -4.9 kcal/mol by imipenem and meropenem showed binding energy of -3.6 kcal/mol each while doripenem showed a binding score of -3.9 kcal/mol in RecA and with blaOXA-143 docking energy was -3.0 kcal/mol by imipenem and meropenem showed a binding score of -1.9 kcal/mol, while doripenem showed the binding score of -2.5 kcal/mol respectively. Doripenem, imipenem, and meropenem docking findings with blaOXA-24 confirmed their binding energies. Doripenem had the highest docking energy of -5.5 kcal/mol, meropenem had a binding score of -4.0 kcal/mol, and imipenem had a binding score of -3.9 kcal/mol. PyRx was used to dock the doripenem, imipenem, and meropenem to NMD-1. Docking energies for doripenem were all - 4.0 kcal/mol, whereas meropenem had docking energy of -3.3 kcal/mol and imipenem was -1.50 kcal/mol. To the best of our knowledge the underlying mechanism of phenotypic with genotypic resistance molecular docking regarding carbapenem resistance A. baumannii is unclear. Our molecular docking finds the possible protein targeting mechanism for carbapenem-resistant A.baumannii.

A review on the mechanistic details of OXA enzymes of ESKAPE pathogens

The production of β-lactamases is a prevalent mechanism that poses serious pressure on the control of bacterial resistance. Furthermore, the unavoidable and alarming increase in the transmission of bacteria producing extended-spectrum β-lactamases complicates treatment alternatives with existing drugs and/or approaches. Class D β-lactamases, designated as OXA enzymes, are characterized by their activity specifically towards oxacillins. They are widely distributed among the ESKAPE bugs that are associated with antibiotic resistance and life-threatening hospital infections. The inadequacy of current β-lactamase inhibitors for conventional treatments of 'OXA' mediated infections confirms the necessity of new approaches. Here, the focus is on the mechanistic details of OXA-10, OXA-23, and OXA-48, commonly found in highly virulent and antibiotic-resistant pathogens Acinetobacter baumannii, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Enterobacter spp. to describe their similarities and differences. Furthermore, this review contains a specific emphasis on structural and computational perspectives, which will be valuable to guide efforts in the design/discovery of a common single-molecule drug against ESKAPE pathogens.