The Molecular Detection of Class B and Class D Carbapenemases in Clinical Strains of Acinetobacter calcoaceticus-baumannii Complex: The High Burden of Antibiotic Resistance and the Co-Existence of Carbapenemase Genes

• Published in: Antibiotics (Basel) Vol. 11; no. 9; p. 1168
• Main Authors: Ejaz, Hasan, Qamar, Muhammad Usman, Junaid, Kashaf, Younas, Sonia, Taj, Zeeshan, Bukhari, Syed Nasir Abbas, Abdalla, Abualgasim E., Abosalif, Khalid O. A., Ahmad, Naveed, Saleem, Zikria, Salem, Eman H. M.
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 30.08.2022; MDPI
• Subjects: Acinetobacter calcoaceticus; Acinetobacter calcoaceticus-baumannii; Amides; Amikacin; Antibiotic resistance; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; blaNDM; blaOXA; Carbapenemase; Carbapenems; Ciprofloxacin; Colistin; Critical care; Drug resistance; Genes; Hospitals; Infections; Intensive care; Intensive care units; Mortality; Pathogens; Phenotypes; Pneumonia; Secretions; Tigecycline; β Lactamase; β-Lactam antibiotics; β-lactams; Pakistan
• ISSN: 2079-6382; 2079-6382
• DOI: 10.3390/antibiotics11091168

The emergence of carbapenem-resistant Acinetobacter calcoaceticus-baumannii complex (CRACB) in clinical environments is a significant global concern. These critical pathogens have shown resistance to a broad spectrum of antibacterial drugs, including carbapenems, mostly due to the acquisition of various β-lactamase genes. Clinical samples (n = 1985) were collected aseptically from multiple sources and grown on blood and MacConkey agar. Isolates and antimicrobial susceptibility were confirmed with the VITEK-2 system. The modified Hodge test confirmed the CRACB phenotype, and specific PCR primers were used for the molecular identification of blaOXA and blaNDM genes. Of the 1985 samples, 1250 (62.9%) were culture-positive and 200 (43.9%) were CRACB isolates. Of these isolates, 35.4% were recovered from pus samples and 23.5% from tracheal secretions obtained from patients in intensive care units (49.3%) and medical wards (20.2%). An antibiogram indicated that 100% of the CRACB isolates were resistant to β-lactam antibiotics and β-lactam inhibitors, 86.5% to ciprofloxacin, and 83.5% to amikacin, while the most effective antibiotics were tigecycline and colistin. The CRACB isolates displayed resistance to eight different AWaRe classes of antibiotics. All isolates exhibited the blaOXA-51 gene, while blaOXA-23 was present in 94.5%, blaVIM in 37%, and blaNDM in 14% of the isolates. The blaOXA-51, blaOXA-23, and blaOXA-24 genes co-existed in 13 (6.5%) isolates. CRACB isolates with co-existing blaOXA-23, blaOXA-24, blaNDM, blaOXA-51 and blaVIM genes were highly prevalent in clinical samples from Pakistan. CRACB strains were highly critical pathogens and presented resistance to virtually all antibacterial drugs, except tigecycline and colistin.