Abstract
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
bla
OXA
and
bla
NDM
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
bla
OXA-51
gene, while
bla
OXA-23
was present in 94.5%,
bla
VIM
in 37%, and
bla
NDM
in 14% of the isolates. The
bla
OXA-51
,
bla
OXA-23
, and
bla
OXA-24
genes co-existed in 13 (6.5%) isolates. CRACB isolates with co-existing
bla
OXA-23
,
bla
OXA-24
,
bla
NDM
,
bla
OXA-51
and
bla
VIM
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.