Characterization of Acinetobacter baumannii Isolated from Raw Milk

Abstract

Acinetobacter baumannii (A. baumannii) is an opportunistic pathogen associated with nosocomial infections. In this study, 100 raw milk samples were collected from Qena, Egypt, and subjected to conventional and molecular assays to determine the presence of A. baumannii and investigate their antimicrobial resistance and biofilm formation. Our findings revealed that, among the 100 samples, Acinetobacter spp. were found in 13 samples based on CHROM agar results. We further characterized them using rpoB and 16S-23SrRNA sequencing and gyrB multiplex PCR analysis and confirmed that 9 out of the 13 Acinetobacter spp. isolates were A. baumannii and 4 were other species. The A. baumannii isolates were resistant to β-lactam drugs, including cefotaxime (44%), ampicillin-sulbactam and levofloxacin (33.3% for each), imipenem, meropenem and aztreonam (22.2% for each). We observed different antimicrobial resistance patterns, with a multi-antibiotic resistant (MAR) index ranging from 0.2 to 0.3. According to the PCR results, blaOXA-51 and blaOXA-23 genes were amplified in 100% and 55.5% of the A. baumannii isolates, respectively, while the blaOXA-58 gene was not amplified. Furthermore, the metallo-β-lactamases (MBL) genes blaIMP and blaNDM were found in 11.1% and 22.2% of isolates, respectively, while blaVIM was not amplified. Additionally, eight A. baumannii isolates (88.8%) produced black-colored colonies on Congo red agar, demonstrating their biofilm production capacity. These results showed that, besides other foodborne pathogens, raw milk should also be examined for A. baumannii, which could be a public health concern.

Carbapenem-resistant Acinetobacter baumannii in Raw Milk from Egyptian Dairy Farm Animals with Subclinical Mastitis

“…Because CHROM agar contains chromogenic substrates that Acinetobacter spp. enzymes cleave to produce distinctive, red-colored Acinetobacter colonies, many researchers have recommended using this medium as a rapid and simple way to detect Acinetobacter, this finding supported by (Mohamed et al 2022).…”

“…Likewise, (Ndegwa et al 2001) discovered that from 21 goat milk samples in Kenya, 10 isolates of Acinetobacter spp were isolated. In Egypt, among the 100 milk samples, the authors found in 13 samples Acinetobacter spp based on CHROM agar results (Mohamed et al 2022).…”

Extensive Drug Resistance of Strong Biofilm-Producing Acinetobacter baumannii Strains Isolated from Infections and Colonization Hospitalized Patients in Southern Poland

“…For all strains, the multi-antibiotic-resistant (MAR) index was calculated. The MAR index is the number of antibiotics that an isolate is resistant to divided by the total number of antibiotics utilized in the study [ 28 ]. …”

Extensive Drug Resistance of Strong Biofilm-Producing <em>Acinetobacter baumannii</em> Strains Isolated from Infections and Colonization Hospitalized Patients in Southern Poland

“…For all strains, the multi-antibiotic-resistant (MAR) index was calculated. The MAR index is the number of antibiotics that an isolate is resistant to divided by the total number of antibiotics utilized in the study [28].…”