An examining study was carried out at the Microbiology Laboratory of JOOTRH, Kisumu county-Kenya on the stock isolates from the intensive care unit (ICU) swabs which shows Multidrug resistance. The samples were thawed and inoculated on blood agar (BA), Mac-conkey agar (MA) and chocolate agar (CA) using standard protocol [18]. BA and MacConkey agar plates were incubated aerobically, while CBA plates were incubated in anaerobic condition at 37⁰C for 24 to 48 hours in the incubator. The isolates were identified by colony morphology, Gram staining reaction and the biochemical properties [18]. The antimicrobial susceptibility test of isolates was performed by disk diffusion technique method using the standard guidelines and interpretive criteria of the CLSI (2022) [19]. The tests were performed by making a series of antibiotic concentrations on Mueller–Hinton agar plates. A reference strain, P. aeruginosa spp. ATCC^® 12934 and S. aureus ATCC^® 29213 were used as control. All the data were entered in SPSS version 20 and Excel 2019. Statistical analyses were done using the same software.

Biofilm formation inhibition assay
As described by Awuor et al. [16], microtiter plate assay was performed to quantify the effect of commonly used antibiotics on the biofilm formation of Acinetobacter baumannii. strains. The test bacteria were first inoculated on Luria-Bertani medium (LB) agar and incubated at 37 °C overnight. Then a colony was identified, picked and inoculated in 10 ml of LB broth and incubated at 37 ˚C overnight while shaking at 100 r.p.m. for 18 h. By use of a parafilm the flat-bottomed polystyrene tissue culture microplate was sealed for purposes of preventing medium evaporation. After 48 h incubation, the wells were carefully rinsed with double-distilled water to remove loosely attached cells. The microplate was air-dried for 1 h before adding 200 μL per well of 0.4 % crystal violet (CV) solution to the adhered cells in the wells and then stood at room temperature for 15 min. Excess stain was removed by rinsing the wells gently with 200 μL per using distilled water. This was repeated thrice. The microtiter plate was then air-dried for 1 h after, followed by addition of 200 μL of absolute ethanol to each well to solubilize the dye. The OD was measured at OD_590nm using a Safire Tecan-F129013 Microplate Reader (Tecan, Crailsheim, Germany). For each experiment, background staining was corrected by subtracting

the crystal violet bound to un-treated controls (Blank) from those of the tested sample. The experiments were done in triplicate and average OD_590nm values were calculated. To estimate the antibiofilm activity (Abf A) of a given antibiotic the following equation was used.

Abf A (%) = (1-(OD_{Test sample} - OD_Blank)/ (OD _{Untreated sample} - OD _Blank) × 100.

Detection of other virulence factors of Acinetobacter baumannii.

Detection of haemolysin
Haemolysin production by the Acinetobacter baumannii isolates were detected following protocols by Benson et al. [16]. The β-haemolytic activity was tested for on base agar (Himedia, India) supplemented with 7 % sheep erythrocytes for 18–24 h. Pure isolates were cultured on TSA, before streaking on blood agar and further incubated for 24 h at 37 °C. Zones of haemolysis around the colonies indicated the ability of these bacteria to haemolyse RBCs [39].

Detection of protease
To detect protease production by the Acinetobacter baumannii isolate skim milk agar was used and the protocol that was described in [16]. Briefly, two solutions (A and B) were made and used in this study. Solution A was prepared by adding 10 g skim milk to 90 ml of distilled water then volume was completed to 100 ml gently heated at 50 °C, then autoclaved and cooled to 50–55 °C. And solution B was also prepared by adding 2 g of agar powder to 100 mL of distilled water, mixed thoroughly, then autoclaved and cooled to 50–55 °C. Aseptically, 100 ml of solution A was mixed with 100 mL of solution B. Then the mixture was poured into sterile petri dishes, and then stored at 4 °C until use. This media is used to detect the ability of the bacteria to produce protease. The appearance of a cleared hydrolysis zone indicates a positive test [17].

Detection of lipase
Lipase production ability by Acinetobacter baumannii isolates were determined by methods outlined by Elliot et al. [17]. Briefly, a single colony of an overnight growth was cultured on Rhan medium, and then incubated for 1–5 days at 37 °C. The appearance of a turbid zone around colonies indicates a positive result [16].

Detection of lecithinase (phospholipase)
To detect lecithinase, I followed a standard procedure [18]. One pure colony was cultured on a medium of phospholipase activity assay followed by incubation for 1–3 days at 37 °C using established procedures [17]. The appearance of a white to brown colour elongated precipitated zone around colonies is considered a positive result [17].

Validity and reliability
All experiments were conducted in triplicates that were independent of each other to validate reproducibility.

Data analysis
Statistical analysis was performed using Graph pad. Data on socio-demographics were summarized by frequencies and percentages. All values of diameter zones of inhibition are reported as mean ± standard error.

Ethical consideration
Confidentiality and privacy were strictly adhered to and no names of individuals were recorded or made known in the reporting of information. The study was granted ethical clearance by the Institutional Research Ethics Committee (IREC) at Jaramogi Oginga Odinga Teaching and Referral Hospital (JOOTRH).