Minocycline

Antimicrobial susceptibility testing (AST) of isolates was performed based on the Clinical and Laboratory Standards Institute (CLSI 2022) on Mueller–Hinton agar [22 ]. Antibiotic discs based on the CLSI 2022 were chosen and included in the current study: Meropenem (10 mg), Trimethoprim/Sulfamethoxazole (1.25/23.75 mg), Levofloxacin (5 mg), Ampicillin/Sulbactam (10/10 µg), Piperacillin/Tazobactam (PTZ, 100 /10 µg), and Minocycline (30 mg) (Mast Group Ltd., UK) which was determined using Kirby-Bauer disc diffusion method supplementary Fig. 1 (S1). The MICs for Ceftazidime and Chloramphenicol were determined using the E-test method (S2) based on CLSI 2022.

Antimicrobial susceptibility testing of S. maltophilia isolates against meropenem (10 mg), imipenem (10 mg), trimethoprim/sulfamethoxazole (1.25/23.75 mg), levofloxacin (5 mg), and minocycline (30 mg) (Mast Group Ltd., UK) was determined using Kirby-Bauer disc diffusion method according to the criteria of the Clinical and Laboratory Standards Institute (CLSI 2020) guidelines [52 ]. The critical breakpoints of ceftazidime (30 mg) and ticarcillin/clavulanate (75/10 mg) of Pseudomonas aeruginosa were used for interpretation of the results because no breakpoints for S. maltophilia were recommended by the CLSI. The results of chloramphenicol (30 mg) and tigecycline (15 mg) were interpreted according to the CLSI breakpoints of Enterobacteriaceae and the Food and Drug Administration (FDA), respectively. The P. aeruginosa ATCC 27853 and S. maltophilia ATCC 13637 were used for susceptibility testing. Due to the intrinsic resistance nature of S. maltophilia to carbapenems, susceptibility to meropenem and imipenem was also determined to confirm the identity of the isolates [5 (link), 23 , 53 ].

Antimicrobial susceptibility testing was carried out by the Kirby–Bauer disc diffusion method according to Clinical and Laboratory Standards Institute (CLSI) [12 ] and breakpoint interpretations for including amikacin (30 µg), gentamicin (10 µg), tobramycin (10 µg), cotrimoxazole (trimethoprim–sulfamethoxazole) (25 µg), tigecycline (15 µg), doxycycline (30 µg), tetracycline (30 µg), minocycline (30 µg) ceftriaxone (30 µg), ceftazidime (30 µg), cefepime (30 µg), cefotaxime (30 µg), piperacillin/tazobactam (100/10 µg), ampicillin-sulbactam (10/10 µg), imipenem (10 µg), meropenem (10 µg), ciprofloxacin (5 µg), levofloxacin (5 µg), (Mast Group Ltd., Bootle, UK). The minimum inhibitory concentrations (MICs) of colistin (Colistin sulfate salt powder, Sigma-Aldrich, St. Louis, MO, USA) were determined using the broth microdilution method according to CLSI guidelines (CLSI, 2020). Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27,853 strains were used as the standard strains.