Comparison of the Effects of Antibiotic Sensitivity and Physical Parameters on the Growth of <i>Burkholderia cepacia</i> complex and <i>Burkholderia cenocepacia</i>

Abstract

B<i>urkholderia cepacia</i> complex (Bcc) has been tied to various FDA drug recalls over the past years. It was found that these bacteria can survive on a broad range of molecules in oxygenic and anoxygenic environments as well as sterilized and non-sterilized environments. The main research question focused on how physical requirements and antibiotics can be used to control Bcc and <i>B. cenocepacia </i>growth. Four replicates of TSB tubes that had pH 4, 6, 7, and 8 were inoculated with Bcc and <i>B. cenocepacia</i> and incubated overnight at 4, 20, 25, 37, and 85°C. The transmission readings of the broth cultures were measured to estimate bacterial growth using a Genesys 2 spectrophotometer. The Kirby-Bauer test was performed using Polymyxin, Ticarcillin, Ticarcillin with Clavulanic acid, Penicillin, Ampicillin, Chloramphenicol, Tetracycline, Erythromycin, and Streptomycin. The E-test was performed using gradient strips of Cefiderocol (C) l (0.016-256 mg/L) and Imipenem-relebactam (IR) (0.002/4-32/4 mg/L). The antibiotic dilution test was performed for Chloramphenicol and Tetracycline after observing larger zones of inhibitions with the Kirby-Bauer test. There was no visible growth of Bcc and <i>B cenocepacia</i> at 4°C and 85 °C at any pH and pH 4 across the temperatures. However, subcultures showed bacterial growth the following day. The growth rates increased significantly at 25 and 37°C as well as pH 6 and 7. The average diameters of the zones of inhibitions of PXB, TCC, TIC, C30, and TE30 for Bcc were 1.3, 3.7, 3.1, 2.0, and 1.16 mm and for <i>B. cenocepacia</i> were 0, 1.2, 1.3, 1.1, and 1.6 mm, respectively. Both Bcc and <i>B. cenocepacia</i> were resistant to P10, AM10, E15, and S10. MIC for the E-test of Bcc and <i>B. cenocepacia</i> for IR and C were 0.67 and 10 and 0.88 and 0. 016. mg/L, respectively. MIC and MBC for the dilution test of the C30 and TE30 for Bcc were 1 and 8 and 64 and 128 and <i>B. cenocepacia</i> 8 and 128 and 16 and 128 µg/ml. These bacteria had faster growth rates with no significant difference in their growth under the various temperature and pH conditions used. The research concluded that both Bcc and <i>B. cenocepacia</i> can grow in typical storage conditions such as 4°C and pH 4, without showing any visible signs of growth. This study showed that <i>B. cenocepacia</i> has significantly higher resistance to antibiotics than Bcc. These results are beneficial for developing strategies to prevent <i>Burkholderia</i> cross-contamination in clinical environments.