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Effect of some antibiotics on pigmentation in Serratia marcescens
M Anğ-Küçüker1, O Büyükbaba-Boral, V Tolun
1Department of Microbiology, Istanbul Medical Faculty, Capa.
Abstract:
Serratia marcescens is characterized by its ability to produce a red pigment called prodigiosin. It is well known that there are some substances affecting pigmentation in bacteria. Cefoxitin, erythromycin, tobramycin, co-trimoxazole, imipenem and nitrofurantoin were found to have an inhibitory effect on pigmentation in a S. marcescens strain isolated from urine. It was also shown that the LD50 dose determined by inoculation of eight-week-old BALB/c mice with serial dilutions of overnight cultures of pigmented and nonpigmented variants was lower (LD50 = 300 x 10(3.94)) in the nonpigmented variant than in the pigmented one (LD50 = 300 x 10(5.58)). In addition, the Sereny test showed that in contrast to the pigmented variant, the nonpigmented variant caused keratitis in guinea pig eye.
Insights
Certain antibiotics inhibit the red pigment prodigiosin production in Serratia marcescens. Nonpigmented variants of this bacterium showed increased virulence in mice and caused eye infections in guinea pigs.
Area of Science:
- Microbiology
- Bacterial Pigmentation
- Antimicrobial Effects
Background:
- Serratia marcescens produces a red pigment, prodigiosin.
- Bacterial pigmentation can be influenced by various substances.
- Antibiotic resistance and virulence factors are critical in clinical microbiology.
Purpose of the Study:
- To investigate the effect of specific antibiotics on prodigiosin production in Serratia marcescens.
- To compare the virulence of pigmented and nonpigmented variants of S. marcescens.
- To assess the pathogenicity of S. marcescens variants using animal models.
Main Methods:
- Testing the inhibitory effect of cefoxitin, erythromycin, tobramycin, co-trimoxazole, imipenem, and nitrofurantoin on S. marcescens pigmentation.
- Determining the LD50 (lethal dose for 50% of subjects) in BALB/c mice for pigmented and nonpigmented variants.
- Conducting the Sereny test on guinea pig eyes to evaluate keratitis induction.
Main Results:
- Cefoxitin, erythromycin, tobramycin, co-trimoxazole, imipenem, and nitrofurantoin inhibited prodigiosin production in the tested S. marcescens strain.
- The nonpigmented variant exhibited a significantly lower LD50 in mice compared to the pigmented variant.
- The nonpigmented S. marcescens variant induced keratitis in guinea pigs, unlike the pigmented variant.
Conclusions:
- Several common antibiotics can suppress prodigiosin synthesis in Serratia marcescens.
- Loss of pigmentation in S. marcescens is associated with increased virulence and pathogenicity.
- Pigmentation may play a role in the attenuation of Serratia marcescens virulence.