From the Guidelines
No, Serratia marcescens and Serratia fonticola do not share the same intrinsic antibiotic resistance profiles. While both are members of the Serratia genus, they differ significantly in their natural resistance patterns.
- Serratia marcescens is known to have acquired plasmid-mediated metallo-lactamases active against carbapenems and antipseudomonal penicillins and cephalosporins, such as IMP-1, which first appeared in Japan in 1991 and has since spread to other gram-negative pathogens 1.
- In contrast, there is no mention of Serratia fonticola having the same level of intrinsic resistance or acquiring such metallo-lactamases in the provided evidence.
- The difference in intrinsic resistance between the two species is crucial for clinical decision-making, particularly in empiric antibiotic selection.
- For S. marcescens infections, third-generation cephalosporins, fluoroquinolones, or carbapenems are often necessary, whereas S. fonticola may be susceptible to a broader range of antibiotics.
- These resistance differences stem from variations in chromosomally encoded beta-lactamases and efflux pumps between the species, similar to those seen in Pseudomonas aeruginosa 1.
- Antimicrobial susceptibility testing is essential to guide appropriate therapy for both species, as they can acquire additional resistance mechanisms beyond their intrinsic profiles.
From the Research
Intrinsic Antibiotic Resistance of Serratia marcescens and Serratia fonticola
- There are no direct studies comparing the intrinsic antibiotic resistance of Serratia marcescens and Serratia fonticola in the provided evidence.
- However, studies on Serratia marcescens show that it has intrinsic resistance to certain antibiotics, such as benzylpenicillin, oxacillin, and tetracycline 2.
- Serratia marcescens also exhibits uniform natural sensitivity to most aminoglycosides, several acylureidopenicillins, ticarcillin, newer cephalosporins, carbapenems, aztreonam, quinolones, and antifolates 2.
- The natural antibiotic susceptibility of Serratia marcescens and other Serratia species, including S. liquefaciens, S. proteamaculans, and S. grimesii, has been examined, but there is no mention of Serratia fonticola in these studies 3, 2.
- Serratia marcescens has been found to be resistant to various antibiotics, including ceftriaxone, ceftazidime, and piperacillin/tazobactam, but susceptible to cefotaxime and gentamicin 4, 5.
Comparison with Other Serratia Species
- Studies have compared the antibiotic susceptibility of Serratia marcescens with other Serratia species, such as S. liquefaciens, S. proteamaculans, and S. grimesii 3, 2.
- These studies have found species-related differences in susceptibility to certain antibiotics, but there is no information on Serratia fonticola.
- The lack of data on Serratia fonticola makes it difficult to determine whether it shares the same intrinsic antibiotic resistance as Serratia marcescens.