Yes, indeed at the superbug, the multi drug resistant Staphylococcus aureus. Generally referred to as Methicillin resistant Staphylococcus aureus (MRSA for short) this strain is not only resistant to the beta lactam antibiotic methicillin(production and use of which have since been discontinued) but also to subsequent generations of more potent versions of such as oxacillin, nafcillin, cloxacillin, flucloxacillin, dicloxacillin etc. Indiscriminate use of antibiotics has given rise to multi drug resistant bacteria. Sturdier strains evolve naturally as part of survival strategy. Currently methicillin resistant S. aureus, vancomycin resistant enterococci, and third generation cephalosporin resistant gram negative bacteria all have become a reality. For quite sometime now the last remaining weapon in our armoury has been carbapenem, and suspicions abound that carbapenem resistant varieties too have made their appearance. According to WHO report (2014) in a couple of decades antimicrobial resistance will pose more dangers to mankind than perhaps even cancer.
Multi drug resistant Staphylococcus aureus is the root cause of alarmingly high percentages of hospital associated infections (HA-MRSA) and community associated infections (CA-MRSA). It is known that one of the niche sites where S.aureus sets up colonies in human body is the nasal passage. But amazingly, only 30% of the human population permit S.aureus to colonize in their the nasal passage. So how does the rest 70% prevent S.aureus colonisation? What is the barrier? An interdisciplinary research team at Tubingen University (Germany) sought answers to this key question. Samples of nasal microbiota were collected, screened and analysed which revealed that in presence of Staphylococcus lugdunensis, S. aureus just couldn't survive. The team then conducted experiments on cotton rats, the well established model for studying infectious diseases because they are vulnerable to various human pathogens. Focused studies revealed that S. lugdunensis secretes a compound which proves lethal to S. aureus. The compound has been named lugdunin.
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| Lugdunin (courtesy:wikipedia) |
Zipperer et al tested the efficacy of lugdunin against several other pathogenic bacteria and found the results extremely encouraging. The team feels that lugdunin could open up a new class of antibiotics: Macrocyclic thiazolidine peptide antibiotics. This might prove to be a paradigm shift from the beta lactam family of antibiotics which bacteria have learned to counter.
But again we need to tread cautiously, because S.lugdunensis is neither benign nor innocuous; it is pathogenic and can cause cardio-vascular and soft tissue infections. Indiscriminate use of lugdunin shouldn't create another Frankenstein.
Tailpiece:
References:
2. Carbapenems: Past, present and future: Antimicrobial agents and Chemotherapy Papp-Wallace et al 55(11) 4943-4960, 2011
3. The role of nasal carriage in Staphylococcus aureus infections: Lancet Infectious
diseases5 751-762 (2005)
4. Human commensals producing a novel antibiotic impair pathogen colonization: Zipperer et al Nature(28 July 2016) vol.535, pp511-516.
