Which came first – the antibiotic or the resistance? How infection control and MRSA are related

What challenges do we have to face in relation to MRSA? We asked one of the most profound experts in this field, Dr. Fred Tenover, Vice President for Scientific Affairs at Cepheid and Consulting Professor at the University of Stanford. His most important message in this context: infection control works!

Mr. Tenover, your publication on the emergence of vancomycin resistance in Staphylococcus aureus is among your most cited papers. This was in 1999. Now, exactly 20 years later, the situation has become much more dangerous. The germ seems to be resistant even against antibiotics of last resort. How do you deal with such a phenomenon on the part of infection control?

First and foremost, don’t give up. We are making progress. The majority of Staphylococcus aureus infections, including methicillin-resistant strains (i.e., MRSA), are still treatable even though the choice of antimicrobial agents available to physicians may be growing smaller. Screening and decolonization is still an effective pre-surgical strategy. From the infection control perspective, our jobs have never been more important in terms of limiting the spread of multidrug resistant organisms, including MRSA and the rare but scary vancomycin-resistant S. aureus (VRSA). Collaboration and communication are the keys to success. Working with both the microbiology laboratory and hospital epidemiologist to stay informed of patients who are infected is critical. Most importantly, look at the data – in many places, MRSA rates are declining. Infection control works!

Staphylococcus aureus was the first bacterium in which penicillin resistance was found (1947) – just four years after the drug started being mass-produced. Despite this fact, antibiotics were often used carelessly in the last decades. Which measures must be taken to reduce antibiotic consumption in the future?

Dr. William Kirby at the University of Washington in Seattle described the first beta-lactamase (penicillinase) producing S. aureus strain in 1944. However, it wasn’t until 22 years later that Dr. Kirby collaborated with Dr. Alfred Bauer to standardize the disk diffusion susceptibility testing method (the Kirby-Bauer method), which gave the laboratory an easy way to test bacteria for resistance. Despite major advances in microbiology laboratory techniques (including culture, susceptibility testing, and rapid molecular methods) many physicians still treat infections empirically, i.e., without the benefit of laboratory data.  In many cases, this means treating patients who have viral infections or in some cases patients who have no infection at all. One of the major goals of antimicrobial stewardship programs is to make prescribing evidence-based. This means using laboratory data to change empiric therapy to targeted therapy. We all have to become proficient antibiotic stewards.

How important is the topic of hand disinfection in this context? Is MRSA a germ that is transmitted easily by hands?

Hand hygiene remains a cornerstone of infection prevention. MRSA is just one of many infectious diseases that are transmitted via the hands of healthcare works, patients, and others in a hospital. Wash those hands!

In your publications you often speak about MRSA as a community-acquired (CA) pathogen. Which groups of people are particularly affected by this phenomenon? And how serious is it?

Community-acquired MRSA is an equal opportunity pathogen. In fact, young healthy individuals in the community are as much at risk as immunocompromised patients in a hospital. The early days of community-acquired MRSA saw professional athletes, healthy college students, and otherwise healthy prisoners acquiring very severe MRSA infections, losing limbs, and in several cases even dying within 48 hours of getting an infection. What made the discovery of community-acquired MRSA infections so troubling was the severity of the disease as being seen. This remains a critical public health problem globally. In fact, in a number of hospitals, the rates of community-acquired MRSA bacteremia equal or exceed those of hospital-acquired disease.

How is the evolution of MRSA connected to patient safety and hospital hygiene? Can you forge a bridge in that regard?

The evolution of MRSA is a fascinating constellation of events including increasing complexity of antimicrobial resistance mechanisms, acquisition and expression of novel virulence genes, increased ability to colonize humans and animals, and shifting epidemiological patterns among human and animal hosts, including livestock. We should not think of preventing the spread of MRSA in hospitals and communities as though MRSA was a single entity. Resistance patterns, virulence factors, and the epidemiology of disease will vary from place to place and the infection-prevention-community need to recognize that to be effective. I am convinced that there is no “one size fits all” when it comes to infection prevention. I first became aware of this while working in the Hospital Infections Program at the Centers for Disease Control and Prevention in Atlanta over 20 years ago. What worked in one hospital did not necessarily work in another. For example, a large, urban 600-bed tertiary care hospital with a 100-bed nursing home attached to it has different issues than a 250-bed community hospital in a farming community. Your approach to infection prevention must address your hospital, your community, your patients, and your resources. Once again, we are making progress in controlling the spread of MRSA, so we must be relentless at getting our colleagues to wash their hands, use gloves and gowns effectively when needed, and respect the ability of MRSA to adapt to any novel environment.


Dr. Fred Tenover will be giving a speech about “The ongoing evolution of MRSA – does it matter for infection control” at our 3rd CEE Conference on Hospital Hygiene and Patient Safety on 13 March.