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Post-Operative Infection Risk Is Multi-factorial. Patient’s Health Status Is Key Risk Factor

  • Routine surgery on who? Man or woman? Young or old? Person without or with conditions that predispose to post-operative infections, e.g., immunodeficiency, immunosuppression, diabetes, obesity, etc.?
  • What does ‘routine surgery’ entail? Superficial or invasive? Brief, less than a couple of hours, or prolonged, more than 5 or 6 hours? With local or general anesthesia? Brief or prolonged post-operative hospital stay? Device inserted during surgery or not? Surgical site closed (healing by primary intention) or left open (healing by secondary intention)?
  • Clearly, post-operative infection is the outcome of multiple factors (1). Not just the skill and rigor of the surgical team, skill in performing the surgery and rigor in maintaining sterility while doing it. Not just post-operative care that minimizes exposure to potential pathogens. The health status of the patient itself is a major factor in their post-operative infection risk. After all, harboring those sickest within a population makes hospitals a magnet for disease-causing microbes. The word Nosocomial means Hospital-acquired infection. Thus, language itself teaches us that likelihood of catching infections is heightened in hospitals, which is where most surgeries are performed.

More Frequent, Deadly Hospital-Acquired Infections Are Collateral Cost Of Widespread Human-Driven Antibiotic Resistance

Hospital-acquired infections have become more frequent in recent years for a few reasons.

  • More of us live longer though not necessarily in the best of health in old age.
  • Next, and perhaps most importantly, unnecessary antibiotic use has fueled global bacterial antibiotic resistance (2). Since hospitalized patients are those sickest among us, they’re also more likely to harbor and spread antibiotic-resistant bacteria. Such resistant bacteria can easily evade even the most rigorous control methods in even the wealthiest of countries (3, 4, 5, 6, 7, 8).
  • Finally, unrealistic expectations on the part of caretakers fuel unnecessary, prolonged and extensive medical assistance. As Atul Gawande has written extensively, the unrealistic attempt to evade death at all costs has taken root in countries like the US (9, 10). Even when such interventions are clearly futile, continuing with them has become part of a rote script, a script that includes more antibiotic Rx. Many elderly thus spend considerable time in nursing homes and long-term acute care centers. Hand in glove, cost-cutting measures in healthcare mean errors are more, not less, likely as fewer staff are mandated to provide futile care for those seriously ill (11). This makes infection transmissions between patients more, not less, likely. In turn such places become stable sources of antibiotic-resistant bacteria (11).

Beyond such technicalities is the self-evident difficulty in getting trustworthy data. After all, hospitals aren’t going to advertise their rates of post-operative infections, are they? Thus, these rates could vary vastly from one hospital to another and from country to country.

Some Numbers On Post-Operative Infections

Surgical Site Infections (SSI): Defined as an infection occurring within 30 days post-operation, surgical site infections (SSI) (see figure below from 12) are among the most common post-operative complications.

  • Between 1986 and 1996, the US CDC (Centers for Disease Control and Prevention) performed one of the 1st comprehensive SSI assessments (1). They assessed ~600000 operations of which ~2.6% (15523) developed SSI. 551/15523 (3.5%) of SSI patients died and 77% of those deaths were attributed to SSIs.
  • 2002 data suggested SSI were cause of >8000 deaths per year in the US (13).
  • A 2008 four country survey examined rates of healthcare-associated infections (HCAI) across acute hospitals in England, Wales, Northern Ireland and the Republic of Ireland and found SSI to be the 3rd most frequent nosocomial infection among hospital patients (14).
  • SSI were estimated to occur in 2.3% of cases based on 2005-2010 data from 30 hospitals in America, Asia, Africa and Europe (15).

Device-Associated Healthcare-Associated Infections (DA-HAIs)

  • As medicine increasingly incorporates complex technologies, approaches such as central-line catheters (16) to continuously deliver medicine directly into the bloodstream have mushroomed. No surprise, device-associated healthcare-associated infections (DA-HAIs) have become a major risk in the ICU.
  • A 2005 Canadian study found they’re a major cause of patient morbidity and mortality (17).
  • A 2002 to 2004 survey of 21069 patients in 55 ICUs of 46 hospitals across Argentina, Brazil, Colombia, India, Mexico, Morocco, Peru and Turkey found 3095 (14.7%) DA-HAIs (18).
  • Starting in 2006, the non-profit INICC (International Nosocomial Infection Control Consortium) published 5 pooled, multinational studies that suggest DA-HAIs in developing countries are 3 to 5 times higher compared to more developed economies (19).

Longer Answer: Read On If Interested

Specific Example Of How Infections Can Spread In Hospitals In Spite Of Best Efforts To Stop Them

Though not calling cards and therefore not advertised, every now and then an example comes along that offers us in great detail the process by which deadly, multi-drug resistant infections can take root and spread through a hospital these days, stubbornly evading and outwitting even the most determined and costly efforts to eliminate them.

Considered one of the world’s premier research hospitals, the case of the 2011 KPC (Klebsiella pneumoniae carbapenemase-producing K. pneumoniae) outbreak at the 243-bed US National Institutes of Health (NIH) National Institutes of Health Clinical Center (CC) offers a tragic example of how deadly infections can spread through a hospital in spite of the best precautions humans can think to devise (3, 4).

  • Patient one: On June 13, 2011, a 43-year old lung transplant patient with complications is transferred to the US NIH CC from a New York City hospital. On carefully checking her medical records, an alert infection control consultant notes she’s known to harbor a highly resistant ‘super bug’ called KPC (5). K. pneumoniae is a normal human gut inhabitant. Problem with KPC is it’s acquired additional antibiotic resistance rendering it a multi-drug resistant ‘super bug’, leaving only two less-than-optimal antibiotic choices (colistin, tigecycline) to treat it. Never having dealt with a KPC-harboring patient previously, the NIH CC takes obvious and necessary precautions, placing this patient in strict isolation within the ICU. This meant everyone entering her room donned a new protective gown and gloves, and even rigorously washed their hands after. Even her medical equipment gets specially decontaminated (6). Meantime, all other ICU patients also get their throats and groins tested regularly to track if KPC’s spread from patient one (6, 7). At first, all is well. The patient spends 24 hours in the ICU, is transferred to a private room, briefly returns to the ICU on June 29, then recovers and is discharged on 15 July, 2011.
  • Patient #2: Weeks after patient one leaves, on August 5, 2011, a 34-year old male ICU cancer patient shows KPC infection. No overlap between the two patients, either in ICU presence or healthcare staff who cared for them. Suggests KPC’s somehow stably present in the ICU.
  • Patient #3: On August 15, 2011, a 27-year old female patient shows KPC infection.

And thus a dreadful, seemingly inexorable process unfolds over the next four months. Starting in August other patients start acquiring KCP at the rate of ~1 per week (8) and eventually, a total of 18 patients come down with KPC and 7 die (see below from 3, 4). KPC-positive patients weren’t just in the ICU but also among non-ICU, meaning KPC had somehow escaped out of the ICU. Since patients at the NIH CC are usually seriously ill and only there by invitation to participate in a clinical trial, some had recently undergone chemotherapy, some had Leaky gut syndrome, some had been on Medical ventilator, and some had been on central-line catheters. In other words, all seriously sick and most with medical interventions that increase chances of bloodstream infections.

While this unfolds, the hospital takes unprecedented measures to root out and eliminate KPC from its ICU.

  • Patients and staff are grouped to eliminate any scope that staff caring for someone with KPC comes in contact with someone who doesn’t.
  • Every patient is repeatedly checked for KPC by sampling multiple sites on their bodies.
  • Entire rooms are fumigated with peroxide.
  • Plumbing lines are ripped out and replaced.
  • Finally, even the ICU is rebuilt.

Yet none of this seems to help.

How did patient one’s KPC spread in spite of such efforts? Genetic sleuthing reveals strains isolated from all these subsequent patients resemble that found in patient one and the transmission was anything but straightforward. Mutations it acquired as it spread allowed the geneticists to decipher its transmission path (5). In fact, genetic sequencing suggested KPC spread from patient one’s in three clusters (7),

  • From patient one’s throat to patient three who, while infected and asymptomatic, spread it to patients five and two.
  • From patient one’s lung to patient four from whom it spread to every other patient except one.
  • From patient one’s lung to patient eight and not spreading beyond.

Patients one and four were in different wards and never in the ICU at the same time, suggesting a silent carrier linked them, one who remained undiscovered. KPC was spreading stealthily in ways that wouldn’t be picked up by patient throat and groin cultures, i.e., by standard surveillance practice. Then, just as mysteriously as it started, KPC stops spreading in December 2011. Stops spreading but ominously, doesn’t disappear.

  • In April 2012, a young Minnesota man with severe graft-versus-host disease and Pseudomonas aeruginosa-associated pneumonia is admitted to the CC.
  • Shortly after, he tests positive for KPC. Genetic sequencing shows it’s the same strain first isolated there in June 2011.
  • On September 7, 2012, this young man dies in the isolation ward.
  • Several days later NIH staff swab a handrail outside his room and culture the same KPC from it.

Funded by the US government, evidently cost is no bar at a place like the NIH CC when it comes to stopping spread of infections. Yet this example shows how nearly impossible it is to do so even there (see below from 5, emphasis mine).

‘What was unusual about the Clinical Center’s experience with KPC klebsiella was not that it had an outbreak but that it quickly identified it and responded with such vigor. According to epidemiologists, in many other hospitals the patients would simply have died of an unspecified bloodstream infection, without anyone ever knowing the precise cause of their illness or how the infection had spread.

That will likely change. DNA sequencing is rapidly becoming more affordable. As a result, all hospitals will eventually have access to the tools that now exist only at NIH and other very specialized hospitals. However, very few will be able to afford to take the steps NIH did to contain the outbreak.’

And that’s not all. Decades of unnecessary antibiotic use have made outbreaks of such deadly antibiotic-resistant ‘superbugs’ more, not less, inevitable. Rampant antibiotic use in global industrial livestock production means that antibiotics are now everywhere in our environment, having leached into soil and entered waterways (2), thereby applying antibiotic resistance-selection pressures on all manner of microbes everywhere, not just on those associated with humans. Since many antibiotic resistance mechanisms can be horizontally transferred between bacteria, stopping unnecessary human antibiotic consumption alone may not minimize chances of such outbreaks.

‘Superbugs’ like KPC are now spreading faster than our capacity to control them. See below from 20 the rate and extent of KPC spread across the US since just 1999. For example, 2010-2011 surveys in Maryland, the state in which the NIH CC is located, found that ~80% of hospitals in that state had identified at least one case of carbepenem-resistant enterobacteriaceae like KPC (5). As things stand, this means risk of post-operative infections is now counter-intuitively higher, especially among the elderly and those with pre-existing conditions.


1. Mangram, Alicia J., et al. “Guideline for prevention of surgical site infection, 1999.” American journal of infection control 27.2 (1999): 97-134. http://www.anes.pt/files/documen…

2. Tirumalai Kamala’s answer to If we know that overusing antibiotics will cause resistant bacteria, why do we still give out so much of it? Especially in some parts of the world?

3. Snitkin, Evan S., et al. “Tracking a hospital outbreak of carbapenem-resistant Klebsiella pneumoniae with whole-genome sequencing.” Science translational medicine 4.148 (2012): 148ra116-148ra116. Tracking a Hospital Outbreak of Carbapenem-Resistant Klebsiella pneumoniae with Whole-Genome Sequencing

4. Lau, A., et al. “Laboratory response to a KPC outbreak at the NIH Clinical Center. Abstr. 112th Gen.” Meet. Am. Soc. Microbiol (2012): 16-19. https://www.chromagar.com/fichie…

5. Washingtonian, John Buntin, June 4, 2013. Outbreak at NIH | Washingtonian

6. Promed, Sep 17, 2012. ProMED-mail post

7. Bethesda magazine, Bara Vaida, Jan-Feb, 2013. The KPC Killer

8. Wired, Maryn McKenna, Aug 24, 2012. The ‘NIH Superbug’: This Is Happening Every Day

9. New Yorker, Atul Gawande, May 11, 2015. America’s Epidemic of Unnecessary Care

10. Being Mortal: Medicine and What Matters in the End: Atul Gawande: 9780805095159: Amazon.com: Books

11. Scientific American, Judy Stone, Aug 24, 2012. The NIH Superbug Story a Missing Piece

12. Young, Pang Y., and Rachel G. Khadaroo. “Surgical site infections.” Surgical Clinics of North America 94.6 (2014): 1245-1264. http://saludesa.org.ec/bibliotec…

13. Klevens, R. Monina, et al. “Estimating health care-associated infections and deaths in US hospitals, 2002.” Public health reports (2007): 160-166. https://www.cdc.gov/HAI/pdfs/hai…

14. Smyth, E. T. M., et al. “Four country healthcare associated infection prevalence survey 2006: overview of the results.” Journal of Hospital Infection 69.3 (2008): 230-248. https://www.researchgate.net/pro…

15. Rosenthal, Victor D., et al. “Surgical site infections, International Nosocomial Infection Control Consortium (INICC) report, data summary of 30 countries, 2005–2010.” Infection Control & Hospital Epidemiology 34.06 (2013): 597-604.

16. Vox, Sarah Kliff, July 9, 2015. Do no harm: There’s an infection hospitals can nearly always prevent. Why don’t they?

17. Laupland, Kevin B., et al. “One-year mortality of bloodstream infection-associated sepsis and septic shock among patients presenting to a regional critical care system.” Intensive care medicine 31.2 (2005): 213-219. https://www.researchgate.net/pro…

18. Rosenthal, Victor D., et al. “Device-associated nosocomial infections in 55 intensive care units of 8 developing countries.” Annals of internal medicine 145.8 (2006): 582-591. https://www.researchgate.net/pro…

19. Rosenthal, V. D., et al. “International Nosocomial Infection Control Consortium (INICC) report, data summary of 43 countries for 2007-2012. Device-associated module.” American journal of infection control 42.9 (2014): 942. http://www.inicc.org/media/docs/…

20. https://microbewiki.kenyon.edu/i…