The World Health Organization defines nosocomial infections as those acquired in the hospital by patients admitted for a reason other than that infection, and also includes occupational exposures among the staff of health-care facilities. Over the years, these infections have constantly posed a great danger not only to the sick, but also to those who take care of them. It has also taken a toll on hospital and other health resources: in 1995 in the US alone, it has cost US$4.5 B, leading to more than 88,000 deaths. Institution of infection surveillance and control programs have lead to reductions in nosocomial infection rates; however, occasional breaks in standard precautions and inherent host-parasite risks can sometimes lead to dramatic cases of inpatient and health-care worker infection. The agents, their targets, and the environment may vary from case to case, but all exemplify the grave consequences of keeping the chain of transmission intact.

Age-old and Emerging Infections

    Staphylococci, Pseudomonas, and Escherichia coli have been historically known as the nosocomial infection troika. In the earlier days, Gram-positive cocci, especially streptococci and Staphylococcus aureus, were the pathogens of major concern. Major problems caused by these organisms culminated in the S. aureus phage type 94/96 pandemic of 1940 to 1950. By the 1970s, Gram-negative bacilli, particularly Pseudomonas aeruginosa and Enterobacteriaciae, have become synonymous with nosocomial infection, while the late 1980s to the early 1990s signaled the return of methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE)-the so-called "blue bugs."

    The last decade, meanwhile, has witnessed the emergence of multidrug resistant non-Enterobacteriaciae organisms. In 1991, the first nosocomial outbreak of carbapenem-resistant Acinetobacter baumannii (CRAB) took place in the US, and since then, has been reported in several countries worldwide, including the rapid emergence, from zero before 1998 to 6.5 percent in 2000, of a pandrug resistant isolate in Taiwan.

    A patient on cardiac pacemaker suddenly developed fever. After extensive work-up, it was found that the infection was caused by a strain of Staphylococcus that was most probably coming from the implant. No pacemaker was available at that time, so the patient was first started on oxacillin, one of the first-line drugs against the organism. Later on, the strain turned out to be resistant, and there was no other recourse but to put him on vancomycin, the drug-of-last resort for such non-responsive infections.

    While hospital-acquired bacterial infection is clearly the major problem, viral and fungal organisms have also become serious threats in the past few decades. Of course, the most prominent is HIV, and so severe are the implications of exposure with this lethal virus that it has profoundly changed the standards of care for these immunodeficient patients.

    In the hospital setting, HIV may be acquired from contaminated blood transfusion, and as a result, routine testing of donor blood has been standard practice in many countries. Accidental needlestick injury is the concern for health-care workers, with the risk of transmission pegged at 0.3 percent on the average.

    Other viral infections that can be transmitted through occupational exposure include hepatitis B and C, and in other countries, viral hemorrhagic fevers like Ebola.

    On the other hand, more benign viral infections, such as measles or varicella, have at times appeared in health-care facilities. The culprits are varied, and may range from simple lapses in infection control, to increases in the number of immunocompromised patients or adult cases of infection.

    A mother who had just given birth was known to always go to the nursery to breastfeed her baby. One day, however, she suddenly noticed that her baby developed vesicular eruptions. At first, she didn't mind them, but in seven to 14 days, she also developed the same lesions all over her body. She thought that it looked like chickenpox, and indeed, it was chickenpox. Suddenly, everyone in the nursery staff wanted to go on leave. Of course, not all were clearly susceptible, and when their medical records were checked at the health service, it was found that some of the health-care workers who said they didn't have chickenpox before actually had it on record.

    Fortunately, only two or three more babies got infected. They were subsequently isolated, and the nursery was temporarily closed to new admissions. Those who had close contact with a known case and found to be susceptible were quarantined and asked to go on leave. All nonimmune personnel were also vaccinated.

    Fungal infections are also a rising concern, especially in a number of immunocompromised patients in intensive care units, where they have become major sources of systemic infection. Environmental contamination by airborne organisms like as Aspergillus spp. is also problematic, especially during hospital construction and renovation.

    The mortality rate in the nursery of a certain local government hospital suddenly rose to unusual levels. A frantic search for the probable source of infection was done, and when the results of the blood cultures arrived, it turned out to be Candida. A chart review of all affected patients then revealed that more than half of babies who had been placed on special diet administered through IV line had acquired the infection. A thorough inquiry revealed a newly hired and untrained personnel preparing the TPN as the likely source of transmission in this case.

Breaking the Chain

    By all accounts, every hospital must be an infection-free place where patients are treated, and hopefully, brought back to good health. However, when these supposedly sterile environments, with all its devices and instruments, and its occupants included, become breeding grounds for more infection, then they cease to become a safe haven for the sick. Although it is true that many lives have already been lost to what could have been a preventable cause of illness and death, it is by no means insurmountable or unavoidable.

    Dr. Melecia Velmonte, founder of the Philippine Hospital Infection Control Society, and chair of the hospital infection control unit at the University of the Philippines-Philippine General Hospital, emphasizes that the 10 most important sources of cross infection are your ten fingers. Studies have already demonstrated the vital role of hand transmission in the chain of infection, thereby stressing the efficiency of what is yet the most cost-effective means of prevention: handwashing. Says the top infection control specialist: "If you don't wash your hands as frequently as you should, then there's the risk of transferring the infection from one patient to another. If personnel are well-trained and use their common sense, then you can always minimize the risk of cross infection."

    Of course, many elements must be taken into account when measures to reduce person-to-person transmission and environmental contamination are instituted, but the point is still to break the chain of transmission in all cases.

 

 

 

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