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In Microbiology Parts I and II, you learned about microbes, their needs, how they reproduce and the shapes and categories of microorganisms. This module will complete Microbiology.

Problem Areas - the areas of concern in the microbe world are:

Emerging infectious disease - This is a disease that results from newly identified, previously unknown infections, which cause public health problems locally or internationally.

--Re-emerging infectious disease - the reappearance of and increase in the number of infections from a disease which is known but which formerly was not a public health threat.

Diseases which once plagued us since early man are once more becoming a threat in the US and around the world. Pneumonia and influenza-combined the sixth most common cause of death in the US are on the rise. Old diseases are no longer responding to old drugs (e.g. TB). Diseases once not considered to be infectious have been proved to be pathogenic (e.g. staph epidermitis). Because we do not know what new disease will present, we must always be prepared for the unexpected.

For example, the IE 1997 - strain of influenza that had never before attacked humans began to kill previously healthy people in Hong Kong. The Ebola Virus had its first outbreak in 1976; the virus was discovered in 1977. The cases are mainly confined to four countries in Africa. Through June 1997, 1,054 cases identified and reported to the World Health Organization (WHO); 754 were fatal. It was recently discovered that a strain of the virus that causes HIV/AIDS has been circulating at least since 1959. This illustrates the way in which emerging infectious agents can insinuate themselves into human populations and remain undetected for years before emerging as a public health problem. This is a reminder that we are only one step ahead of the bugs!

In the 1970's the following diseases were identified: Legionnaires' disease; Ebola hemorrhagic fever; Lyme disease; toxic shock syndrome; AIDS; and multiple drug resistant TB finalized the assault.

About 10 years ago, scientists were saying, "with vaccines and antibiotics, infectious diseases were under control. We now know life is not that simple". A major cause of the problem is drug resistance - the ability of infectious microorganisms to evade the drugs designed to stop them. These drug resistant strains now include some pneumonias, TB, malaria, and AIDS. The second problem is the emergence of new infectious diseases. While AIDS and Lyme disease are obvious examples, more than 30-new disease-causing organisms have been discovered since 1976.

In some cities up to 35% of patients no longer respond completely to antibiotics because some strains of bacteria are now resistant to penicillin. There is concern now that pneumonia will become resistant to vancomycin, considered the antibiotic of last resort.

Staph Aureus - Has been a common cause of nosocomial infections from 1990-1996. It is the leading cause of nosocomial pneumonia and surgical site infections and the second leading cause of nosocomial bloodstream infections. More than 95% of patients with Staph. aureus infections do not respond to first-line antibiotics such as penicillin or ampicillin. Methicillin is the next antibiotic in line for treatment.

Methicillin Resistant Staph Aureus (MRSA) - was first reported in 1960s. It has become increasingly prevalent since the 1980s. Now it is prevalent in many hospitals and even epidemic in some facilities. With this strain if Staph, the bacteria has learned to become resistant to Methicillin, the treatment of choice. The resistance in approximately 30% of all S. aureus infections. It was previously found in Nursing Homes and when these patients were transferred to a hospital, the hospital dealt with it. However, MRSA is now in the general community (e.g. ear piercing parlors) outside of hospitals and Nursing Homes. Recently a young boy who fell on a ball field playing softball, scrapped his knee. He developed a severe MRSA infection. This is a serious concern for all of the medical community. Vancomycin is the only drug that can consistently treat MRSA and is considered the antibiotic of last resort. However Vancomycin is now showing some resistance.

Another Vancomycin resistant microbe is Vancomycin Resistant Enterococcus (VRE). In 1989 hospitals reported a rapid increase in VRE. It is thought that even a small increase in the incidence of VRE infection could lead to cross-resistance in S. Aureus Vancomycin Resistant Staphylococcus Aureus. Three vancomycin resistant cases have shown up in the US and Japan. In the fourth case, the infection proved fatal. Three initial cases showed a moderate resistance to Vancomycin. All four cases appeared in patients who had received repeated and prolonged treatment with Vancomycin. This is the tip of the iceberg and such cases are very rare. However, staph is giving us a warning sign that it is changing and to be prepared. Some tests suggest that similar staph bacteria, already found in hospitals in the NY metropolitan area, have accumulated the raw material needed to develop full-blown resistance to Vancomycin. One small mutation may be enough to complete the process. The appearance of vancomycin resistant staph aureus threatens to return us to the era before antibiotics.

E. Coli O157:H7 - This is a new, and more virulent pathogen. Original E. Coli is present in all humans intestines. There was a multi-state outbreak in 1993 where the E.Coli was transmitted by hamburger meat used by a fast food restaurant chain causing 700 people to become ill and four children died of kidney failure. E. Coli O157:H7 was found to be the cause of another smaller outbreak involving fruit juices which were not pasteurized. Unlike other food borne pathogens, this E. Coli has no margin for error; even a microscopic amount can cause serious illness and even death

Cryptosporidium - This microbe caused a major outbreak of gastrointestinal (GI) illness in Milwaukee when it invaded the water supply in 1993. More than 400,000 people became ill.

Others

Hantavirus - This illness was first identified in 1993 in US. It is a pulmonary (lung) syndrome resulting from rodent (rats, mice) excrement. SARS was first identified in 2003 in Asia and is now worldwide. Bird Flu was first identified in 2005, and it may result in worldwide pandemic. West Nile Fever was initially identified in Russia and the US; now it is found all over the world. In 2003, there were 115 deaths and 6000 human cases of West Nile Fever reported. It has now been learned that West Nile Fever can be transmitting by transplanted organs (2003); transfused blood (23 confirmed cases in 2002); and via the human placenta.

Dr. Francis Waldvogel of University Hospital in Geneva said "The adaptive potential of the microbial world is such that for each new antibiotic that is introduced, several escape mechanisms are soon developed. It was naïve to believe for 40 years that vancomycin would remain an exception to this law".

Re-emerging Infectious Diseases

Cholera - In 1991, the seventh cholera pandemic reached the Americas where cholera had not been registered for a century. It occurred due to deteriorating water and sanitation systems. Dengue fever increased due to deteriorating mosquito control measures. Diphtheria - re-emerged in Russia in 1994 and culminated with over 50,000 cases reported. It was caused by a dramatic decline in immunization programs.

Creutzfeldt-Jakob Disease - this disease is uncommon; however due to a new variant strain that has been transmitted thorough contaminated meat, it has brought a renewed interest. The causative agent for CJD is the prion, an infectious protein. These proteins are virtually indestructible to virtually all known forms of sterilization and disinfection. There is some new reach indicating high alkaline detergents may inactivate prions. For now, however, health care facilities need to focus on patients having surgery involving "high risk" tissue. Prions have an affinity for spinal cord, eye and brain tissue so these are high risk. Prions are not transmitted casually, only infected tissue to infected tissue. Instruments used on high risk tissue should be steam sterilized (pre-vacuum for 18 minutes at 270F (132C).

REMEMBER…...

The only thing that remains constant with microorganism is their ability to change to adapt to adverse changes in their environment. If we are prepared for they may not get an upper hand.