this transmission. it is unclear whether or not nail polish or rings affected surgical wound infection rates. gloves in addition to hand washing, gloves play an important role in reducing the risks of transmission of microorganisms. gloves are worn for three important reasons in hospitals. first, they are worn to provide a protective barrier for personnel, preventing large scale contamination of the hands when touching blood, body fluids, secretions, excretions, mucous membranes, and non-intact skin. in the united states, the occupational safety and health administration has mandated wearing gloves to reduce the risk of bloodborne pathogen infections. second, gloves are worn to reduce the likelihood that microorganisms present on the hands of personnel will be transmitted to patients during invasive or other patient-care procedures that involve touching a patient's mucous membranes and nonintact skin. third, they are worn to reduce the likelihood that the hands of personnel contaminated with micro-organisms from a patient or a fomite can transmit those micro-organisms to another patient. in this situation, gloves must be changed between patient contacts, and hands should be washed after gloves are removed. antimicrobial surfaces micro-organisms are known to survive on inanimate "touch" surfaces for extended periods of time. this can be especially troublesome in hospital environments where immunodeficient patients are at enhanced risk for contracting nosocomial infections. patients with hospital-acquired infections are predominantly hospitalized in different types of intensive care units (icus). touch surfaces commonly found in hospital rooms, such as bed rails, call buttons, touch plates, chairs, door handles, light switches, grab rails, intravenous poles, dispensers (alcohol gel, paper towel, soap), dressing trolleys, and counter and table tops are known to be contaminated with staphylococcus, methicillin-resistant staphylococcus aureus (one of the most virulent strains of antibiotic-resistant bacteria) and vancomycin-resistant enterococcus. objects in closest proximity to patients have the highest levels of methicillin-resistant staphylococcus aureus and vancomycin-resistant enterococcus. this is why touch surfaces in hospital rooms can serve as sources, or reservoirs, for the spread of bacteria from the hands of healthcare workers and visitors to patients. a number of compounds can decrease the risk of bacteria growing on surfaces including: copper, silver, and germicides. there have been a number of studies evaluating the use of no-touch cleaning systems particularly the use of ultraviolet c devices. one review was inconclusive due to lack of, or of poor quality evidence. other reviews have found some evidence, and growing evidence of their effectiveness. treatment two of the bacteria species most likely to infect patients are the gram-positive strains of methicillin-resistant staphylococcus aureus, and gram-negative acinetobacter baumannii. while antibiotic drugs to treat diseases caused by methicillin-resistant staphylococcus aureus are available, few effective drugs are available for acinetobacter. acinetobacter bacteria are evolving and becoming immune to antibiotics, so in many cases, polymyxin-type antibacterials need to be used. "in many respects it's far worse than mrsa", said a specialist at case western reserve university. another growing disease, especially prevalent in new york city hospitals, is the drug-resistant, gram-negative klebsiella pneumoniae. an estimated more than 20% of the klebsiella infections in brooklyn hospitals "are now resistant to virtually all modern antibiotics, and those supergerms are now spreading worldwide." the bacteria, classified as gram-negative because of their color on the gram stain, can cause severe pneumonia and infections of the urinary tract, bloodstream, and other parts of the body. their cell structures make them more difficult to attack with antibiotics than gram-positive organisms like methicillin-resistant staphylococcus aureus. in some cases, antibiotic resistance is spreading to gram-negative bacteria that can infect people outside the hospital. "for gram-positives we need better drugs; for gram-negatives we need any drugs", said brad spellberg, an infectious-disease specialist at harbor–ucla medical center, and the author of rising plague, a book about drug-resistant pathogens. hospital-acquired pneumonia (hap) is the second most common nosocomial infection and accounts for approximately one-fourth of all infections in the intensive care unit (icu). hap, or nosocomial pneumonia, is a lower respiratory infection that was not incubating at the time of hospital admission and that presents clinically two or more days after hospitalization. ventilator-associated pneumonia (vap) is defined as hap in patients receiving mechanical ventilation. the incidence of vap is 10–30% among patients who require mechanical ventilation for >48 h. a standard treatment protocol is based on accurate diagnosis definitions, microbiological confirmation of vap, and the administration of imipenem plus ciprofloxacin as initial empirical antibiotic treatment. one-third of nosocomial infections are considered preventable. the cdc estimates 2 million people in the united states are infected annually by hospital-acquired infections, resulting in 99,000 deaths. the most common nosocomial infections are of the urinary tract, surgical site and various pneumonias. an alternative treatment targeting localised infections is the use of irradiation by ultraviolet c. epidemiology the methods used differ from country to country (definitions used, type of nosocomial infections covered, health units surveyed, inclusion or exclusion of imported infections, etc.), so the international comparisons of nosocomial infection rates should be made with the utmost care. belgium in belgium the prevalence of nosocomial infections is about 6.2%. annually about 125,500 patients become infected by a nosocomial infection, resulting in almost 3000 deaths. the extra costs for the health insurance are estimated to be approximately €400 million/year. france estimates ranged from 6.7% in 1990 to 7.4% (patients may have several infections). at national level, prevalence among patients in health care facilities was 6.7% in 1996, 5.9% in 2001 and 5.0% in 2006. the rates for nosocomial infections were 7.6% in 1996, 6.4% in 2001 and 5.4% in 2006. in 2006, the most common infection sites were urinary tract infections (30.3%), pneumopathy (14.7%), infections of surgery site (14.2%). infections of the skin and mucous membrane (10.2%), other respiratory infections (6.8%) and bacterial infections / blood poisoning (6.4%). the rates among adult patients in intensive care were 13.5% in 2004, 14.6% in 2005, 14.1% in 2006 and 14.4% in 2007. nosocomial infections are estimated to make patients stay in the hospital four to five additional days. around 2004–2005, about 9,000 people died each year with a nosocomial infection, of which about 4,200 would have survived without this infection. finland rate was estimated at 8.5% of patients in 2005. italy since 2000, estimates show about a 6.7% infection rate, i.e. between 450,000 and 700,000 patients, which caused between 4,500 and 7,000 deaths. a survey in lombardy gave a rate of 4.9% of patients in 2000. switzerland estimates range between 2 and 14%. a national survey gave a rate of 7.2% in 2004. united kingdom in 2012, the health protection agency reported the prevalence rate of hospital-acquired infections in england was 6.4% in 2011, against a rate of 8.2% in 2006, with respiratory tract, urinary tract and surgical site infections the most common types of infections reported. in 2018, it was reported that in-hospital infections had risen from 5,972 in 2008 to 48,815 in 2017. united states the centers for disease control and prevention (cdc) estimated roughly 1.7 million hospital-associated infections, from all types of bacteria combined, cause or contribute to 99,000 deaths each year. other estimates indicate 10%, or 2 million, patients a year become infected, with the annual cost ranging from $4.5 billion to $11 billion. in the us, the most frequent type of hospital infection is urinary tract infection (36%), followed by surgical site infection (20%), and bloodstream infection and pneumonia (both 11%). history mortality rates 1841–1846 in two clinics documented by semmelweis in 1841, ignaz semmelweis, a hungarian obstetrician was working at a vienna maternity hospital. he was "shocked" by the death rate of women who developed puerperal fever. he documented that mortality was three times higher in the ward where the medical students were delivering babies than in the next ward that was staffed by midwifery students. the medical students were also routinely working with cadavers. he compared the rates of infection with a similar hospital in dublin, ireland, and hypothesized that it was the medical students who somehow were infecting the women after labor. he instituted mandatory hand-washing in may 1847 and infection rates dropped dramatically. louis pasteur proposed the germ theory of disease and began his work on cholera in 1865 by identifying that it was microorganisms that were associated with disease.