Despite a paucity of appropriate randomized controlled trials, there is substantial evidence that hand antisepsis reduces the transmission of health care-associated pathogens and the incidence of HCAI.58,179,180 In what would be considered an intervention trial using historical controls, Semmelweis179 demonstrated in 1847 that the mortality rate among mothers delivering at the First Obstetrics Clinic at the General Hospital of Vienna was significantly lower when hospital staff cleaned their hands with an antiseptic agent than when they washed their hands with plain soap and water.
In the 1960s, a prospective controlled trial sponsored by the USA National Institutes of Health (NIH) and the Office of the Surgeon General compared the impact of no handwashing versus antiseptic handwashing on the acquisition of S. aureus among infants in a hospital nursery.52 The investigators demonstrated that infants cared for by nurses who did not wash their hands after handling an index infant colonized with S. aureus acquired the organism significantly more often, and more rapidly, than did infants cared for by nurses who used hexachlorophene to clean their hands between infant contacts. This trial provided compelling evidence that when compared with no handwashing, hand cleansing with an antiseptic agent between patient contacts reduces transmission of health care-associated pathogens.
A number of studies have demonstrated the effect of hand cleansing on HCAI rates or the reduction in cross-transmission of antimicrobial resistant pathogens (see Part I, Section 22 and Table I.22.1). For example, several investigators have found that health care-associated acquisition of MRSA was reduced when the antimicrobial soap used for hygienic hand antisepsis was changed.181,182 In one of these studies, endemic MRSA in a neonatal ICU was eliminated seven months after introduction of a new hand antiseptic agent (1% triclosan) while continuing all other infection control measures, including weekly active surveillance cultures.181 Another study reported an MRSA outbreak involving 22 infants in a neonatal unit.182 Despite intensive efforts, the outbreak could not be controlled until a new antiseptic agent was added (0.3% triclosan) while continuing all previous control measures, which included the use of gloves and gowns, cohorting, and surveillance cultures. Casewell & Phillips121 reported that increased handwashing frequency among hospital staff was associated with a decrease in transmission of Klebsiella spp. among patients, but they did not quantify the level of handwashing among HCWs. It is important to highlight, however, that although the introduction of a new antiseptic product was a key factor to improvement in all these studies, in most cases, system change has been only one of the elements determining the success of multimodal hand hygiene promotion strategies; rather, success results from the overall effect of the campaign.
In addition to these studies, outbreak investigations have suggested an association between infection and understaffing or overcrowding that was consistently linked with poor adherence to hand hygiene. During an outbreak, Fridkin183 investigated risk factors for central venous catheter-associated BSI. After adjustment for confounding factors, the patient-to-nurse ratio remained an independent risk factor for BSI, suggesting that nursing staff reduction below a critical threshold may have contributed to this outbreak by jeopardizing adequate catheter care. Vicca184 demonstrated the relationship between understaffing and the spread of MRSA in intensive care. These findings show indirectly that an imbalance between workload and staffing leads to relaxed attention to basic control measures, such as hand hygiene, and spread of microorganisms. Harbarth and colleagues185 investigated an outbreak of Enterobacter cloacae in a neonatal ICU and showed that the daily number of hospitalized children was above the maximal capacity of the unit, resulting in an available space per child well below current recommendations. In parallel, the number of staff on duty was significantly below that required by the workload, and this also resulted in relaxed attention to basic infection control measures. Adherence to hand hygiene practices before device contact was only 25% during the workload peak, but increased to 70% after the end of the understaffing and overcrowding period. Continuous surveillance showed that being hospitalized during this period carried a fourfold increased risk of acquiring an HCAI. This study not only shows the association between workload and infections, but also highlights the intermediate step – poor adherence to hand hygiene practices. Robert and colleagues suggested that suboptimal nurse staffing composition for the three days before BSI (i.e. lower regular-nurse-to-patient and higher pool-nurse-to-patient ratios) was an independent risk factor for infection.186 In another study in ICU, higher staff level was indeed independently associated with a > 30% infection risk reduction and the estimate was made that, if the nurse-to patient ratio was maintained > 2.2, 26.7% of all infections could be avoided.187
Overcrowding and understaffing are commonly observed in health-care settings and have been associated throughout the world, particularly in developing countries where limited personnel and facility resources contribute to the perpetuation of this problem.183–186,188–190 Overcrowding and understaffing were documented in the largest nosocomial outbreak attributable to Salmonella spp. ever reported191; in this outbreak in Brazil, there was a clear relationship between understaffing and the quality of health care, including hand hygiene.
