Methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii: An unexpected difference in epidemiologic behavior

Background: The Dutch guideline on hospital policy for the prevention of nosocomial spread of methicillin-resistant Staphylococcus aureus (MRSA) states that patients transferred from hospitals abroad must be placed in strict isolation immediately on admission to a hospital in the Netherlands. Three patients colonized with both MRSA and a multiresistant Acinetobacter were transferred from hospitals in Mediterranean countries to 3 different hospitals in the Netherlands. Despite isolation precautions, Acinetobacter spread in 2 of the 3 hospitals, whereas nosocomial spread of MRSA did not occur. Methods: For outbreak analysis, the Acinetobacter isolates, identified as Acinetobacter baumannii by the use of amplified ribosomal DNA restriction analysis, were comparatively typed by 4 methods. Comparison of isolation measures in the hospitals was performed retrospectively. Results: In the 2 hospitals in which nosocomial spread of Acinetobacter occurred, most of the epidemiologically related isolates were indistinguishable from the index strains. In these 2 hospitals, isolation measures were in concordance with those recommended for the prevention of contact transmission. The precautions of the hospital in which no outbreak occurred included the prevention of airborne transmission. Conclusions: Precautions recommended for multiresistant gram-negative organisms are insufficient for the prevention of nosocomial spread of multiresistant Acinetobacter . The airborne mode of spread of acinetobacters should be taken into account, and guidelines should be revised accordingly. (AJIC Am J Infect Control 1998;26:544-51)     

Rethinking the role of isolation practices in the prevention of nosocomial infections

To prevent nosocomial infections, hospitals use two types of procedures: routine patient care practices (handwashing, for example), which are used in appropriate circumstances on all patients, and more intensive isolation precautions, which are implemented only when patients are suspected of having particular infections. Aspects of these current practices, however, may limit their effectiveness. We propose the use of body substance isolation, a simpler alternative system that is used for all patients, not just in response to a specific diagnosis, and that emphasizes the increased use of barrier precautions, especially gloving, when contact with potentially infectious bodily secretions is anticipated. Because of its rationale and simplicity, body substance isolation has been enthusiastically accepted at our hospitals, and we encourage others to consider and evaluate this approach.     

Risk of respiratory infections in health care workers: lessons on infection control emerge from the SARS outbreak

Close proximity of persons together with handling of human secretions (eg respiratory secretions) make health care workers (HCW) particularly vulnerable to transmission of droplet-transmitted respiratory infections. This was tragically highlighted during the international outbreak of severe acute respiratory syndrome (SARS) in 2003 with attack rates of more than 50% in HCW. The purpose of this article is to review common airborne and droplet-transmitted bacterial and viral respiratory tract infections with regard to their impact on health care workers. Lessons need to be learned from the SARS epidemic. The three main strategies to prevent or control occupationally acquired infections are relatively simple and cost-effective-droplet and contact precautions and for some pathogens also vaccination. Enforced implementation of stringent droplet precautions during the SARS crisis should be maintained; and this will most likely have a major additional impact on other nosocomial infections. Employee health services should proactively and creatively devise delivery systems that enhance compliance with vaccination programs for all health care workers. Hospital surveillance should be expanded to all respiratory diseases to facilitate early detection of nosocomial outbreaks, and this should also include surveillance of all HCW. Integrated syndromic and virological surveillance systems set up during the SARS epidemic will also further our understanding of other respiratory infections in the hospital setting. Even if pursuing early diagnosis for unspecific respiratory illnesses is expensive, identification of the causative organism may reduce unnecessary isolation, contact tracing and anxiety, in particular during an outbreak situation. We have a duty to protect our health care workers.     

SARS in the intensive care unit

Approximately 20% of patients with severe acute respiratory syndrome (SARS) develop respiratory failure that requires admission to an intensive care unit (ICU). Old age, comorbidity, and elevated lactate dehydrogenase on hospital admission are associated with increased risk for ICU admission. ICU admission usually is late and occurs 8 to 10 days after symptom onset. Acute respiratory distress syndrome occurs in almost all admitted patients and most require mechanical ventilation. ICU admission is associated with significant morbidity, particularly an apparent increase in the incidence of barotrauma and nosocomial sepsis. Long-term mortality for patients admitted to the ICU ranges from 30% to 50%. Many procedures in ICUs pose a high risk for transmission of SARS coronavirus to health care workers. Contact and airborne infection isolation precautions, in addition to standard precautions, should be applied when caring for patients with SARS. Ensuring staff safety is important to maintain staff morale and delivery of adequate services.     

Risks and prevention of nosocomial transmission of rare zoonotic diseases.

Americans are increasingly exposed to exotic zoonotic diseases through travel, contact with exotic pets, occupational exposure, and leisure pursuits. Appropriate isolation precautions are required to prevent nosocomial transmission of rare zoonotic diseases for which person-to-person transmission has been documented. This minireview provides guidelines for the isolation of patients and management of staff exposed to the following infectious diseases with documented person-to-person transmission: Andes hantavirus disease, anthrax, B virus infection, hemorrhagic fevers (due to Ebola, Marburg, Lassa, Crimean-Congo hemorrhagic fever, Argentine hemorrhagic fever, and Bolivian hemorrhagic fever viruses), monkeypox, plague, Q fever, and rabies. Several of these infections may also be encountered as bioterrorism hazards (i.e., anthrax, hemorrhagic fever viruses, plague, and Q fever). Adherence to recommended isolation precautions will allow for proper patient care while protecting the health care workers who provide care to patients with known or suspected zoonotic infections capable of nosocomial transmission.     

Protecting health care workers from SARS and other respiratory pathogens: a review of the infection control literature

BACKGROUND: Severe Acute Respiratory Syndrome (SARS) was responsible for outbreaks in Canada, China, Hong Kong, Vietnam, and Singapore. SARS focused attention on the adequacy of and compliance with infection control practices in preventing airborne and droplet-spread transmission of infectious agents. METHODS: This paper presents a review of the current scientific knowledge with respect to the efficacy of personal protective equipment in preventing the transmission of respiratory infections. The effectiveness of infection control policies and procedures used in clinical practice is examined. RESULTS: Literature searches were conducted in several databases for articles published in the last 15 years that related to infection control practices, occupational health and safety issues, environmental factors, and other issues of importance in protecting workers against respiratory infections in health care settings. CONCLUSION: Failure to implement appropriate barrier precautions is responsible for most nosocomial transmissions. However, the possibility of a gradation of infectious particles generated by aerosolizing procedures suggests that traditional droplet transmission prevention measures may be inadequate in some settings. Further research is needed in this area.     

Detection of airborne severe acute respiratory syndrome (SARS) coronavirus and environmental contamination in SARS outbreak units

Severe acute respiratory syndrome (SARS) is characterized by a risk of nosocomial transmission; however, the risk of airborne transmission of SARS is unknown. During the Toronto outbreaks of SARS, we investigated environmental contamination in SARS units, by employing novel air sampling and conventional surface swabbing. Two polymerase chain reaction (PCR)-positive air samples were obtained from a room occupied by a patient with SARS, indicating the presence of the virus in the air of the room. In addition, several PCR-positive swab samples were recovered from frequently touched surfaces in rooms occupied by patients with SARS (a bed table and a television remote control) and in a nurses' station used by staff (a medication refrigerator door). These data provide the first experimental confirmation of viral aerosol generation by a patient with SARS, indicating the possibility of airborne droplet transmission, which emphasizes the need for adequate respiratory protection, as well as for strict surface hygiene practices.     

An outbreak of the 2009 influenza a (H1N1) virus in a children's hospital

Please cite this paper as: Bearden et al. (2012) An outbreak of the 2009 influenza a (H1N1) virus in a children’s hospital. Influenza and Other Respiratory Viruses 6(5), 374–379. Context Preventing nosocomial transmission of influenza is essential to reduce the morbidity and mortality associated with this infection. In October 2009, an outbreak of the 2009 influenza A (H1N1) virus occurred in a hematology ward of a children’s hospital over a 21‐day period and involved two patients and four healthcare workers. Objective To investigate nosocomial transmission of the 2009 influenza A (H1N1) virus in patients and healthcare workers. Design, setting, and participants An outbreak investigation was initiated in response to suspected nosocomial transmission of the 2009 influenza A (H1N1) virus during the peak of the 2009 pandemic. Cases were confirmed using a polymerase chain reaction (PCR) test specific for the 2009 H1N1 influenza A virus. Viruses isolated from nasopharyngeal swabs were genetically characterized using Sanger sequencing of uncloned “bulk” PCR products. Main outcome measures Virus sequencing to investigate nosocomial transmission. Results Two immunocompromised patients and four healthcare workers were found to be part of a nosocomial outbreak of the 2009 influenza A (H1N1) virus. One immunocompromised patient had a second episode of clinical influenza infection after isolation precautions had been discontinued, resulting in additional exposures. Strain‐specific PCR showed that all cases were caused by infection of the 2009 H1N1 virus. Sequencing of viral genes encoding hemagglutinin and polymerase basic subunit 2 (PB2) revealed that all viruses isolated were genetically identical at these loci, including the two episodes occurring in the same immunocompromised patient. Conclusions Prompt institution of isolation precautions is essential in preventing nosocomial outbreaks of the 2009 novel influenza A (H1N1) virus. Our data suggest that isolation precautions may need to be continued for a prolonged period of time in immunocompromised patients with influenza infection.     

Effectiveness of precautions against droplets and contact in prevention of nosocomial transmission of severe acute respiratory syndrome (SARS)

We did a case-control study in five Hong Kong hospitals, with 241 non-infected and 13 infected staff with documented exposures to 11 index patients with severe acute respiratory syndrome (SARS) during patient care. All participants were surveyed about use of mask, gloves, gowns, and hand-washing, as recommended under droplets and contact precautions when caring for index patients with SARS. 69 staff who reported use of all four measures were not infected, whereas all infected staff had omitted at least one measure (p=0.0224). Fewer staff who wore masks (p=0.0001), gowns (p=0.006), and washed their hands (p=0.047) became infected compared with those who didn't, but stepwise logistic regression was significant only for masks (p=0.011). Practice of droplets precaution and contact precaution is adequate in significantly reducing the risk of infection after exposures to patients with SARS. The protective role of the mask suggests that in hospitals, infection is transmitted by droplets.     

Isolation practices: a historical perspective

Isolation practices assume a major role in the activities of many hospital infection prevention and control programs, yet few of the practices have been studied for efficacy. The origins for some of these practices can be traced to the nursing literature published in the American Journal of Nursing in the early part of the century. Others originated with public health measures for quarantine of communicable diseases in the community or attempts to simulate operating room practices for compromised patients. This historical review presents information about isolation practices from the perspective of the American Journal of Nursing with additional information from some Centers for Disease Control and American Hospital Association publications. The American Journal of Nursing was selected because it is a major source for content of nursing textbooks from which most nurses first learn isolation practices. Nurses are also the persons primarily responsible for the implementation of isolation practices in hospitals. Two themes emerged from this historical review: (1) a continuing debate about the importance of the inanimate environment and the importance of the airborne route versus the importance of contact with moist body substances as major modes of transmission of infectious agents and (2) a continuing debate between those who believe in special isolation techniques only for persons with diagnosed infections and those who believe all persons may harbor potentially infectious agents and who therefore focus attention on assessment of care requirements where contact with body substances is anticipated. This review is intended to encourage critical evaluation of isolation practices in use in hospitals today.     

Outbreak of methicillin-resistant Staphylococcus aureus in a Norwegian hospital.

Methicillin-resistant Staphylococcus aureus (MRSA) occurred sporadically in Norwegian hospitals in the 1960s and 1970s, but disappeared in the late 1970s for unknown reasons. Only 1 outbreak has subsequently been reported. We describe herein a second outbreak in a different hospital, this time featuring a more resistant strain. Staff and patients were screened immediately after detection of the first MRSA isolate. Colonized and infected patients were nursed using contact precautions, and the staff were not allowed to work until 3 nose samples were MRSA-negative. We treated colonized persons with topical administration of mupirocin to the nostrils and a chlorhexidine body wash. The outbreak affected 7 patients and 5 healthcare workers. Pulsed-field gel electrophoresis proved all isolates to be of the same type, and the MRSA phage type was M3. There was no sign of transmission of MRSA after contact precautions were implemented. MRSA was eradicated in 4 of the patients and all 5 healthcare workers. One patient died and 1 was still colonized 3 y after onset of the outbreak. Contact precautions proved to be sufficient to prevent transmission of MRSA.     

Effectiveness of preemptive barrier precautions in controlling nosocomial colonization and infection by methicillin-resistant Staphylococcus aureus in a burn unit

BACKGROUND: We report the effectiveness of preemptive enhanced barrier precautions in containing a methicillin-resistant Staphylococcus aureus (MRSA) outbreak in a university hospital burn unit and further controlling endemic nosocomial MRSA infection in the unit during the succeeding 27 months. METHODS: During a 6-month period, 12 patients in a 7-bed burn unit were found to be colonized (7) or infected (5) by MRSA. An epidemiologic study was undertaken. RESULTS: Seven of the 10 strains of MRSA from patients that were available for DNA typing were clonally identical. Early in the outbreak, a health care worker was found to be a concordant nasal carrier and was successfully decolonized with nasal mupirocin. However, despite stringent compliance with isolation of MRSA-positive patients (targeted precautions), new cases of MRSA colonization or infection continued to occur. The outbreak was rapidly terminated after implementing preemptive barrier precautions with all patients in the unit: a new, clean gown and gloves for any physical contact with the patient or their environment. Although 25% of all nosocomial S aureus isolates in our hospital are resistant to methicillin, the incidence of endemic MRSA colonization and infection in the burn unit has remained very low since implementing barrier precautions unit wide (baseline rate, 2.2 [95% CI: 1.0-4.2] cases per 1000 patient-days; outbreak rate, 7.2 [95% CI: 4.4-11.0] cases per 1000 patient-days; post-outbreak termination endemic rate, 1.1 (95% CI: 0.4-2.3) cases per 1000 patient-days). The rate ratio comparing the outbreak and the baseline period was 3.20 (95% CI: 1.40-7.95, P = .002); the rate ratio comparing the post-outbreak period with the baseline period was 0.48 (95% CI: 0.14-1.53, P = .10), and it has not been necessary to screen personnel for MRSA carriage to prevent nosocomial MRSA infections in this highly vulnerable population. CONCLUSION: Preemptive barrier precautions were highly effective in controlling the outbreak and, most notably, have also been highly effective in maintaining a very low incidence of nosocomial MRSA infection endemically in the succeeding 27 months of follow-up. Use of clean gloves, with or without a gown, bears consideration for all high-risk hospitalized patients to prevent cross transmission of all multiresistant nosocomial pathogens.     

Severe acute respiratory syndrome

PURPOSE OF REVIEW: Severe acute respiratory syndrome (SARS) is an infectious disease first recognized in November 2002 in Guangdong Province, China. It spread to many countries all over the world during February to June 2003, with 8098 cases reported. Twenty-one percent of the affected people were health care workers. Because SARS is a new emerging disease, this review describes the current understanding about the etiology, clinical pictures, laboratory and radiological findings of SARS. RECENT FINDINGS: Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) was quickly found to be the etiological agent of SARS in April 2003. The transmission of SARS-CoV between human beings is mainly due to close contact. Using barrier precautions, the transmission of SARS-CoV can be prevented. The most common clinical presentations of patients with SARS include fever, cough, and dyspnea. The common laboratory findings include lymphopenia, thrombocytopenia, elevated serum alanine and aspartate aminotransferase, lactate dehydrogenase, creatine phosphokinase, and C-reactive protein. The most common radiological finding is pneumonic lesion(s) in the chest radiogram. Many patients experience exacerbation of clinical symptoms in the second week of disease course and some may progress to respiratory failure and need mechanical ventilatory support. The overall case fatality rate is 9.6%. The current method of treatment of SARS is still controversial. SUMMARY: SARS is an infectious disease with high contagiousness and a high mortality rate. Early case identification and infection control are two important factors to limit its spread.     

Severe Acute Respiratory Syndrome

Severe acute respiratory syndrome (SARS) is a newly emerged infection that is caused by a previously unrecognized virus - a novel coronavirus designated as SARS-associated coronavirus (SARS-CoV). From November 2002 to July 2003 the cumulative number of worldwide cases was >8000, with a mortality rate of close to 10%. The mortality has been higher in older patients and those with co-morbidities. SARS has been defined using clinical and epidemiological criteria and cases are considered laboratory-confirmed if SARS coronavirus is isolated, if antibody to SARS coronavirus is detected, or a polymerase chain reaction test by appropriate criteria is positive. At the time of writing (24 May 2004), no specific therapy has been recommended. A variety of treatments have been attempted, but there are no controlled data. Most patients have been treated throughout the illness with broad-spectrum antimicrobials, supplemental oxygen, intravenous fluids, and other supportive measures. Transmission of SARS is facilitated by close contact with patients with symptomatic infection. The majority of cases have been reported among healthcare providers and family members of SARS patients. Since SARS-CoV is contagious, measures for prevention center on avoidance of exposure, and infection control strategies for suspected cases and contacts. This includes standard precautions (hand hygiene), contact precautions (gowns, goggles, gloves) and airborne precautions (negative pressure rooms and high efficiency masks). In light of reports of new cases identified during the winter of 2003-4 in China, it seems possible that SARS will be an important cause of pneumonia in the future, and the screening of outpatients at risk for SARS may become part of the pneumonia evaluation.     

An evaluation of portable high-efficiency particulate air filtration for expedient patient isolation in epidemic and emergency response

Extraordinary incidents resulting in airborne infectious disease outbreaks could produce patient isolation requirements that exceed most hospitals' capacity. This article investigates expedient methods to establish airborne infection isolation areas using a commercially available portable filtration unit and common hardware supplies. The study was conducted within a conventional, nonisolation hospital room, and researchers evaluated several airborne isolation configurations that did not require building ventilation or structural modifications. A portable high-efficiency particulate air filtration unit and full-length plastic curtains established a "zone-within-zone" protective environment using local capture and directional airflows. The cost of constructing the expedient configurations was less than US2,300 dollars and required fewer than 3 person-hours to construct. A medical nebulizer aerosolized polystyrene latex microspheres to generate respirable condensation nuclei. Aerosol spectrometers sized and counted respirable particles at the source patient and health care worker positions and in areas outside the inner zone. The best-performing designs showed no measurable source migration out of the inner isolation zone and mean respirable particle counts up to 87% lower at the health care worker position(s) than those observed directly near the source patient location. Investigators conclude that with careful implementation under emergency circumstances in which engineered isolation rooms are unavailable, expedient methods can provide affordable and effective patient isolation while reducing exposure risks and potential disease transmission to health care workers, other patients, and visitors.     

Rotavirus outbreak on a pediatric oncology floor: possible association with toys

BACKGROUND: Several outbreaks of rotavirus gastroenteritis have occurred in hospitals and day care centers. In the spring of 1997, an outbreak of rotavirus occurred on our pediatric unit. Aggressive infection control measures were instituted, and potential lapses in infection control were assessed. METHODS: Memorial Sloan-Kettering Cancer Center is a 434-bed cancer hospital in New York City. The pediatric unit is a 42-bed ward with both bone marrow transplant patients and non-bone marrow transplant oncology patients. Nosocomially acquired rotavirus was defined as diarrhea, vomiting, or gastrointestinal upset with onset 48 hours or more after hospital admission, accompanied by a positive enzyme immunoassay for rotavirus antigen. RESULTS: Between February 24 and April 4, 1997, 8 patients on the pediatric unit had nosocomial rotavirus. Aggressive infection control measures were instituted. Patients with rotavirus were cohorted and placed on contact precautions (strict handwashing, gloves, and gown). Investigation by the infection control team revealed that communal toys in the playroom were not being cleaned according to the weekly protocol. CONCLUSIONS: An outbreak of nosocomial rotavirus occurred on our pediatric oncology unit. Shared toys may have served as fomites in the transmission of rotavirus.     

严重急性呼吸综合征传播影响因素病例对照研究

目的探讨严重急性呼吸综合征(SARS)传播的影响因素。方法采用病例对照研究,分别对有明确流行病学接触史的SARS患者与密切接触者,无明确流行病学接触史的SARS患者与一般人群进行比较。结果工作环境不通风、去公共场所无戴口罩的习惯、和患者接触时不通风与SARS呈正相关;疫情流行期间未到过医院,外出不采用人口密度相对较大的公交车、地铁等交通工具与SARS负相关。结论应加强医院建设和管理,以应对传染病的流行;当与患者接触时应注意通风;疫情暴发期间到公共场所应戴口罩;患者尽量减少到医院的机会和使用人口密度相对较大的交通工具。     

Implementing and evaluating a system of generic infection precautions: body substance isolation

Body substance isolation (BSI) is a system of infection precautions intended to reduce nosocomial transmission of infectious agents among patients and to reduce the risk of transmission of hepatitis B virus, human immunodeficiency virus, and other infectious agents to health care personnel. Harborview Medical Center in Seattle, Wash., was the first facility in the United States to implement the BSI system. Between 1984 and 1988 a systematic evaluation of the implementation process was conducted and the effects of BSI on appropriate glove use by hospital personnel and on the incidence of nosocomial colonization and infection by sentinel organisms was measured. Results of the evaluation showed (1) significant increments in knowledge of infection control procedures and practices as measured by comparing written examination responses before and after training sessions, (2) significant increases in appropriate glove use as determined by direct observation of hospital employees for 18 months, and (3) significant reductions in nosocomial colonization and infection caused by sentinel microorganisms during the period from 1984 to 1988.     

Survey of isolation practices at a tertiary care pediatric hospital

BACKGROUND: Although isolation precautions are an important aspect of hospital infection control, current rates of isolation in a pediatric hospital and rates of compliance with established precautions are unknown. We therefore initiated hospital-wide point prevalence studies to determine unit-specific rates of patient isolation and compliance with proper isolation requirements focusing on communication of isolation status and availability of personal protective equipment. In this report, we present data from the first 14 months of the study. METHODS: This was a prospective observational study. Twice monthly, between January 2004 and February 2005, infection control professionals reviewed the types and appropriateness of isolation of all hospitalized patients, except for those on the psychiatry unit. RESULTS: Seventeen percent of patients in the hospital during the study period were isolated, most frequently for community-acquired infections. Droplet isolation precautions were the most common form of isolation. Overall, only 74.6% of patients were isolated appropriately. The solid organ transplantation, hematology/oncology, and bone marrow transplantation units were those with the highest rates of inappropriate isolation. CONCLUSION: At our hospital, community-acquired infections, in particular respiratory infections, were the most common reasons for patient isolation. Monitoring of the appropriateness of isolation precautions offers the opportunity to reduce health care-related transmission of infection and identify specific target areas for improvement.     

A nosocomial outbreak of ampicillin-resistant Haemophilus influenzae type b in a geriatric unit

A nosocomial outbreak of Haemophilus influenzae type b (Hib) bronchitis occurred in a geriatric unit. The three infected patients were grouped together in an isolation unit and treated. A prevalence survey was done by obtaining pharyngeal cultures from patients and staff in the unit. One patient and a nurse were asymptomatic pharyngeal carriers of Hib. One infected patient was bedridden, and his only known Hib contact was the nurse. Geographic clustering was the only significant risk factor, as determined by a case-control study. Carriers were treated with rifampin. The isolates were characterized for strain relatedness by using three methods. All produced beta-lactamase and all were serotype b. Plasmid profiles and restriction endonuclease analysis of bacterial DNA were performed; chromosomes were digested with the restriction endonucleases HindIII and HaeIII. Strains were confirmed as identical by using these methods and were different from two Hib control strains producing beta-lactamase. This study documents nosocomial transmission of Hib, by using molecular typing methods.