Combating the spread of carbapenemases in Enterobacteriaceae: a battle that infection prevention should not lose.

The emergence of carbapenemases in Enterobacteriaceae has raised global concern among the scientific, medical and public health communities. Both the CDC and the WHO consider carbapenem-resistant Enterobacteriaceae (CRE) to constitute a significant threat that necessitates immediate action. In this article, we review the challenges faced by laboratory workers, infection prevention specialists and clinicians who are confronted with this emerging infection control issue.

The role of 'no-touch' automated room disinfection systems in infection prevention and control.

BACKGROUND: Surface contamination in hospitals is involved in the transmission of pathogens in a proportion of healthcare-associated infections. Admission to a room previously occupied by a patient colonized or infected with certain nosocomial pathogens increases the risk of acquisition by subsequent occupants; thus, there is a need to improve terminal disinfection of these patient rooms. Conventional disinfection methods may be limited by reliance on the operator to ensure appropriate selection, formulation, distribution and contact time of the agent. These problems can be reduced by the use of 'no-touch' automated room disinfection (NTD) systems. AIM: To summarize published data related to NTD systems. METHODS: Pubmed searches for relevant articles. FINDINGS: A number of NTD systems have emerged, which remove or reduce reliance on the operator to ensure distribution, contact time and process repeatability, and aim to improve the level of disinfection and thus mitigate the increased risk from the prior room occupant. Available NTD systems include hydrogen peroxide (H(2)O(2)) vapour systems, aerosolized hydrogen peroxide (aHP) and ultraviolet radiation. These systems have important differences in their active agent, delivery mechanism, efficacy, process time and ease of use. Typically, there is a trade-off between time and effectiveness among NTD systems. The choice of NTD system should be influenced by the intended application, the evidence base for effectiveness, practicalities of implementation and cost constraints. CONCLUSION: NTD systems are gaining acceptance as a useful tool for infection prevention and control.

Public reporting of health care-associated infections (HAIs): approach to choosing HAI measures.

OBJECTIVE: To develop a method for selecting health care-associated infection (HAI) measures for public reporting. CONTEXT: HAIs are common, serious, and costly adverse outcomes of medical care that affect 2 million people in the United States annually. Thirty-seven states have introduced or passed legislation requiring public reporting of HAI measures. State legislation varies widely regarding which HAIs to report, how the data are collected and reported, and public availability of results. DESIGN: The Maryland Health Care Commission developed an HAI Technical Advisory Committee (TAC) that consisted of a group of experts in the field of healthcare epidemiology, infection prevention and control (IPC), and public health. This group reviewed public reporting systems in other states, surveyed Maryland hospitals to determine the current state of IPC programs, performed a literature review on HAI measures, and developed six criteria for ranking the measures: impact, improvability, inclusiveness, frequency, functionality, and feasibility. The committee and experts in the field then ranked each of 18 proposed HAI measures. A composite score was determined for each measure. RESULTS: Among outcome measures, the rate of central line-associated bloodstream infections ranked highest, followed by the rate of post-coronary artery bypass grafting surgical-site infections. Among process measures, perioperative antimicrobial prophylaxis, compliance with central-line bundles, compliance with hand hygiene, and healthcare-worker influenza vaccination ranked highest. CONCLUSIONS: Our qualitative criteria facilitated consensus on the HAI TAC and provided a useful framework for public reporting of HAI measures. Validation will be important for such approaches to be supported by the scientific community.

Quantitative analysis and molecular fingerprinting of methicillin-resistant Staphylococcus aureus nasal colonization in different patient populations: a prospective, multicenter study.

OBJECTIVES: To better understand the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization or infection in different patient populations, to perform quantitative analysis of MRSA in nasal cultures, and to characterize strains using molecular fingerprinting. DESIGN: Prospective, multicenter study. SETTING: Eleven different inpatient and outpatient healthcare facilities. PARTICIPANTS: MRSA-positive inpatients identified in an active surveillance program; inpatients and outpatients receiving hemodialysis; inpatients and outpatients with human immunodeficiency virus (HIV) infection; patients requiring cardiac surgery; and elderly patients requiring long-term care. METHODS. Nasal swab samples were obtained from January 23, 2006, through July 27, 2007; MRSA strains were quantified and characterized by molecular fingerprinting. RESULTS: A total of 444 nares swab specimens yielded MRSA (geometric mean quantity, 794 CFU per swab; range, 3-15,000,000 CFU per swab). MRSA prevalence was 20% for elderly residents of long-term care facilities (25 of 125 residents), 16% for HIV-infected outpatients (78 of 494 outpatients), 15% for outpatients receiving hemodialysis (31 of 208 outpatients), 14% for inpatients receiving hemodialysis (86 of 623 inpatients), 3% for HIV-infected inpatients (5 of 161 inpatients), and 3% for inpatients requiring cardiac surgery (6 of 199 inpatients). The highest geometric mean quantity of MRSA was for inpatients requiring cardiac surgery (11,500 CFU per swab). An association was found between HIV infection and colonization with the USA300 or USA500 strain of MRSA (P < or = .001). The Brazilian clone was found for the first time in the United States. Pulsed-field gel electrophoresis patterns for 11 isolates were not compatible with known USA types or clones. CONCLUSION: Nasal swab specimens positive for MRSA had a geometric mean quantity of 794 CFU per swab, with great diversity in the quantity of MRSA at this anatomic site. Outpatient populations at high risk for MRSA carriage were elderly residents of long-term care facilities, HIV-infected outpatients, and outpatients receiving hemodialysis.

Methicillin-resistant Staphylococcus caprae in a neonatal intensive care unit.

Staphylococcus caprae, a hemolytic coagulase-negative staphylococcus that is infrequently associated with humans, was initially detected in specimens from six infants in our neonatal intensive care unit due to phenotypic characteristics common to methicillin-resistant Staphylococcus aureus. These isolates were subsequently identified as S. caprae by the Automated RiboPrinter microbial characterization system. This prompted an 8-month retrospective investigation in our neonatal intensive care unit. S. caprae was the cause of 6 of 18 episodes of coagulase-negative staphylococcal bacteremia, was the most common coagulase-negative staphylococcus recovered from the nares of 6 of 32 infants surveyed in a methicillin-resistant S. aureus surveillance program, and was isolated from 1 of 37 health care providers' hands. Of 13 neonatal intensive care unit isolates tested, all were methicillin resistant and positive for the mecA gene. All 21 isolates were found to be a single strain by Automated RiboPrinter and pulsed-field gel electrophoresis with ApaI or SmaI digestion; ApaI was more discriminating in analyzing epidemiologically unrelated strains than Automated RiboPrinter or electrophoresis with SmaI. These findings extend the importance of S. caprae, emphasize its similarities to methicillin-resistant S. aureus, and demonstrate its ability to persist in an intensive care unit setting.

Staphylococcus aureus with reduced susceptibility to vancomycin.

Infections with Staphylococcus aureus with reduced susceptibility to vancomycin continue to be reported, including 2 cases caused by S. aureus isolates with full resistance to vancomycin. This review first outlines the definitions of vancomycin-intermediate S. aureus (VISA) and vancomycin-resistant S. aureus (VRSA) and risk factors for infection. Next, we describe the mechanisms of resistance and methods of laboratory detection of the organisms. Finally, we address infection control and management issues associated with isolation of VISA and VRSA.

Ventriculitis complicating use of intraventricular catheters in adult neurosurgical patients.

Ventriculitis is a serious complication of intraventricular catheter (IVC) use, with rates of IVC-related infections ranging from 0% to 45% and gram-positive organisms predominating. We prospectively analyzed ventriculostomy-related infections occurring among 157 adult neurosurgical patients (mean age, 54.9 years; 90 [57%] were women) from 1995 through 1998, to determine the incidence of, risk factors for, and organisms that cause ventriculitis. A total of 196 IVC events resulted in 11 infections (5.6%; 9 were caused by gram-negative organisms and 2 by coagulase-negative staphylococci). Independent risk factors for IVC-related infection include length of IVC placement (8.5 days [infected] vs. 5.1 days [uninfected]; P=.007) and cerebrospinal fluid leakage about the IVC (P=.003). The length of hospital stay (30.8 days vs. 22.6 days; P=.03) and mean total hospital charges ($85,674.27 vs. $55,339.21; P=.009) were greater for infected patients than for uninfected patients. In addition, a microbiologic shift from gram-positive organisms toward gram-negative organisms was noted. This study suggests that IVC-related infections remain serious infections that increase the length of hospitalization.

Anthrax as a biological weapon: medical and public health management - consensus statement.

It presents recommendations are made regarding the diagnosis of anthrax, indications for vaccination, therapy for those exposed, postexposure prophylaxis, decontamination of the environment, and additional research needs. Published in JAMA, 281:1735-1745, 1999. Document in pdf format; Acrobat Reader required.

Tularemia as a biological weapon: medical and public health management.

OBJECTIVE: The Working Group on Civilian Biodefense has developed consensus-based recommendations for measures to be taken by medical and public health professionals if tularemia is used as a biological weapon against a civilian population. PARTICIPANTS: The working group included 25 representatives from academic medical centers, civilian and military governmental agencies, and other public health and emergency management institutions and agencies. EVIDENCE: MEDLINE databases were searched from January 1966 to October 2000, using the Medical Subject Headings Francisella tularensis, Pasteurella tularensis, biological weapon, biological terrorism, bioterrorism, biological warfare, and biowarfare. Review of these references led to identification of relevant materials published prior to 1966. In addition, participants identified other references and sources. CONSENSUS PROCESS: Three formal drafts of the statement that synthesized information obtained in the formal evidence-gathering process were reviewed by members of the working group. Consensus was achieved on the final draft. CONCLUSIONS: A weapon using airborne tularemia would likely result 3 to 5 days later in an outbreak of acute, undifferentiated febrile illness with incipient pneumonia, pleuritis, and hilar lymphadenopathy. Specific epidemiological, clinical, and microbiological findings should lead to early suspicion of intentional tularemia in an alert health system; laboratory confirmation of agent could be delayed. Without treatment, the clinical course could progress to respiratory failure, shock, and death. Prompt treatment with streptomycin, gentamicin, doxycycline, or ciprofloxacin is recommended. Prophylactic use of doxycycline or ciprofloxacin may be useful in the early postexposure period.

Botulinum toxin as a biological weapon: medical and public health management.

OBJECTIVE: The Working Group on Civilian Biodefense has developed consensus-based recommendations for measures to be taken by medical and public health professionals if botulinum toxin is used as a biological weapon against a civilian population. PARTICIPANTS: The working group included 23 representatives from academic, government, and private institutions with expertise in public health, emergency management, and clinical medicine. EVIDENCE: The primary authors (S.S.A. and R.S.) searched OLDMEDLINE and MEDLINE (1960-March 1999) and their professional collections for literature concerning use of botulinum toxin as a bioweapon. The literature was reviewed, and opinions were sought from the working group and other experts on diagnosis and management of botulism. Additional MEDLINE searches were conducted through April 2000 during the review and revisions of the consensus statement. CONSENSUS PROCESS: The first draft of the working group's consensus statement was a synthesis of information obtained in the formal evidence-gathering process. The working group convened to review the first draft in May 1999. Working group members reviewed subsequent drafts and suggested additional revisions. The final statement incorporates all relevant evidence obtained in the literature search in conjunction with final consensus recommendations supported by all working group members. CONCLUSIONS: An aerosolized or foodborne botulinum toxin weapon would cause acute symmetric, descending flaccid paralysis with prominent bulbar palsies such as diplopia, dysarthria, dysphonia, and dysphagia that would typically present 12 to 72 hours after exposure. Effective response to a deliberate release of botulinum toxin will depend on timely clinical diagnosis, case reporting, and epidemiological investigation. Persons potentially exposed to botulinum toxin should be closely observed, and those with signs of botulism require prompt treatment with antitoxin and supportive care that may include assisted ventilation for weeks or months. Treatment with antitoxin should not be delayed for microbiological testing.

Outpatient vancomycin use and vancomycin-resistant enterococcal colonization in maintenance dialysis patients.

BACKGROUND: Although outpatient vancomycin is widely used as empiric therapy for dialysis-associated infections, its relationship with vancomycin-resistant enterococcal (VRE) colonization is not established. METHODS: During a two-year prospective cohort study, rectal swabs obtained from patients at the start and finish of the study period and during interim hospitalizations were cultured for VRE. RESULTS: Ten of 124 patients initially grew VRE. Twenty-four of the remaining patients had no follow-up cultures because of patient death (62%), transfer to another dialysis facility (17%), patient's refusal (7%), and transplantation (4%), and were thus excluded. The remaining patients (N = 90) had a median age of 54.3 years and were 92% African American and 50% male. Fifty-eight percent were treated by hemodialysis. They received 403 g of intravenous vancomycin over 157.2 patient-years of follow-up, 73% as outpatients. Sixteen of 90 patients (17.8%) became colonized with VRE, an incidence rate of one case per 9.8 patient-years of follow-up. None of the 29 patients who did not receive vancomycin developed VRE compared with 26% of those treated with vancomycin (P = 0.001). The odds ratio (95% CI) for the association of outpatient vancomycin (g per year) with VRE colonization was 1.23 (1.05, 1.44, P = 0.008). The association remained significant following adjustment in separate logistic regression analyses for relevant demographic, clinical, antimicrobial (inpatient vancomycin, oral or intravenous cephalosprins, aminoglycosides, quinalones, or antianaerobics), and hospitalization exposures. The unadjusted relative risk of death in patients growing VRE was significantly higher than in those not colonized with VRE (P = 0.005). CONCLUSIONS: VRE colonization is a relatively common and under recognized problem among chronic dialysis patients. It is strongly and independently associated with the outpatient use of vancomycin, which should be avoided whenever possible.

Surveillance strategies and impact of vancomycin-resistant enterococcal colonization and infection in critically ill patients.

OBJECTIVE: To determine the optimal site and frequency for vancomycin-resistant enterococci (VRE) surveillance to minimize the number of days of VRE colonization before identification and subsequent isolation. SUMMARY BACKGROUND DATA: The increasing prevalence of VRE and the limited therapeutic options for its treatment demand early identification of colonization to prevent transmission. METHODS: The authors conducted a 3-month prospective observational study in medical and surgical intensive care unit (ICU) patients with a stay of 3 days or more. Oropharyngeal and rectal swabs, tracheal and gastric aspirates, and urine specimens were cultured for VRE on admission to the ICU and twice weekly until discharge. RESULTS: Of 117 evaluable patients, 23 (20%) were colonized by VRE. Twelve patients (10%) had VRE infection. Of nine patients who developed infections after ICU admission, eight were colonized before infection. The rectum was the first site of colonization in 92% of patients, and positive rectal cultures preceded 89% of infections acquired in the ICU. This was supported by strain delineations using pulsed-field gel electrophoresis. Twice-weekly rectal surveillance alone identified 93% of the maximal estimated VRE-related patient-days; weekly or admission-only surveillance was less effective. As a test for future VRE infection, rectal surveillance culture twice weekly had a negative predictive value of 99%, a positive predictive value of 44%, and a relative risk for infection of 34. CONCLUSIONS: Twice-weekly rectal VRE surveillance of critically ill patients is an effective strategy for early identification of colonized patients at increased risk for VRE transmission, infection, and death.

An outbreak of scabies in a teaching hospital: lessons learned.

OBJECTIVE: To investigate an outbreak of scabies in an inner-city teaching hospital, identify pathways of transmission, institute effective control measures to end the outbreak, and prevent future occurrences. DESIGN: Outbreak investigation, case-control study, and chart review. SETTING: Large tertiary acute-care hospital. RESULTS: A patient with unrecognized Norwegian (crusted) scabies was admitted to the acquired immunodeficiency syndrome (AIDS) service of a 940-bed acute-care hospital. Over 4 months, 773 healthcare workers (HCWs) and 204 patients were exposed to scabies. Of the exposed HCWs, 147 (19%) worked on the AIDS service. Risk factors for being infested with scabies among HCWs included working on the AIDS service (odds ratio [OR], 5.3; 95% confidence interval [CI95], 2.17-13.15) and being a nurse, physical therapist, or HCW with extensive physical contact with infected patients (OR, 4.5; CI95, 1.26-17.45). Aggressive infection control precautions beyond Centers for Disease Control and Prevention barrier and isolation recommendations were instituted, including the following: (1) early identification of infected patients; (2) prophylactic treatment with topical applications for all exposed HCWs; (3) use of two treatments 1 week apart for all cases of Norwegian scabies; (4) maintaining isolation for 8 days and barrier precautions for 24 hours after completing second treatment for a diagnosis of Norwegian scabies; and (5) oral ivermectin for treatment of patients who failed conventional therapy. CONCLUSIONS: HCWs with the most patient contact are at highest risk of acquiring scabies. Because HCWs who used traditionally accepted barriers while caring for patients with Norwegian scabies continued to develop scabies, we found additional measures were required in the acute-care hospital. HCWs with skin exposure to patients with scabies should receive prophylactic treatment. We recommend (1) using heightened barrier precautions for care of patients with scabies and (2) extending the isolation period for 8 days or 24 hours after the second treatment with a scabicide for those patients with Norwegian scabies. Oral ivermectin was well tolerated for treating patients and HCWs who failed conventional treatment. Finally, we developed a surveillance system that provides a "barometric measure" of the infection rate in the community. If scabies increases in the community, a tiered triage system is activated to protect against transmission among HCWs or hospital patients.

Should we routinely use mupirocin to prevent staphylococcal infections?

Routine use of mupirocin to prevent staphylococcal infections is controversial. We assessed attitudes and practices of healthcare professionals attending the Fourth Decennial International Conference on Nosocomial and Healthcare-Associated Infections regarding mupirocin prophylaxis. Eighty percent of participants did not use mupirocin routinely. At the end of the session, 58% indicated they would consider increased use of mupirocin.

Plague as a biological weapon: medical and public health management. Working Group on Civilian Biodefense.

OBJECTIVE: The Working Group on Civilian Biodefense has developed consensus-based recommendations for measures to be taken by medical and public health professionals following the use of plague as a biological weapon against a civilian population. PARTICIPANTS: The working group included 25 representatives from major academic medical centers and research, government, military, public health, and emergency management institutions and agencies. EVIDENCE: MEDLINE databases were searched from January 1966 to June 1998 for the Medical Subject Headings plague, Yersinia pestis, biological weapon, biological terrorism, biological warfare, and biowarfare. Review of the bibliographies of the references identified by this search led to subsequent identification of relevant references published prior to 1966. In addition, participants identified other unpublished references and sources. Additional MEDLINE searches were conducted through January 2000. CONSENSUS PROCESS: The first draft of the consensus statement was a synthesis of information obtained in the formal evidence-gathering process. The working group was convened to review drafts of the document in October 1998 and May 1999. The final statement incorporates all relevant evidence obtained by the literature search in conjunction with final consensus recommendations supported by all working group members. CONCLUSIONS: An aerosolized plague weapon could cause fever, cough, chest pain, and hemoptysis with signs consistent with severe pneumonia 1 to 6 days after exposure. Rapid evolution of disease would occur in the 2 to 4 days after symptom onset and would lead to septic shock with high mortality without early treatment. Early treatment and prophylaxis with streptomycin or gentamicin or the tetracycline or fluoroquinolone classes of antimicrobials would be advised.

Does the Centers for Disease Control's NNIS system risk index stratify patients undergoing cardiothoracic operations by their risk of surgical-site infection?

BACKGROUND: In 1991, the Centers for Disease Control and Prevention devised the National Nosocomial Infection Surveillance (NNIS) System risk index to stratify populations of surgical patients by the risk of acquiring surgical-site infections (SSIs). OBJECTIVE: To determine whether the NNIS risk index adequately stratifies a population of cardiothoracic surgery patients by the risk of developing SSI. DESIGN: Case-control study. SETTING: The University of Iowa Hospitals and Clinics, a 900-bed, midwestern, tertiary-care hospital. PATIENTS: 201 patients with SSIs identified by prospective infection control surveillance and 398 controls matched by age, gender, type of procedure, and date of procedure. All patients underwent cardiothoracic operative procedures between November 1990 and January 1994. RESULTS: The SSI rate was 7.8%. Seventy-four percent of cases and 80% of controls had a NNIS risk index score of 1; 24% of cases and 16% of controls had a score of 2 (P=.05). Patients with a NNIS risk score > or =2 were 1.8 times more likely to develop an SSI than those with a NNIS score <2 (odds ratio, 1.83; 95% confidence interval, 1.14-2.94, P=.01). The duration of the procedure was the only component of the index that stratified the population by risk of SSI. CONCLUSIONS: The risk of SSI after cardiothoracic operations increases as the NNIS risk index score increases. However, this index only dichotomized the patient population on the basis of the procedure duration. More research is needed to develop a risk index that adequately stratifies the risk of SSI after cardiothoracic operations.

Refinements of environmental assessment during an outbreak investigation of invasive aspergillosis in a leukemia and bone marrow transplant unit.

OBJECTIVES: To investigate an outbreak of aspergillosis in a leukemia and bone marrow transplant (BMT) unit and to improve environmental assessment strategies to detect Aspergillus. DESIGN: Epidemiological investigation and detailed environmental assessment. SETTING: A tertiary-care university hospital with a 37-bed leukemia and BMT unit PARTICIPANTS: Leukemic or BMT patients with invasive aspergillosis identified through prospective surveillance and confirmed by chart review. INTERVENTIONS: We verified the diagnosis of invasive fungal infection by reviewing medical charts of at-risk patients, performing a case-control study to determine risk factors for infection, instituting wet mopping to clean all floors, providing N95 masks to protect patients outside high-efficiency particulate air (HEPA)-filtered areas, altering traffic patterns into the unit, and performing molecular typing of selected Aspergillus flavus isolates. To assess the environment, we verified pressure relationships between the rooms and hallway and between buildings, and we compared the ability of large-volume (1,200 L) and small-volume (160 L) air samplers to detect Aspergillus spores. RESULTS: Of 29 potential invasive aspergillosis cases, 21 were confirmed by medical chart review. Risk factors for developing invasive aspergillosis included the length of time since malignancy was diagnosed (odds ratio [OR], 1.0; P=.05) and hospitalization in a patient room located near a stairwell door (OR, 3.7; P=.05). Two of five A. flavus patient isolates were identical to one of the environmental isolates. The pressure in most of the rooms was higher than in the corridors, but the pressure in the oncology unit was negative with respect to the physically adjacent hospital; consequently, the unit acted essentially as a vacuum that siphoned non-HEPA-filtered air from the main hospital. Of the 78 samples obtained with a small-volume air sampler, none grew an Aspergillus species, whereas 10 of 40 cultures obtained with a large-volume air sampler did. CONCLUSIONS: During active construction, Aspergillus spores may have entered the oncology unit from the physically adjacent hospital because the air pressure differed. Guidelines that establish the minimum acceptable pressures and specify which pressure relationships to test in healthcare settings are needed. Our data show that large-volume air samples are superior to small-volume samples to assess for Aspergillus in the healthcare environment.

Requirements for infrastructure and essential activities of infection control and epidemiology in out-of-hospital settings: a Consensus Panel report.

In 1997 the Association for Professionals in Infection Control and Epidemiology and the Society for Healthcare Epidemiology of America established a consensus panel to develop recommendations for optimal infrastructure and essential activities of infection control and epidemiology programs in out-of-hospital settings. The following report represents the Consensus Panel's best assessment of requirements for a healthy and effective out-of-hospital-based infection control and epidemiology program. The recommendations fall into 5 categories: managing critical data and information; developing and recommending policies and procedures; intervening directly to prevent infections; educating and training of health care workers, patients, and nonmedical caregivers; and resources. The Consensus Panel used an evidence-based approach and categorized recommendations according to modifications of the scheme developed by the Clinical Affairs Committee of the Infectious Diseases Society of America and the Centers for Disease Control and Prevention's Healthcare Infection Control Practices Advisory Committee.