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.

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.

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.

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.

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.

An outbreak of vancomycin-dependent Enterococcus faecium in a bone marrow transplant unit

Outbreaks of vancomycin-resistant enterococci (VRE) are well described. The presence of mutants of VRE, such as vancomycin-dependent enterococci (VDE), in individual patients has been documented, but their potential to spread nosocomially has not been known. We present the first cluster of patients who acquired VDE nosocomially. Five bone marrow transplantation patients were infected or colonized by a genotypically indistinguishable multiantibiotic-resistant strain of Enterococcus faecium. Vancomycin dependence in 3 of the 5 isolates was demonstrated. All cluster patients had received protracted prophylactic treatment with vancomycin (mean, 22.6 days), and specimens from >/=2 body sites were repeatedly culture-positive for the outbreak strain. The outbreak was controlled with aggressive infection control strategies, and prophylactic antibiotic policies were revised. Awareness of the potential for nosocomial spread of multiantibiotic-resistant VDE is vital for the care of immunocompromised patients, especially those receiving prophylactic antibiotics.

Requirements for infrastructure and essential activities of infection control and epidemiology in out-of-hospital settings: a consensus panel report. Association for Professionals in Infection Control and Epidemiology and Society for Healthcare Epidemiology of America

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.

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.

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

OBJECTIVE

To develop consensus-based recommendations for measures to be taken by medical and public health professionals following the use of anthrax as a biological weapon against a civilian population.

PARTICIPANTS

The working group included 21 representatives from staff of 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 April 1998, using the Medical Subject Headings anthrax, Bacillus anthracis, biological weapon, biological terrorism, biological warfare, and biowarfare. Review of references identified by this search led to identification of relevant references published prior to 1966. In addition, participants identified other unpublished references and sources.

CONSENSUS PROCESS

The first draft of the consensus statement was a synthesis of information obtained in the formal evidence-gathering process. Members of the working group provided formal written comments which were incorporated into the second draft of the statement. The working group reviewed the second draft on June 12, 1998. No significant disagreements existed and comments were incorporated into a third draft. The fourth and final statement incorporates all relevant evidence obtained by the literature search in conjunction with final consensus recommendations supported by all working group members.

CONCLUSIONS

Specific consensus 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.

The threat of vancomycin resistance

Vancomycin, produced in 1958, an essential antibiotic in the modern age, often is reserved for use in patients who are gravely ill or for infections caused by organisms resistant to penicillin, cephalosporin, or other antibiotics. Bacterial resistance to vancomycin has caused great concern among many healthcare professionals. First reported in 1986 in Europe and in 1988 in the United States, vancomycin-resistant enterococci (VRE) have become a major cause of nosocomial infections. During this time, scattered reports of clinical infections caused by vancomycin-resistant coagulase-negative staphylococci also were reported. Recently, enterococci that require vancomycin in media for growth, vancomycin-dependent enterococci (VDE), have been reported to cause clinically significant infections. Vancomycin or other glycopeptide intermediately resistant Staphylococcus aureus (VISA/GISA) also has emerged. The mechanisms of resistance to vancomycin for VRE, and probably for VISA/GISA, relate to the acquired ability of these organisms to circumvent the vancomycin-mediated disruption of bacterial cell wall synthesis. Risk factors that lead to VRE colonization or infection include prior antibiotic therapy, prolonged hospitalization, hospitalization in an intensive care unit, concomitant serious medical and surgical illnesses, exposure to equipment contaminated with VRE, and exposure to patients with VRE. Patients colonized or infected with VRE, healthcare workers with contaminated hands, and environmental surfaces in healthcare facilities are major reservoirs of VRE. Risk factors for VDE and VISA/GISA are less well understood, although both organisms emerge in patients receiving vancomycin or other glycopeptide antibiotics. Infection and antibiotic control procedures for both organisms, including restriction of vancomycin use, optimization of the antibiotic formulary, education of hospital personnel, early detection and reporting of vancomycin resistance, isolation of colonized patients, and appropriate cleansing of the environment are used to prevent the spread of these organisms in healthcare settings.

Reducing the rate of nosocomially transmitted respiratory syncytial virus

BACKGROUND

A large number (17) of nosocomial respiratory syncytial virus cases led to the development of control measures to prevent transmission of respiratory syncytial virus (RSV) within the Johns Hopkins Hospital's Children's Center.

METHODS

The control plan is based on a 2-stage process. In stage 1, the staff are notified that RSV is in the community, and information is distributed through a communication tree. Stage 2 requires that nasopharyngeal aspirates be obtained from all children <3 years of age who have respiratory symptoms. The aspirates are tested directly for RSV antigen and cultured for RSV. The children are placed on pediatric droplet precautions pending those results.

RESULTS

The proportion of nosocomial RSV cases dropped from 16.5% before the use of RSV control measures to 7.2% after the initiation of the control program. A case of RSV identified in the hospital was 2.6 times more likely to be nosocomially acquired before the intervention compared with after the intervention. Approximately 14 cases of RSV are prevented each year, which results in a savings of 56 hospital-days and more than $84,000 in direct hospital-related charges alone.

CONCLUSIONS

The nosocomial spread of RSV can be reduced by a specific and feasible control plan that includes early identification and rapid isolation of potential RSV cases.

Investigation of suspected nosocomial clusters of Staphylococcus haemolyticus infections

OBJECTIVE

To determine whether typing methods can discriminate among Staphylococcus haemolyticus isolates.

DESIGN

Molecular epidemiological evaluation of S. haemolyticus isolates obtained from patients hospitalized on a hematology service and in a surgical intensive-care unit (SICU).

SETTING

A large Midwestern teaching hospital.

INTERVENTIONS

None.

RESULTS

Over 22 days, S. haemolyticus was isolated from five patients on the hematology service. Isolates from four patients had the same unusual antibiogram and biotype. Ribotyping, restriction endonuclease digestion of plasmid DNA (REAP), and whole chromosomal DNA analysis by pulsed-field gel electrophoresis (PFGE) confirmed that these isolates were identical and different from the fifth patient's isolate and from 6 control isolates. In a second cluster, 11 S. haemolyticus isolates obtained from eight patients in the SICU had similar antibiograms and biotypes. By REAP and ribotype analysis, isolates from four patients were identical. However, PFGE indicated that only two of these patients shared a common strain.

CONCLUSIONS

Antibiograms or biotyping may discriminate among isolates of S. haemolyticus if the results of these tests are unusual. Many clinical isolates can be differentiated by REAP analysis, ribotyping, or PFGE. However, some isolates are identical by all of these methods, suggesting that they may have been transmitted nosocomially.

An outbreak of Serratia marcescens infections related to contaminated chlorhexidine

An outbreak of Serratia marcescens infections occurred in a university tertiary-care hospital. Alcohol-free chlorhexidine solutions were contaminated with S marcescens. The majority of patient and chlorhexidine strains had similar pulsed field-gel electrophoresis banding patterns. Chlorhexidine was recalled, and the rate of S marcescens isolation returned to baseline. Chlorhexidine without alcohol should not be used as an antiseptic.

Learning and memory difficulties after environmental exposure to waterways containing toxin-producing Pfiesteria or Pfiesteria-like dinoflagellates

BACKGROUND

At the beginning of autumn, 1996, fish with "punched-out" skin lesions and erratic behaviour associated with exposure to toxins produced by Pfiesteria piscicida or Pfiesteria-like dinoflagellate species were seen in the Pocomoke River and adjacent waterways on the eastern shore of the Chesapeake Bay in Maryland, USA. In August, 1997, fish kills associated with Pfiesteria occurred in these same areas. People who had had contact with affected waterways reported symptoms, including memory difficulties, which raises questions about the human-health impact of environmental exposure to Pfiesteria toxins.

METHODS

We assessed 24 people who had been exposed. We collected data on exposure history and symptoms, did a complete medical and laboratory assessment (13 people), and carried out a neuropsychological screening battery. Performance on neuropsychological measures was compared with a matched control group.

RESULTS

People with high exposure were significantly more likely than occupationally matched controls to complain of neuropsychological symptoms (including new or increased forgetfulness); headache; and skin lesions or a burning sensation of skin on contact with water. No consistent physical or laboratory abnormalities were found. However, exposed people had significantly reduced scores on the Rey Auditory Verbal Learning and Stroop Color-Word tests (indicative of difficulties with learning and higher cognitive function), and the Grooved Pegboard task. There was a dose-response effect with the lowest scores among people with the highest exposure. By 3-6 months after cessation of exposure, all those assessed had test scores that had returned to within normal ranges.

INTERPRETATION

People with environmental exposure to waterways in which Pfiesteria toxins are present are at risk of developing a reversible clinical syndrome characterised by difficulties with learning and higher cognitive functions. Risk of illness is directly related to degree of exposure, with the most prominent symptoms and signs occurring among people with chronic daily exposure to affected waterways.

Occupationally acquired infections and the healthcare worker

Much of the recent research related to occupational infections in healthcare workers has focused on the evaluation of the effectiveness of preventive measures, the cost-effectiveness of such measures, and alternative approaches to preventing common occupational infections. This article reviews recent information on healthcare workers about occupationally acquired diseases and considers the risks from unusual or re-emerging pathogens. Among recent advances of note are effective post-exposure prophylaxis for HIV, approaches to achieving immunity to hepatitis B in vaccine non-responders, better diagnostic tests for hepatitis C and improved equipment for preventing blood exposure and tuberculosis.

Septic shock: an analysis of outcomes for patients with onset on hospital wards versus intensive care units

OBJECTIVE

To determine if early interventions for septic shock were associated with reduced mortality.

DESIGN

Retrospective cohort study.

SETTING

University hospital intensive care unit (ICU) and general wards.

PATIENTS

Forty-one consecutive patients prospectively identified with positive blood cultures and septic shock. Although all patients were eventually treated in an ICU, ten (24%) patients were on a general ward at the onset of septic shock, and 31 (76%) were in an ICU setting.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Over a period of 9 mos, a cohort of 41 patients who had positive blood cultures and septic shock was prospectively identified. The 28-day crude mortality was 46% (19 deaths). We compared the management of septic shock and outcome for patients on a general ward vs. those patients in an ICU setting. Of the ten patients on the ward at time of shock onset (median age 55.5 yrs; median Acute Physiology and Chronic Health Evaluation [APACHE] II score of 18.5), seven (70%) died. In contrast, the 31 patients receiving intensive care when shock developed were older and more ill (median age 66 yrs; median APACHE II 24), yet had a mortality of 39% (12 deaths). The odds ratio (OR) for death for ward patients compared with ICU patients was 3.57 (p=.17). In a multivariate logistic regression analysis, two risk factors for mortality were important: APACHE II score (p=.015) and ward status (p=.08). Candida species in the bloodstream is known to have a high attributable mortality. When type of bloodstream pathogen (Candida species vs. bacteria) was added to the model, APACHE II (OR 2.64 for 10-unit increase) remained significant (p=.014), but ward status (OR 3.97) became statistically nonsignificant (p=.222). The patients who were on a general ward when their shock developed had a median delay of 67 mins before transfer to an ICU setting. Ward patients received an intravenous fluid bolus after a median delay of 27 mins, whereas those in the ICU who received a fluid bolus did so after a median of 15 mins (p=.48). Ward patients also had a median delay of 310 mins to receive inotropic support compared with a median 22.5 mins (p=.037) for the patients in an ICU setting when shock started.

CONCLUSIONS

The data suggest that for patients with septic shock on wards, there were clinically important delays in transfer of patients to the ICU, receipt of intravenous fluid boluses, and receipt of inotropic agents. However, the most powerful predictors of mortality were APACHE II scores and bloodstream infection with Candida species.

Pfiesteria in Maryland: preliminary epidemiologic findings

In the fall of 1996, fish kills in Maryland rivers were attributed to the dinoflagellate, Pfiesteria piscicida. After a group of researchers established a potential link between exposure to Pfiesteria and an illness causing memory problems, state health authorities closed a portion of the Pocomoke River. To determine the extent of illness, the range of symptoms, potential risk factors for disease, and to provide information to concerned citizens, a toll-free hotline was created. All symptomatic persons who called the toll-free number were administered a standardized questionnaire. Persons who had been exposed to Pfiesteria or Pfiesteria-laden waters were more likely to have respiratory, neurologic, dermatologic, and gastrointestinal problems than those persons without exposure. Among the persons calling the hotline, many had extensive neuropsychologic testing. Of the neuropsychologic test battery, low scores on the Rey Auditory Verbal Learning Test (RAVLT), a standardized measure of learning and memory, best characterized illness related to Pfiesteria exposure. Patients with low RAVLT scores were more likely to have neurologic symptoms and skin lesions than control subjects. Low RAVLT scores were associated with fishing (OR, 9.00, 95% CI, 106, 409.87), catching fish with lesions (OR, 6.17, 95% CI 1.27, 32.10), and handling fish with lesions (OR, 5.34, 95% CI, 1.05, 29.92), but not with consumption of seafood. While preliminary, these results do suggest that some risk factors for Pfiesteria-related illness may be easy to modify and used to prevent unnecessary human exposure.

The epidemiology of hemorrhage related to cardiothoracic operations

OBJECTIVE

To define the epidemiology, risk factors, and unadjusted cost of hemorrhages related to cardiothoracic operations.

STUDY DESIGN

We conducted two case-control studies to evaluate the risk of hemorrhage following cardiothoracic operations. The definition of hemorrhage required one of the following: reoperation for bleeding, postoperative loss of greater than 800 mL of blood over 4 hours, or surgeon-diagnosed excessive intraoperative bleeding.

SETTING

The cardiothoracic surgery service of a university hospital.

RESULTS

Of 511 patients undergoing cardiothoracic operations, 93 (18%) met the definition of hemorrhage. In the first case-control study, 3 (14%) of 21 cases and 0 of 42 controls died (odds ratio [OR], 15.0; 95% confidence interval [CI95], 1.18-191.55). Compared with controls, cases received significantly more packed red blood cells intraoperatively (OR, 1.18/100 mL; CI95, 1.01-1.38), and significantly more platelets (OR, 3.26/100 mL; CI95, 1.47-7.26) and fresh frozen plasma (OR, 1.73/100 mL; CI95, 1.05-.84) in the intensive-care unit. Cases were more likely than controls to receive protamine postoperatively (OR, 3.74; CI95, 1.27-11.02). Previous sternotomy, preoperative aspirin or heparin, and preoperative laboratory values did not predict bleeding. The median unadjusted hospital cost was $3,458 higher for patients who suffered hemorrhage than for controls. To decrease costs, hetastarch (acquisition cost $45/500 mL) was substituted for albumin (acquisition cost $76/100 mL) in the pump priming solution (estimated possible cost savings, $7,000-$53,000/year). Because hemorrhage rates increased subsequently, we conducted a second case-control study that identified patient age (P=.02) and use of greater than 5 mL/kg of hetastarch (OR, 1.82) as risk factors for hemorrhage. The cost of treating hemorrhages exceeded all estimates of possible cost savings ($7,000-$53,000 per year).

CONCLUSIONS

Our definition of hemorrhage identified patients who required increased volumes of blood products and who had an increased crude mortality rate and a higher unadjusted cost of hospitalization. Patient age and hetastarch use were risk factors for hemorrhage. Efforts to save money by substituting less expensive products inadvertently may increase costs by increasing the probability of perioperative adverse events.

New approaches to reduce Staphylococcus aureus nosocomial infection rates: treating S. aureus nasal carriage

BACKGROUND

Nosocomial infections cause significant patient morbidity and mortality. The 2.5 million nosocomial infections that occur each year cost the US healthcare system $5 million to $10 million. Staphylococcus aureus has long been recognized as an important pathogen in human disease and is the most common cause of nosocomial infections.

OBJECTIVE

To describe the epidemiology of S. aureus nosocomial infections that are attributable to patients' endogenous colonization.

DATA SOURCES

Review of the English-language literature and a MEDLINE search (as of September 1997).

DATA SYNTHESIS

The ecologic niche of S. aureus is the anterior nares. The prevalence of S. aureus nasal carriage is approximately 20-25%, but varies among different populations, and is influenced by age, underlying illness, race, certain behaviors, and the environment in which the person lives or works. The link between S. aureus nasal carriage and development of subsequent S. aureus infections has been established in patients on hemodialysis, on continuous ambulatory peritoneal dialysis, and those undergoing surgery. S. aureus nasal carriers have a two-to tenfold increased risk of developing S. aureus surgical site or intravenous catheter infections. Thirty percent of 100% of S. aureus infections are due to endogenous flora and infecting strains were genetically identical to nasal strains. Three treatment strategies may eliminate nasal carriage: locally applied antibiotics or disinfectants, systemic antibiotics, and bacterial interference. Among these strategies, locally applied or systemic antibiotics are most commonly used. Nasal ointments or sprays and oral antibiotics have variable efficacy and their use frequently results in antimicrobial resistance among S. aureus strains. Of the commonly used agents, mupirocin (pseudomonic acid) ointment has been shown to be 97% effective in reducing S. aureus nasal carriage. However, resistance occurs when the ointment has been applied for a prolonged period over large surface areas.

CONCLUSIONS

Given the importance of S. aureus nosocomial infections and the increased risk of S. aureus nasal carriage in patients with nosocomial infections, investigators need to study cost-effective strategies to prevent certain types of nosocomial infections or nosocomial infections that occur in specific settings. One potential strategy is to decrease S. aureus nasal carriage among certain patient populations.

Basics of surgical-site infection surveillance

Surgical-site infections, the third most common class of nosocomial infections, cause substantial morbidity and mortality and increase hospital costs. Surveillance programs can lead to reductions in surgical-site infection rates of 35% to 50%. Herein, we will discuss the practical aspects of implementing a hospital-based surveillance program for surgical-site infections. We will review surveillance methods, patient populations that should be screened, and interventions that could reduce infection rates.

Basics of surveillance--an overview

Surveillance of nosocomial infections is the foundation of an infection control program. This article describes components of a surveillance system, methods for surveillance, methods for case-finding, and data sources. We encourage the epidemiology team to use this background information as they design surveillance systems that meet the goals of their individual institution's infection control program.

Staphylococcus cohnii: a case report on an unusual pathogen

Coagulase-negative staphylococci have become increasingly important causes of infection in predisposed hosts. such as patients receiving immunosuppressive therapy and broad-spectrum antimicrobial drugs, patients who have prosthetic devices, or those who have prolonged hospital or intensive care unit stays. However, human infections caused by Staphylococcus cohnii rarely have been reported in the literature. In this report, we review the current literature and describe a 38 year-old immunosuppressed woman who developed catheter-related S. cohnii bacteremia. The case illustrates why microbiology laboratories under certain circumstances should identify coagulase-negative staphylococci to the species level. This information may be critical because it may allow clinicians to identify the source of the infecting organism and to choose appropriate antibiotics. Yet in this era of cost containment many laboratories may decrease costs by decreasing services, including species identification.

The significance of nasal carriage of Staphylococcus aureus and the incidence of postoperative wound infection

Staphylococcus aureus infections are associated with considerable morbidity and, in certain situations, mortality. The association between the nasal carriage of S. aureus and subsequent infection has been comprehensively established in a variety of clinical settings, in particular, patients undergoing haemodialysis and continuous ambulatory peritoneal dialysis (CAPD), and in patients undergoing surgery. Postoperative wound infections are associated with a high degree of morbidity and represent an important medical issue. Until recently, eradication of S. aureus nasal carriage by various topical and systemic agents had proved unsuccessful. Mupirocin is a novel topical antibiotic with excellent antibacterial activity against staphylococci. Recent studies have demonstrated that intranasal administration of mupirocin is effective in eradicating the nasal carriage of S. aureus and in reducing the incidence of S. aureus infections in haemodialysis and CAPD patients. It has been suggested that sufficient evidence now exists to test the hypothesis that eradication of the carrier state in surgical patients preoperatively may reduce the incidence of S. aureus postoperative wound infections.

Long-term survival and function after suspected gram-negative sepsis

OBJECTIVE

To determine the long-term (> 3 months) survival of septic patients, to develop mathematical models that predict patients likely to survive long-term, and to measure the health and functional status of surviving patients.

SETTING

A large tertiary care university hospital and an associated Veterans Affairs Medical Center.

DESIGN

From December 1986 to December 1990, a total of 103 patients with suspected gram-negative sepsis entered a double-blind, placebo-controlled efficacy trial of monoclonal antiendotoxin antibody. Of these, we followed up 100 patients for 7667 patient-months. Beginning in May 1992, we reviewed hospital records and contacted all known survivors. We measured the health status of all surviving patients.

MAIN OUTCOME MEASURES

The determinants of long-term survival (up to 6 years) were identified through two Cox proportional hazard regression models: one that included patient characteristics identified at the time of sepsis (bedside model) and another that included bedside, infection-related, and treatment characteristics (overall model).

RESULTS

Of the 60 patients in the cohort who died at a median interval of 30.5 days after sepsis, 32 died within the first month of the septic episode, seven died within 3 months, and four more died within 6 months. In the bedside multivariate model constructed to predict long-term survival, large hazard ratios (HRs) were associated with severity of underlying illness as classified by McCabe and Jackson criteria (for rapidly fatal disease, HR = 30.4, P < .001; for ultimately fatal disease, HR = 7.6, P < .001) and the use of vasopressors (HR = 2.5; P = .001). In the overall model for long-term survival, severity of underlying illness (rapidly fatal disease, HR = 23.7, P < .001; ultimately fatal disease, HR = 6.5, P < .001), number of active comorbid illnesses (HR = 1.3; P = .04), use of vasopressors at the time of sepsis (HR = 2.0; P = .02), and development of adult respiratory distress syndrome (HR = 2.3; P = .02) predicted patients most likely to die. The Acute Physiology and Chronic Health Evaluation II score was not a significant predictor of outcome when either model included the simpler McCabe and Jackson classification of underlying disease severity. We compared the health status scores with norms for the general population and found that patients with resolved sepsis reported more physical dysfunction (P < .001), including problems with work and activities of daily living (P = .02), and more poorly perceived general health (P < .01). In contrast, patients' scores for perceived emotional health were higher than those in the general population (P = .004). The mean Barthel score of our patients was 85 (100 = total independence) and the mean Eastern Cooperative Oncology Group score was 0.7 (0 = normal, 4 = 100% bedridden), suggesting that the patients' physical function was not normal.

CONCLUSIONS

At the onset of suspected gram-negative sepsis, severity of underlying illness and in-hospital use of vasopressors are strong and consistent predictors of short- and long-term survival. Our data validate the McCabe and Jackson severity of illness scoring system for predicting long-term survival after sepsis. Physical dysfunction and more poorly perceived general health occur commonly after sepsis.

Postoperative wound infections: risk factors and role of Staphylococcus aureus nasal carriage

In the United States the rate of postoperative wound infection varies from one to nine per cent, depending on the surgical procedure. Each postoperative wound infection increases the length of stay in hospital, the cost of the procedure and is associated with significant morbidity. Staphylococcus aureus is the causative agent in 15 to 20% of these infections, although the pathogen isolated varies according to the surgical site. Risk factors for acquiring an infection can be divided into the following categories: host factors, surgical and environmental factors, and microbial characteristics. Host factors which may contribute to an increased risk of infection include: age, prolonged pre-operative length of stay, and concurrent infection at another body site. Increased infection risk may result from an extended surgical procedure, the wound classification, the use of a razor for hair removal before surgery and may also be dependent on the surgeon's technical skill. Microbial factors related to the risk of developing an infection postoperatively are less well defined, however, many outbreaks of surgical wound infections have been linked to personnel carrying an organism which is then transmitted to the patient. Furthermore, patients who carry intranasal S. aureus have a two-to ten-fold increased likelihood of developing a postoperative wound infection due to S. aureus. Identification of patients most at risk of developing an infection is the ultimate goal, however, risk indices must be highly sensitive, specific and accurate. To summarize, the epidemiology of postoperative wound infections remains poorly studied, however, since wound infections contribute significantly to morbidity, mortality and cost, future research is warranted.

A second large controlled clinical study of E5, a monoclonal antibody to endotoxin: results of a prospective, multicenter, randomized, controlled trial. The E5 Sepsis Study Group

OBJECTIVE

To evaluate the safety and efficacy of E5, a murine, monoclonal antibody directed against endotoxin, in the treatment of patients with Gram-negative sepsis.

DESIGN

A multicenter, randomized, double-blind, placebo-controlled trial.

SETTING

Fifty-three hospitals across the United States, including university medical centers, Veterans Affairs Medical Centers, and community hospitals.

PATIENTS

847 patients were randomized into this study. Enrolled patients met criteria for three conditions: a) known or suspected Gram-negative infection; b) clinical evidence of sepsis; and c) signs of end-organ dysfunction. Patients with refractory shock were excluded from the study.

INTERVENTIONS

Two doses of E5 (2 mg/kg/day by intravenous infusion 24 hrs apart), or placebo that was identical in appearance were administered. In addition, all patients received standard supportive therapy and broad-spectrum antibiotics.

MEASUREMENTS AND MAIN RESULTS

The primary end point was mortality over 30 days. Secondary outcome measures included the resolution and prevention of organ failure in the same two populations. Additionally, the safety of E5 was evaluated. There was no significant improvement in survival over 30 days among patients with Gram-negative sepsis who received E5 compared with those patients who received placebo (n = 530; p = .21). In addition, E5 did not improve survival for patients with Gram-negative sepsis and organ failure (n = 139; p = .3). However, a significantly greater percentage of patients with Gram-negative sepsis experienced resolution of major organ failure if they received E5, compared with those patients who received placebo (n = 139; 48% E5 vs. 25% placebo; p = .005). This result extended to all patients who entered the study with one or more major organ failures, regardless of the etiology of the infection (n = 225; 41% E5 vs. 27% placebo; p = .024). E5 also provided protection against the development of some organ failures, but significant prevention was only observed for adult respiratory distress syndrome (p = .007) and central nervous system dysfunction (p = .050). Hypersensitivity reactions attributable to E5 occurred in 2.6% of patients. An asymptomatic antibody response occurred in 44% of the E5-treated patients and in 12% of the patients who received placebo.

CONCLUSIONS

In this study, E5 did not reduce mortality in nonshock patients with Gram-negative sepsis whether or not those patients also had organ failure. However, E5 did result in greater resolution of organ failure in patients with Gram-negative sepsis. This benefit extended to those patients with suspected Gram-negative etiology. This finding is important because patients with suspected Gram-negative sepsis and organ failure can be identified without waiting for culture results. In addition, E5 resulted in the prevention of adult respiratory distress syndrome and central nervous system organ failure. However, more studies are needed to determine if this result can be extended to organ failure in general. E5 is safe as a treatment for patients with Gram-negative sepsis.

Nosocomial transmission of Serratia odorifera biogroup. 2: Case report demonstration by macrorestriction analysis of chromosomal DNA using pulsed-field gel electrophoresis

OBJECTIVES

To investigate a cluster of Serratia odorifera in a cardiothoracic surgery unit (CTSU) and to evaluate the applicability of three typing methods for this species.

DESIGN

During a surveillance surgical wound study, S odorifera was isolated from two patients in the CTSU. The patients' hospital charts were reviewed for the details of surgery and for common personnel, procedures, or medications. Cultures were obtained of water, soap, and unit dose medications from the CTSU, the operating room, and the surgical intensive care unit. The isolates' antibiograms, biotypes (Vitek identification card and API 20E), and patterns of chromosomal DNA (chrDNA) by pulsed-field gel electrophoresis (PFGE) were examined. S odorifera isolates from our organism collection were used as controls.

SETTING

A 900-bed university hospital with a 22-bed CTSU.

RESULTS

ChrDNA patterns of isolates from the two patients were identical, suggesting a possible nosocomial source. However, no source of organisms or mode of transmission was identified. Neither biotype nor antibiogram were useful for epidemiologically typing S odorifera, and PFGE was necessary to discriminate among isolates.

CONCLUSIONS

Although rarely isolated, S odorifera and other non-marcescens Serratia species may cause nosocomial outbreaks. PFGE of chrDNA seems to be a reliable method for epidemiologically typing this species.

Comparison of identification systems for Staphylococcus epidermidis and other coagulase-negative Staphylococcus species

Three commercially available systems (API Staph-Trac, API 20GP, and Vitek GPI), used to identify coagulase-negative staphylococci, were evaluated against 277 bloodstream isolates, including 94 isolates of Staphylococcus epidermidis and 183 isolates of other coagulase-negative Staphylococcus species. The conventional method of Kloos and Schleifer served as the reference method. Controls included 14 ATCC type culture strains of coagulase-negative staphylococci. The API Staph-Trac system showed the highest rate of agreement with reference method, correctly identifying 73% of the isolates. The Vitek GPI System had an overall rate of agreement of 67% and the API 20GP system correctly identified 61%. The API Staph-Trac system correctly identified 94% of the isolates of S. epidermidis compared with 64% by both Vitek GPI and API 20GP. The most common error for both Vitek GPI and API 20GP systems was the failure to identify organisms contained within the database of the systems. Because none of the tested commercial identification systems identified "non-epidermidis" coagulase-negative Staphylococcus species with a high degree of accuracy, the systems need to be markedly improved or new systems developed.

Effect of serum on the in vitro activities of 11 broad-spectrum antibiotics

We evaluated the effect of serum on the in vitro activities of 11 antimicrobial agents against gram-negative isolates obtained from 100 patients with nosocomial bacteremia. The test organisms included 25 stains of Pseudomonas aeruginosa and 75 strains of the family Enterobacteriaceae. MICs were determined by broth microdilution with Mueller-Hinton broth alone or supplemented with 25 or 50% pooled, heat-inactivated human serum (25S or 50S, respectively). Among the antibiotics evaluated, the protein binding ranged from 9 to 95%. The antibiotics tested and their MICs for 90% of the strains tested in 50S included ciprofloxacin (0.12 micrograms/ml), ceftazidime (1 micrograms/ml), imipenem (1 micrograms/ml), aztreonam (4 micrograms/ml), cefpirome (4 micrograms/ml), cefotaxime (16 micrograms/ml), cefoperazone (16 micrograms/ml), desacetylcefotaxime plus cefotaxime (32 micrograms/ml), ceftriaxone (greater than 32 micrograms/ml), ticarcillin (128 micrograms/ml), and desacetylcefotaxime (greater than 128 micrograms/ml). MICs for 90% of the strains tested were calculated with 95% confidence intervals to show the precision of the MICs for these strains. With the exceptions of ceftriaxone (greater than 95% protein bound) and cefoperazone (90% protein bound), serum had no significant effect on the in vitro activities of various agents. A fourfold-or-greater increase in the MIC of ceftriaxone was observed in 45 of 100 isolates with 50S and in 30 of 100 isolates with 25S. With cefoperazone, 17 of 100 isolates demonstrated more than 2 twofold dilution increases in 50S. Testing of antibiotics which were less protein bound illustrated minor effects primarily with members of the Enterobacteriaceae. The presence of serum did not adversely affect the in vitro activities of broad-spectrum agents against these nosocomial isolates.