Proinflammatory cytokine expression profile in degenerated and herniated human intervertebral disc tissues

OBJECTIVE

Prior reports document macrophage and lymphocyte infiltration with proinflammatory cytokine expression in pathologic intervertebral disc (IVD) tissues. Nevertheless, the role of the Th17 lymphocyte lineage in mediating disc disease remains uninvestigated. We undertook this study to evaluate the immunophenotype of pathologic IVD specimens, including interleukin-17 (IL-17) expression, from surgically obtained IVD tissue and from nondegenerated autopsy control tissue.

METHODS

Surgical IVD tissues were procured from patients with degenerative disc disease (n = 25) or herniated IVDs (n = 12); nondegenerated autopsy control tissue was also obtained (n = 8) from the anulus fibrosus and nucleus pulposus regions. Immunohistochemistry was performed for cell surface antigens (CD68 for macrophages, CD4 for lymphocytes) and various cytokines, with differences in cellularity and target immunoreactivity scores analyzed between surgical tissue groups and between autopsy control tissue regions.

RESULTS

Immunoreactivity for IL-4, IL-6, IL-12, and interferon-gamma (IFNgamma) was modest in surgical IVD tissue, although expression was higher in herniated IVD samples and virtually nonexistent in control samples. The Th17 lymphocyte product IL-17 was present in >70% of surgical tissue fields, and among control samples was detected rarely in anulus fibrosus regions and modestly in nucleus pulposus regions. Macrophages were prevalent in surgical tissues, particularly herniated IVD samples, and lymphocytes were expectedly scarce. Control tissue revealed lesser infiltration by macrophages and a near absence of lymphocytes.

CONCLUSION

Greater IFNgamma positivity, macrophage presence, and cellularity in herniated IVDs suggests a pattern of Th1 lymphocyte activation in this pathology. Remarkable pathologic IVD tissue expression of IL-17 is a novel finding that contrasts markedly with low levels of IL-17 in autopsy control tissue. These findings suggest involvement of Th17 lymphocytes in the pathomechanism of disc degeneration.

Risk factors for Candida species colonization of neonatal intensive care unit patients

BACKGROUND

Candida spp. are increasingly important pathogens in neonatal intensive care units (NICU). Prior colonization is a major risk factor for candidemia, but few studies have focused on risk factors for colonization, particularly in NICU patients.

METHODS

A prospective, multicenter cohort study was performed in six NICUs to determine risk factors for Candida colonization. Infant gastrointestinal tracts were cultured on admission and weekly until NICU discharge and health care worker hands were cultured monthly for Candida spp.

RESULTS

The prevalence of Candida spp. colonization was 23% (486 of 2157 infants); 299 (14%), 151 (7%) and 74 (3%) were colonized with Candida albicans, Candida parapsilosis and other Candida spp., respectively. Multiple logistic regression analysis adjusting for length of stay, birth weight < or = 1000 g and gestational age < 32 weeks revealed that use of third generation cephalosporins was associated with either C. albicans (155 incident cases) or C. parapsilosis (104 incident cases) colonization. Use of central venous catheters or intravenous lipids were risk factors for C. albicans, whereas delivery by cesarean section was protective. Use of H2 blockers was an independent risk factor for C. parapsilosis. Of 2989 cultures from health care workers' hands, 150 (5%) were positive for C. albicans and 575 (19%) for C. parapsilosis, but carriage rates did not correlate with NICU site-specific rates for infant colonization.

CONCLUSIONS

We speculate that NICU patients acquire Candida spp., particularly C. parapsilosis, from the hands of health care workers. H2 blockers, third generation cephalosporins and delayed enteral feedings alter gastrointestinal tract ecology, thereby facilitating colonization.

Intracellular cytokines in the acute response to highly active antiretroviral therapy

OBJECTIVES

Successful highly active antiretroviral therapy (HAART) is usually associated with a rapid decline in HIV plasma RNA levels and a gradual increase in CD4 T cells. We examined whether changes in cytokine production and profile precede other immunological changes and whether these might occur in temporal association with plasma HIV RNA changes.

DESIGN AND METHODS

Eleven HIV-1-infected patients were enrolled into a prospective cohort study; eight patients were naive to antiretroviral therapy. Blood samples were collected pre-therapy (week 0) and at 1, 2, and 3 weeks post-initiation of therapy.

RESULTS

All 11 patients enrolled remained on triple HAART for 1 week, eight for 2 weeks, and six for > or = 3 weeks. When compared to week 0, these patients had a > or = 2-log10 decline in HIV plasma RNA levels and/or a decline to < or = 400 copies/ml by week 3 of therapy (p = 0.004). The numbers and percentages of CD4 and CD8 T cells, and the percentage of naive, memory, and activated T cells did not change significantly between weeks 0 and 1 or 0 and 3. Of all the immune parameters examined only: the percentage of CD4 T cells spontaneously producing tumor necrosis factor (TNF)-alpha (median, 2.4 versus 0.5% P = 0.025); the percentage of CD8 T cells spontaneously producing TNF-alpha (median, 0.6 versus 0.2% P = 0.037); and the percentage of CD3 T cells spontaneously producing interleukin-4 (median, 1.8 versus 0.8% P = 0.004) changed significantly between weeks 0 and 3.

CONCLUSIONS

In these patients, decreases in the percentage of T cells spontaneously producing TNF-alpha or interleukin-4 preceded changes in CD4 T cells. If confirmed by others, these observations may be useful as early predictors of response to and early failure of HAART.

Infection control programs at children's hospitals: a description of structures and processes

BACKGROUND

Infection control (IC) structures and processes determine the effectiveness of surveillance efforts to prevent infections in health care settings.

METHODS

A survey was sent to 56 children's hospitals collaborating in the Pediatric Prevention Network (PPN).

RESULTS

Completed surveys were returned from 48 hospitals. Responsibility for the IC program resided with the medical director (21%); vice president for patient care (18%); quality improvement director (17%); other senior hospital administrator (15%); or other hospital personnel (18%). Forty-two hospitals had an IC committee; 32 had antimicrobial restriction/control policies; and 21 had an antimicrobial restriction/control task force or committee. Components of antimicrobial restriction programs included infectious disease specialist approval, restricted formularies, selective susceptibility test reporting, and staff education programs. Many methods were used to detect infections, including microbiology laboratory reports (100%); record reviews (98%); informal reports from providers (90%); and readmission reviews (77%).

CONCLUSIONS

Children's hospitals vary widely in how they design and implement their IC functions. These variations influence adverse event detection and nosocomial infection rate calculations. If medical errors, including nosocomial infections, are to be detected and hospital rates compared, standardized methods to collect, analyze, and report data are needed. The PPN has initiated activities to standardize surveillance and IC practices in participating hospitals.

Pediatric Prevention Network: a multicenter collaboration to improve health care outcomes

Nosocomial infections and antimicrobial resistance are major causes of mortality and morbidity and have become a major public health focus. To date, most national and international nosocomial infection surveillance and prevention activities have been focused on adults, despite the fact that pediatric patients are at high risk for nosocomial infections because of their immature immune systems and prevalent device usage. In 1997 the Hospital Infections Program at the Centers for Disease Control and Prevention and the National Association of Children's Hospitals and Related Institutions partnered to establish a Pediatric Prevention Network. Infection control professionals and their hospital administrators at all children's hospitals were invited to participate. The objectives of the network are to establish baseline infection rates; design, implement, and evaluate prevention interventions; establish benchmark rates and best practices; and serve as a site for multicenter studies to improve outcomes for hospitalized children. This network serves as a model for quality improvement systems in health care.

[Risk factors associated with nosocomial bacteremia in low birth weight neonates. Grady Memorial Hospital, Atlanta]

BACKGROUND

Nosocomial bloodstream infections occur frequently in Neonatal Intensive Care Units and are associated with recognized and unrecognized risk factors. Little has been published regarding risk factors for bloodstream infections in low birth weight neonates.

OBJECTIVE

To investigate risk factors for bloodstream infection in neonates < 1,500 g admitted at a Neonatal Intensive Care Unit.

METHODS

A prospective study was undertaken in low birth weight neonates (< 1,500g) during a 22 months period. Bivariant, and logistic regresion (stepwise procedure) analysis was used to determine the significance association of bloodstream infection and perinatal and nosocomial risk factors.

RESULTS

A total of 72 patiens with nosocomial bacteriemia and 147 non bacteriemic patients were studied. Independent risk factors associated with bloodstream infection were birth weight, persistence of umbilical catheter > 7 days and persistence of peripheral arterial catheter > 1 day.

CONCLUSIONS

The uses of umbilical catheter > 7 days, peripheral arterial catheter > 1 day and birth weight < 1,500 g were significant determinants of nosocomial bloodstream infection risk. Because of the importance of invasive procedures as a source of nosocomial bloodstream infections, the lines duration needs to be reviewed with the aim of reducing the incidence of blood stream infection.

Multistate outbreak of hemolysis in hemodialysis patients traced to faulty blood tubing sets

BACKGROUND

Hemolysis associated with hemodialysis is rare. The most frequent causes of hemodialysis-associated hemolysis are chemical contamination, heat, or mechanical injury of erythrocytes from occluded or kinked hemodialysis blood lines. When patients in three states developed hemolysis while undergoing hemodialysis between May 13 and 23, 1998, an investigation was initiated.

METHODS

A case-patient was defined as any patient at healthcare facilities A (Nebraska), B (Maryland), or C (Massachusetts) during May 13 through 23, 1998 (epidemic period), who had hemolysis diagnosed > or =48 hours after undergoing hemodialysis. To identify case-patients and to determine background rates, the medical records of patients from facilities A, B, and C who were undergoing hemodialysis during the epidemic and pre-epidemic (that is, May 5 through 19, 1998) periods were reviewed. Experiments simulating hemodialysis with the same lot numbers of hemodialysis blood tubing cartridge sets used on case- and control-patients were conducted.

RESULTS

The rates of hemolysis among patients at facilities A, B, and C were significantly higher during the epidemic than the pre-epidemic period (13 out of 118 vs. 0 out of 118, P < 0.001; 12 out of 298 vs. 0 out of 298, P = 0.001; and 5 out of 62 vs. 0/65, P = 0.03, respectively). All case-patients had hemolysis. Twenty (66%) had hypertension. Eighteen (60%) had abdominal pain, and 10 (36%) were admitted to an intensive care unit. There were two deaths. The only commonality among the three outbreaks was the use of the same lot of disposable hemodialysis blood tubing from one manufacturer. Examination of the implicated hemodialysis blood tubing cartridge sets revealed narrowing of an aperture through which blood was pumped before entering the dialyzers. In vitro experiments with the hemodialysis blood tubing revealed that hemolysis was caused by increased pressure on erythrocytes as they passed through the partially occluded hemodialysis blood tubing.

CONCLUSIONS

Our investigation traced the multiple hemolysis outbreaks to partially occluded hemodialysis blood tubing produced by a single manufacturer. On May 25, 1998, the manufacturer issued a voluntary nationwide recall of the implicated lots of hemodialysis blood tubing cartridge sets.

Risk factors for candidemia in Neonatal Intensive Care Unit patients. The National Epidemiology of Mycosis Survey study group

BACKGROUND

Candida species are important nosocomial pathogens in neonatal intensive care unit (NICU) patients.

METHODS

A prospective cohort study was performed in six geographically diverse NICUs from 1993 to 1995 to determine the incidence of and risk factors for candidemia, including the role of gastrointestinal (GI) tract colonization. Study procedures included rectal swabs to detect fungal colonization and active surveillance to identify risk factors for candidemia. Candida strains obtained from the GI tract and blood were analyzed by pulsed field gel electrophoresis to determine whether colonizing strains caused candidemia.

RESULTS

In all, 2,847 infants were enrolled and 35 (1.2%) developed candidemia (12.3 cases per 1,000 patient discharges or 0.63 case per 1,000 catheter days) including 23 of 421 (5.5%) babies < or =1,000 g. After adjusting for birth weight and abdominal surgery, forward multivariate logistic regression analysis demonstrated significant risk factors, including gestational age <32 weeks, 5-min Apgar <5; shock, disseminated intravascular coagulopathy, prior use of intralipid, parenteral nutrition, central venous catheters, H2 blockers, intubation or length of stay > 7 days before candidemia (P < 0.05). Catheters, steroids and GI tract colonization were not independent risk factors, but GI tract colonization preceded candidemia in 15 of 35 (43%) case patients.

CONCLUSIONS

Candida spp. are an important cause of late onset sepsis in NICU patients. The incidence of candidemia might be decreased by the judicious use of treatments identified as risk factors and avoiding H2 blockers.

Elucidating the origins of nosocomial infections with Candida albicans by DNA fingerprinting with the complex probe Ca3

Computer-assisted DNA fingerprinting with the complex probe Ca3 has been used to analyze the relatedness of isolates collected from individuals with nosocomial bloodstream infections (BSIs) and hospital care workers (HCWs) in the surgical and neonatal intensive care units (ICUs) of four hospitals. The results demonstrate that for the majority of patients (90%), isolates collected from commensal sites before and after collection of a BSI isolate were highly similar or identical to the BSI isolate. In addition, the average similarity coefficient for BSI isolates was similar to that for unrelated control isolates. However, the cluster characteristics of BSI isolates in dendrograms generated for each hospital compared to those of unrelated control isolates in a dendrogram demonstrated a higher degree of clustering of the former. In addition, a higher degree of clustering was observed in mixed dendrograms for HCV isolates and BSI isolates for each of the four test hospitals. In most cases, HCW isolates from an ICU were collected after the related BSI isolate, but in a few cases, the reverse was true. Although the results demonstrate that single, dominant endemic strains are not responsible for nosocomial BSIs in neonatal ICUs and surgical ICUs, they suggest that multiple endemic strains may be responsible for a significant number of cases. The results also suggest that cross-contamination occurs between patients and HCWs and between HCWs in the same ICU and in different ICUs. The temporal sequence of isolation also suggests that in the majority of cases HCWs are contaminated by isolates from colonized patients, but in a significant minority, the reverse is true. The results of this study provide the framework for a strategy for more definitive testing of the origins of Candida albicans strains responsible for nosocomial infections.

National epidemiology of mycoses survey (NEMIS): variations in rates of bloodstream infections due to Candida species in seven surgical intensive care units and six neonatal intensive care units

Candida species are the fourth most frequent cause of nosocomial bloodstream infections, and 25%-50% occur in critical care units. During an 18-month prospective study period, all patients admitted for > or = 72 hours to the surgical (SICUs) or neonatal intensive care units (NICUs) at each of the participant institutions were followed daily. Among 4,276 patients admitted to the seven SICUs in six centers, there were 42 nosocomial bloodstream infections due to Candida species (9.8/1,000 admissions; 0.99/1,000 patient-days). Of 2,847 babies admitted to the six NICUs, 35 acquired a nosocomial bloodstream infection due to Candida species (12.3/1,000 admissions; 0.64/1,000 patient-days). The following were the most commonly isolated Candida species causing bloodstream infections in the SICU: Candida albicans, 48%; Candida glabrata, 24%; Candida tropicalis, 19%; Candida parapsilosis, 7%; Candida species not otherwise specified, 2%. In the NICU the distribution was as follows: C. albicans, 63%; C. glabrata, 6%; C. parapsilosis, 29%; other, 3%. Of the patients, 30%-50% developed incidental stool colonization, 23% of SICU patients developed incidental urine colonization, and one-third of SICU health care workers' hands were positive for Candida species.

Costs associated with tuberculosis control programs at hospitals caring for children

OBJECTIVE

No data are available on the costs of implementing infection control measures for the control of Mycobacterium tuberculosis (MTB) in pediatric settings. In this study we determined the cost of MTB control measures at three hospitals caring for children.

DESIGN

Infection control and tuberculosis (TB) coordinators obtained cost data retrospectively for the years 1994 to 1995 for tuberculin skin test programs, respiratory protection programs and the retrofit or new construction of environmental controls in pediatric settings.

SETTING

Two pediatric hospitals and one pediatric ward in a large tertiary care hospital.

RESULTS

Total expenditures for TB controls ranged from $15270 to $28158 for the 2-year study period. Engineering controls involved the largest capital outlay at two of three facilities. Average yearly tuberculin skin test costs ranged from $949 to $12504/hospital. Respiratory protection programs cost from $480 to $1680 during the 2-year study period.

CONCLUSIONS

Costs associated with implementing control measures varied slightly by hospital but were less than those incurred by hospitals caring for adults. These costs represent improvements made to upgrade selected aspects of hospital TB control programs, not the cost of an optimal TB control program. Optimal TB control programs in pediatric settings have yet to be described.

Invasive Aspergillus spp infections in rheumatology patients

OBJECTIVE

The number of immunocompromised patients in hospitals has increased, resulting in a concomitant increase in the number of Aspergillus spp infections, with an exceedingly high death rate. From January 1995 through June 1996, 7 patients acquired invasive aspergillosis at a Maryland hospital (Hospital A). No cases had been detected in 1994.

METHODS

To determine risk factors for infection, we conducted a case-control study and an environmental evaluation. A case was defined as histopathologic evidence of invasive Aspergillus spp infection in any Hospital A patient admitted from January 1994 through July 1996.

RESULTS

Of 7 case patients identified, 5 were rheumatology patients hospitalized on 2 wards. Rheumatology case patients were more likely than randomly selected rheumatology patients without invasive Aspergillus spp infection (controls) to die (p = 0.004), to have longer hospitalization both in current (p = 0.008) and prior (p = 0.001) admissions, to receive high doses of intravenous immunosuppressive agents (p = 0.03), or to receive immunosuppressive agents for a longer period of time (p = 0.001). The environmental evaluation showed that construction areas were neither sealed off from patient care areas nor under negative pressure relative to patient-care areas. The air flow from patients' rooms was not positive in relation to the hallway and had only 1.6 air changes per hour.

CONCLUSION

This investigation suggests that rheumatology patients, particularly those receiving high dose intravenous immunosuppressive agents, are at increased risk of invasive Aspergillus spp infection. A high index of suspicion for the diagnosis of nosocomial aspergillosis should be maintained in these patients and, when hospitalized, they should be assigned to rooms removed from or physically separated from construction activity.

APIC and CDC survey of Mycobacterium tuberculosis isolation and control practices in hospitals caring for children. Part 2: Environmental and administrative controls. Association for Professionals in Infection control and Epidemiology, Inc

BACKGROUND

The 1994 Centers for Disease Control and Prevention draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities did not exempt pediatric facilities from instituting controls to prevent nosocomial tuberculosis (TB) transmission. Many researchers contend that TB disease in children does not require such rigid controls. We surveyed acute-care pediatric facilities in the United States to determine adherence to environmental and administrative control recommendations.

METHODS

The study included 4 mailings of a survey to infection control professionals at 284 US children's hospitals and adult acute-care hospitals with > 30 pediatric beds.

RESULTS

Isolation rooms (IRs) generally conformed to recommended guidelines; 92% of respondents reported IRs with > or = 6 air changes per hour, 90% reported 1-pass air and negative pressure, and 89% reported that IRs were private rooms. A sufficient number of inpatient IRs were reported by 88%, but only 42% had IRs in outpatient areas, and 19% had IRs in off-site clinics. Employee tuberculin skin-test programs were in place at 98% of facilities, but policies pertaining to implementation varied. Employees' use of personal respirators increased at respondent hospitals from 1991 to 1994, but as late as 1994, nearly one third still used surgical masks for high-risk procedures.

CONCLUSIONS

Environmental and administrative controls used by respondent hospitals largely conformed to published guidelines. Because definitive studies that quantify the risk of nosocomial M tuberculosis transmission in pediatric settings have yet to be performed, pediatric facilities are required to have the same protections in place as do their adult counterparts.

APIC and CDC survey of Mycobacterium tuberculosis isolation and control practices in hospitals caring for children. Part 1: Patient and family isolation policies and procedures. Association for Professionals in Infection and Epidemiology, Inc

BACKGROUND

The 1994 Centers for Disease Control and Prevention draft Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities did not exempt pediatric facilities from instituting controls to prevent nosocomial tuberculosis (TB) transmission. Many researchers contend that TB disease in children does not require such rigid controls. We surveyed acute-care pediatric facilities in the United States to determine adherence to patient and family isolation policies and procedures.

METHODS

The study included 4 mailings of a survey to infection control professionals at 284 US children's hospitals and adult acute-care hospitals with > 30 pediatric beds.

RESULTS

The overall response rate was 69%. Only 41% of respondents reported having a written TB policy specifically designed for pediatric patients. Whereas 98% of respondents isolated pediatric patients with confirmed pulmonary TB, only 69% reported isolation of patients with miliary TB, and 79% reported isolation of patients with positive gastric aspirates. TB isolation policies for adult visitors were in place at 69% of hospitals, and 50% of hospitals evaluated adults for TB as part of the child's TB treatment plan. A median of 3 contact investigations occurred at each of 47% of respondent hospitals in the preceding 5 years.

CONCLUSIONS

Isolation and infection control policies for children with pulmonary TB largely conformed to published guidelines but varied for children with nonpulmonary TB. Because the greatest risk of nosocomial TB transmission in pediatric facilities comes from adults with TB, a rapid TB screening process for parents and adult contacts accompanying affected children should be instituted at facilities caring for children.

Use of urokinase in pediatric hematology/oncology patients

PURPOSE

This study was conducted to determine urokinase use practices in pediatric hematology/oncology centers.

METHODS

Pediatric hematology/oncology centers were surveyed by telephone regarding urokinase use in children with central venous catheters (CVCs).

RESULTS

A total of 92 centers participated in the study. Urokinase is the primary thrombolytic agent used in pediatric hematology/oncology centers; 67 of 92 (73%) centers had a written protocol for its use. Multiple boluses of urokinase were used in most centers; only 16 of 92 (17%) centers limited urokinase use to 1 bolus per episode of CVC occlusion. At 10 of 92 (11%) centers, adverse events (e.g., fever, chills, or bleeding) after urokinase administration were reported. At 83 of 91 (91%) centers, urokinase was routinely used to clear thrombi in children with central nervous system tumors despite contraindications. At 80 of 92 (87%) centers, occluded CVCs were replaced after unsuccessful thrombolytic therapy, but only 21% of the centers altered the CVC maintenance protocol after replacement. Written protocols, the use of multiple boluses, and urokinase infusions were more likely at larger centers (i.e., > 200 patients) than in medium (100-200 patients) or small (< 100 patients) centers.

CONCLUSIONS

Urokinase is a widely used alternative to replacement of occluded CVCs, but protocols very widely. Indiscriminate urokinase use can be expensive and potentially hazardous. Centers that use urokinase should have standardized protocols, monitor use and adverse effects, and periodically review efficacy data.

National epidemiology of mycoses survey: a multicenter study of strain variation and antifungal susceptibility among isolates of Candida species

The National Epidemiology of Mycoses Survey (NEMIS) involves six academic centers studying fungal infections in surgical and neonatal intensive care unit (ICU) patients. We studied variation in species and strain distribution and anti-fungal susceptibility of 408 isolates of Candida spp. Candida spp. were isolated from blood, other normally sterile site cultures, abscesses, wounds, catheters, and tissue biopsies of 141 patients hospitalized in the surgical (107 patients) and neonatal (34 patients) ICUs of medical centers located in Oregon, Iowa, California, Texas, Georgia, and New York. Isolates were also obtained from selected colonized patients (16 patients) and the hands of health care workers (27 individuals). DNA typing was performed using pulsed field gel electrophoresis, and antifungal susceptibility to amphotericin B, 5-fluorocytosine, fluconazole, and itraconazole was determined using National Committee for Clinical Laboratory Standards (NCCLS) methods. Important variation in susceptibility to itraconazole and fluconazole was noted: MICs of itraconazole ranged from 0.25 microgram/mL (MIC90) in Texas to 2.0 micrograms/mL (MIC90) in New York. Similarly, the MIC90 for fluconazole was higher for isolates from New York (64 micrograms/mL) compared to the other sites (8-16 micrograms/mL). In general, DNA typing revealed patient-unique strains; however, there were 13 instances of possible cross-infection noted in 5 of the medical centers. Notably, 9 of the 13 clusters involved species of Candida other than C. albicans. Potential transmission from patient-to-patient (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis) and health care worker-to-patient (C. albicans, C. parapsilosis, C. krusei) was noted in both surgical ICU and neonatal ICU settings. These data provide further insight into the epidemiology of nosocomial candidiasis in the ICU setting.

Are clinical laboratories in California accurately reporting vancomycin-resistant enterococci?

In order to determine whether hospital-based clinical laboratories conducting active surveillance for vancomycin-resistant enterococci in three San Francisco Bay area counties (San Francisco, Alameda, and Contra Costa counties) were accurately reporting vancomycin resistance, five vancomycin-resistant enterococcal strains and one vancomycin-susceptible beta-lactamase-producing enterococcus were sent to 31 of 32 (97%) laboratories conducting surveillance. Each strain was tested by the laboratory's routine antimicrobial susceptibility testing method. An Enterococcus faecium strain with high-level resistance to vancomycin (MIC, 512 microg/ml) was correctly reported as resistant by 100% of laboratories; an E. faecium strain with moderate-level resistance (MIC, 64 microg/ml) was correctly reported as resistant by 91% of laboratories; two Enterococcus faecalis strains with low-level resistance (MICs, 32 microg/ml) were correctly reported as resistant by 97 and 56% of laboratories, respectively. An Enterococcus gallinarum strain with intrinsic low-level resistance (MIC, 8 microg/ml) was correctly reported as intermediate by 50% of laboratories. A beta-lactamase-producing E. faecalis isolate was correctly identified as susceptible to vancomycin by 100% of laboratories and as resistant to penicillin and ampicillin by 68 and 44% of laboratories, respectively; all 23 (74%) laboratories that tested for beta-lactamase recognized that it was a beta-lactamase producer. This survey indicated that for clinically significant enterococcal isolates, laboratories in the San Francisco Bay area have problems in detecting low- to moderate-level but not high-level vancomycin resistance. Increasing accuracy of detection and prompt reporting of these isolates and investigation of cases are the next steps in the battle for control of the spread of vancomycin resistance.

An outbreak of Enterobacter hormaechei infection and colonization in an intensive care nursery

Enterobacter hormaechei was first identified as a unique species in 1989. Between 29 November 1992 and 17 March 1993, an outbreak of E. hormaechei occurred among premature infants in the intensive care nursery (ICN) at The Hospital of the University of Pennsylvania. The 10 infants whose cultures were positive for E. hormaechei (six were infected and four were colonized) had a lower median estimated gestational age and birth weight than did other ICN infants; other risk factors for infection or colonization with E. hormaechei were not identified. Cultures from three isolettes and a doorknob in the ICN were positive for E. hormaechei. Pulsed-field gel electrophoresis of isolates from six patients and two isolettes were identical. Observations of health care workers revealed breaks in infection control techniques that may have allowed transmission of this organism. We found that E. hormaechei is a nosocomial pathogen that can infect vulnerable hospitalized patients and that can be transmitted from patient to patient when infection control techniques are inadequate.

Enterococci resistant to multiple antimicrobial agents, including vancomycin. Establishment of endemicity in a university medical center

OBJECTIVES

To determine the distribution of and risk factors for colonization and infection with vancomycin-resistant enterococci; to evaluate the molecular epidemiology of these strains; and to assess the effect of interventions, including 1) strict adherence to infection control procedures and 2) restricted use of vancomycin.

DESIGN

Problem identification based on descriptive studies, point-prevalence surveys, and case-control studies and followed by specific interventions and evaluation of the response to these interventions.

SETTING

University medical center.

PARTICIPANTS

All patients hospitalized between May 1992 and June 1994 (59,196 admissions).

MAIN RESULTS

75 active infections attributed to vancomycin-resistant enterococci were identified. Thirty-one patients (41%) had bloodstream infections and 6 (8%) died. The incidence of active infection was highest in the organ transplantation unit (13.2 infections/1000 admissions). In the point-prevalence studies, vancomycin-resistant enterococci were isolated from 20% of a random sample of hospitalized patients in July, August, and September 1993 (adjusted prevalence, 16.9%). Case-control studies showed significant associations between colonization and infection and 1) receipt of antimicrobial agents, particularly vancomycin, and 2) severity of illness. Although several small case clusters had isolates with identical banding patterns on pulsed field gel electrophoresis, at least 45 different banding patterns were noted among medical center isolates. Interventions took place in November and December 1993. Vancomycin restriction policies resulted in a 59% decrease in intravenous vancomycin use and an 85% decrease in oral vancomycin use. Point-prevalence surveys done in April, May, and June 1994 showed a consistent 20% level of colonization with vancomycin-resistant enterococci strains (adjusted prevalence, 18.7%). No significant changes were seen in rates of vancomycin-resistant enterococci infection.

CONCLUSIONS

Vancomycin-resistant enterococci are an important cause of illness and death in the study institution, particularly among organ transplant recipients and other seriously ill persons; they have also become a common intestinal colonizer among hospitalized patients. The diversity of isolates (based on molecular typing studies) suggests that resistant organisms have been introduced from multiple sources. Interventions that effectively lower the overall level of colonization with vancomycin-resistant enterococci must still be identified.

Transmission of HIV in dialysis centre

In August, 1993, 13 dialysis patients at one dialysis centre in Colombia, South America, were found to be HIV positive, and this prompted an epidemiological investigation. We carried out a cohort study of all dialysis centre patients during January, 1992 to December, 1993 (epidemic period) to determine risk factors for HIV seroconversion. Haemodialysis and medical records were reviewed, dialysis centre staff and surviving patients were interviewed, and dialysis practices were observed. Stored sera from all dialysis centre patients were tested for HIV antibody. 12 (52%) of 23 patients tested positive for HIV antibody by enzyme immunoassay and western blot during the epidemic period. Of the 23 tested, 9 (39%) converted from HIV antibody negative to positive (seroconverters) and 10 (44%) remained HIV negative (seronegatives). The HIV seroconversion rate was higher among patients dialysed at the centre while a new patient, who was HIV seropositive, was dialysed there (90% vs 0%; p < 0.01), or when the dialysis centre reprocessed access needles, dialysers, and bloodlines (60% vs 0%). While 2 of 9 HIV seroconverters had had sex with prostitutes, none had received unscreened blood products or had other HIV risk factors. No surgical or dental procedures were associated with HIV seroconversion. Dialysers were reprocessed separately with 5% formaldehyde and were labelled for use on the same patient. Access needles were reprocessed by soaking them in a common container with a low-level disinfectant, benzalkonium chloride; 4 pairs of needles were placed in one pan creating the potential for cross-contamination or use of one patient's needles on another patient. HIV transmission at the dialysis centre was confirmed. Improperly reprocessed patient-care equipment, most probably access needles, is the likely mechanism of transmission. This outbreak was discovered by accident and similar transmission may be occurring in many other countries where low-level disinfectants are used to sterilise critical patient-care equipment.

Ability of clinical laboratories to detect antimicrobial agent-resistant enterococci

To test the ability of clinical laboratories to detect antimicrobial resistance among enterococci, we sent four vancomycin-resistant enterococcal strains and one beta-lactamase-producing enterococcus to all 93 nongovernment, hospital-based clinical laboratories in New Jersey; 76 (82%) participated in the study. Each organism was tested by the laboratory's routine antimicrobial susceptibility testing method. The proportion of laboratories that correctly reported that an isolate was resistant to vancomycin varied according to the resistance level of the isolate: high-level resistance (MIC for Enterococcus faecium = 512 micrograms/ml), 96% of laboratories correct; moderate-level resistance (MIC for E. faecium = 64 micrograms/ml), 27% correct; low-level resistance (MIC for Enterococcus faecalis = 32 micrograms/ml), 16% correct; and intrinsic low-level resistance (MIC for Enterococcus gallinarum = 8 micrograms/ml), 74% correct. The beta-lactamase-producing E. faecalis isolate was identified as resistant to penicillin and ampicillin by 66 and 8% of laboratories, respectively, but only three laboratories recognized that it was a beta-lactamase producer. This survey suggests that many laboratories may fail to detect antimicrobial agent-resistant enterococci.

Modeling and molecular mechanical studies of the cis-thymine glycol radiation damage lesion in DNA

Computer graphics and energy minimization techniques were used to construct a model of DNA containing cis-thymine glycol, an oxidation product of thymine formed in DNA by ionizing radiation. The model simulated an experimental DNA substrate used to study the effects of this lesion on DNA synthesis in vitro. The results derived from the model indicate that cis-thymine glycol lesions introduce localized perturbations of DNA structure. Specifically the model shows that interactions with the neighboring base pair on the 5' side are significantly destabilized by thymine glycol whereas interactions with the 3' base pair are stabilized by the lesion. The magnitude of these effects is modulated by the nucleotide sequence around the lesion, particularly by the nature of the base on the 3' side. The base pair formed between adenine and thymine glycol is energetically stable and shows minimal distortion, suggesting that this lesion retains the ability to direct the insertion of the correct nucleotide during DNA synthesis.