To determine the cause of an outbreak of Klebsiella pneumoniae bloodstream infections (BSIs) among neonates in a high-risk nursery and to institute control measures.

During the on-site investigation, a cohort study to identify risk factors for K. pneumoniae BSI, a point-prevalence study to assess K. pneumoniae colonization, a maternal cohort study to determine maternal K. pneumoniae colonization, and an observational study to evaluate healthcare worker (HCW) compliance with infection control practices were conducted.

Neonates in a 40-bed high-risk nursery in a 700-bed university hospital in Cali, Colombia.

Cohorting of neonates colonized with K. pneumoniae.

The overall K. pneumoniae BSI attack rate was 10 of 105 (9.5%). In the retrospective cohort study, the number of blood transfusions (OR, 3.1 per transfusion; P = .02; CI95,1.4–9.7) and intravenous injections (OR, 1.2 per injection; P = .04; CI95, 1.0–1.5) were independently associated with K. pneumoniae BSI. The overall prevalence of K. pneumoniae colonization was 61% among neonates and 7% among mothers. During the HCW assessment, suboptimal intravenous therapy practices were observed. A cohorting intervention resulted in a significant reduction in K. pneumoniae colonization (12% vs 61%; RR, 0.19; P < .001). During the intervention period, no K. pneumoniae BSIs occurred.

This investigation suggested that the outbreak probably occurred due to widespread colonization and suboptimal infection control and intravenous therapy practices. Cohorting successfully reduced the overall prevalence of K. pneumoniae colonization and, along with improved infection control practices, probably prevented K. pneumoniae BSIs.

Nosocomial infections due to medical devices are of increasing concern to infection control practitioners. Attempts to prevent such infections have included surveillance cultures of endoscopes and bronchoscopes. In July 2002, the infectious disease consultation service was asked to see three patients with sepsis due to multidrug-resistant Pseudomonas aeruginosa after endoscopic retrograde cholangiopancreatography (ERCP).

To describe an outbreak of multidrug-resistant P. aeruginosa sepsis after ERCP at an institution that performs routine surveillance cultures of endoscopes.

A traditional outbreak investigation supplemented by pulsed-field gel electrophoresis (PFGE) was undertaken, including a case-control analysis based on the hypothesis that all infected individuals had their ERCP performed with the same endoscope.

A tertiary-care academic medical center.

The case-control analysis confirmed the hypothesis that undergoing ERCP with the implicated endoscope was associated with a culture positive for Pseudomonas (P = .01). The available strains were identical by PFGE. This outbreak occurred despite a negative surveillance culture of the implicated endoscope 1 month earlier.

Infectious morbidity can occur after endoscopy despite negative surveillance cultures. The practice of routine endoscope cultures does not prevent device-related infectious morbidity.

To identify risk factors associated with the development of surgical-site infection (SSI) following total knee arthroplasty (TKA).

A case-control study.

A 1,100-bed, university-affiliated, tertiary-care teaching hospital.

Case-patients with SSI occurring up to 1 year following primary TKA performed between January 1999 and December 2001 were identified prospectively by infection control practitioners using National Nosocomial Infections Surveillance (NNIS) System methods. Three control-patients were selected for each case-patient, matched by date of surgery. Stepwise logistic regression analysis was used to determine the relation of potential risk factors to the development of infection.

Twenty-two patients with infections (6 superficial and 16 deep) were identified. Infection rates per year were 0.95%, 1.07%, and 1.19% in 1999, 2000, and 2001, respectively. Logistic regression analysis identified two variables independently associated with the development of infection: the use of closed suction drainage (odds ratio [OR], 7.0; 95% confidence interval [CI95], 2.1-25.0; P = .0015) and increased international normalized ratio (INR) (OR, 2.4; CI95, 1.1-5.7; P = .035). Factors not statistically associated with the development of infection included age, NNIS System risk index score, presence of various comorbidities, surgeon, duration of procedure or tourniquet time, type of bone cement or prosthesis used, or receipt of blood product transfusions.

The use of closed suction drainage and a high postoperative INR were associated with the development of SSI following TKA. Avoiding the use of surgical drains and careful monitoring of anticoagulant prophylaxis in patients undergoing TKA should reduce the risk of infection.

To evaluate the immune status of healthcare workers (HCWs) against measles, rubella, mumps, and varicella in Japan, and to promote an adequate vaccination program among HCWs.

University of Tokyo Hospital.

Eight hundred seventy-seven HCWs.

Serologic screening for measles, rubella, mumps, and varicella was performed on HCWs. Antibodies against measles, rubella, and mumps were detected using hemagglutination inhibition (HI) assay ($4.20 per test). If serum was negative by HI assay, enzyme-linked immunosorbent assay (EIA) was performed ($12.60 per test). Anti-varicella antibodies were detected by EIA only.

Among tested HCWs, 98.5%, 90.4%, 85.8%, and 97.2% had immunity to measles, rubella, mumps, and varicella, respectively. All those born before 1970 were seropositive for measles. However, individuals susceptible to rubella, mumps, and varicella were present in all age groups. The sensitivities and negative predictive values of HI assay compared with EIA were 86.6% and 11.3% for measles, 99.1% and 92.2% for rubella, and 47.8% and 24.1% for mumps, respectively. For measles and mumps, prevaccination screening by HI assay in combination with EIA led to significant savings compared with EIA only. In contrast, it was estimated that prevaccination screening using only HI assay would be more economical for rubella.

Aggressive screening and vaccination of susceptible HCWs was essential regardless of age. Prevaccination serologic screening using a combination of HI assay and EIA was more economical for measles and mumps.

To evaluate the incidence of nosocomial bacteremias related to the use of non-impregnated central venous catheters (CVCs) when only non-technologic strategies were used to prevent them.

This was a prospective study of infectious complications of CVCs placed in intensive care unit (ICU) patients from April 1997 to December 2001.

The medical–surgical ICU of a tertiary-care, university-affiliated hospital in Argentina.

We studied all patients admitted to the ICU using non-impregnated CVCs. Maximal sterile barrier precautions (ie, use of cap, mask, sterile gown, sterile gloves, and large sterile drape), strict handwashing, preparation of the patients' skin with antiseptic solutions, insertion and management of catheters by trained personnel, and continuing quality improvement programs aimed at appropriate insertion and maintenance of catheters were employed.

During the study period, 2,525 patients were admitted to the ICU. Eight hundred sixty-eight patients had 1,037 CVCs inserted. The number of CVC-related bloodstream infections (BSIs), acquired in the ICU, was 2.7 per 1,000 CVC-days (13 nosocomial CVC-related BSIs during 4,770 days of CVC use). Microorganisms isolated included methicillin-susceptible Staphylococcus aureus (n = 6), methicillin-resistant S. aureus (n = 2), coagulase-negative methicillin-resistant Staphylococcus (n = 2), Escherichia coli (n = 1), Klebsiella pneumoniae (n = 1), and Enterobacter cloacae (n = 1).

A low rate of catheter-related BSI was achieved without antimicrobial-impregnated catheters. The incidence of CVC-associated bacteremias corresponded to the 10th to 20th percentile range of the National Nosocomial Infections Surveillance System hospitals for the same type of ICU.

To determine whether footwear exchange affects the incidence of febrile neutropenia among patients undergoing chemotherapy for hematologic malignancies.

Open trial with historical comparison.

The 12-bed high-efficiency particulate air-fil-tered hematology unit at Osaka University Hospital, Suita, Japan.

Those with hematologic malignancies who underwent chemotherapy from January 1997 through January 2003. Footwear exchange was discontinued in January 2000.

The surveillance system was based on the National Nosocomial Infections Surveillance System of the Centers for Disease Control and Prevention. Rates of febrile neutropenia were calculated for neutropenic patient-days (ie, days with neutropenia < 500/μL).

From January 1997 through December 1999 and from February 2000 through January 2003, 58 and 54 patients endured 237 and 184 neutropenic periods following chemotherapy, and their total neutropenic days were 3,123 and 2,503, respectively. They showed episodes of febrile neutropenia 89 and 68 times, respectively. Infection rates were 28.5 and 27.2 per 1,000 neutropenic patient-days (P = .83), respectively.

The incidence of febrile neutropenia was not affected by footwear exchange. In hematology units, changing shoes does not appear to affect the rate of infections during neutropenic periods.

To investigate and determine the cause of an outbreak of Mycobacterium mucogenicum bacteremias in bone marrow transplant (BMT) and oncology patients.

Case–control study and culturing of hospital water sources. Isolates were typed using molecular methods.

University-affiliated, tertiary-care medical center.

Case-patients were adult and pediatric BMT patients or hematopoietic stem cell transplant (BMT) (n = 5) and oncology (n = 1) patients who were diagnosed as having M. mucogenicum bacteremia during the study period of August through November 1998. Two control-patients were selected for each case-patient matched by age, time of hospitalization, inpatient unit, and type of patient (BMT or oncology).

There were no significant differences between case-patients and control-patients regarding intravenous products received or procedures performed, frequency of bathing, neutropenia, or steroid use. Nontuberculous mycobacteria were isolated from several water sources at the medical center including tap water from sinks and showerheads, the hospital hot water source, and the city water supply to the hospital. Analysis by multilocus enzyme electrophoresis and randomly amplified polymorphic DNA showed a match between one patient's blood isolate and an isolate from shower water from that patient's prior hospital room.

The cause of the outbreak seemed to be water contamination of central venous catheters (CVCs) during bathing. A recommendation in early 2001 that CVCs be protected from water during bathing was followed by no M. mucogenicum bacteremias during the second half of 2001, only one in 2002, and none at all during 2003.

To determine the magnitude of van-comycin-resistant enterococci (VRE) in three counties in the San Francisco Bay area.

Active laboratory-based surveillance for VRE from January 1995 through December 1996 and a laboratory-based and hospital-based questionnaire survey for 1993 to 1994 and 1997 to 1998.

All 33 general acute care hospitals in three counties in the San Francisco Bay area.

Laboratories and infection control professionals serving these hospitals, and staff of the California Emerging Infections Program.

The number of hospitals reporting 1 or more patient clinical VRE isolates was 1 (3%) in 1993, 7 (21%) in 1994, 31 (94%) in 1995, and 33 (100%) in 1996 to 1998. The number of patient isolates increased from 1 in 1993 to 24 in 1994, 176 in 1995,429 in 1996, 730 in 1997, and 864 in 1998. Most VRE isolates in 1995 and 1996 were from urine and were not associated with serious clinical disease. However, the number of isolates from blood increased from 9 (6% of total) in 1995 to 44 (12% of the total) in 1996, 90 (14%) in 1997, and 100 (13%) in 1998.

Our data document the rapid emergence and increase of VRE in all hospitals in three counties in the San Francisco Bay area during 1994 to 1998. Infection control measures for VRE together with antibiotic utilization programs should be implemented to limit further spread.

To assess influenza vaccination rates of healthcare workers (HCWs) in neonatal intensive care units (NICUs), pediatric intensive care units (PICUs), and oncology units in Pediatric Prevention Network (PPN) hospitals.

Infection control practitioners and HCWs in NICUs, PICUs, and oncology units.

In November 2000, posters, electronic copies of a slide presentation, and an influenza fact sheet were distributed to 32 of 76 PPN hospitals. In January 2001, a survey was distributed to PPN hospital participants to obtain information about the immunization campaigns. On February 7, 2001, a survey of influenza immunization was conducted among HCWs in NICU, PICU, and oncology units at participating hospitals.

Infection control practitioners from 19 (25%) of the 76 PPN hospitals completed the surveys. The median influenza immunization rate was 43% (range, 12% to 63%), with 7 hospitals exceeding 50%. HCWs (n = 1,123) at 15 PPN hospitals completed a survey; 53% of HCWs reported receiving influenza immunization. Immunization rates varied by work site: 52% in NICUs and PICUs compared with 60% in oncology units. Mobile carts and PPN educational fact cards were associated with higher rates among these subpopulations (P < .001) (361 [63%] of 575 vs 236 [44%] of 541 for mobile carts; 378 [60%] of 633 vs 219 [45%] of 483 for fact cards).

Despite delayed distribution of influenza vaccine during the 2000–2001 season, immunization rates at 7 hospitals and among HCWs in high-risk units exceeded the National Association of Children's Hospitals and Related Institutions goal of 50%.

To determine the incidence, clinical characteristics, and risk factors associated with the first culture-proven episode of sepsis among neonates in a neonatal intensive care unit (NICU).

Level-II NICU in the United Kingdom.

Neonates with their first culture-proven sepsis between January 1, 1996, and December 31, 2000.

Demographic data were obtained from the NICU database and chart review. Sepsis was considered early (EOS; < 72 hours old) or late (LOS; > 72 hours old). Data were also collected on potential risk factors.

Among 14,767 live births, 1,612 (11%) neonates were admitted to the NICU during the study period. Nine hundred eight were screened for sepsis. One hundred twenty-four had at least one positive culture (overall sepsis rate of 8.4 per 1,000 live births [1%] or 77 per 1,000 NICU admissions). Twenty-four neonates had EOS and 100 had LOS. Coagulase-negative staphylococci (CoNS) and group B Streptococcus were the most frequent organisms causing EOS, whereas CoNS and Escherichia coli most frequently caused LOS. Birth before 30 weeks' gestation and birth weight less than 1,500 g were risk factors for sepsis. Resuscitation at birth was the leading risk factor for EOS and respiratory support prior to sepsis, presence of a central or peripheral catheter, and total parenteral nutrition were leading risk factors for LOS.

A strong inverse relationship existed between gestational age of 30 weeks or younger and birth weight of 1,500 g or less and LOS. Resuscitation and indwelling intravenous catheters were also risk factors.

To compare the prevalence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) carriage among injection drug users (IDUs) treated in an injection heroin maintenance program with that among IDUs treated in an oral methadone program, and to determine predictors of S. aureus carriage.

Survey.

Two opiate maintenance programs at a psychiatrie university clinic.

A volunteer sample consisting of 94 (74%) of 127 IDUs treated in an injection opiate maintenance program with at least twice daily injections of heroin, and 70 (56%) of 125 IDUs treated in an oral methadone program.

Addicts treated in the intravenous heroin substitution program had a significantly lower overall rate of S. aureus carriage (37 of 94 [39.4%] vs 42 of 70 [60%]; P = .009) and a significantly lower rate of nasal carriage (21 of 94 [22.3%] vs 30 of 70 [42.9%]; P = .005) than did addicts treated in the oral methadone program. Being treated in the oral methadone program was the only independent predictor of S. aureus carriage (odds ratio, 2.27; 95% confidence interval, 1.19-4.31; P=.012). All S. aureus isolates were susceptible to oxacillin.

The regular use of needles under aseptic conditions did not increase the rate of S. aureus carriage among IDUs. Further studies are necessary to investigate whether the lower rate of S. aureus carriage among IDUs treated with intravenous heroin leads to a lower incidence of S. aureus infections in these patients.

To determine risk factors for hemodialysis catheter-related bloodstream infections (HCRBSIs) and investigate whether use of maximal sterile barrier precautions would prevent HCRBSIs.

Tertiary-care medical center hemodialysis unit.

Open trial with historical comparison and case-control study of risk factors for HCRBSIs.

Prospective surveillance was used to compare HCRBSI rates for 1 year before and after implementation of maximal sterile barrier precautions. A case–control study compared 50 case-patients with HCRBSI with 51 randomly selected control-patients.

The HCRBSI rate was 1.6% per 100 dialysis runs (CI95, 1.1%–2.3%) in the first year and 0.77% (CI95, 0.5%–1.1%) in the second year (P = .0106). The most frequent cause of HCRBSI was MRSA in the first year (15 of 32) and MSSA in the second year (13 of 18). Ten MRSA blood isolates in the first year were identical by PFGE. Diabetes mellitus was a risk factor for HCRBSI. Age, gender, site of hemodialysis central venous catheter (CVC), other underlying diseases, coma score, APACHE II score, serum albumin level, and cholesterol level were not associated with HCRBSI and did not change between the 2 years. Hospital stay was prolonged for case-patients (32.78 ± 20.96 days) versus control-patients (22.75 ± 17.33 days), but mortality did not differ.

Use of maximal sterile barrier precautions during the insertion of CVCs reduced HCRBSIs in dialysis patients and seemed cost-effective. Diabetes mellitus was associated with HCRBSI. An outbreak of MRSA in the first year was likely caused by cross-infection via medical personnel.

To determine the relationship between immunity and a history of chickenpox based on a self-administered questionnaire.

We investigated immunity to varicella-zoster virus in a cohort of newly recruited employees with different job categories and different nationalities using enzyme-linked immunosorbent assay IgG.

There were 1,058 new recruits. Of these, 890 (84%) were immune and 168 (16%) were susceptible. The susceptibility rate was 23% (n = 77) for Asian, 15% (n = 14) for South African, 13% (n = 66) for Middle Eastern, and 9% (n = 11) for Western employees. Physicians were more likely to be immune (93%) than were nurses (85%), medical technicians (75%), or administrative clerks (84%). Seropositivity was not affected by age or gender. The positive predictive value of a history of chickenpox for the seropositivity was 89% (511 of 574); the negative predictive value was 22% (105 of 484). History of chickenpox had a sensitivity of 57% (511 of 890) and a specificity of 63% (105 of 168).

The varicella-zoster virus seroprevalence among new employees was low, posing an important risk to existing employees and patients. Positive or negative history of chickenpox was an unreliable indicator of susceptibility among healthcare workers of different nationalities. Serologic screening of all employees and vaccination of those susceptible was recommended.

Staphylococcus aureus nasal carriage is a risk factor for surgical-site infections (SSIs) caused by S. aureus, and eradication of carriage reduces postoperative nosocomial infections caused by it. No study has compared large groups of preoperative carriers and non-carriers to identify factors that are linked to S. aureus nasal carriage.

While conducting a clinical trial evaluating whether mupirocin prevented S. aureus SSIs, we prospectively collected data on 70 patient characteristics that might be associated with S. aureus carriage. We performed stepwise logistic regression analysis.

Of the 4,030 patients, 891 (22%) carried S. aureus. Independent risk factors for S. aureus nasal carriage were obesity (odds ratio [OR], 1.29; 95% confidence interval [CI95], 1.11-1.50), male gender (OR, 1.29; CI95,1.11-1.51), and a history of a cerebrovascular accident (OR, 1.53; CI95, 1.03-2.25) for all patients. Factors associated with nasal carriage varied somewhat by surgical specialty. In all groups, preoperative use of antimicrobial agents was independently associated with a lower risk of carrying S. aureus in the nares. Previously identified risk factors were not significantly associated with S. aureus nasal carriage in this large group of surgical patients.

Male gender, obesity, and a history of a cerebrovascular accident were identified as risk factors for S. aureus nasal carriage. It remains to be seen whether preoperative weight loss would reduce the rate of nasal carriage. In addition, the value of screening this patient population for S. aureus nasal carriage merits further investigation.

To acquire data on pediatric nosocomial infections (NIs), which are associated with substantial morbidity and mortality and for which data are scarce.

Prevalence survey and evaluation of a new comorbidity index.

Seven Swiss pediatric hospitals.

Those hospitalized for at least 24 hours in a medical, surgical, intensive care, or intermediate care ward.

Thirty-five NIs were observed among 520 patients (6.7%; range per hospital, 1.4% to 11.8%). Bacteremia was most frequent (2.5 per 100 patients), followed by urinary tract infection (1.3 per 100 patients) and surgical-site infection (1.1 per 100 patients; 3.2 per 100 patients undergoing surgery). The median duration until the onset of infection was 19 days. Independent risk factors for NI were age between 1 and 12 months, a comorbidity score of 2 or greater, and a urinary catheter. Among surgical patients, an American Society of Anesthesiologists (ASA) score of 2 or greater was associated with any type of NI (P = .03). Enterobacteriaceae were the most frequent cause of NI, followed by coagulase-negative staphylococci; viruses were rarely the cause.

This national prevalence survey yielded valuable information about the rate and risk factors of pediatric NI. A new comorbidity score showed promising performance. ASA score may be a predictor of NI. The season in which a prevalence survey is conducted must be considered, as this determines whether seasonal viral infections are observed. Periodic prevalence surveys are a simple and cost-effective method for assessing NI and comparing rates among pediatric hospitals.

Oral vancomycin therapy has been a risk factor for turning culture positive for vancomycin-resistant Enterococcus (VRE). VRE colonization status was reviewed for all patients who received oral vancomycin and underwent prospective cultures.

Data were extracted from the medical records of all patients receiving oral vancomycin between August 1995 and February 2001 regarding history, hospital course, and perirectal VRE cultures. Hospital policy required contact isolation for patients receiving oral vancomycin until colonization with VRE was excluded.

Twenty-six courses of oral vancomycin were given to 22 patients. VRE colonization status after completion of therapy was evaluated for 23 courses in 20 (91%) of these patients. None of these patients became VRE culture positive during a median follow-up of 18 days (range, 9 to 39 days), with a median duration of treatment of 10 days (range, 3 to 58 days), and with a median total dose of 6,500 mg (range, 1,250 to 29,000 mg). All patients received other antibiotics within 30 days prior to therapy with oral vancomycin, during therapy with oral vancomycin, or both; 95% had received anti-anaerobic therapy and 35% had received parenteral vancomycin.

Even when other risk factors were present, no patient receiving oral vancomycin at our facility subsequently became culture positive for VRE. This suggests that oral vancomycin therapy or other antibiotic use, including anti-anaerobic therapy, may not be a significant independent risk factor for turning culture positive for VRE among patients not previously exposed to the microbe.

To evaluate risk factors and treatment outcomes of bloodstream infections caused by extended-spectrum beta-lactamase-producing Klebsiella pneumoniae (ESBL-KP).

Retrospective case-control study. Stored blood isolates of K. pneumoniae were tested for ESBL production by NCCLS guidelines, double-disk synergy test, or both.

A 1,500-bed, tertiary-care university hospital and referral center.

Sixty case-patients with bacteremia due to ESBL-KP were compared with 60 matched control-patients with non-ESBL-KP.

There were no significant differences in age, gender, APACHE II score, or underlying diseases between the groups. Independent risk factors for infections caused by ESBL-KP were urinary catheterization, invasive procedure within the previous 72 hours, and an increasing number of antibiotics administered within the previous 30 days. Complete response rate, evaluated 72 hours after initial antimicrobial therapy, was higher among control-patients (13.3% vs 36.7%; P = .003). Treatment failure rate was higher among case-patients (35.0% vs 15%; P = .011). Overall 30-day mortality rate was 30% for case-patients and 28.3% for control-patients (P = .841). Case-patients who received imipenem or ciprofloxacin as a definitive antibiotic had 10.5% mortality. The mortality rate for initially ineffective therapy was no higher than that for initially effective therapy (9.1% vs 11.1%; P = 1.000), but statistical power was low for evaluating mortality in the absence of septic shock.

For K. pneumoniae bacteremia, patients with ESBL-KP had a higher initial treatment failure rate but did not have higher mortality if antimicrobial therapy was appropriately adjusted in this study with limited statistical power.

To assess the rate of bacterial contamination of intravenous administration sets at their rubber injection ports and matching infusates.

Cultures of injection ports and infusate during 26 visits to 4 hospitals.

Four public general pediatric hospitals in Mexico City with substandard care practices.

Hospitalized pediatric patients receiving intravenous solutions.

Overall, 176 of 251 injection ports were contaminated (70.1%; 95% confidence interval [CI95], 64.5% to 75.8%), 35 (13.9%; CI95, 9.7% to 18.2%) with gram-negative rods, primarily of the tribe Klebsielleae. Cultures of infusates were positive in 17 cases (6.8%, CI95, 3.7% to 9.9%), 5 of which grew gram-negative rods (2%; CI95, 0.6% to 4.6%). In 3 cases (1.2%), the same species with gram-negative rods was found in the infusates and on the injection ports. During one visit, 8 clustered cases of injection port contamination with a clonal Enterobacter cloacae were found; this agent was also found in the blood culture, intravenous fluid, and parenteral nutrition of one patient. Inadequate chlorination of tap water, a potential risk factor, was recorded during 22 visits (84.6%).

These data suggest that external contamination of the intravenous administration set could play a role in infusate contamination.