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Biomedical subjects

Stephen P Baker

Publications and source records attributed to Stephen P Baker.

At least 19 recordsLinked to original sources
PubMed2006

Impact of alcohol-based, waterless hand antiseptic on the incidence of infection and colonization with methicillin-resistant Staphylococcus aureus and vancomycin-resistant enterococci.

OBJECTIVE: Colonized and infected inpatients are major reservoirs for methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), and transient carriage of these pathogens on the hands of healthcare workers remains the most common mechanism of patient-to-patient transmission. We hypothesized that use of alcohol-based, waterless hand antiseptic would lower the incidence of colonization and/or infection with MRSA and VRE. METHODS: On June 19, 2001, alcohol hand antiseptic was introduced at the University campus and not the nearby Memorial campus of the University of Massachusetts Medical School (Worcester, MA), allowing us to evaluate the impact of this antiseptic on the incidence of MRSA and VRE colonization and infection. From January 1 through December 31, 2001, the incidence of MRSA colonization or infection was compared between the 2 campuses before and after the hand antiseptic was introduced. Its effect on VRE colonization and infection was only studied in the medical intensive care unit at the University campus. RESULTS: At the University campus, the incidence of MRSA colonization or infection decreased from 1.26 cases/1,000 patient-days before the intervention to 0.75 cases/1,000 patient-days after the intervention, for a 1.46-fold decrease (95% confidence interval, 1.04-2.58; P = .037). At the Memorial campus, the incidence of MRSA colonization or infection remained virtually unchanged, from 0.34 cases/1,000 patient-days to 0.49 cases/1,000 patient-days during the same period. However, a separate analysis of the University campus data that controlled for proximity to prevalent cases did not show a significant improvement in the rates of infection or colonization. The incidence of nosocomial VRE colonization or infection before and after the hand antiseptic decreased from 12.0 cases/1,000 patient-days to 3.0 cases/1,000 patient-days, a 2.25-fold decrease (P = .018). Compliance with rectal surveillance for detection of VRE was 86% before and 84% after implementation of the hand antiseptic intervention. The prevalences of VRE cases during these 2 periods were 25% and 29%, respectively (P = .017). CONCLUSIONS: Alcohol hand antiseptic appears to be effective in controlling the transmission of VRE. However, after controlling for proximity to prevalent cases (ie, for clustering), it does not appear to be more effective than standard methods for controlling MRSA. Further controlled studies are needed to evaluate its effectiveness.

Alcohols↗
PubMed2006

Microwave-assisted synthesis of thieno[2,3-c]pyridine derivatives as a new series of allosteric enhancers at the adenosine A(1) receptor.

The microwave-assisted aromatization method has been used for the synthesis of a series of novel thieno[2,3-c]pyridines. This rapid method produces compounds in good yield within minutes in comparison with conventional heating method. The synthesized molecules have been evaluated as a potential new series of allosteric enhancers acting at the adenosine A(1) receptor. In a functional assay, one compound (3h) showed activity comparable with that of reference compound PD 81,723.

Allosteric Regulation↗
PubMed2006

Dihydropyridine receptors and type 1 ryanodine receptors constitute the molecular machinery for voltage-induced Ca2+ release in nerve terminals.

Ca2+ stores were studied in a preparation of freshly dissociated terminals from hypothalamic magnocellular neurons. Depolarization from a holding level of -80 mV in the absence of extracellular Ca2+ elicited Ca2+ release from intraterminal stores, a ryanodine-sensitive process designated as voltage-induced Ca2+ release (VICaR). The release took one of two forms: an increase in the frequency but not the quantal size of Ca2+ syntillas, which are brief, focal Ca2+ transients, or an increase in global [Ca2+]. The present study provides evidence that the sensors of membrane potential for VICaR are dihydropyridine receptors (DHPRs). First, over the range of -80 to -60 mV, in which there was no detectable voltage-gated inward Ca2+ current, syntilla frequency was increased e-fold per 8.4 mV of depolarization, a value consistent with the voltage sensitivity of DHPR-mediated VICaR in skeletal muscle. Second, VICaR was blocked by the dihydropyridine antagonist nifedipine, which immobilizes the gating charge of DHPRs but not by Cd2+ or FPL 64176 (methyl 2,5 dimethyl-4[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylate), a non-dihydropyridine agonist specific for L-type Ca2+ channels, having no effect on gating charge movement. At 0 mV, the IC50 for nifedipine blockade of VICaR in the form of syntillas was 214 nM in the absence of extracellular Ca2+. Third, type 1 ryanodine receptors, the type to which DHPRs are coupled in skeletal muscle, were detected immunohistochemically at the plasma membrane of the terminals. VICaR may constitute a new link between neuronal activity, as signaled by depolarization, and a rise in intraterminal Ca2+.

Animals↗
PubMed2006

Midline anterior repair alone vs anterior repair plus vaginal paravaginal repair: a comparison of anatomic and quality of life outcomes.

Our aim was to study the anatomic recurrence rates and quality of life outcomes of patients who had undergone either anterior colporrhaphy (AC) or anterior colporrhaphy and vaginal paravaginal repair (AC + VPVR) as part of surgery for pelvic organ prolapse. Chart reviews were used to identify anatomic prolapse recurrence. Phone interviews assessed quality of life outcomes [Urogenital Distress Inventory (UDI) and the Incontinence Impact Questionnaire (IIQ)] outcomes. There was a trend towards longer time to anatomic recurrence (any compartment > or =grade 2) in the AC group compared with the AC + VPVR group (median 24 vs 13 months, p=0.069). If only patients who had undergone previous surgery were compared, time to anatomic recurrence appeared significantly longer in the AC group (median 41 vs 12 months, p=0.022). There were 55% of women in the AC group and 46% of women in the AC + VPVR group who reported significant bladder or bulge symptoms based on responses to the phone-administered UDI and IIQ (p=0.89). Our retrospective study did not suggest that adding VPVR was superior in terms of anatomic or quality of life outcomes. Prospective assessment of the role of VPVR in the treatment of pelvic organ prolapse is needed.

Aged↗
PubMed2006

Duodenal intraepithelial lymphocytes in inflammatory disorders of the esophagus and stomach.

BACKGROUND & AIMS: Duodenal cluster designation 3 positive (CD3+) intraepithelial T lymphocytes (IELs) are increased in gluten-sensitive enteropathy (GSE) and, because of the dispersed nature of the gut immune system, might also be increased in mucosa distant from the duodenum. Conversely, little is known about their frequency in the duodenum during inflammatory conditions of the stomach and esophagus. This study assessed whether CD3+ IELs are increased in duodenal biopsies in patients with esophagitis or gastritis relative to normal control subjects. METHODS: Cases (n=46) with concurrent mucosal biopsies of the duodenum, stomach, and esophagus were divided into 4 groups: I, no inflammation in any site; II, active esophagitis only; III, chronic active gastritis only, with Helicobacter pylori bacteria; IV, chronic gastritis only, without H pylori bacteria. Immunostains against CD3 were performed by using standard techniques, the number of CD3+ cells/100 enterocytes in 3 well-oriented villi was recorded, and the results for the groups were compared statistically. RESULTS: The average number of CD3+ IELs/100 enterocytes for each group was I, 6.7; II, 11.8; III, 7.2; and IV, 9.1. The differences among the groups were not statistically significant. There was no correlation between the number of duodenal IELs and severity of inflammation, patient age or sex, or symptoms. CONCLUSIONS: Duodenal mucosal biopsies from patients with esophagitis and/or gastritis may have a slightly increased number of CD3+ IELs relative to normal control subjects. This finding may reflect an underlying mechanism of diffuse inflammation in the gastrointestinal tract.

Adolescent↗
PubMed2005

The proteasome: not just degrading anymore.

The proteasome is a large multiprotein complex that has a critical role in the degradation of ubiquitylated proteins. A fascinating paper in this issue of Cell (Lee et al., 2005) now reveals that the proteasome recruits the SAGA histone acetyltransferase complex to a target promoter during gene activation. This finding adds to the growing body of evidence indicating that the proteasome has nonproteolytic functions.

Gene Expression Regulation, Fungal↗
PubMed2005

DNA replication origins fire stochastically in fission yeast.

DNA replication initiates at discrete origins along eukaryotic chromosomes. However, in most organisms, origin firing is not efficient; a specific origin will fire in some but not all cell cycles. This observation raises the question of how individual origins are selected to fire and whether origin firing is globally coordinated to ensure an even distribution of replication initiation across the genome. We have addressed these questions by determining the location of firing origins on individual fission yeast DNA molecules using DNA combing. We show that the firing of replication origins is stochastic, leading to a random distribution of replication initiation. Furthermore, origin firing is independent between cell cycles; there is no epigenetic mechanism causing an origin that fires in one cell cycle to preferentially fire in the next. Thus, the fission yeast strategy for the initiation of replication is different from models of eukaryotic replication that propose coordinated origin firing.

DNA Replication↗
PubMed2005

Serine 31 phosphorylation of histone variant H3.3 is specific to regions bordering centromeres in metaphase chromosomes.

Histones are the fundamental components of the nucleosome. Physiologically relevant variation is introduced into this structure through chromatin remodeling, addition of covalent modifications, or replacement with specialized histone variants. The histone H3 family contains an evolutionary conserved variant, H3.3, which differs in sequence in only five amino acids from the canonical H3, H3.1, and was shown to play a role in the transcriptional activation of genes. Histone H3.3 contains a serine (S) to alanine (A) replacement at amino acid position 31 (S31). Here, we demonstrate by both MS and biochemical methods that this serine is phosphorylated (S31P) during mitosis in mammalian cells. In contrast to H3 S10 and H3 S28, which first become phosphorylated in prophase, H3.3 S31 phosphorylation is observed only in late prometaphase and metaphase and is absent in anaphase. Additionally, H3.3 S31P forms a speckled staining pattern on the metaphase plate, whereas H3 S10 and H3 S28 phosphorylation localizes to the outer regions of condensed DNA. Furthermore, in contrast to phosphorylated general H3, H3.3 S31P is localized in distinct chromosomal regions immediately adjacent to centromeres. These findings argue for a unique function for the phosphorylated isoform of H3.3 that is distinct from its suspected role in gene activation.

Amino Acid Sequence↗
PubMed2005

Chromatin alterations associated with down-regulated metabolic gene expression in the prefrontal cortex of subjects with schizophrenia.

BACKGROUND: Schizophrenia is frequently accompanied by hypometabolism and altered gene expression in the prefrontal cortex. Cellular metabolism regulates chromatin structure, including covalent histone modifications, which are epigenetic regulators of gene expression. OBJECTIVE: To test the hypothesis that down-regulated metabolic gene expression is associated with histone modification changes in the prefrontal cortex of subjects with schizophrenia. DESIGN AND SUBJECTS: Histones and gene transcripts were profiled in the postmortem prefrontal cortex of 41 subjects with schizophrenia and 41 matched controls. The phosphorylation, acetylation, and methylation of 6 lysine, serine, and arginine residues of histones H3 and H4 were examined together with 16 metabolic gene transcripts using serial immunoblotting, immunohistochemical analysis, custom-made complementary DNA arrays, and quantitative real-time reverse transcriptase-polymerase chain reaction. RESULTS: Subjects with schizophrenia, as a group, showed no significant alterations in histone profiles or gene expression. In a subgroup of 8 patients with schizophrenia, levels of H3-(methyl)arginine 17, H3meR17, exceeded control values by 30%, and this was associated with the decreased expression of 4 metabolic transcripts. CONCLUSIONS: High levels of H3-(methyl)arginine 17 are associated with down-regulated metabolic gene expression in the prefrontal cortex of a subset of subjects with schizophrenia. Histone modifications may contribute to the pathogenesis of prefrontal dysfunction in schizophrenia.

Chromatin↗
PubMed2005

Low risk of ureteral obstruction with "deep" (dorsal/posterior) uterosacral ligament suture placement for transvaginal apical suspension.

OBJECTIVE: Transvaginal uterosacral ligament fixation (USLF), often called "high" USLF, is associated with a 1.0% to 10.9% ureteral obstruction rate. Anatomic relations and pelvic rotation with positioning imply "high" (cephalad) suture placement may bring sutures closer to the ureter. We examined the ureteral obstruction rate with a "deep" (dorsal/posterior) uterosacral ligament suture placement modification of a standard USLF procedure. STUDY DESIGN: At the University of Massachusetts and Tufts, 411 consecutive patients underwent Mayo culdoplasty utilizing > or = 3 uterosacral sutures placed "deep" bilaterally. Intraoperative cystoscopy was performed. RESULTS: One patient (0.24% [.01%-1.35%]) had ureteral obstruction attributable to USLF. Two had obstruction secondary to concomitant procedures. Compared with previous published series, the odds of ureteral injury secondary to USLF was 4.6 times lower (95% CI 2.31-9.24; P < .0001). CONCLUSION: Placement of USLF sutures "deep" (dorsal/posterior) increases the margin of safety for the ureter and, in this study, decreased the ureteral injury rate nearly 5-fold.

Aged↗
PubMed2005

Cholangitis: a histologic classification based on patterns of injury in liver biopsies.

Inflammatory disorders of the biliary tract present difficult diagnostic problems in liver needle biopsies. The aim of this study was to perform a detailed histologic analysis of liver biopsies from patients with biliary tract disorders, classify them by pattern of inflammation, and determine the accuracy of the histologic classification by clinical follow-up. Percutaneous liver needle biopsies from the surgical pathology files of UmassMemorial Healthcare (UMMHC) from 2000 to 2003 with a diagnosis suggesting a biliary tract process (n = 32) and four biopsies from cases with systemic non-biliary tract disorders were analyzed for multiple histologic features and classified as one of five patterns: acute cholangitis/pericholangitis (ACP), lymphocytic cholangitis (LC), granulomatous (G), ductopenia (D), or non-specific (NS). When compared to the "gold standard" diagnosis based on all clinical data, the concordance between the histologic classification and the clinical diagnosis was: 50% for ACP and bile duct obstruction; 77% for LC and immune-mediated cholangitis NOS; 100% for G and G cholangitis; 100% for D and idiopathic adulthood D; and 50% for NS and non-biliary tract disorders. Our findings suggest that classifying biopsies by pattern of injury is helpful in guiding the subsequent clinical work-up. ACP pattern correlates with bile duct obstruction, infection, and ischemia. LC correlates with serologic studies supporting immune-mediated processes. G pattern suggests further work-up for PBC, drug, tuberculosis, or sarcoidosis. D pattern establishes the clinical diagnosis. NS pattern includes cases of primary sclerosing cholangitis, which cannot be diagnosed by biopsy alone.

Acute Disease↗
PubMed2005

Histone methylation at gene promoters is associated with developmental regulation and region-specific expression of ionotropic and metabotropic glutamate receptors in human brain.

Glutamatergic signaling is regulated, in part, through differential expression of NMDA and AMPA/KA channel subunits and G protein-coupled metabotropic receptors. In human brain, region-specific expression patterns of glutamate receptor genes are maintained over the course of decades, suggesting a role for molecular mechanisms involved in long-term regulation of transcription, including methylation of lysine residues at histone N-terminal tails. Using a native chromatin immunoprecipitation assay, we studied histone methylation marks at proximal promoters of 16 ionotropic and metabotropic glutamate receptor genes (GRIN1,2A-D; GRIA1,3,4; GRIK2,4,5; GRM1,3,4,6,7 ) in cerebellar cortex collected across a wide age range from midgestation to 90 years old. Levels of di- and trimethylated histone H3-lysine 4, which are associated with open chromatin and transcription, showed significant differences between promoters and a robust correlation with corresponding mRNA levels in immature and mature cerebellar cortex. In contrast, levels of trimethylated H3-lysine 27 and H4-lysine 20, two histone modifications defining silenced or condensed chromatin, did not correlate with transcription but were up-regulated overall in adult cerebellum. Furthermore, differential gene expression patterns in prefrontal and cerebellar cortex were reflected by similar differences in H3-lysine 4 methylation at promoters. Together, these findings suggest that histone lysine methylation at gene promoters is involved in developmental regulation and maintenance of region-specific expression patterns of ionotropic and metabotropic glutamate receptors. The association of a specific epigenetic mark, H3-(methyl)-lysine 4, with the molecular architecture of glutamatergic signaling in human brain has potential implications for schizophrenia and other disorders with altered glutamate receptor function.

Aged↗
PubMed2004

Pubertal and adult Leydig cell function in Mullerian inhibiting substance-deficient mice.

Mullerian inhibiting substance (MIS) causes Mullerian duct regression during sexual differentiation and regulates postnatal Leydig cell development. MIS knockout (MIS-KO) mice with targeted deletions of MIS develop Leydig cell hyperplasia, but their circulating androgen concentrations are reportedly unaltered. We compared reproductive hormone profiles, androgen biosynthesis, and the expression of key steroidogenic and metabolic enzymes in MIS-KO and wild-type (WT) mice at puberty (36 d) and sexual maturity (60 d). In pubertal animals, basal testosterone and LH concentrations in plasma were lower in MIS-KO than WT mice, whereas human chorionic gonadotropin-stimulated testosterone concentrations were similar. In adults, basal LH, and both basal and human chorionic gonadotropin (hCG)-stimulated testosterone concentrations were similar. Purified Leydig cells from pubertal MIS-KO mice had lower testosterone but higher androstanediol and androstenedione production rates. In contrast, testosterone, androstanediol, and androstenedione production rates were all lower in adult MIS-KO Leydig cells. Steroidogenic acute regulatory protein expression was lower in pubertal MIS-KO mice compared with WT, whereas 17beta-hydroxy-steroid dehydrogenase and 5alpha-reductase were greater, and P450c17 and P450scc were similar. The expression of steroidogenic acute regulatory protein and 17beta-hydroxysteroid dehydrogenase was lower in adult MIS-KO mice, whereas that of 5alpha-reductase, P450c17, and P450scc was similar. Collectively, these results suggest that in the absence of MIS, Leydig cells remain less differentiated, causing an altered intratesticular androgen milieu that may contribute to the infertility of MIS-KO mice. In immature mice, this deficit in steroidogenic capacity appears to be mediated by a direct loss of MIS action in Leydig cells as well as by indirect effects via the hypothalamic-pituitary-gonadal axis.

Age Factors↗
PubMed2004

Ca(2+) spark sites in smooth muscle cells are numerous and differ in number of ryanodine receptors, large-conductance K(+) channels, and coupling ratio between them.

Ca(2+) sparks are highly localized Ca(2+) transients caused by Ca(2+) release from sarcoplasmic reticulum through ryanodine receptors (RyR). In smooth muscle, Ca(2+) sparks activate nearby large-conductance, Ca(2+)-sensitive K(+) (BK) channels to generate spontaneous transient outward currents (STOC). The properties of individual sites that give rise to Ca(2+) sparks have not been examined systematically. We have characterized individual sites in amphibian gastric smooth muscle cells with simultaneous high-speed imaging of Ca(2+) sparks using wide-field digital microscopy and patch-clamp recording of STOC in whole cell mode. We used a signal mass approach to measure the total Ca(2+) released at a site and to estimate the Ca(2+) current flowing through RyR [I(Ca(spark))]. The variance between spark sites was significantly greater than the intrasite variance for the following parameters: Ca(2+) signal mass, I(Ca(spark)), STOC amplitude, and 5-ms isochronic STOC amplitude. Sites that failed to generate STOC did so consistently, while those at the remaining sites generated STOC without failure, allowing the sites to be divided into STOC-generating and STOC-less sites. We also determined the average number of spark sites, which was 42/cell at a minimum and more likely on the order of at least 400/cell. We conclude that 1) spark sites differ in the number of RyR, BK channels, and coupling ratio of RyR-BK channels, and 2) there are numerous Ca(2+) spark-generating sites in smooth muscle cells. The implications of these findings for the organization of the spark microdomain are explored.

Animals↗
PubMed2004

A survey of the complications of vaginal prolapse surgery performed by members of the Society Of Gynecologic Surgeons.

This study aimed to examine the frequency and nature of complications of vaginal prolapse surgery performed by members of SGS over a year and to determine the feasibility and the problems associated with prospective, multicentered collaborative data acquisition. A survey form, which included demographics, surgical indications, colpopexy type, concomitant procedures, technique, estimated blood loss (EBL), OR time, and intra/postoperative complications, was distributed to society members. The nature, extent, and solution of the complications were examined. There were 147 members of SGS at the time of the study. Many were reproductive endocrinologists and gynecologic oncologists. Twenty-one (14%) members participated. Three hundred forty-nine (349) completed forms were received: 187 sacrospinous fixations (SSF), 92 colposacropexies (CSP), and 70 high utero sacral suspensions (HUS). There were seven (3.7%) intraoperative complications for SSF, seven (7.6%) for CSP and three (4.3%) for HUS. There were four (2.1%) postoperative complications for SSF, six (6.5%) for CSP and none for HUS (NS). OR time was significantly longer for CSP vs. HUS ( P<.003) and for SSF vs. HUS ( p=.042). The EBL was significantly higher for SSF compared with CSP for the colpopexy procedure ( p=.013) and for entire cases ( p<.003). Analysis showed that all three colpopexies had significant intraoperative and postoperative complications of less than 8%. Intraoperative visceral damage was a concern for all three procedures. With SSF and CSP there was risk of bleeding and with HUS there was a risk of ureteral obstruction. Postoperative CSP complications were bowel obstruction, bleeding or hernia; for SSF neuropathy, and for HUS none. No life-threatening intraoperative or postoperative complications were reported. OR time was significantly shorter for HUS than SSF. The highest EBL was with SSF. Only 14% of the SGS membership responded, despite multiple requests for participation, demonstrating the difficulty of multicenter data gathering.

Adult↗
PubMed2004

Recombinant human thrombomodulin inhibits arterial neointimal hyperplasia after balloon injury.

OBJECTIVE: Smooth muscle cell proliferation is a major pathophysiologic factor in injury-induced neointimal hyperplasia and recurrent stenosis. We have demonstrated that recombinant human thrombomodulin (rTM) inhibits thrombin-induced arterial smooth muscle cell proliferation in vitro. The purpose of this study was to investigate the effect of rTM on neointimal hyperplasia in vivo. METHODS: A rabbit femoral artery balloon injury model was used. Bilateral superficial femoral arteries were deendothelialized with a 2F arterial embolectomy catheter. rTM (145 microg/kg; 2.0 microg/mL in circulation) or Tris-hydrochloride vehicle control was administered intravenously during the procedure, then either discontinued (group A) or administered twice daily for an additional 48 hours (group B). Rabbits were euthanized at 4 days and at 1, 2, and 4 weeks, and femoral artery specimens were prepared with in situ perfusion fixation and paraffin embedding. Luminal, intima, media, and whole artery areas were quantitated with digital imaging computerized planimetry. Intima-media and lumen-whole artery ratios were calculated. The injury-induced inflammatory reaction was also evaluated with light microscopy, scanning and transmission electron microscopy, and immunohistochemical and immunohistofluorescence staining. RESULTS: In the buffer control group, neointimal hyperplasia after femoral artery balloon injury was evident at 2 weeks, and was pronounced at 4 weeks (P <.0001). Infusion of rTM significantly inhibited intimal hyperplasia at both 2 and 4 weeks (P <.0001). In group A, rTM reduced the intima-media ratio by 27% and 39% at 2 and 4 weeks, respectively. Extended administration of rTM (group B) resulted in inhibition of hyperplasia by 57% and 30% at 2 and 4 weeks, respectively, but failed to reach significance compared with the shorter exposure. rTM infusion significantly inhibited thrombosis (8.1-fold) compared with the buffer control group (P =.012). rTM had no significant effect on lumen area or lumen-whole artery ratio, but treated arteries demonstrated significantly less compensatory dilatation (P =.045), as measured by whole artery area in response to less intimal hyperplasia. rTM administration inhibited platelet adhesion and inhibition of neutrophil infiltration to a degree that approached statistical significance (P =.0675). CONCLUSIONS: Systemic intravenous administration of rTM significantly decreases neointimal hyperplasia and improves patency in the rabbit femoral artery after balloon injury. In addition to exhibiting antithrombotic and antiproliferative effects, rTM may also invoke an anti-inflammatory mechanism, and may alter vascular remodeling in a multidimensional role to inhibit recurrent stenosis after arterial injury.

Angioplasty, Balloon↗
PubMed2004

Rapid eradication of a cluster of Serratia marcescens in a neonatal intensive care unit: use of epidemiologic chromosome profiling by pulsed-field gel electrophoresis.

OBJECTIVE: To investigate a cluster of patients infected and colonized with Serratia marcescens in a neonatal intensive care unit (NICU). METHODS: In June 2001, two neonates in the NICU had clinical infections with S. marcescens and one died. Infection control surveillance data for the NICU revealed that S. marcescens was rarely isolated from clinical specimens. Surveillance and environmental cultures were performed and isolates were typed using pulsed-field gel electrophoresis. Staff and neonates were cohorted and a waterless, alcohol-based handwashing agent was introduced. A case-control study was performed. RESULTS: From June 2 through August 20, 2001, 11 neonates with S. marcescens infection and colonization were identified. The incidence of S. marcescens infections increased from 0.19 per 1,000 patient-days in 2000 to 0.52 per 1,000 patient-days in 2001 (P < .0001). In the first 3 weeks of the investigation, there were 2 sets of patients and sinks with indistinguishable strains; however, in subsequent weeks, all isolates were of unique strains, signifying no further transmission of the two initial predominant strains. Neonates with S. marcescens were more likely to have a lower gestational age and birth weight. There was no association between cases and healthcare workers (HCWs). CONCLUSIONS: A cluster of S. marcescens was quickly terminated after the introduction of preventive measures including cohorting of infected and colonized neonates and HCWs, contact precautions, surveillance cultures, and a waterless, alcohol-based hand antiseptic. Chromosomal typing determined that strains with an indistinguishable pattern were no longer present in the unit after control measures were implemented.

Case-Control Studies↗