Identification of the Causative Bacteria in Musculoskeletal Infections Using 16s rDNA - Denaturing Gradient Gel Electrophoresis Analysis

Musculoskeletal infections are infections of the bone and surrounding tissues. They are currently diagnosed based on culture analysis, which is the gold standard for pathogen identification. However, these clinical laboratory methods are frequently inadequate for the identification of the causative agents, because a large percentage (25-50%) of confirmed musculoskeletal infections are false negatives in which no pathogen is identified in culture. My data supports these results. The goal of this project was to use PCR amplification of a portion of the 16S rRNA gene to test an alternative approach for the identification of these pathogens and to assess the diversity of the bacteria involved. The advantages of this alternative method are that it should increase sample sensitivity and the speed of detection. In addition, bacteria that are non-culturable or in low abundance can be detected using this molecular technique. However, a complication of this approach is that the majority of musculoskeletal infections are polymicrobial, which prohibits direct identification from the infected tissue by DNA sequencing of the initial 16S rDNA amplification products. One way to solve this problem is to use denaturing gradient gel electrophoresis (DGGE) to separate the PCR products before DNA sequencing. Denaturing gradient gel electrophoresis (DGGE) separates DNA molecules based on their melting point, which is determined by their DNA sequence. This analytical technique allows a mixture of PCR products of the same length that electrophoreses through agarose gels as one band, to be separated into different bands and then used for DNA sequence analysis. In this way, the DGGE allows for the identification of individual bacterial species in polymicrobial-infected tissue, which is critical for improving clinical outcomes. By combining the 16S rDNA amplification and the DGGE techniques together, an alternative approach for identification has been used. The 16S rRNA gene PCR-DGGE method includes several critical steps: DNA extraction from tissue biopsies, amplification of the bacterial DNA, PCR product separation by DGGE, amplification of the gel-extracted DNA, and DNA sequencing and analysis. Each step of the method was optimized to increase its sensitivity and for rapid detection of the bacteria present in human tissue samples. The limit of detection for the DNA extraction from tissue was at least 20 Staphylococcus aureus cells and the limit of detection for PCR was at least 0.05 pg of template DNA. The conditions for DGGE electrophoreses were optimized by using a double gradient of acrylamide (6 – 10%) and denaturant (30-70%), which increased the separation between distinct PCR products. The use of GelRed (Biotium) improved the DNA visualization in the DGGE gel. To recover the DNA from the DGGE gels the gel slices were excised, shredded in a bead beater, and the DNA was allowed to diffuse into sterile water overnight. The use of primers containing specific linkers allowed the entire amplified PCR product to be sequenced and then analyzed. The optimized 16S rRNA gene PCR-DGGE method was used to analyze 50 tissue biopsy samples chosen randomly from our collection. The results were compared to those of the Memorial Hermann Hospital Clinical Microbiology Laboratory for the same samples. The molecular method was congruent for 10 of the 17 (59%) culture negative tissue samples. In 7 of the 17 (41%) culture negative the molecular method identified a bacterium. The molecular method was congruent with the culture identification for 7 of the 33 (21%) positive cultured tissue samples. However, in 8 of the 33 (24%) the molecular method identified more organisms. In 13 of the 15 (87%) polymicrobial cultured tissue samples the molecular method identified at least one organism that was also identified by culture techniques. Overall, the DGGE analysis of 16S rDNA is an effective method to identify bacteria not identified by culture analysis.

Regulation of hepatic cytochrome P450 expression in mice with intestinal or systemic infections of citrobacter rodentium.

We reported previously that infection of C3H/HeOuJ (HeOu) mice with the murine intestinal pathogen Citrobacter rodentium caused a selective modulation of hepatic cytochrome P450 (P450) gene expression in the liver that was independent of the Toll-like receptor 4. However, HeOu mice are much more sensitive to the pathogenic effects of C. rodentium infection, and the P450 down-regulation was associated with significant morbidity in the animals. Here, we report that oral infection of C57BL/6 mice with C. rodentium, which produced only mild clinical signs and symptoms, produced very similar effects on hepatic P450 expression in this strain. As in HeOu mice, CYP4A mRNAs and proteins were among the most sensitive to down-regulation, whereas CYP4F18 was induced. CYP2D9 mRNA was also induced 8- to 9-fold in the C57BL/6 mice. The time course of P450 regulation followed that of colonic inflammation and bacterial colonization, peaking at 7 to 10 days after infection and returning to normal at 15 to 24 days as the infection resolved. These changes also correlated with the time course of significant elevations in the serum of the proinflammatory cytokines interleukin (IL)-6 and tumor necrosis factor-alpha, as well as of interferon-gamma and IL-2, with serum levels of IL-6 being markedly higher than those of the other cytokines. Intraperitoneal administration of C. rodentium produced a rapid down-regulation of P450 enzymes that was quantitatively and qualitatively different from that of oral infection, although CYP2D9 was induced in both models, suggesting that the effects of oral infection on the liver are not due to bacterial translocation.

Identification of antigen-encoding genes of Enterococcus faecalis during human infections and characterization of a gene cluster for the biosynthesis of an antigenic polysaccharide

Genomic libraries of two Enterococcus faecalis strains, OG1RF and TX52 (an isolate from an endocarditis patient), were constructed in Escherichia coli and were screened with serum from a rabbit immunized with surface proteins of an E. faecalis endocarditis isolate and sera from four patients with enterococcal endocarditis. Thirty-eight immunopositive cosmid clones reacted with at least two of the patient sera and contained distinct inserts based on their DNA restriction patterns. These were chosen for further subcloning in a pBluescript SK ($-$) vector. Each sublibrary was screened with one of the five sera. Analysis of sequences from the immunopositive subclones revealed similarities to a range of proteins, including bacterial virulence factors, transporters, two-component regulators, metabolic enzymes, and membrane or cell surface proteins. Fourteen subclones did not show significant similarity to any sequence in the databases and may contain novel genes. Thirteen of the immunopositive cosmid clones did not yield immunopositive subclones and one such cosmid clone, TX5159, produced an antigenic polysaccharide in Escherichia coli. The insert of TX5159 was found to contain a multicistronic gene cluster containing genes similar to those involved in the biosynthesis and export of polysaccharides from both Gram-positive and Gram-negative organisms. Insertions in several genes within the cluster abolished the immunoreactivity of TX5159. RT-PCR of genes within the cluster with total RNA from OG1RF showed that these genes are transcribed. The polysaccharide was detected in two recently reported E. faecalis mucoid strains using specific antibody, but not in the other strains tested. This is the first report on a gene cluster of E. faecalis involved in the biosynthesis of an antigenic polysaccharide. ^

Diagnosis of sexually transmitted infections in developing nations using syndromic management: Is it working?

Sexually transmitted infections (STIs) are a major public health problem, and controlling their spread is a priority. According to the World Health Organization (WHO), there are 340 million new cases of treatable STIs among 15–49 year olds that occur yearly around the world (1). Infection with STIs can lead to several complications such as pelvic inflammatory disorder (PID), cervical cancer, infertility, ectopic pregnancy, and even death (1). Additionally, STIs and associated complications are among the top disease types for which healthcare is sought in developing nations (1), and according to the UNAIDS report, there is a strong connection between STIs and the sexual spread of HIV infection (2). In fact, it is estimated that the presence of an untreated STI can increase the likelihood of contracting and spreading HIV by a factor up to 10 (2). In addition, developing countries are poorer in resources and lack inexpensive and precise diagnostic laboratory tests for STIs, thereby exacerbating the problem. Thus, the WHO recommends syndromic management of STIs for delivering care where lab testing is scarce or unattainable (1). This approach utilizes the use of an easy to use algorithm to help healthcare workers recognize symptoms/signs so as to provide treatment for the likely cause of the syndrome. Furthermore, according to the WHO, syndromic management offers instant and legitimate treatment compared to clinical diagnosis, and that it is also more cost-effective for some syndromes over the use of laboratory testing (1). In addition, even though it has been shown that the vaginal discharge syndrome has low specificity for gonorrhea and Chlamydia and can lead to over treatment (1), this is the recommended way to manage STIs in developing nations. Thus, the purpose of this paper is to specifically address the following questions: is syndromic management working to lower the STI burden in developing nations? How effective is it, and should it still be recommended? To answer these questions, a systematic literature review was conducted to evaluate the current effectiveness of syndromic management in developing nations. This review examined published articles over the past 5 years that compared syndromic management to laboratory testing and had published sensitivity, specificity, and positive predicative value data. Focusing mainly on vaginal discharge, urethral discharge, and genital ulcer algorithms, it was seen that though syndromic management is more effective in diagnosing and treating urethral and genial ulcer syndromes in men, there still remains an urgent need to revise the WHO recommendations for managing STIs in developing nations. Current studies have continued to show decreased specificity, sensitivity and positive predicative values for the vaginal discharge syndrome, and high rates of asymptomatic infections and healthcare workers neglecting to follow guidelines limit the usefulness of syndromic management. Furthermore, though advocate d as cost-effective by the WHO, there is a cost incurred from treating uninfected people. Instead of improving this system, it is recommended that better and less expensive point of care and the development of rapid test diagnosis kits be the focus and method of diagnosis and treatment in developing nations for STI management. ^

Emerging arboviruses in Harris County, Texas

Harris County, which includes Houston, Texas, is an endemic and epidemic area for two viruses transmitted by arthropods (arboviruses). These viruses are maintained in cycles involving mosquitoes and wild birds, and transmission to humans is accidental. The majority of human infections is asymptomatic or may result in a flu-like syndrome. However, some infections can result in meningitis or encephalitis. These neuroinvasive infections may cause death, and those who survive may experience serious neurological complications requiring costly and lengthy medical care. The most important arboviruses in terms of morbidity are St. Louis encephalitis (SLEV) and West Nile (WNV) viruses. In fact, Harris County reports more SLEV encephalitis cases than any other county in the U.S. Most arboviral human cases occur from July through September, when mosquitoes are most active. Those at risk for encephalitis and death are the elderly and those with a history of hypertension or immunosuppresion. There is no specific treatment and no human vaccines are commercially available in the U.S. The approach for control of arboviruses in Harris County during epidemics is multidisciplinary and executed by several agencies. It includes surveillance, vector control, and educational messages for the population. Prevention of outbreaks consists of elimination of the vector and its breeding grounds, and practicing personal protective measures to prevent exposure to mosquitoes. ^ Current findings indicate that mosquito-borne viruses other than SLEV and WNV could pose an additional threat for the population. Eastern equine encephalitis virus (EEEV) activity has been detected in dogs and sentinel chickens in Houston and surrounding areas. Several serotypes of dengue virus have caused recent outbreaks in south Texas, and some locally-acquired cases have been detected in Houston. Since the clinical presentation of all arboviruses that cause encephalitis is very similar, and current surveillance is focused on detecting SLEV and WNV, there is a possibility that other arboviruses could be present in the area but are not being detected. Additionally, Harris County's ample annual rainfall and flooding problems, warm weather, multiple mosquito species, local and migrating birds that are susceptible to arboviral infection, and a constant flow of goods and travelers from many parts of the world could favor the emergence or re-emergence of other arboviruses. ^ The aims of this project were to determine if other arboviruses were circulating in the county, to assess the knowledge and attitudes about mosquito-borne viruses in a sample of the population, and to conduct an analysis of the initial WNV epidemic in Harris County. Through the retrospective analysis of clinical specimens collected during the 2002-2005 epidemic seasons, serologic evidence of dengue infection was detected suggesting the possibility that this virus may be co-circulating with SLEV and WNV. A cross-sectional survey revealed high awareness about arboviruses but not a consistent use of protective measures to avoid mosquitoes. The third component for this project included a retrospective review and geographical analysis of the 2002 WNV epidemic. ^ Overall, this study documented valuable information about the dengue virus, a potentially emerging arbovirus in Texas, revealed the need for more educational preventative programs, reinforced the value of mosquito and avian surveillance, and indicated the importance of continuing to investigate the factors that contribute to the development of outbreaks. ^

Hepatitis B and C infections in U.S. incarcerated populations: Prevalence and related mortality

Published reports have consistently indicated high prevalence of serologic markers for hepatitis B (HBV) and hepatitis C (HCV) infection in U.S. incarcerated populations. Quantifying the current and projected burden of HBV and HCV infection and hepatitis-related sequelae in correctional healthcare systems with even modest precision remains elusive, however, because the prevalence and sequelae of HBV and HCV in U.S. incarcerated populations are not well-studied. This dissertation contributes to the assessment of the burden of HBV and HCV infections in U.S. incarcerated populations by addressing some of the deficiencies and gaps in previous research. ^ Objectives of the three dissertation studies were: (1) To investigate selected study-level factors as potential sources of heterogeneity in published HBV seroprevalence estimates in U.S. adult incarcerated populations (1975-2005), using meta-regression techniques; (2) To quantify the potential influence of suboptimal sensitivity of screening tests for antibodies to hepatitis C virus (anti-HCV) on previously reported anti-HCV prevalence estimates in U.S. incarcerated populations (1990-2005), by comparing these estimates to error-adjusted anti-HCV prevalence estimates in these populations; (3) To estimate death rates due to HBV, HCV, chronic liver disease (CLD/cirrhosis), and liver cancer from 1984 through 2003 in male prisoners in custody of the Texas Department of Criminal Justice (TDCJ) and to quantify the proportion of CLD/cirrhosis and liver cancer prisoner deaths attributable to HBV and/or HCV. ^ Results were as follows. Although meta-regression analyses were limited by the small body of literature, mean population age and serum collection year appeared to be sources of heterogeneity, respectively, in prevalence estimates of antibodies to HBV antigen (HBsAg+) and any positive HBV marker. Other population characteristics and study methods could not be ruled out as sources of heterogeneity. Anti-HCV prevalence is likely somewhat higher in male and female U.S. incarcerated populations than previously estimated in studies using anti-HCV screening tests alone without the benefit of repeat or additional testing. Death rates due to HBV, HCV, CLD/cirrhosis, and liver cancer from 1984 through 2003 in TDCJ male prisoners exceeded state and national rates. HCV rates appeared to be increasing and disproportionately affecting Hispanics. HCV was implicated in nearly one-third of liver cancer deaths. ^

Hepatitis C and human immunodeficiency virus infections in injecting drug users in drug treatment centers in Vietnam

Background. Injecting drug users (IDUs) are at risk of infection with Hepatitis C Virus (HCV) and Human Immunodeficiency Virus (HIV). Independently, each of these viruses is a serious threat to health, with HIV ravaging the body’s immune system, and HCV causing cirrhosis, liver cancer and liver failure. Co-infection with HIV/HCV weakens the response to antiretroviral therapy in HIV patients. IDUs with HIV/HCV co-infection are at a 20 times higher risk of having liver-related morbidity and mortality than IDUs with HIV alone. In Vietnam, studies to ascertain the prevalence of HIV have found high rates, but little is known about their HCV status. ^ Purpose. To measure the prevalence of HCV and HIV infection and identify factors associated with these viruses among IDUs at drug treatment centers in northern Vietnam. ^ Methods. A cross-sectional study was conducted from November 2007 to February 2008 with 455 injecting drug users aged 18 to 39 years, admitted no more than two months earlier to one of four treatment centers in Northern Vietnam (Hatay Province) (response rate=95%). Participants, all of whom had completed detoxification and provided informed consent, completed a risk assessment questionnaire and had their blood drawn to test for the presence of antibody-HCV and antibody-HIV with enzyme immuno assays. Univariate and multivariable logistic regression models were utilized to explore the strength of association using HIV, HCV infections and HIV/HCV co-infection as outcomes and demographic characteristics, drug use and sexual behaviors as factors associated with these outcomes. Unadjusted and adjusted odds ratios and 95% confidence intervals were calculated. ^ Results. Among all IDU study participants, the prevalence of HCV alone was 76.9%, HIV alone was 19.8%. The prevalence of HIV/HCV co-infection was 92.2% of HIV-positive and 23.7% of HCV-positive respondents. No sexual risk behaviors for lifetime, six months or 30 days prior to admission were significantly associated with HCV or HIV infection among these IDUs. Only duration of injection drug use was independently associated with HCV and HIV infection, respectively. Longer duration was associated with higher prevalence. Nevertheless, while HCV infection among IDUs who reported being in their first year of injecting drugs were lower than longer time injectors, their rates were still substantial, 67.5%. ^ Compared with either HCV mono-infection or HIV/HCV non-infection, HIV/HCV co-infection was associated with the length of drug injection history but was not associated with sexual behaviors. Higher education was associated with a lower prevalence of HIV/HCV co-infection. When compared with HIV/HCV non-infection, current marriage was associated with a lower prevalence of HIV/HCV co-infection. ^ Conclusions. HCV was prevalent among IDUs from 18 to 39 years old at four drug treatment centers in northern Vietnam. Co-infection with HCV was predominant among HIV-positive IDUs. HCV and HIV co-infection were closely associated with the length of injection drug history. Further research regarding HCV/HIV co-infection should include non-injecting drug users to assess the magnitude of sexual risk behaviors on HIV and HCV infection. (At these treatment centers non-IDUs constituted 10-20% of the population.) High prevalence of HCV prevalence among IDUs, especially among HIV-infected IDUs, suggests that drug treatment centers serving IDUs should include not only HIV prevention education but they should also include the prevention of viral hepatitis. In addition, IDUs who are HIV-positive need to be tested for HCV to receive the best course of therapy and achieve the best response to HIV treatment. These data also suggest that because many IDUs get infected with HCV in the first year of their injection drug career, and because they also engaged in high risk sexual behaviors, outreach programs should focus on harm reduction, safer drug use and sexual practices to prevent infection among drug users who have not yet begun injecting drugs and to prevent further spread of HCV, HIV and co-infection. ^

Deployed military women: A second look at gender-specific infections

This descriptive, cross-sectional study addressed the relationship between variables of deployed military women and prevalence of gender-specific infections. The analysis of secondary data will look at the last deployment experience of 880 randomly selected U.S. military women who completed a mailed questionnaire (Deployed Female Health Practice Questionnaire (FHPQ)) in June 1998. The questionnaire contained 191 items with 80 data elements and one page for the subject's written comments. The broad categories of the questionnaire included: health practices, health promotion, disease prevention and treatment, reproduction, lifestyle management, military characteristics and demographics. The research questions are: (1) What is the prevalence of sexually transmitted diseases (STD), urinary tract infections (UTI) and vaginal infections (VI) related to demographic data, military characteristics, behavioral risk factors and health practices of military women during their last deployment? and (2) What are the differences between STD, UTI and VI related to the demographic data, military characteristics, behavioral risk factors and health practices of military women during their last deployment. The results showed that (1) STDs were found to be significantly associated with age and rank but not location of deployment or military branch; (2) UTI were found to be significantly associated with intrauterine device (IUD) use, prior UTI and type of items used for menses management, but not education or age; and (3) VI were significantly associated with age, rank and deployment location but not ethnicity or education. Although quantitative research exploring hygiene needs of deployed women continues, qualitative studies may uncover further “hidden” issues of importance. It cannot be said that the military has not made proactive changes for women, however, continued efforts to hone these changes are still encouraged. Mandatory debriefings of “seasoned” deployed women soldiers and their experiences would benefit leadership and newly deployed female soldiers with valuable “lessons learned.” Tailored hygiene education material, prevention education classes, easy access website with self-care algorithms, pre-deployment physicals, revision of military protocols for health care providers related to screening, diagnosing and treatment of gender-specific infections and process changes in military supply network of hygiene items for women are offered as recommendations. ^

Epidemiology of tuberculosis and nontuberculous mycobacterial infections in Houston children

Background. Nontuberculous mycobacteria (NTM) are environmentally ubiquitous organisms whose epidemiology is poorly understood. Species differ with respect to disease presentation, prognosis, and antimicrobial susceptibility. We reviewed one Texas pediatric hospital's experience with NTM and tuberculosis (TB) disease.^ Methods. This was a retrospective case series of children with culture-confirmed mycobacterial infections seen at a children's hospital from 2003-2008.^ Results. One hundred sixty-two isolates were identified from 150 children; 132 (81.5%) had NTM species isolated, and 30 (18.5%) had M. tuberculosis isolated; 2 children had both NTM and M. tuberculosis isolated. The most common species were Mycobacterium avium complex (MAC) (29%), M. tuberculosis (18.5%), M. abscessus (13%), M. fortuitum (11.7%), and M. chelonae-abscessus (9.9%). TB was the most common organism isolated from respiratory specimens. MAC and M. simiae were significantly more likely to be associated with lymphadenopathy than other NTM species (p < 0.001). Mycobacterium fortuitum was significantly more likely to be associated with soft tissue infections than other NTM species (p < 0.001). Seventy-five children met criteria for NTM disease (30 lymphadenopathy, 17 pulmonary, 17 soft tissue infections, 11 bacteremia). Children with NTM lymphadenopathy were more likely to be Hispanic (OR 24, CI 2.8-1063), younger (3.3 years vs. 10.6 years, p < 0.001), and previously healthy (OR 0.004, CI 0-0.06) than children with NTM pulmonary disease. Children with NTM disease were less likely to be previously healthy (OR 0.30, 95% CI 0.09-0.88) and foreign-born (OR 0.09, CI 0.03-0.29) than children with TB.^ Conclusions. Children with NTM lymphadenopathy were younger and more likely to be healthy than children with NTM pulmonary disease. Tuberculosis comprised a large proportion of mycobacterial disease in this series. Children with NTM pulmonary disease were less likely to be previously healthy and born abroad when compared to children with TB. There was wide variation in antimicrobial susceptibility patterns among NTM species. This, together with the large percentage of disease caused by TB, emphasizes the importance of securing a specific microbiologic diagnosis in children with pulmonary or lymph node disease caused by mycobacteria.^

The movement toward patient safety: State action related to reporting and disclosure of healthcare-associated infections

Increasing attention has been given to the problem of medical errors over the past decade. Included within that focused attention has been a strong interest in reducing the occurrence of healthcare-associated infections (HAIs). Acting concurrently with federal initiatives, the majority of U.S. states have statutorily required reporting and public disclosure of HAI data. Although the occurrence of these state statutory enactments and other state initiatives represent a recognition of the strong concern pertaining to HAIs, vast differences in each state’s HAI reporting and public disclosure requirements creates a varied and unequal response to what has become a national problem.^ The purpose of this research was to explore the variations in state HAI legal requirements and other state mandates. State actions, including statutory enactments, regulations, and other initiatives related to state reporting and public disclosure mechanisms were compared, discussed, and analyzed in an effort to illustrate the impact of the lack of uniformity as a public health concern.^ The HAI statutes, administrative requirements, and other mandates of each state and two U.S. territories were reviewed to answer the following seven research questions: How far has the state progressed in its HAI initiative? If the state has a HAI reporting requirement, is it mandatory or voluntary? What healthcare entities are subject to the reporting requirements? What data collection system is utilized? What measures are required to be reported? What is the public disclosure mechanism? How is the underlying reported information protected from public disclosure or other legal release?^ Secondary publicly available data, including state statutes, administrative rules, and other initiatives, were utilized to examine the current HAI-related legislative and administrative activity of the study subjects. The information was reviewed and analyzed to determine variations in HAI reporting and public disclosure laws. Particular attention was given to the seven key research questions.^ The research revealed that considerable progress has been achieved in state HAI initiatives since 2004. Despite this progress, however, when reviewing the state laws and HAI programs comparatively, considerable variations were found to exist with regards to the type of reporting requirements, healthcare facilities subject to the reporting laws, data collection systems utilized, reportable measures, public disclosure requirements, and confidentiality and privilege provisions. The wide variations in state statutes, administrative rules, and other agency directives create a fragmented and inconsistent approach to addressing the nationwide occurrence of HAIs in the U.S. healthcare system. ^

Nosocomial infections and their relationship to non-traditional risk factors in a medical intensive care unit

Background. Nosocomial infections are a source of concern for many hospitals in the United States and worldwide. These infections are associated with increased morbidity, mortality and hospital costs. Nosocomial infections occur in ICUs at a rate which is five times greater than those in general wards. Understanding the reasons for the higher rates can ultimately help reduce these infections. The literature has been weak in documenting a direct relationship between nosocomial infections and non-traditional risk factors, such as unit staffing or patient acuity.^ Objective. To examine the relationship, if any, between nosocomial infections and non-traditional risk factors. The potential non-traditional risk factors we studied were the patient acuity (which comprised of the mortality and illness rating of the patient), patient days for patients hospitalized in the ICU, and the patient to nurse ratio.^ Method. We conducted a secondary data analysis on patients hospitalized in the Medical Intensive Care Unit (MICU) of the Memorial Hermann- Texas Medical Center in Houston during the months of March 2008- May 2009. The average monthly values for the patient acuity (mortality and illness Diagnostic Related Group (DRG) scores), patient days for patients hospitalized in the ICU and average patient to nurse ratio were calculated during this time period. Active surveillance of Bloodstream Infections (BSIs), Urinary Tract Infections (UTIs) and Ventilator Associated Pneumonias (VAPs) was performed by Infection Control practitioners, who visited the MICU and performed a personal infection record for each patient. Spearman's rank correlation was performed to determine the relationship between these nosocomial infections and the non-traditional risk factors.^ Results. We found weak negative correlations between BSIs and two measures (illness and mortality DRG). We also found a weak negative correlation between UTI and unit staffing (patient to nurse ratio). The strongest positive correlation was found between illness DRG and mortality DRG, validating our methodology.^ Conclusion. From this analysis, we were able to infer that non-traditional risk factors do not appear to play a significant role in transmission of infection in the units we evaluated.^

Non routine hospital settings: Significant sources of nosocomial infections often overlooked

Non routine hospital settings are those that are infrequently used in hospitals and that often do not come to mind when sanitation and disinfection practices are used. These settings are a major source of nosocomial, or hospital acquired, infections, and are often overlooked. Data on these sources are often scattered and scarce, but these sources are significant such that they warrant equal attention of commonly recognized nosocomial infection sources in order to help reduce incidence of nosocomial infections. ^

Non-staphylococcal infections of cardiac implantable electronic devices

Background. The number of infections of cardiac implantable electronic devices (CIED) continues to escalate out of proportion to the increase rate of device implantation. Staphylococcal organisms account for 70% to 90% of all CIED infections. However, little is known about non-staphylococcal infections, which have been described only in case reports, small case series or combined in larger studies with staphylococcal CIED infections, thereby diluting their individual impact. ^ Methods. A retrospective review of hospital records of patients admitted with a CIED-related infections were identified within four academic hospitals in Houston, Texas between 2002 and 2009. ^ Results. Of the 504 identified patients with CIED-related infection, 80 (16%) had a non-staphylococcal infection and were the focus of this study. Although the demographics and comorbities of subjects were comparable to other reports, our study illustrates many key points: (a) the microbiologic diversity of non-staphylococcal infections was rather extensive, as it included other Gram-positive bacteria like streptococci and enterococci, a variety of Gram-negative bacteria, atypical bacteria including Nocardia and Mycobacteria, and fungi like Candida and Aspergillus; (b) the duration of CIED insertion prior to non-staphylococcal infection was relatively prolong (mean, 109 ± 27 weeks), of these 44% had their device previously manipulated within a mean of 29.5 ± 6 weeks; (c) non-staphylococcal organisms appear to be less virulent, cause prolonged clinical symptoms prior to admission (mean, 48 ± 12.8 days), and are associated with a lower mortality (4%) than staphylococcal organisms; (d) thirteen patients (16%) presented with CIED-related endocarditis; (e) although not described in prior reports, we identified 3 definite and 2 suspected cases of secondary Gram-negative bacteremia seeding of the CIED; and (f) inappropriate antimicrobial coverage was provided in approximately 50% of patients with non-staphylococcal infections for a mean period of 2.1 days. ^ Conclusions. Non-staphylococcal CIED-related infections are prevalent and diverse with a relatively low virulence and mortality rate. Since non-staphylococcal organisms are capable of secondarily seeding the CIED, a high suspicion for CIED-related infection is warranted in patients with bloodstream infection. Additionally, in patients with suspected CIED infection, adequate Gram positive and -negative antibacterial coverage should be administered until microbiologic data become available.^

Clinical and economic outcomes of serious postoperative infections following resection of common respiratory and gastrointestinal solid tumors

Unlike infections occurring during periods of chemotherapy-induced neutropenia, postoperative infections in patients with solid malignancy remain largely understudied. The purpose of this population-based study was to evaluate the clinical and economic burden, as well as the relationship of hospital surgical volume and outcomes associated with serious postoperative infection (SPI) – i.e., bacteremia/sepsis, pneumonia, and wound infection – following resection of common solid tumors.^ From the Texas Discharge Data Research File, we identified all Texas residents who underwent resection of cancer of the lung, esophagus, stomach, pancreas, colon, or rectum between 2002 and 2006. From their billing records, we identified ICD-9 codes indicating SPI and also subsequent SPI-related readmissions occurring within 30 days of surgery. Random-effects logistic regression was used to calculate the impact of SPI on mortality, as well as the association between surgical volume and SPI, adjusting for case-mix, hospital characteristics, and clustering of multiple surgical admissions within the same patient and patients within the same hospital. Excess bed days and costs were calculated by subtracting values for patients without infections from those with infections computed using multilevel mixed-effects generalized linear model by fitting a gamma distribution to the data using log link.^ Serious postoperative infection occurred following 9.4% of the 37,582 eligible tumor resections and was independently associated with an 11-fold increase in the odds of in-hospital mortality (95% Confidence Interval [95% CI], 6.7-18.5, P < 0.001). Patients with SPI required 6.3 additional hospital days (95% CI, 6.1 - 6.5) at an incremental cost of $16,396 (95% CI, $15,927–$16,875). There was a significant trend toward lower overall rates of SPI with higher surgical volume (P=0.037). ^ Due to the substantial morbidity, mortality, and excess costs associated with SPI following solid tumor resections and given that, under current reimbursement practices, most of this heavy burden is borne by acute care providers, it is imperative for hospitals to identify more effective prophylactic measures, so that these potentially preventable infections and their associated expenditures can be averted. Additional volume-outcomes research is also needed to identify infection prevention processes that can be transferred from higher- to lower-volume providers.^

Impact of real time polymerase chain reaction technology on the therapeutic approach to treatment of staphylococcal infections

Can the early identification of the species of staphylococcus responsible for infection by the use of Real Time PCR technology influence the approach to the treatment of these infections? ^ This study was a retrospective cohort study in which two groups of patients were compared. The first group, ‘Physician Aware’ consisted of patients in whom physicians were informed of specific staphylococcal species and antibiotic sensitivity (using RT-PCR) at the time of notification of the gram stain. The second group, ‘Physician Unaware’ consisted of patients in whom treating physicians received the same information 24–72 hours later as a result of blood culture and antibiotic sensitivity determination. ^ The approach to treatment was compared between ‘Physician Aware’ and ‘Physician Unaware’ groups for three different microbiological diagnoses—namely MRSA, MSSA and no-SA (or coagulase negative Staphylococcus). ^ For a diagnosis of MRSA, the mean time interval to the initiation of Vancomycin therapy was 1.08 hours in the ‘Physician Aware’ group as compared to 5.84 hours in the ‘Physician Unaware’ group (p=0.34). ^ For a diagnosis of MSSA, the mean time interval to the initiation of specific anti-MSSA therapy with Nafcillin was 5.18 hours in the ‘Physician Aware’ group as compared to 49.8 hours in the ‘Physician Unaware’ group (p=0.007). Also, for the same diagnosis, the mean duration of empiric therapy in the ‘Physician Aware’ group was 19.68 hours as compared to 80.75 hours in the ‘Physician Unaware’ group (p=0.003) ^ For a diagnosis of no-SA or coagulase negative staphylococcus, the mean duration of empiric therapy was 35.65 hours in the ‘Physician Aware’ group as compared to 44.38 hours in the ‘Physician Unaware’ group (p=0.07). However, when treatment was considered a categorical variable and after exclusion of all cases where anti-MRS therapy was used for unrelated conditions, only 20 of 72 cases in the ‘Physician Aware’ group received treatment as compared to 48 of 106 cases in the ‘Physician Unaware’ group. ^ Conclusions. Earlier diagnosis of MRSA may not alter final treatment outcomes. However, earlier identification may lead to the earlier institution of measures to limit the spread of infection. The early diagnosis of MSSA infection, does lead to treatment with specific antibiotic therapy at an earlier stage of treatment. Also, the duration of empiric therapy is greatly reduced by early diagnosis. The early diagnosis of coagulase negative staphylococcal infection leads to a lower rate of unnecessary treatment for these infections as they are commonly considered contaminants. ^