Quantitative Culture Techniques Research Articles

A Bibliometric Analysis of the Role and Research Trending of Bronchoalveolar Lavage in the Diagnosis and Treatment of Ventilator-Associated Pneumonia.

Ventilator-associated pneumonia (VAP) is one of the most common complications in intensive care units (ICUs) and negatively affects patient outcomes. Despite its widespread use as a diagnostic and therapeutic measure, the application and effectiveness of bronchoalveolar lavage (BAL) in the management of VAP require further exploration. This study aimed to evaluate the research dynamics, major trends, and scientific networks of BAL in the diagnosis and treatment of VAP using bibliometric analysis. Literature from the Web of Science database on BAL for the diagnosis and treatment of VAP from 1990 to 2024 was screened and analyzed. Keyword co-occurrence, trend analysis, and citation burst analyses were conducted using CiteSpace to identify research hotspots, core authors, institutions, and countries, as well as the evolution of research domains. The bibliometric analysis included 968 publications. Trend analysis indicated growing interest in BAL techniques, particularly in the categories of RESPIRATORY SYSTEM (burst score: 27.82) and MEDICINE, RESEARCH, and EXPERIMENTAL (burst score: 7.41). The co-citation analysis highlighted influential authors in the field, such as Torres(burst score: 9.35), Croce (burst score: 5.86), and Meduri(burst score: 5.71). Keyword analysis results revealed core clusters in the treatment of VAP with BAL, including "nonbronchoscopic lavage" (silhouette value: 0.703), "ICU-acquired infection" (silhouette value: 0.7), and "ventilator-associated tracheobronchitis" (silhouette value: 0.637). Additionally, geographic analysis showed that North America and Europe dominated the research in this field. Recently, research trends regarding protected specimen brushes and quantitative culture techniques have emerged. This study found broad applications of BAL in VAP management, especially in improving diagnostic accuracy and treatment outcomes. Optimized strategies such as improvement of lavage techniques and multidisciplinary collaboration may emerge as potential research hotspots in the future.

No viable bacterial communities reside in the urinary bladder of cats with feline idiopathic cystitis

Urinary microbial diversities have been reported in humans according to sex, age and clinical status, including painful bladder syndrome/interstitial cystitis (PBS/IC). To date, the role of the urinary microbiome in the pathogenesis of PBS/IC is debated. Feline idiopathic cystitis (FIC) is a chronic lower urinary tract disorder affecting cats with similarities to PBS/IC in women and represents an important problem in veterinary medicine as its aetiology is currently unknown. In this study, the presence of a bacterial community residing in the urinary bladder of cats with a diagnosis of FIC was investigated. Nineteen cats with clinical signs and history of FIC and without growing bacteria in standard urine culture were included and urine collected with ultrasound-guided cystocentesis. Bacterial community was investigated using a culture-dependent approach consisted of expanded quantitative urine culture techniques and a culture-independent approach consisted of 16S rRNA NGS. Several methodological practices were adopted to both avoid and detect any contamination or bias introduced by means of urine collection and processing which could be relevant due to the low microbial biomass environment of the bladder and urinary tract, including negative controls analysis. All the cats included showed no growing bacteria in the urine analysed. Although few reads were originated using 16S rRNA NGS, a comparable pattern was observed between urine samples and negative controls, and no taxa were confidently classified as non-contaminant. The results obtained suggest the absence of viable bacteria and of bacterial DNA of urinary origin in the urinary bladder of cats with FIC.

The Urobiomes of Adult Women With Various Lower Urinary Tract Symptoms Status Differ: A Re-Analysis.

The discovery of the urinary microbiome (urobiome) has created opportunities for urinary health researchers who study a wide variety of human health conditions. This manuscript describes an analysis of catheterized urine samples obtained from 1,004 urobiome study participants with the goal of identifying the most abundant and/or prevalent (common) taxa in five clinically relevant cohorts: unaffected adult women (n=346, 34.6%), urgency urinary incontinence (UUI) (n=255, 25.5%), stress urinary incontinence (SUI) (n=50, 5.0%), urinary tract infection (UTI) (n=304, 30.4%), and interstitial cystitis/painful bladder syndrome (IC/PBS) (n=49, 4.9%). Urine was collected via transurethral catheter and assessed for microbes with the Expanded Quantitative Urine Culture (EQUC) technique. For this combined analytic cohort, the mean age was 59 ± 16; most were Caucasian (n=704, 70.2%), Black (n=137, 13.7%), or Hispanic (n=130, 13.0%), and the mean BMI was 30.4 ± 7.7. Whereas many control or IC/PBS cohort members were EQUC-negative (42.4% and 39.8%, respectively), members of the other 3 cohorts were extremely likely to have detectable microbes. The detected urobiomes of the controls and IC/PBS did not differ by alpha diversity or genus level composition and differed by only a few species. The other 3 cohorts differed significantly from the controls. As expected, Escherichia was both prevalent and highly abundant in the UTI cohort, but other taxa also were prevalent at more moderate abundances, including members of the genera Lactobacillus, Streptococcus, Staphylococcus, Corynebacterium, Actinomyces, and Aerococcus. Members of these genera were also prevalent and highly abundant in members of the UUI cohort, especially Streptococcus anginosus. Intriguingly, these taxa were also detected in controls but at vastly lower levels of both prevalence and abundance, suggesting the possibility that UUI-associated symptoms could be the result of an overabundance of typical urobiome constituents. Finally, prevalence and abundance of microbes in the SUI cohort were intermediate to those of the UUI and control cohorts.These observations can inform the next decade of urobiome research, with the goal of clarifying the mechanisms of urobiome community composition and function. There is tremendous potential to improve diagnosis, evaluation and treatment for individuals affected with a wide variety of urinary tract disorders.

Evaluation of semi-quantitative compared to quantitative cultures of tracheal aspirates for the yield of culturable respiratory pathogens \u2013 a cross-sectional study

BackgroundDiagnosis of lower respiratory tract infections (LRTI) depends on the presence of clinical, radiological and microbiological findings. Endotracheal suction aspirate (ETSA) is the commonest respiratory sample sent for culture from intubated patients. Very few studies have compared quantitative and semi-quantitative processing of ETSA cultures for LRTI diagnosis. We determined the diagnostic accuracy of quantitative and semi-quantitative ETSA culture for LRTI diagnosis, agreement between the quantitative and semi quantitative culture techniques and the yield of respiratory pathogens with both methods.MethodsThis was a cross-sectional study conducted at the Aga Khan University clinical laboratory, Karachi, Pakistan. One hundred and seventy-eight ETSA samples sent for routine bacteriological cultures were processed quantitatively as part of regular specimen processing method and semi-quantitatively. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy was calculated for both methods using clinical diagnosis of pneumonia as reference standard. Agreement between the quantitative and semi quantitative methods was assessed via the kappa statistic test. Pathogen yield between the two methods was compared using Pearson’s chi-square test.ResultsThe quantitative and semi-quantitative methods yielded pathogens in 81 (45.5%) and 85 (47.8%) cases respectively. There was complete concordance of both techniques in 155 (87.1%) ETSA samples. No growth was observed in 45 (25.3%) ETSA specimens with quantitative culture and 37 (20.8%) cases by semi-quantitative culture. The diagnostic accuracy of both techniques were comparable; 64.6% for quantitative and 64.0% for semi-quantitative culture. The kappa agreement was found to be 0.84 (95% CI, 0.77–0.91) representing almost perfect agreement between the two methods. Although semi-quantitative cultures yielded more pathogens (47.8%) as compared to quantitative ETSA cultures (45.5%), the difference was only 2.3%. However, this difference achieved statistical (chi-square p-value < 0.001) favoring semi-quantitative culture methods over quantitative culture techniques for processing ETSA.ConclusionIn conclusion, there is a strong agreement between the performances of both methods of processing ETSA cultures in terms of accuracy of LRTI diagnosis. Semi-quantitative cultures of ETSA yielded more pathogens as compared to quantitative cultures. Although both techniques were comparable, we recommend processing of ETSA using semi-quantitative technique due to its ease and reduced processing time.

Respiracinės infekcijos sukėlėjų mikrobiologinių tyrimų diagnostinė vertė

Apatinių kvėpavimo takų infekcijos (AKT), įskaitant ūminį ir lėtinį bronchitą, visuomenėje įgyta pneumonija (VIP), ligoninėje įgyta pneumonija (kitaip dar vadinamą hospitaline pneumonija, HP) arba pneumonija imunosupresiniams bei kitomis lėtinėmis ligomis sergantiems pacientams yra dažniausios infekcijos tiek visuomenėje, tiek stacionare. Ligų prevencijos ir kontrolės centro (angl. Centers for Disease Control and Prevention, CDC) duomenimis, AKT infekcijos sukelia nuo 5 iki 10 proc. visų pacientų mirčių. Lyginant kelis dešimtmečius, pacientų populiacija sparčiai kinta. Daugėja vyresnio amžiaus, vyresnių nei 65metų, slaugos ligoninėse besigydančių, imunosupresinių pacientų, todėl AKT etiologija ir potencialių sukėlėjų spektras taip pat kinta. Klinikinė mikrobiologinė laboratorija atlieka svarbų vaidmenį nustatant šių infekcijų sukėlėjus, tačiau susiduria su daugybe iššūkių, susijusių su AKT infekcijų tyrimo sudėtingumu. Taimėginių kokybė ir įvairovė, tiriamosiosmedžiagos užteršimas orofaringine flora, įvairi galimų patogenų populiacija, įskaitant bakterijas, virusus ir grybus, kompleksinė kvėpavimo takų infekcijų patofiziologija, ypač specialiose sergančiųjų populiacijose. Dažniausi klausimai ir problemos, kurias tenka spręsti: 1. Kokia yra tikroji skreplių, dažytų Gramo būdu, mikroskopijos ir pasėlio vertė? 2. Kokia yra pusiau kiekybinių mikrobiologinių bronchų išplovų ir kiekybinių bronchoalveolinio lavažo pasėlių reikšmė? 3. Koks yra klinikinės mikrobiologijos laboratorijos vaidmuo diagnozuojant lėtinio bronchito paūmėjimą? 4. Kaip reikia optimizuoti cistine fibroze (CF) sergančių pacientų, ypač ligai paūmėjus, mikrobiologinį vertinimą?

Culture-Dependent and Sequencing Methods Revealed the Absence of a Bacterial Community Residing in the Urine of Healthy Cats.

A growing number of studies suggest that the lower urinary tract of humans and dogs can harbor a urinary microbiota. Nevertheless, a certain concern has developed that the microbiota reported could be due to unaccounted contamination, especially in low-biomass samples. The aim of this study was to investigate the bacterial community which populates the urine of healthy cats using two approaches: a culture-dependent approach which consisted of the expanded quantitative urine culture (EQUC) techniques capable of identifying live bacteria not growing in standard urine cultures, and a culture-independent approach which consisted of 16S ribosomal RNA next generation sequencing (16S rRNA NGS) capable of identifying bacterial DNA and exploring microbial diversity with high resolution. To avoid confounding factors of possible bacterial contamination, the urine was sampled using ultrasound-guided cystocentesis, and several sample controls and negative controls were analyzed. The urine sampled from the 10 cats included in the study showed no bacterial growth in the EQUC procedure. Although several reads were successfully originated using 16S rRNA NGS, a comparable pattern was observed between urine samples and the negative control, and no taxa were statistically accepted as non-contaminant. Taken together, the results obtained allowed stating that no viable bacteria were present in the urine of healthy cats without lower urinary tract disease and urinary tract infections, and that the bacterial DNA detected was of contaminant origin.

Mycobacterium avium complex bacteria remain viable in sputum during storage and refrigeration

Diagnostic mycobacteriology often involves shipping of samples to centralized laboratories. Using two quantitative culture techniques, we show that 7 days storage of sputum samples at room temperature or 4 °C does not affect the number of viable Mycobacterium avium complex bacteria. Storage at room temperature increases the chance of contamination.

Correlation between biofilm formation and resistance toward different commonly used antibiotics along with extended spectrum beta lactamase production in uropathogenic Escherichia coli isolated from the patients suspected of urinary tract infections visiting Shree Birendra Hospital, Chhauni, Kathmandu, Nepal.

BackgroundEscherichia coli is the most predominant causative agent of urinary tract infection (UTI). Recently, increase in drug resistance among the uropathogenic bacteria has caused great problem in treatment of UTI. The main objective of this research is to determine the correlation between biofilm formation and resistance toward different commonly used antibiotics along with extended spectrum beta lactamase production in uropathogenic Escherichia coli.MethodsThe urine samples collected from the patients suspected of urinary tract infections (visiting Shree Birendra Hospital, Chhauni, Kathmandu, Nepal between July to December 2013) were cultured in cystine lactose electrolyte deficient (CLED) agar by using semi quantitative culture technique. Extended spectrum beta lactamase (ESBL) production was detected by combined disc diffusion technique and biofilm formation was detected by Congo red agar method. Chi-square test was applied and p-value < 0.05 was considered statistically significant.ResultsOut of 1480 urine samples, E. Coli was isolated from 208 (14.1 %) samples. Of total 69 (33.2 %) ESBL producing uropathogenic strains of E. coli, 20 (29 %) were strong biofilm producers, 22 (31.9 %) were moderate biofilm producers, 11 (15.9 %) were weak biofilm producers and 16 (23.2 %) were biofilm non producers. Whereas among 139 ESBL non producing E. coli, 22 (15.8 %) were strong biofilm producers, 20 (14.4 %) were moderate biofilm producers, 13 (9.4 %) were weak biofilm producers and 84 (60.4 %) were biofilm non producers. Among total 108 biofilm producing E. coli, maximum resistance was observed toward cephalexin followed by amoxicillin and highest susceptibility was seen toward amikacin.ConclusionThe ability of biofilm formation was found to be significantly higher in ESBL producing strains of E. coli than that in ESBL non producing strains (p < 0.05). There was higher resistance rate to antimicrobial agents among biofilm producing strains of E. coli than that in biofilm non producing strains. According to our antimicrobial susceptibility pattern for E. coli, to start preliminary treatment for UTI in Nepal, we recommend to use amikacin or nitrofurantoin. Further, for the treatment of the UTI, the antibiotics should be selected on the basis of the urine culture and sensitivity report.

Antibiotic resistance & pathogen profile in ventilator-associated pneumonia in a tertiary care hospital in India.

Background & objectives:Ventilator-associated pneumonia (VAP) is an important hospital-acquired infection with substantial mortality. Only a few studies are available from India addressing the microbiological aspects of VAP, which have been done with small study populations. This study was carried out in the intensive care units (ICUs) of a tertiary care hospital to assess the profile of pathogens and to determine the pattern of antimicrobial resistance.Methods:This was a retrospective study of clinically suspected cases of VAP. Over a three year period, a total of 247 cases in 2011, 297 in 2012 and 303 in 2013 admitted in ICUs on mechanical ventilation with clinical evidence of VAP were included in our study. The endotracheal aspirate samples from these suspected cases were subjected to quantitative culture technique, and colony count of ≥105 colony forming units/ml was considered significant. Antimicrobial susceptibility test for the isolates was done.Results:VAP rates of 44.1, 43.8 and 26.3 were seen in 2011, 2012 and 2013, respectively. In all the three years, non-fermentative Gram-negative bacilli were the predominant organisms, followed by Pseudomonas spp. and Klebsiella spp. Staphylococcus aureus exhibited a downwards trend in prevalence from 50.0 per cent in 2011 to 34.9 per cent in 2013. An increase in vancomycin-resistant enterococci was seen from 4.3 per cent in 2012 to 8.3 per cent in 2013, while methicillin resistance amongst the S. aureus crossed the 50 per cent mark in 2013. An increasing trend in resistance was shown by Pseudomonas spp. for piperacillin-tazobactam (PTZ), amikacin and imipenem (IPM). For the non-fermenters, resistance frequency remained very high except for IPM (33.1%) and polymyxin-B (2.4%).Interpretation & conclusions:Our findings show VAP as an important problem in the ICU setting. The incidence of multidrug-resistant pathogens was on the rise. The resistance pattern of these pathogens can help an institution to formulate effective antimicrobial policy. To have a comprehensive pan-India picture, multicentric studies are needed.

Inability of polymerase chain reaction, pyrosequencing, and culture of infected and uninfected site skin biopsy specimens to identify the cause of cellulitis.

The cause of cellulitis is unclear. Streptococcus pyogenes, and to a lesser extent, Staphylococcus aureus, are presumed pathogens. We conducted a study of adults with acute cellulitis without drainage presenting to a US emergency department research network. Skin biopsy specimens were taken from the infected site and a comparable uninfected site on the opposite side of the body. Microbiology was evaluated using quantitative polymerase chain reaction (PCR), pyrosequencing, and standard culture techniques. To determine the cause, the prevalence and quantity of bacterial species at the infected and uninfected sites were compared. Among 50 subjects with biopsy specimens from infected and uninfected sites, culture rarely identified a bacterium. Among 49 subjects with paired specimens from infected and uninfected sites tested with PCR, methicillin-susceptible S. aureus was identified in 20 (41%) and 17 (34%), respectively. Pyrosequencing identified abundant atypical bacteria in addition to streptococci and staphylococci. Among 49 subjects with paired specimens tested by pyrosequencing, S. aureus was identified from 11 (22%) and 15 (31%) and streptococci from 15 (31%) and 20 (41%) of the specimens, respectively. Methicillin-resistant S. aureus was not found by culture or PCR, and S. pyogenes was not identified by any technique. The bacterial cause of cellulitis cannot be determined by comparing the prevalence and quantity of pathogens from infected and uninfected skin biopsy specimens using current molecular techniques. Methicillin-susceptible S. aureus was detected but not methicillin-resistant S. aureus or S. pyogenes from cellulitis tissue specimens. For now, optimal treatment will need to be guided by clinical trials. Noninfectious causes should also be explored.

Bacteriology of expectorated sputum with quantitative culture and wash technique compared to transtracheal aspirates.

Techniques to improve the reliability of expectorated sputum culture were evaluated in 46 patients using a wash technique, quantitative culture, and a combination of washing and quantification. The wash procedure consisted of a jet of tap water over the specimen contained in a tea strainer. The true lower respiratory tract flora was determined by percutaneous transtracheal aspirates, which served as the basis for evaluating the methods of processing expectorated specimens. Either washing alone or quantification alone decreased the number of specimens with organisms that were not present in companion transtracheal aspirates; however, results that were sufficiently improved to be clearly advantageous for clinical interpretation were achieved only when washing and quantification were combined. Washed sputum specimens yielded oropharyngeal "contaminants" in concentrations exceeding 10(6) bacteria per ml in 12 of 46 specimens (26 per cent). Using this technique, only one specimen contained a misleading potential pathogen, and only one specimen failed to yield a potential pathogen that was recovered with the transtracheal aspirate. The wash procedure decreased the mean concentrations of contaminants approximately 100-fold for all specimens and 1,000-fold for purulent specimens.

The female urinary microbiome: a comparison of women with and without urgency urinary incontinence.

ABSTRACTBacterial DNA and live bacteria have been detected in human urine in the absence of clinical infection, challenging the prevailing dogma that urine is normally sterile. Urgency urinary incontinence (UUI) is a poorly understood urinary condition characterized by symptoms that overlap urinary infection, including urinary urgency and increased frequency with urinary incontinence. The recent discovery of the urinary microbiome warrants investigation into whether bacteria contribute to UUI. In this study, we used 16S rRNA gene sequencing to classify bacterial DNA and expanded quantitative urine culture (EQUC) techniques to isolate live bacteria in urine collected by using a transurethral catheter from women with UUI and, in comparison, a cohort without UUI. For these cohorts, we demonstrated that the UUI and non-UUI urinary microbiomes differ by group based on both sequence and culture evidences. Compared to the non-UUI microbiome, sequencing experiments revealed that the UUI microbiome was composed of increased Gardnerella and decreased Lactobacillus. Nine genera (Actinobaculum, Actinomyces, Aerococcus, Arthrobacter, Corynebacterium, Gardnerella, Oligella, Staphylococcus, and Streptococcus) were more frequently cultured from the UUI cohort. Although Lactobacillus was isolated from both cohorts, distinctions existed at the species level, with Lactobacillus gasseri detected more frequently in the UUI cohort and Lactobacillus crispatus most frequently detected in controls. Combined, these data suggest that potentially important differences exist in the urinary microbiomes of women with and without UUI, which have strong implications in prevention, diagnosis, or treatment of UUI.

Diagnostic accuracy of semi-quantitative and quantitative culture techniques for the diagnosis of catheter-related infections in newborns and molecular typing of isolated microorganisms.

BackgroundCatheter-related bloodstream infections (CR-BSIs) have become the most common cause of healthcare-associated bloodstream infections in neonatal intensive care units (ICUs). Microbiological evidence implicating catheters as the source of bloodstream infection is necessary to establish the diagnosis of CR-BSIs. Semi-quantitative culture is used to determine the presence of microorganisms on the external catheter surface, whereas quantitative culture also isolates microorganisms present inside the catheter. The main objective of this study was to determine the sensitivity and specificity of these two techniques for the diagnosis of CR-BSIs in newborns from a neonatal ICU. In addition, PFGE was used for similarity analysis of the microorganisms isolated from catheters and blood cultures.MethodsSemi-quantitative and quantitative methods were used for the culture of catheter tips obtained from newborns. Strains isolated from catheter tips and blood cultures which exhibited the same antimicrobial susceptibility profile were included in the study as positive cases of CR-BSI. PFGE of the microorganisms isolated from catheters and blood cultures was performed for similarity analysis and detection of clones in the ICU.ResultsA total of 584 catheter tips from 399 patients seen between November 2005 and June 2012 were analyzed. Twenty-nine cases of CR-BSI were confirmed. Coagulase-negative staphylococci (CoNS) were the most frequently isolated microorganisms, including S. epidermidis as the most prevalent species (65.5%), followed by S. haemolyticus (10.3%), yeasts (10.3%), K. pneumoniae (6.9%), S. aureus (3.4%), and E. coli (3.4%). The sensitivity of the semi-quantitative and quantitative techniques was 72.7% and 59.3%, respectively, and specificity was 95.7% and 94.4%. The diagnosis of CR-BSIs based on PFGE analysis of similarity between strains isolated from catheter tips and blood cultures showed 82.6% sensitivity and 100% specificity.ConclusionThe semi-quantitative culture method showed higher sensitivity and specificity for the diagnosis of CR-BSIs in newborns when compared to the quantitative technique. In addition, this method is easier to perform and shows better agreement with the gold standard, and should therefore be recommended for routine clinical laboratory use. PFGE may contribute to the control of CR-BSIs by identifying clusters of microorganisms in neonatal ICUs, providing a means of determining potential cross-infection between patients.

Personal and household hygiene, environmental contamination, and health in undergraduate residence halls in New York City, 2011.

BackgroundWhile several studies have documented the importance of hand washing in the university setting, the added role of environmental hygiene remains poorly understood. The purpose of this study was to characterize the personal and environmental hygiene habits of college students, define the determinants of hygiene in this population, and assess the relationship between reported hygiene behaviors, environmental contamination, and health status.Methods501 undergraduate students completed a previously validated survey assessing baseline demographics, hygiene habits, determinants of hygiene, and health status. Sixty survey respondents had microbiological samples taken from eight standardized surfaces in their dormitory environment. Bacterial contamination was assessed using standard quantitative bacterial culture techniques. Additional culturing for coagulase-positive Staphylococcus and coliforms was performed using selective agar.ResultsWhile the vast majority of study participants (n = 461, 92%) believed that hand washing was important for infection prevention, there was a large amount of variation in reported personal hygiene practices. More women than men reported consistent hand washing before preparing food (p = .002) and after using the toilet (p = .001). Environmental hygiene showed similar variability although 73.3% (n = 367) of subjects reported dormitory cleaning at least once per month. Contamination of certain surfaces was common, with at least one third of all bookshelves, desks, refrigerator handles, toilet handles, and bathroom door handles positive for >10 CFU of bacteria per 4 cm2 area. Coagulase-positive Staphylococcus was detected in three participants' rooms (5%) and coliforms were present in six students' rooms (10%). Surface contamination with any bacteria did not vary by frequency of cleaning or frequency of illness (p>.05).ConclusionsOur results suggest that surface contamination, while prevalent, is unrelated to reported hygiene or health in the university setting. Further research into environmental reservoirs of infectious diseases may delineate whether surface decontamination is an effective target of hygiene interventions in this population.

The STOP (Staff Taking Ownership for Prevention) FLU Initiative: Improving Influenza Vaccination Rates Among Staff in a Long-Term Care Facility

handle, and bathroom stall/door handle. Bacterial contaminationwas assessed using standard quantitative bacterial culture techniques. Results: Four hundred and fourteen students (196men, 217women, 1 transgender), 17-23 years old, completed the survey. Less than half of students were aware that hand washing reduces transmission of colds, flu, and gastroenteritis, and 39.8% believed that hand washing is unimportant to prevent disease (Table 1). More women than men reported handwashing always or most of the time for all indications surveyed and reported that handwashing can prevent colds, flu, and gastroenteritis. More underclassmen than upperclassmen reported hand washing prior to preparing food and eating, but no significant differences were noted between science and humanities majors. Most students (56%) felt that their personal hygienewas the same as others', and only 5% felt theirs was worse. Microbiologic data were collected from the dorms of 40 participants (18men and 22women). Bacterial growth ranged from 0-35 colony forming units (CFUs) with little variation by type of dorm, frequency of cleaning, or frequency of illnesses (Table 2). Staphylococcus aureus was detected in three participants' rooms (on a dish, bookshelf, and remote control), and coliforms were present in six students' rooms (on a remote control, keyboard, desk, light switch, refrigerator handle, bathroom door handle, and three bookshelves). Two of these students reported cleaning daily, three weekly, two monthly, and one never. Conclusions: Despite reporting frequent cleaning, coliforms were found in some students' rooms, on surfaces used for cooking and eating, and on surfaces shared bymultiple students, suggesting that opportunities for transmission may be possible, even when hygienic measures are taken.

Meta-analysis of subclavian insertion and nontunneled central venous catheter-associated infection risk reduction in critically ill adults*

Catheter-associated infections are common, costly, and potentially lethal. The impact of catheter insertion site on infection risk remains controversial. We aimed to establish whether nontunneled central venous catheters inserted in the subclavian vein are associated with lower risk of catheter-associated infection compared to femoral or internal jugular vein insertion. We searched MEDLINE (2000-2011), EMBASE (2000-2011), and Cochrane Library plus meta-analyses, gray literature, reference lists, and articles recommended by experts. We selected peer-reviewed, randomized, or prospective cohort studies with systematic catheter culture using semiquantitative or quantitative catheter culture techniques and data available for catheter-associated infection by insertion site. Two reviewers independently performed study selection, assessed study quality, and extraction. Discrepancies were resolved by discussion and consensus. Outcomes were mean catheter duration and catheter-associated infection expressed as incidence density per 1000 catheter days. Ten studies (3250 subclavian, 3053 internal jugular, and 1554 femoral vein) met the inclusion criteria, one of which was randomized (136 subclavian vein and 134 femoral vein). Subclavian vein catheters were left in place significantly longer than alternative catheters (mean difference: 2 days, 95% confidence interval [0.9-3.1], I=92%, p<.001). The subclavian vein site was associated with fewer catheter-associated infections (1.3 compared to 2.7 per 1000 catheter days for alternative sites, incidence density ratio 0.50; 95% confidence interval [0.33- 0.74], I=0%, p<.001). The same was true when comparisons were stratified by alternative sites (subclavian vein vs. internal jugular vein, incidence density ratio 0.46; 95% confidence interval [0.30-0.70], I=0%; subclavian vein vs. femoral vein, incidence density ratio 0.27; 95% confidence interval [0.15-0.48], I=31%). Shortcomings in study design, including channeling, confounding bias, and study heterogeneity, may limit the interpretation of our preliminary study results. Our analysis suggests that the subclavian site may be associated with a lower risk of catheter-associated infection. However, a large, randomized, controlled trial comparing each catheter site complication is warranted before the subclavian site can be unequivocally recommended as a first choice for central venous catheter insertion.

Controversies in Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is the most frequent intensive care unit (ICU)-acquired infection among patients receiving mechanical ventilation. Consensus, however, on the most appropriate diagnostic strategy for patients clinically suspected of having developed VAP has yet to be reached. Concern about the inaccuracy of clinical approaches to VAP recognition and potential for excessive use of antibiotics in the ICU had led numerous investigators to postulate that quantitative cultures of specimens obtained with bronchoscopic or nonbronchoscopic techniques, such as bronchoalveolar lavage (BAL) and/or protected specimen brush (PSB), could improve identification of patients with true VAP and facilitate decisions whether to treat. Other than decision-analysis studies and one retrospective study, only five trials assessed the impact of such a quantitative bacteriological strategy on antibiotic use and outcome of patients suspected of VAP using a randomized scheme. In one study, the invasive management strategy was significantly associated with earlier attenuation of organ dysfunction and less antibiotic exposure, but the four other trials could not replicate these positive findings, including a large Canadian study that enrolled 740 patients. Because antibiotics were continued in most patients with negative BAL cultures in contradiction with the bacteriological algorithm, additional studies will be needed before concluding that a strategy based on the systematic collection of distal pulmonary secretions before introduction of new antibiotics and quantitative culture techniques is useless and cannot prevent the overuse of antimicrobial agents in the ICU.

The value of Gram staining of catheter segments for rapid detection of peripheral venous catheter infections

Catheter-related bloodstream infections are common in hospitalized patients. Peripheral venous catheters (PVCs) are the most frequently used vascular access devices with usually low reported infection rates. We conducted a study to find the rate of PVC-related infections using semiquantitative (roll plate) and quantitative catheter culture techniques. We found significant growth in 9.5% of the PVCs by quantitative culture, which was predictive of a BSI in 43% of cases, which seems to be the major limitation of the method. We conclude that Gram stain is a fast and reliable diagnostic tool for rapid detection of PVC infection.

Periodontal pathogens: A quantitative comparison of anaerobic culture and real-time PCR

Periodontitis is a multi-factorial chronic inflammatory and destructive disease of the tooth-supporting tissues. Quantitative anaerobic culture techniques have been used for microbial diagnosis of the different forms of the disease. The aim of this study was to compare real-time PCR with quantitative anaerobic culture for detection and quantification of 5 prominent periodontal pathogens. Real-time PCR assays with the 16s rRNA genes of Actinobacillus actinomycetemcomitans, Prevotella intermedia, Tannerella forsythensis, Peptostreptococcus micros and Fusobacterium spp. were developed. The PCR was validated on pure cultures of various bacterial strains. Subsequently, subgingival plaque samples from 259 adult patients with periodontitis were analyzed with quantitative anaerobic culture and real-time PCR. A standard curve for DNA quantification was created for each primer-probe set based on colony-forming units equivalents. All bacterial species were correctly identified. The lower limits of detection by PCR varied between 1–50 colony-forming units equivalents depending on the species. No cross-reactivities with heterologous DNA of other bacterial species were observed. Real-time PCR results showed a high degree of agreement with anaerobic culture results. Real-time PCR is a reliable alternative for diagnostic quantitative anaerobic culture of subgingival plaque samples.

Nosocomial pneumonia.

Nosocomial pneumonia (NP) is defined as pneumonia that develops within 48 hours or more of hospital admission and which was not developing at the time of admission. Nosocomial pneumonia, also known as hospital-acquired pneumonia (HAP), is the second most common hospital infection, while ventilator-associated pneumonia represents the most common intensive care unit (ICU) infection. Nosocomial pneumonia significantly contributes to morbidity, mortality, and escalating healthcare costs because of increases in antibiotic prescription and administration, length of ICU stay, and length of hospital stay. Aspiration and colonization of the upper respiratory tract seem to be the major pathogenetic mechanisms for the development of NP, either in intubated or spontaneously breathing patients. The microbiology of NP depends on the timing of onset. In early-onset NP, the responsible pathogens are generally endogenous community-acquired pathogens. In late-onset NP, the responsible microbes include potentially multi-drug-resistant nosocomial organisms residing in oropharyngeal or gastric contents. Important risk factors for development of NP include coma, intubation, prolonged mechanical ventilation, repeated intubations, supine positioning, and long-term antibiotic use. The most significant preventive measures include routine hand washing and avoidance of (1) the supine position, (2) inappropriate antibiotics, and (3) overuse of H2-antagonists for stress ulcer prophylaxis. Accurate diagnosis of NP is difficult and controversial, warranting consideration for the application of invasive quantitative culture techniques over tracheal aspirates. Empiric antibiotic treatment should be prompt, starting on clinical suspicion, and based on local ICU pathogen epidemiology and antibiotic resistance patterns and on a deescalating antibiotic strategy. Innovative antibiotic strategies, such as antibiotic rotation, to help prevent the emergence of multi-drug-resistant pathogens and improve survival should be considered.