Effect of the initial specimen diversion technique on blood culture contamination rates.

The initial specimen diversion technique (ISDT) was first described by Patton and Schmitt (J. Clin. Microbiol. 48:4501-4503, 2010, doi:10.1128/JCM.00910-10). This study looked at the effect of implementation of the ISDT on blood culture contamination rates at our center. We found a reduction of 30.34% in potential blood culture contaminants.

Clinical presentation of patients with aseptic meningitis, factors influencing treatment and hospitalization, and consequences of enterovirus cerebrospinal fluid polymerase chain reaction testing.

INTRODUCTION: Clinical and laboratory features of enteroviral meningitis may overlap with those of bacterial meningitis. In the present retrospective review, we compared features of enteroviral (EV)-positive and -negative patients to determine those that were most influential in admission, discharge and in anti-infective administration. METHODS: Data were analyzed from the records of 117 pediatric and adult patients who underwent cerebrospinal fluid (CSF) EV testing over a three-year period. RESULTS: The oldest EV-positive patient was 34 years of age and the occurrence of the disease was highly seasonal. EV-positive patients were more likely to report fever, rash, photophobia, short onset and exposure to an ill contact. A positive polymerase chain reaction (PCR) result was associated with relatively short hospitalization. Seizure and neurological symptoms were more strongly associated with a negative PCR test result. CSF characteristics did not discriminate well between patients with positive and negative PCR tests. Patients with imperfect Glasgow Coma Scores or with neurological symptoms were more likely to be admitted to hospital than those without. Fever and recent onset predicted determinants of anti-infective use. CONCLUSION: The present retrospective study confirms previous reports regarding seasonality and the young age of positive patients. Factors that indicate nonenteroviral etiology were appropriately also those that influenced hospitalization. Patients with EV meningitis were likely to be treated with empirical anti-infectives, and a substantial proportion continued to take antibiotics for more than 24 h after receiving the positive EV PCR test result. INTRODUCTION: Clinical and laboratory features of enteroviral meningitis may overlap with those of bacterial meningitis. In the present retrospective review, we compared features of enteroviral (EV)-positive and -negative patients to determine those that were most influential in admission, discharge and in anti-infective administration. METHODS: Data were analyzed from the records of 117 pediatric and adult patients who underwent cerebrospinal fluid (CSF) EV testing over a three-year period. RESULTS: The oldest EV-positive patient was 34 years of age and the occurrence of the disease was highly seasonal. EV-positive patients were more likely to report fever, rash, photophobia, short onset and exposure to an ill contact. A positive polymerase chain reaction (PCR) result was associated with relatively short hospitalization. Seizure and neurological symptoms were more strongly associated with a negative PCR test result. CSF characteristics did not discriminate well between patients with positive and negative PCR tests. Patients with imperfect Glasgow Coma Scores or with neurological symptoms were more likely to be admitted to hospital than those without. Fever and recent onset predicted determinants of anti-infective use. CONCLUSION: The present retrospective study confirms previous reports regarding seasonality and the young age of positive patients. Factors that indicate nonenteroviral etiology were appropriately also those that influenced hospitalization. Patients with EV meningitis were likely to be treated with empirical anti-infectives, and a substantial proportion continued to take antibiotics for more than 24 h after receiving the positive EV PCR test result.

HISTORIQUE: Les caractéristiques cliniques et de laboratoire de la méningite entérovirale peuvent chevaucher celles de la méningite bactérienne. Dans la présente analyse rétrospective, les chercheurs ont comparé les caractéristiques des patients positifs et négatifs à l'entérovirus (EV) pour déterminer celles qui avaient le plus d'influence sur l'admission, le congé et l'administration d'anti-infectieux. MÉTHODOLOGIE: Les chercheurs ont analysé les données tirées des dossiers de 117 patients pédiatriques et adultes qui avaient subi un test du liquide céphalorachidien (LCR) positif à l'EV sur une période de trois ans. RÉSULTATS: La patiente positive à l'EV la plus âgée avait 34 ans. L'occurrence de la maladie était hautement saisonnière. Les patients positifs à l'EV étaient plus susceptibles de déclarer de la fièvre, des éruptions, de la photophobie, une apparition rapide et une exposition à un contact malade. Les résultats positifs de la réaction en chaîne de la polymérase (PCR) s'associaient à une hospitalisation relativement courte. Les conclusions et les symptômes neurologiques étaient liés plus fortement aux résultats d'un test de PCR négatif. Les caractéristiques du LCR distinguaient mal les patients ayant des tests de PCR positifs de ceux ayant des résultats négatifs. Les patients dont l'indice de coma de Glasgow était imparfait ou qui avaient des symptômes neurologiques étaient plus susceptibles d'être hospitalisés que les autres. La fièvre et une apparition récente étaient prédictives de l'utilisation d'anti-infectieux. CONCLUSION: La présente étude rétrospective confirme les rapports antérieurs au sujet du caractère saisonnier et du jeune âge des patients positifs. Comme de juste, les facteurs indicateurs d'une étiologie non entérovirale étaient aussi ceux qui influaient sur l'hospitalisation. Les patients ayant une méningite EV étaient susceptibles d'être traités à l'aide d'anti-infectieux empiriques, et une forte proportion d'entre eux continuaient de prendre des antibiotiques pendant plus de 24 heures après avoir reçu le résultat du test PCR positif à EV.

A vignette-based survey to assess clinical decision making regarding antibiotic use and hospitalization of patients with probable aseptic meningitis.

BACKGROUND: The many etiologies of meningitis influence disease severity - most viral causes are self-limiting, while bacterial etiologies require antibiotics and hospitalization. Aided by laboratory findings, the physician judges whether to admit and empirically treat the patient (presuming a bacterial cause), or to treat supportively as if it were viral. OBJECTIVE: To determine factors that lead infectious disease specialists to admit and treat in cases of suspected meningitis. METHODS: A clinical vignette describing a typical case of viral meningitis in the emergency department was presented to clinicians. They were asked to indicate on a Likert scale the likelihood of administering empirical antibiotics and admitting the patient from the vignette and for eight subsequent scenarios (with varied case features). The process was repeated in the context of an inpatient following initial observation and/or treatment. RESULTS: Participants were unlikely to admit or to administer antibiotics in the baseline scenario, but a low Glasgow Coma Score or a high cerebrospinal fluid (CSF) white blood cell count with a high neutrophil percentage led to empirical treatment and admission. These factors were less influential after a negative bacterial CSF culture. These same clinical variables led to maintaining treatment and hospitalization of the inpatient. CONCLUSIONS: Most participants chose not to admit or treat the patient in the baseline vignette. Confusion and CSF white blood cell count (and neutrophil predominance) were the main influences in determining treatment and hospitalization. A large range of response scores was likely due to differing regional practices or to different levels of experience.

HISTORIQUE: Les nombreuses étiologies de la méningite influent sur la gravité de la maladie. La plupart des causes virales sont spontanément résolutives, tandis que les étiologies bactériennes exigent la prise d'antibiotiques et une hospitalisation. À l'aide des résultats de laboratoire, le médecin évalue s'il doit hospitaliser le patient et le traiter de manière empirique (présumant une cause bactérienne) ou lui donner un traitement de soutien comme si la maladie était d'origine virale. OBJECTIF: Déterminer les facteurs qui incitent les infectiologues à hospitaliser et traiter des cas de méningite présumée. MÉTHODOLOGIE: Les cliniciens se sont fait présenter une saynète clinique décrivant un cas classique de méningite virale observé au département d'urgence. Les chercheurs ont invité les cliniciens à indiquer sur une échelle de Likert la probabilité d'administrer des antibiotiques empiriques et d'hospitaliser le patient d'après la saynète et huit autres scénarios (aux diverses caractéristiques). Les cliniciens ont repris le processus chez un patient hospitalisé après une observation initiale ou un traitement. RÉSULTATS: Les participants étaient peu susceptibles d'hospitaliser ou d'administrer des antibiotiques dans le scénario de base, mais un faible indice de coma de Glasgow ou une numération élevée des globules blancs dans le liquide céphalorachidien (LCR) associée à un fort pourcentage de neutrophiles donnait lieu à un traitement et une hospitalisation empiriques. Ces facteurs avaient moins d'influence après une culture bactérienne négative dans le LCR. Ces mêmes variables cliniques suscitaient le maintien du traitement et le prolongement de l'hospitalisation du patient hospitalisé. CONCLUSIONS: La plupart de participants choisissaient de ne pas hospitaliser ou traiter le patient observé dans la saynète de base. La confusion et la numération des globules blancs dans le LCR (et la prédominance en neutrophiles) étaient les principales influences pour déterminer le traitement et l'hospitalisation. La vaste plage d'indices de réponse était probablement attribuable à des pratiques régionales divergentes ou à divers niveaux d'expérience.

Clinical effectiveness of rapid tests for methicillin resistant Staphylococcus aureus (MRSA) in hospitalized patients: a systematic review.

BACKGROUND: Methicillin resistant Staphylococcus aureus (MRSA) are often resistant to multiple classes of antibiotics. The research objectives of this systematic review were to evaluate the clinical effectiveness of polymerase chain reaction (PCR) versus chromogenic agar for MRSA screening, and PCR versus no screening for several clinical outcomes, including MRSA colonization and infection rates. METHODS: An electronic literature search was conducted on studies evaluating polymerase chain reaction techniques and methicillin (also spelled meticillin) resistant Staphylococcus aureus that were published from 1993 onwards using Medline, Medline In-Process & Other Non-Indexed Citations, BIOSIS Previews, and EMBASE. Due to the presence of heterogeneity in the selected studies, the clinical findings of individual studies were described. RESULTS: Nine studies that compared screening for MRSA using PCR versus screening using chromogenic agar in a hospital setting, and two studies that compared screening using PCR with no or targeted screening were identified. Some studies found lower MRSA colonization and acquisition, infection, and transmission rates in screening with PCR versus screening with chromogenic agar, and the turnaround time for screening test results was lower for PCR. One study reported a lower number of unnecessary isolation days with screening using PCR versus screening with chromogenic agar, but the proportion of patients isolated was similar between both groups. The turnaround time for test results and number of isolation days were lower for PCR versus chromogenic agar for MRSA screening. CONCLUSIONS: The use of PCR for MRSA screening demonstrated a lower turnaround time and number of isolation days compared with chromogenic agar. Given the mixed quality and number of studies (11 studies), gaps remain in the published literature and the evidence remains insufficient. In addition to screening, factors such as the number of contacts between healthcare workers and patients, number of patients attended by one healthcare worker per day, probability of colonization among healthcare workers, and MRSA status of hospital shared equipment and hospital environment must be considered to control the transmission of MRSA in a hospital setting.

Switching gears for an influenza pandemic: validation of a duplex reverse transcriptase PCR assay for simultaneous detection and confirmatory identification of pandemic (H1N1) 2009 influenza virus.

Rapid methods for the detection and confirmatory identification of pandemic influenza A virus (also known as pandemic [H1N1] 2009) are of utmost importance. In this study, a conventional reverse transcriptase PCR (RT-PCR) assay for the detection of influenza A virus and the hemagglutinin of swine lineage H1 (swH1) was designed, optimized, and validated. Nucleic acids were extracted from 198 consecutive nasopharyngeal, nasal, or throat swab specimens collected early in the outbreak (127 negative specimens, 66 specimens with pandemic [H1N1] 2009 influenza virus, 3 specimens with seasonal [H1N1] influenza A virus, and 2 specimens with seasonal [H3N2] influenza A virus). The performance characteristics of the duplex RT-PCR assay were assessed and compared to those of various detection methods: a monoplex RT-PCR assay at the National Microbiology Laboratory, a real-time RT-PCR assay using a Centers for Disease Control and Prevention protocol, an in-house multiplex RT-PCR assay (targeting influenza A virus, influenza B virus, and respiratory syncytial virus), and a rapid antigen test (the Binax Now Influenza A & B assay). The sensitivity of the duplex RT-PCR assay for influenza A virus detection was 97.2%, whereas the sensitivities were 74.6%, 71.8%, 47.8%, and 12.7% for the other four assays, respectively. The duplex RT-PCR assay was also able to identify swH1 in 94% of the cases, thereby reducing the number of specimens forwarded to reference laboratories for confirmatory identification. Only a limited number of specimens that contained influenza A virus had amounts of virus that fell below the limit of detection of the assay with the swH1 primers. Overall, the duplex RT-PCR assay is a reliable method for the simultaneous detection and confirmatory identification of pandemic (H1N1) 2009 influenza virus and would be particularly attractive to laboratories without real-time RT-PCR capabilities.

A pilot project for chlamydia screening in adolescent females using self-testing: characteristics of participants and non-participants.

OBJECTIVES: A self-test screening program for genital C. trachomatis infection in female students attending high school in rural Nova Scotia was introduced. The objectives of this pilot study were to determine the extent of uptake, reasons for being/not being screened, and whether students at risk would be more likely to be screened. METHODS: The screening program was carried out between September 2005 and May 2006. Test kits were accessed through the school's health centre without first seeing the school nurse for counselling. Tests were processed non-nominally at the laboratory. A cross-sectional survey was offered to all students in the school to assess factors related to participation or non-participation. Univariate analysis was carried out for young women's sexual activity and risk taking, reasons for being participants or non-participants, risk behaviours, and knowledge about chlamydia. RESULTS: One hundred and sixty-three women (58%) had had vaginal intercourse at least once. Twenty-four of these used the self-test kit. Though 83% of those not using the self-test knew that females with chlamydia are very often asymptomatic, 54% indicated lack of symptoms as a reason for not doing so. Many (49%) gave low probability of infection as a reason for not using the kit, but high-risk sexual activity was frequent in these young DISCUSSION: Uptake of self-testing for C. trachomatis was lower than anticipated. This may be due to lack of counselling meant to encourage testing to overcome a dissonance of knowledge and behaviour. Self-testing should be further explored to better understand its potential to increase chlamydia screening among Canadian adolescents.

Antimicrobial resistance among invasive isolates of Streptococcus pneumoniae collected across Canada.

Between 2002 and 2003, 736 nonduplicate Streptococcus pneumoniae isolated from blood cultures were collected from 7 of 10 Canadian provinces (10 tertiary care centers). Microdilution broth susceptibility testing was performed using the method prescribed by the Clinical Laboratory Standards Institute. Of the isolates, 16.85% were nonsusceptible to penicillin and 5.4% were highly resistant. Of the S.pneumoniae, 14.1% had reduced susceptibility to erythromycin and 47% had been accounted for by the M phenotype. No isolates were recovered that were resistant to telithromycin. Only 6 isolates were resistant to levofloxacin and gatifloxacin. Of these, 5 strains had intermediate susceptibility to moxifloxacin and 1 was considered susceptible. The rates observed in this study are in keeping with previous surveillance studies among noninvasive isolates.

Cephalosporin resistance in Klebsiella pneumoniae from Nova Scotia, Canada.

From 2116 Klebsiella pneumoniae strains isolated between January 2001 and December 2002 in Nova Scotia, Canada, 25 (1.18%) showed a reduced susceptibility to cefoxitin or extended-spectrum cephalosporins. Narrow-spectrum beta-lactamase genes (bla(SHV-11), bla(SHV-1), bla(SHV-26), bla(SHV-32), bla(SHV-36), and bla(SHV-40)) were the most prevalent. Four new variants were identified (bla(LEN-17), bla(OKP-B-13), bla(OKP-B-14), and bla(OKP-A-11)), representing the 1st description of bla(OKP) in the Americas. Among the extended-spectrum beta-lactamase (ESBL) genes, bla(SHV-2), bla(SHV2a), bla(SHV-12), and bla(CTX-M-15) were detected (ESBL prevalence of 0.14%). Nineteen strains were resistant to cefoxitin (MIC, 32 to >256 microg/mL). Nevertheless, an AmpC-like activity was detected in only 1 strain, which expressed CMY-2. The combined effects of narrow-spectrum beta-lactamase production and decreased or nonexpression of OmpK35/36 porins did not account for the cefoxitin resistance observed in some of these strains.

An evaluation of extended incubation time with blind subculture of blood cultures in patients with suspected endocarditis.

BACKGROUND: In a small proportion of patients, bacterial endocarditis is due to organisms that grow slowly and may not be recovered in conventional blood cultures incubated for five days. This has led to recommendations for prolonged incubation and routine subculture of negative cultures. OBJECTIVE: The above-mentioned approach is evaluated. METHOD: The microbiology of all blood cultures subjected to prolonged incubation and the charts of individuals who had organisms recovered after five days were evaluated to determine their clinical significance. RESULTS: In all, 507 blood cultures were handled using an extended incubation and blind subculture protocol. Fifty-three blood cultures in 27 patients were positive. Blood cultures were positive after five days in only five cases; patient outcomes were not affected by the results in any of these cases, although several fastidious organisms (ie, Haemophilus paraphrophilus and Haemophilus parainfluenzae) were recovered in the first five days of incubation. CONCLUSION: Prolonged incubation and blood subcultures in patients with suspected endocarditis or infections due to fastidious organisms do not represent a wise use of increasingly scarce resources.

A comparison between the Strep A Rapid Test Device and conventional culture for the diagnosis of streptococcal pharyngitis.

BACKGROUND: Rapid antigen detection tests are frequently used to diagnose pharyngitis due to Streptococcus pyogenes. Because a large number of kits are available commercially, performance characteristics may vary considerably. The present study evaluated one such kit currently in use in Canadian laboratories for which published evaluations are not available. OBJECTIVE: To evaluate the performance characteristics of the Strep A Rapid Test Device (SARTD) (Nova Century Scientific Inc, Canada). METHODS: Pharyngeal swabs from 818 patients with suspected streptococcal pharyngitis were tested. Swabs were initially inoculated onto the surface of a blood agar plate and then used to perform the rapid antigen test. The test was performed in accordance with the product monograph. Beta-hemolytic colonies were identified as S pyogenes using conventional means. RESULTS: Four hundred ninety specimens were obtained from children and 328 from adults. S pyogenes was recovered from 171 (21%) patients. The SARTD detected S pyogenes antigens in 123 of 171 specimens from which S pyogenes was isolated on culture; the screen was negative in 610 of 647 specimens from which cultures were negative. The positive and negative predictive values of the SARTD were 76.9% and 92.7%, respectively. CONCLUSIONS: The SARTD was much less sensitive (72%) than was suggested in the product monograph (90%). Laboratories should vigorously evaluate such products in-house, optimize specimen collection and transport, and choose more sensitive kits for use.

The impact of switching to polymerase chain reaction for the diagnosis of Chlamydia trachomatis infections in women.

BACKGROUND: We noted a marked increase in Chlamydia trachomatis (CT) infections in the Capital Health Region of NS coincident with substitution of a PCR for an enzyme immunoassay (EIA). We reviewed our experience to determine the cost of switching and the impact on the number of new infections diagnosed. METHODS: Information on the number of EIA and PCR tests performed on women was retrieved from an abstracted laboratory information database. We examined records of testing performed between April 1998 and December 2001. Prior to June 2001, all genital swabs were tested using the MicroTrak, II Chlamydia EIA and confirmed by direct fluorescence examination. After July 2001, genital swabs were tested using the COBAS AMPLICOR C. trachomatis test. RESULTS: During the study period, 62,288 EIA tests were performed on specimens submitted; 2,061 (3.33%) were positive. In the six months when testing was performed by the PCR method, 9,559 PCR tests were performed, 463 (4.84%) were positive; 46% increase. In the three years before PCR testing was implemented, an average of 1,626 specimens were submitted monthly. An average of 54 tests were positive (3.3%). The cost for each positive detected by PCR was 208 dollars Cdn and 226 dollars by EIA. CONCLUSIONS: The switch to PCR for the diagnosis of CT produced a marked increase in the number of chlamydia infections diagnosed. The recent increase in the number of reported CT cases in Canada may be due in large part to more sensitive tests. Surprisingly, the cost of each positive test by PCR was 18 dollars Cdn less than that of the EIA.

Clinical utility of a Legionella pneumophila urinary antigen test in a large university teaching hospital.

OBJECTIVE: To determine the clinical utility of diagnosing Legionella pneumonia by urinary antigen testing (LPUAT) in a low prevalence centre. DESIGN: The results of LPUATs were abstracted and analyzed from the authors' laboratory information system. Medical records were reviewed in detail for all positive tests and a random sample of 50 negative tests. SETTING: The Queen Elizabeth II Health Sciences Centre, a large university hospital complex. POPULATION STUDIED: Patients who were admitted from the emergency room with pneumonia or who had developed pneumonia in hospital and who had a LPUAT performed between April 1998 and October 2000. MAIN RESULTS: One thousand one hundred fifty-four tests were performed on 1007 patients. Seven patients had nine positive LPUATs. Three of these patients had confirmed Legionella pneumophila pneumonia. Three others had probable or possible L pneumophila pneumonia. There was one probable false positive. Six of the seven patients were already on empirical anti-L pneumophila therapy. Of the 50 negative tests reviewed in detail, 31 patients were on one of the antibiotics of choice for L pneumophila at the time the test was ordered; in 21 (68%) of these patients the negative result did not lead to a change in therapy. CONCLUSIONS: The cost to diagnose each case of Legionella pneumonia by LPUAT was approximately $5,770 and most patients were already on appropriate antibiotics. In patients with negative tests, antibiotics were often not changed in response to the test result. Rigorous screening of patients is required to increase pretest probability for LPUAT to be justified.

Predominance of herpes simplex virus type 1 from patients with genital herpes in Nova Scotia.

The epidemiology of genital herpes is changing with evidence to suggest an increasing incidence of herpes simplex virus type 1 (HSV-1) infections. The results of 6529 HSV genital cultures taken between April 1998 and December 2001 were reviewed. overall, HSV-1 was recovered more often than HSV-2; 1213 versus 1045. This trend was particularly striking in young women 30 years of age or less, in whom 70.8% of isolates were HSV-1. In men of the same age range, 45% of isolates were HSV-1. The proportion of women with HSV-1 declined from 73.7% in those younger than 31 years of age to 4.5% in those older than 60 years of age.These observations have important implications. The decline in the relative proportion of HSV-1 isolates from young adults may be the result of changing sexual practices, changing susceptibility or increased exposure to HSV-1 during vaginal intercourse. In this setting HSV-2 vaccines may be less likely to produce the desired reduction in the overall prevalence of genital herpes infections.

Recovery of cephalosporin-resistant Escherichia coli and Salmonella from pork, beef and chicken marketed in Nova Scotia.

BACKGROUND: Antimicrobial use in farm animals is a potentially important contributor to the emergence of antimicrobial resistance. Resistant Salmonella may lead to serious human infections and resistant Escherichia coli may transfer plasmid-encoded resistance genes to other pathogens. OBJECTIVE: To determine the prevalence of E coli and Salmonella species resistant to the third generation of cephalosporins in retail meat products in Halifax, Nova Scotia in 2002. METHODS: Ground beef, ground pork and chicken wings were tested for E coli and Salmonella. E coli were selected on ceftriaxonecontaining media. Beta-lactamases were characterised by isoelectric focusing, polymerase chain reaction and sequencing. Pulsed field gel electrophoresis was performed to determine the relationship of strains. The transferability of plasmids and location of resistance genes was also determined. RESULTS: Forty-three of 75 packages of chicken wings contained ceftriaxone-resistant E coli; 42 of these contained beta-lactamases with isoelectric points at approximately 8.7. Six of seven CMY primer amplicons that were sequenced contained plasmid-mediated Citrobacter freundii-derived blaCMY-2; the other contained a CMY-2- like beta-lactamase. Pulsed field gel electrophoresis patterns demonstrated that strains were not clonal in nature. Four chicken samples contained Salmonella, one of which contained bla CMY-2-mediated resistance and an E coli bearing the same gene, but on different plasmids. Four of 100 beef samples contained blaCMY-2-bearing E coli; none contained Salmonella. Two of 75 pork samples contained ceftriaxone resistant E coli, one of which encoded for CMY-2. One susceptible Salmonella strain was recovered from pork. CONCLUSIONS: Chicken from retail outlets located in Halifax, Nova Scotia, commonly contained blaCMY-2-bearing E coli. The relationship antibiotics used in food-producing animals and its effect on resistance of commensals and pathogens needs to be determined.

Analysis of 3789 in- and outpatient Escherichia coli isolates from across Canada--results of the CANWARD 2007-2009 study.

Escherichia coli was the most commonly isolated pathogen in the Canadian Ward Surveillance Study 2007-2009 (3789 isolates). Susceptibility to cefazolin (34.1%), trimethoprim-sulfamethoxazole (73.8%), ciprofloxacin (78.4%), and levofloxacin (78.8%) was lowest. Susceptibility was above 90% for meropenem (100%), tigecycline (99.9%), piperacillin-tazobactam (97.6%), nitrofurantoin (96.9%), ceftazidime (95.6%), amoxicillin-clavulanate (94.9%), ceftriaxone (94.1%), cefoxitin (92.3%), and gentamicin (90.8%). Over the study period, there was a significant reduction in susceptibility to amoxicillin-clavulanate and trimethoprim-sulfamethoxazole for urinary tract isolates. Inpatient status was associated with greater resistance to nearly all antimicrobials including greater multidrug resistance (MDR). Increasing age was associated with resistance to fluoroquinolones, ceftriaxone, piperacillin-tazobactam, and MDR. Female gender was associated with susceptibility to fluoroquinolones and nitrofurantoin. In conclusion, greater antimicrobial resistance and MDR in E. coli were observed in inpatients, males, and with increasing age. The deterioration of susceptibility to trimethoprim-sulfamethoxazole continues with the greatest reduction in urinary isolates. Significant regional differences in resistance rates were apparent.

Risk of coinfection with Chlamydia trachomatis and Neisseria gonorrhoeae in Nova Scotia.

BACKGROUND: The frequency of Chlamydia trachomatis and Neisseria gonorrhoeae coinfection can vary depending on their individual incidence and prevalence rates. OBJECTIVE: To determine the frequency of C trachomatis and N gonorrhoeae coinfections by evaluating the results of testing in 2007 and 2008 to better inform testing and treatment decisions. METHODS: Specimens from the same patient submitted on the same day served as the basis for the present study. The age, sex and the source of the specimen were also linked to the accession number. Infection and coinfection rates were analyzed in both males and females. RESULTS: Concurrent testing was performed on 41,567 female specimens and 1827 male specimens, of which, 1495 female samples (3.6%) tested positive for C trachomatis infection and 88 (0.2%) tested positive for N gonorrhoeae infections. Only 31 females were coinfected; however, for those between 11 and 25 years of age, 25 of 61 females (40.1%) with N gonorrhoeae infection also tested positive for C trachomatis infection; conversely, 25 of 1248 females (2.0%) with C trachomatis infection also tested positive for N gonorrhoeae infection. For males, 213 (11.7%) tested positive for C trachomatis infection, and 59 (3.2%) tested positive for N gonorrhoeae infection. In 30 males with N gonorrhoeae between 11 and 25 years of age, and 149 males with C trachomatis, eight coinfections were observed (26.7% and 5.3%, respectively). Of those older than 25 years of age, only five of 905 men and six of 19,465 women were coinfected. None of the 10,935 women who were 30 years of age or older had coinfections. CONCLUSION: The N gonorrhoeae coinfection rate in males with C trachomatis may justify empirical antimicrobials; however, in females, the proportion of coinfected may not justify empirical treatment for N gonorrhoeae infection when the C trachomatis test is positive and N gonorrhoeae testing has not been performed.

The value of multiple surveillance cultures for methicillin-resistant Staphylococcus aureus.

BACKGROUND: We evaluated our experience in a low prevalence setting to determine the extent to which multiple swabs increased detection rates and the incremental costs of doing so. METHODS: Nasal and groin swabs submitted in pairs were cultured onto a single plate (Oxoid MRSA Denim Blue Agar; Oxoid Company, Napean, ON, Canada). We determined whether MRSA was detected when swabs submitted in the preceding 3 days were negative. We explored the costs associated with screening and of each additional colonized patient detected. RESULTS: In all, 60,049 paired nose and perineal swabs were submitted from 21,599 patients. In all, there were 12,750 duplicate, 1437 triplicate, and 112 instances when >4 swabs were processed within 3 days. The first culture was positive in 106 of 12,750 (0.83%%), 42 of 12,750 (0.33%) on the second when the first was negative, 7 of 1642 (0.43%) on the third or subsequent swab pair when the preceding 2 were negative. CONCLUSION: Overall, the sensitivity of the first of multiple cultures of a set was 74.3%. Had the 14,392 multiple samples not been submitted, 49 colonized patients would not have been identified. Additional laboratory costs associated with multiple samples equaled $2088 per patient identified.

A study of the prevalence of cytotoxic and non-cytotoxic Klebsiella oxytoca fecal colonization in two patient populations.

BACKGROUND: Klebsiella oxytoca is a cause of antibiotic-associated hemorrhagic colitis. Few reports of the occurrence of K oxytoca within stool exist and there is no gold standard method for its isolation. METHODS: MacConkey agar was modified to culture K oxytoca. Ampicillin was added and adonitol was substituted for lactose. Rectal swabs from 200 patients being screened for vancomycin-resistant enterococci (VRE) and stool specimens from 429 patients who tested negative for Clostridium difficile cytotoxin were cultured. K oxytoca isolates were evaluated for cytotoxicity to HEp-2 cells. Available charts of K oxytoca-positive patients and a convenience sample of 93 K oxytoca-negative patients who underwent testing for C difficile cytotoxicity were reviewed retrospectively for documentation of bloody stool. RESULTS: K oxytoca was isolated from 14 of 200 patients (7.0%) being screened for VRE; only one of the 14 isolates (7.1%) was cytotoxic. The organism was isolated from 42 of 429 patients (9.8%) tested for C difficile cytotoxicity; 10 isolates (23.8%) were cytotoxic. Differences in isolation and cytotoxicity rates between groups were not statistically significant. Two of 13 (15.4%) K oxytoca-positive patients screened for VRE, three of 27 (11.1%) K oxytoca-positive patients tested for C difficile cytotoxicity, and 11 of 93 (11.8%) patients from the convenience sample had documented bloody stool. CONCLUSIONS: A medium that greatly facilitates isolation of K oxytoca was developed. Occurrence of K oxytoca colonization was similar in the two patient populations studied and isolation of cytotoxic K oxytoca was not usually associated with hematochezia. Current understanding of the occurrence and causality of antibiotic-associated hemorrhagic colitis is insufficient for clinical laboratories to begin culturing K oxytoca and testing for cytotoxicity.