On measurements and their quality. Paper 4: Verbal anchors and the number of response options in rating scales

This is the last in a short series of papers on measurement theory and practice with particular relevance to intervention research in nursing, midwifery, and healthcare. Understanding how it is that people respond to the questions posed by researchers is fundamental to progress in the social and health sciences. For decades methodologists in psychology, marketing, education, and survey research have studied this issue. In this paper I review this diverse empirical literature to synthesize basic principles for creating rating scales which can reduce measurement error and increase the quality of resulting data. After introducing a theoretical framework known as the cognitive aspects of survey methods (CASM), I review the fundamentals of psychological scaling theory and discuss how it has been used to study the meanings of verbal response options and provide an illustration of how the quality of measurements may be influenced by our choice of the verbal phrases we present as response options. Next, I review the research on the optimal number of response options to use in various measurement situations and how verbal and numeric anchors can combine to influence data quality. Finally, I summarize the issues covered and present recommendations for best practice when creating and using rating scales in research.     

On measurements and their quality: Paper 2: Random measurement error and the power of statistical tests

This is the second in a short series of papers on measurement theory and practice with particular relevance to intervention research in nursing, midwifery, and healthcare. This paper begins with an illustration of how random measurement error decreases the power of statistical tests and a review of the roles of sample size and effect size in hypothesis testing. A simple formula is presented and discussed for calculating sample size during the planning stages of intervention studies. Finally, an approach for incorporating reliability estimates into a priori power analyses is introduced and illustrated with a practical example. The approach permits researchers to compare alternative study designs, in terms of their statistical power. An SPSS program is provided to facilitate this approach and to assist researchers in making optimal decisions when choosing among alternative study designs.     

KRAS and PIK3CA but not BRAF genes are frequently mutated in Chinese cholangiocarcinoma patients

Cholangiocarcinoma (CCA) is a rare but lethal malignancy arising from the biliary tract epithelium. It has a poor prognosis largely due to the difficulties of early diagnosis and the lack of effective therapies. It is thus imperative to develop new and effective treatments for CCA, which depends heavily on the mechanistic understanding of the disease. Previous studies have suggested that somatic mutations in KRAS, BRAF, and PIK3CA genes are frequently found in several types of human cancers including colon, breast, and lung carcinomas as well as CCA. Yet, the frequency and the involvement of these oncogenic mutations in CCA in Chinese population have not been investigated. In this study, we evaluated the hotspot mutations of KRAS, BRAF, and PIK3CA genes in 34 Chinese CCA patients. Sequencing analysis revealed 13 (38.2%) and 11 (32.4%) patients bearing KRAS and PIK3CA mutations, in which two (5.9%) of them harbored both KRAS and PIK3CA mutations. Surprisingly, no BRAF mutation was detected in all 34 CCA samples. Our findings indicate that somatic mutations in KRAS and PIK3CA but not BRAF oncogenes are closely associated with the development of CCA in Chinese population and provide new potential targets for future therapeutic treatments of the disease.     

NDRG3 and NDRG4, two novel tumor-related genes

The N-myc downstream-regulated genes, NDRG3 and NDRG4, are suggested to play important roles in biological processes and pathogenesis. Expression of NDRG3 and NDRG4 has been shown to be reduced or absent in numerous cancer cell lines and tumor types, suggesting that they may exert function as a tumor suppressor gene. In this review, we will summarize the current research on NDRG3 and NDRG4, including the molecular structure, cellular and tissue distribution, biological function, and function in cancer. We tried to show their significance in studying disease and their therapeutic potential.     

Predictive genetic risk markers for strong biofilm-forming Staphylococcus aureus: fnbB gene and SCCmec type III

To find predictive genetic risk markers for strong biofilm producers of Staphylococcus aureus, we studied the relatedness of agr and SCCmec types and fnbB and IS256 genes to biofilm-forming ability in 465 clinical isolates. fnbB and SCCmec type III are candidates as genetic risk predictors for the strong biofilm producers.     

Co-colonization of vanA and vanB Enterococcus faecium of clonal complex 17 in a patient with bacteremia due to vanA E. faecium

A 53-year-old Vietnamese man with liver cirrhosis was transferred from a Vietnamese hospital to our tertiary care hospital in Korea in order to undergo a liver transplantation. Bacteremia due to vanA Enterococcus faecium was diagnosed, and stool surveillance cultures for vancomycin-resistant enterococci (VRE) were positive for both vanA and vanB E. faecium. Pulsed-field gel electrophoresis analysis revealed that the 2 vanA VRE isolates from the blood and stool were clonal, but the vanB VRE was unrelated to the vanA VRE. vanA and vanB VRE were ST64 and ST18, single-allele variations of clonal complex 17, respectively. This is the first case report of vanA VRE bacteremia in a Vietnamese patient and demonstrates the reemergence of vanB VRE since a single outbreak occurred 15 years ago in Korea. The reemergence of vanB VRE emphasizes the importance of VRE genotyping to prevent the spread of new VRE strains.     

Acinetobacter pittii and Acinetobacter nosocomialis among clinical isolates of the Acinetobacter calcoaceticus-baumannii complex in Sichuan,China

Among 82 clinical isolates of the Acinetobacter calcoaceticus-baumannii complex recovered in 13 hospitals of Sichuan, China, in 2011, 13 were Acinetobacter pittii and 2 were Acinetobacter nosocomialis. Multilocus sequence typing revealed a novel sequence type (ST) of A. nosocomialis and 7 novel STs of A. pittii. Most isolates were hospital-acquired and colonized in the respiratory tract, while 6 cases with pneumonia due to A. pittii were identified. This study provided a snapshot of the local incidence of A. pittii and A. nosocomialis.     

Clinical significance and antimicrobial susceptibilities of Aerococcus sanguinicola and Aerococcus urinae

A retrospective chart review was performed on 92 patients from whom 118 isolates of Aerococcus sanguinicola (n = 52) or Aerococcus urinae (n = 66) were obtained from urine cultures between October 2007 and June 2008 to assess clinical presentation and antimicrobial susceptibilities. The mean patient age was 82 (range 24–101) years. The majority was female (76% and 87% for A. sanguinicola and A. urinae, respectively) and institutionalized (61% and 60%, respectively). The majority of male patients had underlying prostatic disease (55% and 63%, respectively). Thirty-one of 46 patients with A. sanguinicola and 45 of 57 patients with A. urinae isolated from the urine had a clinical diagnosis of urinary tract infection. One subject had A. sanguinicola isolated from blood cultures. A. sanguinicola and A. urinae had low ceftriaxone, penicillin, and vancomycin MICs. MICs to erythromycin and levofloxacin were ≥0.5 and >4 μg/mL in 41% and 78% of A. sanguinicola and 17% and 23% of A. urinae isolates, respectively. In conclusion, A. sanguinicola and A. urinae are not infrequent causes of urinary tract infection and most A. sanguinicola isolates have elevated MICs to levofloxacin.     

A case of osteitis due to Staphylococcus aureus and Arcanobacterium bernardiae coinfection

Arcanobacterium bernardiae human infections remain rare. Only 2 reports are described in the literature. We report on an immunocompetent patient with a long history of chronic osteitis who developed a polymicrobial infection of the knee. The initial isolation of Staphylococcus aureus confounded the diagnosis of A. bernardiae infection, which underlines the need for extended period of incubation and subcultures of enriched liquid culture media. A. bernardiae is a new bacterium implicated in osteoarticular infections.     

Prevalence and characteristics of aac(6′)-Ib-cr in AmpC-producing Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens: a multicenter study from Korea

We investigated the prevalence of aac(6′)-Ib-cr and its association with other resistance genes in AmpC-producing Enterobacteriaceae without any selection criteria. A total of 479 clinical isolates of Enterobacter cloacae (179), Citrobacter freundii (134), and Serratia marcescens (166) from 12 laboratories between March and July 2005 were examined. We performed polymerase chain reaction for aac(6′)-Ib, bla_OXA-1, ISEcp1, and class 1 integron. The aac(6′)-Ib-cr was further identified by digestion with BstF5I and sequencing. The aac(6′)-Ib was detected in 110 (23%) of 479 isolates, and 15 isolates (3.1%) were cr variants (8 E. cloacae, 5 C. freundii, and 2 S. marcescens). The aac(6′)-Ib-cr was significantly associated with various resistance genes (bla_OXA-1, qnrS, qnrA, bla_CTX-M-3, and bla_CTX-M-14), mobile elements (ISEcp1, ISCR1, and class 1 integron), and quinolone resistance. Eleven of 15 aac(6′)-Ib-cr producers coharbored qnr genes. Although aac(6′)-Ib-cr was uncommon in Korean AmpC producers, its association with various resistance genes and mobile elements would facilitate the dissemination of this variant.     

Rapid identification of Salmonella enterica subsp. arizonae and S. enterica subsp. diarizonae by real-time polymerase chain reaction

Reptiles are popular as pets, leading to an increased risk of human infections due to uncommon Salmonella strains including the Arizona group (subspecies arizonae and diarizonae). We present a real-time Arizona-specific polymerase chain reaction demonstrating 100% specificity and 99.6% sensitivity, offering savings in time and labor over traditional identification methods.     

Molecular epidemiology and antifungal susceptibility of Candida parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis in Taiwan

Candida parapsilosis was recently reclassified into 3 closely related species, C. parapsilosis sensu stricto, Candida orthopsilosis, and Candida metapsilosis. Variation in susceptibility characteristics and prevalence of the 3 genomic species could have therapeutic and epidemiologic implications. The aim of this study is to characterize the genetic and antifungal susceptibility profiles of 97 C. parapsilosis isolates from 71 patients. Among the 71 nonduplicate isolates, 85.9% (61/71) were identified as C. parapsilosis sensu stricto, 5.6% (4/71) as C. metapsilosis, and 8.5% (6/71) as C. orthopsilosis species based on sequences of the internal transcribed spacer (ITS) region. The delineation of these 3 species is concordant with that achieved by pulsed-field gel electrophoresis of BssHII restriction fragments at 75% similarity. Antifungal susceptibility tests showed that most isolates were susceptible to flucytosine, azoles, amphotericin B, and echinocandins, whereas 3 C. metapsilosis isolates from 1 patient showed resistance and susceptible-dose dependence to fluconazole. The C. metapsilosis isolates exhibited significantly higher MIC values to both fluconazole and voriconazole than those of C. parapsilosis sensu stricto and C. orthopsilosis. On the other hand, the C. metapsilosis isolates showed significantly lower MIC values on 24 h to caspofungin than those of C. parapsilosis sensu stricto and C. orthopsilosis. For micafungin, the isolates of C. parapsilosis sensu stricto had significantly higher MIC values on 24 h than those of C. orthopsilosis and C. metapsilosis. Compared to Candida albicans, mutations from proline to alanine were identified on the hot spot 1 of Fks1 in all these C. parapsilosis sensu lato isolates regardless of their MIC levels. Some of the C. orthopsilosis and C. metapsilosis isolates expressed the isoleucine to valine substitution on the hot spot 2 region. However, the amino acid variations in these isolates did not correlate to their MIC values of echinocandin.     

Comparison of the clinical and microbiologic characteristics of patients with Enterobacter cloacae and Enterobacter aerogenes bacteremia: a prospective observation study

We compared the characteristics and outcomes of 172 Enterobacter cloacae bacteremia and 67 Enterobacter aerogenes bacteremia (EAB) cases. Antimicrobial resistance rates to E. cloacae were higher than those to E. aerogenes. However, EAB more frequently presented as septic shock and was associated with poorer outcomes.     

Rapid detection of coinfections by Trichomonas vaginalis, Mycoplasma hominis, and Ureaplasma urealyticum by a new multiplex polymerase chain reaction

We developed a multiplex polymerase chain reaction (M-PCR) assay to simultaneously detect Trichomonas vaginalis, Mycoplasma hominis, and Ureaplasma urealyticum. The test is extremely specific and has a sensitivity of 10 cells for T. vaginalis and U. urealyticum and of 1 cell for M. hominis. The technique was validated on vaginal swabs from 240 women presenting symptoms of vaginitis, and results were compared with data obtained using microscopic and culture techniques on the same patients. The M-PCR revealed to be greatly more sensitive and specific than traditional techniques. It has been well demonstrated, in vitro, that T. vaginalis can establish a symbiosis with M. hominis; our data confirm in vivo this strict association: in fact, M. hominis has been detected in 78.6% of all samples positive for T. vaginalis, as compared to only 4.8% of women without trichomoniasis. The species specificity of this association has been confirmed by the absence of any significant correlation between T. vaginalis and U. urealyticum.     

Inhibitory activity of limonene against Leishmania parasites in vitro and in vivo

Limonene is a monoterpene that has antitumoral, antibiotic and antiprotozoal activity. In this study we demonstrate the activity of limonene against Leishmania species in vitro and in vivo. Limonene killed Leishmania amazonensis promastigotes and amastigotes with 50% inhibitory concentrations of 252.0 ± 49.0 and 147.0 ± 46.0 μM, respectively. Limonene was also effective against Leishmania major, Leishmania braziliensis and Leishmania chagasi promastigotes. The treatment of L. amazonensis-infected macrophages with 300 μM limonene resulted in 78% reduction in infection rates. L. amazonensis-infected mice treated topically or intrarectally with limonene had significant reduction of lesion sizes. A significant decrease in the parasite load was shown in the lesions treated topically with limonene by histopathological examination. The intrarectal treatment was highly effective in decreasing the parasite burden, healing established lesions and suppressing the dissemination of ulcers. Limonene presents low toxicity in humans and has been shown to be effective as an agent for enhancing the percutaneous permeation of drugs. Our results suggest that limonene should be tested in different experimental models of infection by Leishmania.     

Species of Propionibacterium and Propionibacterium acnes phylotypes associated with orthopedic implants

Propionibacterium sp. is commonly isolated in association with orthopedic implants, either as a pathogen or a colonizer. Microbial characteristics that indicate whether the isolated species is a likely cause of orthopedic implant infection versus a colonizing agent would be clinically useful. We performed a prospective trial to determine the species of Propionibacterium and the phylotype (IA, IB, II, III) of Propionibacterium acnes isolated from the surface of removed orthopedic implants, and we correlated these findings with the presence or absence of infection. P. acnes represented 61 of 62 isolates. P. acnes type I was more commonly isolated than was type II (62% versus 38%, respectively), whether associated with infection or not. P. acnes type III was not detected. There was no clear association between types I and II P. acnes and infection or colonization of failed orthopedic implants (P = 0.75), however type IB strains were more frequently isolated than type IA from infected prosthese.     

Standardization of multilocus sequence typing scheme for Mycobacterium abscessus and Mycobacterium massiliense

This study aims to develop a multilocus sequence typing (MLST) scheme for Mycobacterium abscessus complex for the typing of stains within each species. A total of 89 clinical isolates of M. abscessus complex from 71 patients of 2 tertiary care hospitals in South Korea were included. Forty-two isolates were identified as M. abscessus, and 29, as Mycobacterium massiliense through sequencing of 8 housekeeping genes and rpoB. The MLST scheme identified 26 different sequence types(STs) and 13 different clonal complexes (CCs) in M. abscessus and 12 different STs and 6 different CCs in M. massiliense. The MLST data showed high concordance with the XbaI-macrorestriction patterns of pulsed-field gel electrophoresis in the duplicated isolates. Our MLST schemes could identify different strains of M. abscessus and M. massiliense, and the schemes also showed a reliable reproducibility. Therefore, our MLST schemes may be useful in studying the epidemiology of M. abscessus and M. massiliense infections.     

Increasing prevalence of blaOXA-23-carrying Acinetobacter baumannii and the emergence of blaOXA-182-carrying Acinetobacter nosocomialis in Korea

Carbapenem-resistant Acinetobacter spp. have been increasingly reported worldwide with the production of OXA-type carbapenemases as the main mechanism of carbapenem resistance. The prevalent bla_OXA genes are known to vary significantly depending on time and place of isolation. We investigated the prevalence of bla_OXA genes by PCR in Acinetobacter spp. isolated in Korea. Among a total of 336 isolates collected from Hospital A from 2002 to 2011, the overall proportion of bla_OXA-23-like, ISAba1-associated bla_OXA-51-like, and bla_OXA-182 genes were 44.0%, 49.7%, and 5.1%, respectively. The bla_OXA-58-like gene was detected in only 1 isolate. A drastic increase in Acinetobacter isolates with bla_OXA-23-like genes and a decrease in isolates harboring ISAba1-associated bla_OXA-51-like genes have been observed since the mid-2000s. The bla_OXA-23-like genes were detected in all carbapenem-nonsusceptible isolates collected in 2011 from 9 hospitals. The OXA-182, which belongs to the fifth group of OXA-type carbapenemase, was detected in Acinetobacter baumannii isolates recovered as early as 2002. It is worrisome results that bla_OXA-182-carrying Acinetobacter nosocomialis has emerged and caused outbreaks of infection.     

Distribution of blaOXA-carrying imipenem-resistant Acinetobacter spp. in 3 hospitals in Taiwan

We investigated the molecular epidemiology and OXA-type carbapenemase genes of 83 imipenem-resistant Acinetobacter spp. collected from 2 university hospitals (hospitals A and B) and a regional hospital (hospital C) during 2007 in Taiwan. Genotyping by pulsed-field gel electrophoresis identified 51 pulsotypes. None of the pulsotypes established predominance throughout the 3 hospitals. Multiplex polymerase chain reaction of blaOXA genes showed that 100% (18/18), 91%(31/34), and 100% (31/31) of the Acinetobacter spp. collected from hospital A, B, and C, respectively, possessed blaOXA-51–like genes. None of the strains carrying blaOXA-23–like and blaOXA-24–like genes were found in hospital A. The coexistences of blaOXA-51–like/blaOXA-23–like and blaOXA-51–like/blaOXA-24–like genes detected in hospitals B and C were 26% (9/34) and 12% (4/34) and 58% (18/31) and 3% (1/31), respectively. Among blaOXA-23–like gene-carrying isolates collected from hospitals, clonal spread of strains carrying the blaOXA-23 gene was detected in the regional hospital but not the other 2 university hospitals. The results suggest that interhospital dissemination of imipenem-resistant Acinetobacter spp. was not found in these hospitals. The increasing percentage of OXA-23 in OXA-type carbapenemases in Acinetobacter spp. from the regional hospitals to medical centers deserves further attention in Taiwan.     

The Utility of Wet Prep in Predicting Neisseria gonorrhoeae and Chlamydia trachomatis

Background

Diagnosing Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) cervical infections can be difficult in the Emergency Department without real-time testing, as historical and physical elements are known to be unreliable.

Objective

To evaluate the utility of the vaginal wet mount preparation (wet prep) in predicting an infection with NG or CT.

Methods

A retrospective chart review was performed on 12 months of data from September 2007 to August 2008 on patients aged 18 years and above who had a chief complaint requiring a pelvic examination and had concurrent testing for NG/CT and a wet prep. Wet preps were analyzed and reported as quantity of white cells and clue cells present (none, few, moderate, or many) as well as the presence of Trichomonas vaginalis (TV). Wet prep results were evaluated to see if there was a correlation with NG/CT.

Results

There were 2439 patient encounters reviewed. A total of 373/2439 (15.3%) patient encounters were positive for NG or CT; 272/2439 (11.2%) were positive for TV, whereas 966/2439 (39.6%) had white cells and 995/2439 (40.8%) had clue cells on wet prep. Clue cells and TV did not correlate with the presence of NG or CT. Only the presence of “moderate” and “many” white cells correlated with NG or CT (odds ratio [OR] 1.58, 95% confidence interval [CI] 1.12–2.22 and OR 2.47, 95% CI 1.86–3.27, respectively).

Conclusion

In patients who are diagnosed with NG or CT, the presence of TV or clue cells on wet prep is an unreliable marker for diagnosis. However, having moderate or many white cells present on wet prep does increase the probability of concurrent NG or CT infection and may be used in cases where the clinical suspicion is equivocal.