Evaluation of a selection strategy before use of 16S rRNA gene sequencing for the identification of clinically significant gram-negative rods and coccobacilli

Pasteurella multocida urinary tract infection in a patient with cervical cancer

Introduction. Infections caused by Pasteurella species are commonly associated with contact with dogs and cats, typically involving bites and scratches, but casual contact with household pets can also be a risk factor. Urinary tract infection (UTI) caused by Pasteurella species is rare and a significant majority of cases have some known risk factor associated with an underlying chronic illness or structural and/or functional urological abnormality.

Case presentation. Here, we present a case of a UTI due to Pasteurella multocida in a patient with squamous cell carcinoma of the cervix who also had a household cat.

Conclusion. Providers and laboratorians should be aware of risk factors associated with UTIs caused by Pasteurella species.

Disparate prevalence of toxigenic and nontoxigenic Clostridium difficile among distinct adult patient populations in a single institution

Clostridium difficile (CD) disease remains a costly and important hospital-associated infection. Although nontoxigenic CD is detected by some CD testing methods, can interfere with some detection algorithms and has been suggested as a treatment for CD disease, little is known about the relative occurrence of toxigenic and nontoxigenic CD in a single institution.We used both chromogenic and selective agar media to recover CD isolates and a molecular method to detect the toxin B gene from over 2400 fresh unformed stool specimens with isolates further tested for the toxin B gene. We recovered 74 nontoxigenic and 306 toxigenic CD isolates for which a collection site could be assigned.The frequency of recovery of toxigenic and nontoxigenic CD for each hospital location and the ratio of toxigenic to nontoxigenic CD were calculated. Although the overall prevalence of toxigenic and nontoxigenic CD was 12.7 % and 3.1 %, respectively, on some wards, 48 % of all CD were nontoxigenic, while on other wards, ≤5 % were nontoxigenic.The disparate ratios of nontoxigenic CD to toxigenic CD presented here for the various 'groups' within the adult veteran population are important to the ongoing discussion and reexamination of other published work on the occurrence of toxigenic and nontoxigenic CD, for evaluating the performance of CD detection tests, for designing infection control strategies and in ultimately understanding both CD carriage and disease.

Clinical significance and characterization of Haemophilus influenzae type b genogroup isolates from urine samples in an adult male population

The occurrence and significance of Haemophilus spp. isolated from the genitourinary tract are not well known. Herein, we describe the clinical significance and characteristics of Haemophilus influenzae type b genogroup strains isolated from genitourinary tract specimens from an adult male veteran patient population and, in particular, their associations with prostatitis and epididymitis.

Accurate identification of fastidious Gram-negative rods: integration of both conventional phenotypic methods and 16S rRNA gene analysis

Background

Accurate identification of fastidious Gram-negative rods (GNR) by conventional phenotypic characteristics is a challenge for diagnostic microbiology. The aim of this study was to evaluate the use of molecular methods, e.g., 16S rRNA gene sequence analysis for identification of fastidious GNR in the clinical microbiology laboratory.

Results

A total of 158 clinical isolates covering 20 genera and 50 species isolated from 1993 to 2010 were analyzed by comparing biochemical and 16S rRNA gene sequence analysis based identification. 16S rRNA gene homology analysis identified 148/158 (94%) of the isolates to species level, 9/158 (5%) to genus and 1/158 (1%) to family level. Compared to 16S rRNA gene sequencing as reference method, phenotypic identification correctly identified 64/158 (40%) isolates to species level, mainly Aggregatibacter aphrophilus, Cardiobacterium hominis, Eikenella corrodens, Pasteurella multocida, and 21/158 (13%) isolates correctly to genus level, notably Capnocytophaga sp.; 73/158 (47%) of the isolates were not identified or misidentified.

Conclusions

We herein propose an efficient strategy for accurate identification of fastidious GNR in the clinical microbiology laboratory by integrating both conventional phenotypic methods and 16S rRNA gene sequence analysis. We conclude that 16S rRNA gene sequencing is an effective means for identification of fastidious GNR, which are not readily identified by conventional phenotypic methods.