Bacterial Stool Culture Research Articles

Physician-directed microbiological testing versus syndromic multiplex PCR in gastroenteritis.

Syndromic multiplex PCR testing is an alternative to conventional stool testing based on physician-directed request forms. The objective of this study was to compare the etiologic yield of conventional microbiological testing based on physician-directed request forms with that of rapid syndromic testing. In addition, the adequacy of the clinician ordering, which is an important piece of the diagnostic stewardship, was evaluated. Physician-directed conventional microbiological testing and extensive molecular syndromic testing with the Fast Track Diagnostics Gastroenteritis Kit were performed in parallel on 1238 samples to evaluate the contribution of a multiplex panel to the diagnostic process of gastroenteritis. A potential causative pathogen was identified in 18.4% of stool samples by standard microbiological testing and in 41.3% of stool samples tested using the syndromic panel. Only 15.1% of the request forms could be considered successful of which 88.2% were labeled inadequate. Conventional physician-directed based testing missed the etiologic diagnosis in 32.3% of the specimens (excluding sapovirus and astrovirus). Bacterial infections were theoretically not missed as bacterial stool culture was requested on all stool samples, but in 28.6% of the cases, no isolate could be recovered. In 36.9% of the samples testing positive for a viral pathogen, no viral testing was requested. In addition, 72.5% of all samples positive for a parasite were clinically suspected by the physician. This study suggests that syndromic multiplex PCR assays are a better strategy for pathogen detection in patients with gastroenteritis than physician-directed laboratory testing based on the clinical presentation.

The Effect of a Planetary Health Diet on the Human Gut Microbiome: A Descriptive Analysis.

In 2019, researchers from the EAT-Lancet Commission developed the 'Planetary Health (PH) diet'. Specifically, they provided recommendations pertaining to healthy diets derived from sustainable food systems. Thus far, it has not been analysed how such a diet affects the human intestinal microbiome, which is important for health and disease development. Here, we present longitudinal genome-wide metagenomic sequencing and mass spectrometry data on the gut microbiome of healthy volunteers adhering to the PH diet, as opposed to vegetarian or vegan (VV) and omnivorous (OV) diets. We obtained basic epidemiological information from 41 healthy volunteers and collected stool samples at inclusion and after 2, 4, and 12 weeks. Individuals opting to follow the PH diet received detailed instructions and recipes, whereas individuals in the control groups followed their habitual dietary pattern. Whole-genome DNA was extracted from stool specimens and subjected to shotgun metagenomic sequencing (~3 GB per patient). Conventional bacterial stool cultures were performed in parallel and bacterial species were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. We analysed samples from 16 PH, 16 OV, and 9 VV diet patterns. The α-diversity remained relatively stable for all dietary groups. In the PH group, we observed a constant increase from 3.79% at inclusion to 4.9% after 12 weeks in relative abundance of Bifidobacterium adolescentis. Differential PH abundance analysis highlighted a non-significant increase in possible probiotics such as Paraprevotella xylaniphila and Bacteroides clarus. The highest abundance of these bacteria was observed in the VV group. Dietary modifications are associated with rapid alterations to the human gut microbiome, and the PH diet led to a slight increase in probiotic-associated bacteria at ≥4 weeks. Additional research is required to confirm these findings.

S1987 Go With Your Gut Feeling: A Case of Invasive Colonic Squamous Cell Carcinoma Not Detected by DNA-Based Stool Testing

Introduction: Though less common, colonic squamous cell carcinoma is a type of colorectal cancer. Current colorectal cancer screening recommendations for average-risk patients include the use of stool DNA-based testing as an alternative to screening colonoscopy. This clinical vignette is an example of colonic squamous cell carcinoma that went undetected by a stool DNA-based colorectal cancer screening test. Case Description/Methods: 57 year-old female with no prior medical history presented to outpatient gastroenterology office for evaluation of tenesmus, mucus in stool with associated diarrhea and LLQ pain of 3 months duration. Physical exam was unremarkable. Recent CBC, BMP, and albumin were within normal limits. Patient had undergone average-risk colorectal cancer screening with a stool DNA-based test 11 months prior to presentation (8 months prior to symptom onset) with a negative result. Patient was asymptomatic at the time of the screening test. Due to her new symptoms, it was recommended she undergo infectious stool studies and colonoscopy. C difficile screen, bacterial stool culture and parasitology exam were negative. Colonoscopy revealed a 6-cm partially circumferential frond-like/villous, infiltrative and ulcerated partially obstructing large mass 4-11cm from the anal verge (Figure 1A, B). Biopsy was positive for invasive squamous cell carcinoma. The patient was referred to oncology and completed definitive chemo-radiation therapy with no evidence on residual disease on most recent imaging. Discussion: This case demonstrates an average-risk patient who underwent stool DNA-based testing for colorectal cancer screening that was negative with subsequent presentation and diagnosis of invasive squamous cell carcinoma of the colon in less than one year’s time. It highlights the importance of colorectal cancer screening and the ability of colonoscopy to detect and diagnosis colorectal cancer. DNA-based stool testing is an alternative non-invasive screening test to colonoscopy in average-risk patients. The current data supports a false negative rate of DNA-based stool testing to be less than 1 in 1500. However, the presence of a false negative test provides patients with a false sense of confidence and reassurance that they do not have cancer. It is imperative that for any new lower GI symptoms or other clinical suspicion for colorectal malignancy, the patient should still undergo evaluation with colonoscopy – endoscopic evaluation should not be deferred because of a recent negative DNA-based stool test.Figure 1.: A. Colon with mass, B. Detailed view of ulcerated mas.

#9: Diagnosis of Campylobacter upsaliensis and Helicobacter canis by plasma-based Next-Generation Sequencing for Microbial Cell-free DNA in twin brothers with XLA

Abstract Background X-linked agammaglobulinemia is a primary immunodeficiency associated with mutations in the B cell tyrosine kinase (BTK) gene leading to failure in B cell maturation and defective antibody production. Campylobacter and closely related Helicobacter species can cause persistent bacteremia, enteritis and cellulitis in patients with XLA and are difficult to diagnose and eradicate. In this context, detection of circulating microbial cell-free DNA (mcfDNA) by next-generation sequencing (NGS) can be used to identify infectious agents in susceptible immunocompromised hosts. Methods We report 4-year-old fraternal twins with XLA presenting with disparate clinical manifestations due to C. upsaliensis and coinfection with C. upsaliensis and H. canis respectively. Results Patient #1 was diagnosed with XLA at 11 months-old and was started on weekly immunoglobulin replacement. At 2.5 yo he developed recurrent fever, abdominal pain and diarrhea. Endoscopy/colonoscopy revealed focal ileocolitis without ulceration or granulomas. Stool infectious workup, including bacterial stool cultures, was negative. At 3 yo he developed gram- rod bacteremia that was not further identified but successfully treated with ceftriaxone. He presented 2 months later with fever and diarrhea; blood cultures were negative, but stool culture grew C. jejuni. His symptoms recrudesced after two months and he was treated for presumed recurrent Campylobacter infection. Intermittent fevers and diarrhea recurred, and repeat stool culture grew C. upsaliensis identified by MALDI-TOF resulting in a 3-month course of azithromycin. Stool PCR remained positive for Campylobacter species after one month of therapy. Fever and diarrhea recurred after completion of therapy and stool culture again grew C. upsaliensis but sensitivities could not be obtained. McfDNA testing confirmed C. upsaliensis and therapy with ertapenem, ciprofloxacin, amoxicillin and doxycycline was initiated. He remained symptom free three months into therapy. Patient #2 was diagnosed with XLA at 1 yo and started weekly immunoglobulin replacement. At 3.5 yo he developed fever, erythema nodosum (EN) and arthritis. Given his twin’s diagnosis of Campylobacter enteritis with likely bacteremia, a presumptive diagnosis of Campylobacter related reactive arthritis and EN was made. Treatment with Naprosyn and 14 days of azithromycin failed to prevent the return of EN post therapy. He had multiple courses of azithromycin each followed by return of EN rash. Following completion of therapy, he presented with high fevers, worsening rash, leukocytosis and elevated ESR. Blood and stool cultures were obtained and returned negative. Despite completion of a 3 month course of azithromycin, stool PCR remained positive for Campylobacter species and his symptoms persisted. The recrudescence of fevers and worsening rash 2 months after completion of therapy prompted repeat blood and stool cultures that returned negative. McfDNA testing was obtained in that context and identified Helicobacter canis and Campylobacter upsaliensis. Treatment with ertapenem, ciprofloxacin, amoxicillin and doxycycline was initiated and he remained symptom free three months into therapy. Conclusions Physicians should be aware of the varied presentations of chronic Campylobacter and Helicobacter infection in XLA patients. Plasma NGS for circulating mcfDNA in immunocompromised patients offers a rapid, non-invasive means of detecting these fastidious organisms that can be difficult to diagnose using more conventional means.

Diarrheal Morbidity During Hematopoietic Cell Transplantation: The Diagnostic Yield of Stool Cultures.

IntroductionDiarrhea affects a significant proportion of patients undergoing hematopoietic cell transplantation (HCT). We explored the diagnostic yield of stool cultures for enteric pathogens among patients undergoing HCT.MethodsThis is a single-center, retrospective study. Between 5/2007 and 4/2020, consecutive patients who underwent HCT were included if inpatient bacterial stool cultures were collected. Patient characteristics, results, and timing of stool cultures obtained during hospitalization were collected.ResultsA total of 1072 individuals underwent autologous (n = 603) and allogeneic (n = 469) HCT. Overall, 947 stool culture samples were obtained from 561 (52%) patients with diarrheal illness during hospitalization for HCT. Most (99%) samples were obtained beyond 3 days of admission, mainly (77%) during neutropenia. Overall, only four (0.42%) (autologous, n = 3; allogeneic, n = 1) patients had a positive stool culture and in all cases Campylobacter spp. were the pathogens identified. The number of stool cultures needed-to-test to diagnose one case of bacterial infection was 237. The cost of diagnosing one case of bacterial diarrhea was US $8770. Patients with a positive stool culture did not have discerning characteristics.ConclusionsIn our experience, the yield of stool cultures for enteropathogens in patients undergoing HCT is extremely low and thus should be avoided in most cases.

Surveillance Stool Culture and its Association with Microbiologically Documented Infection During Febrile Neutropenia in Patients with Acute Leukemia (AL) Undergoing Induction Chemotherapy.

The study aimed at identifying the profile of gut colonization of patients with acute leukemia who underwent induction chemotherapy and its association with induction events and outcome. Baseline bacterial stool culture with resistance pattern of isolates were recorded. Multi-drug resistance was defined as resistance to at least two antibiotic classes including beta lactam and fluoroquinolones. During induction chemotherapy, blood and clinically indicated cultures were taken during febrile neutropenic episodes. Association studies were done between gut colonization and induction events/outcome. Among 109 patients enrolled, 71 (65.13%) patients undergoing induction chemotherapy were colonized with bacteria, with nearly 50% of colonizers harboring multi-drug resistant bacteria. Organisms isolated from stool pre-induction were mostly gram negative (98%), with Escherichia coli and Klebsiella pneumoniae being the commonest. 65.13% patients developed febrile neutropenia. Overall multi-drug resistant positivity during febrile neutropenia was 70.14%. Concordance of 8.45% was observed between isolates from stool and organisms isolated from cultures during febrile neutropenia. There were significant proportion of gut colonized gram-negative multi-drug resistance bacteria among patients with acute leukemia. There was a low concordance rate between baseline stool isolates and subsequent cultures during the induction. There was no significant association between gut colonization and induction events/outcomes studied.

Clinical and Epidemiologic Profiles for Identifying Norovirus in Acute Gastroenteritis Outbreak Investigations.

Noroviruses are the leading cause of acute gastroenteritis (AGE) outbreaks in the United States. However, outbreaks attributed to norovirus often lack confirmation by diagnostic testing. Clinical and epidemiologic profiles, such as the Kaplan criteria (vomiting in >50% cases, mean incubation period of 24-48 hours, mean duration of illness for 12-60 hours, and negative bacterial stool culture), have been used to distinguish norovirus outbreaks from those caused by bacteria. Kaplan criteria were evaluated among 10 023 outbreaks reported to the National Outbreak Reporting System (NORS) during 2009-2012. An alternate profile for distinguishing norovirus outbreaks from outbreaks caused by nonviral etiologies was identified using classification and regression tree (CART) modeling. Performance of the Kaplan criteria and alternate profile were compared among laboratory-confirmed outbreaks. The Kaplan criteria were 63.9% sensitive and 100% specific in discriminating norovirus from nonviral outbreaks, but only 3.3% of norovirus and 1.2% of nonviral outbreaks reported all criteria. Clinical and epidemiologic characteristics identified with CART modeling (ratio of proportion of cases with fever to the proportion of cases with vomiting <1, proportion of cases with bloody stool <0.1, proportion of cases with vomiting ≥0.26) were 85.7% sensitive and 92.4% specific for distinguishing norovirus from nonviral outbreaks and were applicable to more than 8 times as many outbreaks compared with the Kaplan criteria. Compared with the Kaplan criteria, the CART-derived profile had higher sensitivity and broader application in reported AGE outbreaks. Thus, this alternate profile may provide a more useful tool for identifying norovirus during outbreak investigations.

Emergency Medicine Providers' Knowledge and Management of Pediatric Tropical Diseases

The aim of this study was to perform a needs assessment of pediatric (PEM) and general emergency medicine (EM) provider knowledge, comfort, and current practice patterns in the evaluation of pediatric tropical infectious diseases. An online survey was developed based on educational priorities identified by an expert panel via modified Delphi methodology. The survey included assessment of providers' typical evaluation, diagnosis, and treatment of tropical diseases and was distributed to PEM and EM providers in 2 large professional organizations. A total of 333 physicians (285 PEM, 32 EM, 8 combined PEM/EM, and 8 general pediatricians in emergency department) participated. Fifty-five percent of vignettes were answered correctly. Those who trained outside the United States or Canada (odds ratio [OR], 1.8; 95% confidence interval [CI], 1.1-3.0) and PEM-trained providers (OR, 2.6; 95% CI, 1.2-5.9) were more likely to answer questions correctly. Providers answered more questions correctly about dengue (76%) and tuberculosis (77%) than typhoid (53%) and malaria (39%) (OR, 3.8; 95% CI, 3.0-4.9). Diagnostic evaluation for tropical diseases was variable with greater than 75% agreement for only 2 tests: blood smears in febrile patients from Africa (86%) and bacterial stool cultures in patients with bloody stools from Africa, Asia, or Latin America (94%). Providers had low (62%) or medium (35%) comfort level with pediatric tropical diseases, and 93% were interested in accessing emergency department-specific resources. Pediatric EM and EM providers' knowledge and evaluation for pediatric tropical diseases are variable. Providers recognized their knowledge gaps and expressed interest in gaining access to resources and guidelines to standardize and improve evaluation and treatment of these diseases.

Evaluation of a rapid dipstick test (Crystal Vc®) for the diagnosis of cholera in Maiduguri, Northeastern Nigeria

Background: Cholera is a preventable diarrheal disease associated with rapidly progressing dehydration. Early detection of the causative agent, Vibrio cholerae (VC) among symptomatic patients is a key step in cholera outbreak management to minimize disease spread and mortality. Materials and Methods: We prospectively evaluated the performance of Crystal VC®, a commercially available test kit for rapid detection of VC serotypes 01 and 0139 directly from stool samples. Patients included in this study were those admitted to the cholera treatment unit from August 14, 2017, to September 20, 2017, during the cholera outbreak in Maiduguri, northeastern Nigeria. Conventional bacterial stool culture is considered the gold standard and was used as the comparator. Results: A total of 156 stool specimens were collected and tested. Compared with stool culture results, the Crystal VC® test had sensitivity (SE) of 95.1% and specificity (SP) of 59.3%. The positive and negative likelihood ratios were 2.33 and 0.08, respectively. The positive predictive value (PPV) was 81.5% while the negative predictive value (NPV) was 86.5%. There was no gender variation with respect to SE, SP, PPV, and NPV. Conclusion: The cholera rapid dispstick test (RDT), Crystal VC®, is a useful tool for diagnosis of diarrheal disease due to VC serotypes 01 and 0139 and may provide an initial alert in an outbreak situation. It may also be used for case surveillance in cholera epidemic prone situations resulting from displacement to camps or overcrowded shelters due to human conflict or natural disasters. Although it is less sensitive than conventional stool culture, it is a convenient and simple test to perform with faster turnaround time.

Diagnostic Performance of Gastrointestinal Pathogen Panels in Patients With Suspected Infectious Gastroenteritis: A Systematic Review and Meta-Analysis

Introduction: Recently, the Food and Drug Administration has approved several multiplex molecular diagnostic tests (gastrointestinal pathogen panels [GIP]) for evaluating patients with suspected infectious gastroenteritis, which can simultaneously and rapidly detect 4-22 potential bacterial, viral and/or parasitic pathogens. We reviewed the overall diagnostic performance and detection rate of GIPs, specifically it's performance against traditional stool cultures for common bacterial pathogens to identify rates of discordance. Methods: We performed a systematic literature review from January 2011 to April 2017, to identify comparative studies, in which patients with suspected infectious gastroenteritis underwent testing with both FDA-approved GIPs and stool cultures, to assess rates of positivity and discordance, using random-effects meta-analysis. Results: From 1599 studies, we identified 13 cross-sectional comparative studies (9070 patients); only 5 studies were reportedly performed in patients with acute diarrhea, whereas clinical status was not reported in others. Overall, 47.7% patients (95% CI, 34.3-61.5) tested positive for at least one possible pathogen using GIPs, including 7.2% patients (95% CI, 3.6-13.8) who tested positive for 2 or more co-infections. In 5 studies limited to patients with ‘acute diarrhea', 74.1% (95% CI, 55.3-86.8) were positive on GIPs, including 14.5% patients (95% CI, 3.9-41.6) with co-infections. To assess comparative diagnostic performance of GIPs against a gold standard of bacterial stool culture, we limited further analyses to only specific bacterial pathogens in GIPs, which are detectable through traditional stool cultures (Campylobacter, Shigella, Salmonella, E.coli, Yersinia, Vibrio). On this analysis, 19.4% patients (95% CI, 11.4-30.9) tested positive on GIPs, as compared to 13.5% patients (95% CI, 8.1-21.7) who tested positive on stool cultures. Discordance was observed in 4.5% cases - 3.8% patients (95% CI, 1.5-9.2) tested positive for candidate bacterial species on GIPs but not on stool cultures (possible false positives); 0.7% patients (95% CI, 0.3-1.7) tested positive on stool cultures but negative on GIPs. Conclusion: While GIPs are able to identify potential etiologies for diarrhea in more patients than traditional methods, there is potential for false positive results. Longitudinal studies on impact of GIPs on medical decision-making, patient outcomes and public health relevance of findings are warranted.

P158 Could chimerism testing on orthotopic liver transplant patients lead to earlier graft versus host disease intervention and in turn more effective outcomes?

Graft-versus-host disease (GVHD) is a rare but often fatal complication of orthotopic liver transplantation (OLT). Rash, fever, diarrhea and pancytopenia, all hallmarks of GVHD, are symptomatically similar to adverse drug reactions (ADR) or viral infections. In the absence of these classic symptoms, GVHD diagnosis is delayed. We present the case of a 62 year old male with alcoholic cirrhosis and hepatocellular carcinoma who received an allograft from a 0/10 HLA matched 19 year old male donor. Both were CMV seronegative and the retrospective T- and B-cell flow cytometric crossmatch were negative. Following an unremarkable early post-transplant course, the patient was discharged on post-operation day (POD) 8 only to return for a routine follow-up on POD17 complaining of diarrhea and subsequently symptoms of fever and leukopenia. Blood, bacterial stool cultures, and stool parasite antigen screen were all negative. Appropriate care was taken to treat ADR and rule out infection including EBV, CMV and C. difficile PCR. Despite temporary relief with medication adjustments the patient was readmitted on POD27 with recurring diarrhea, syncope, fever, worsening leukopenia and new-onset rash. Repeat blood and stool testing remained negative. While the skin biopsy did not meet criteria to make the diagnosis of GVHD, whole blood chimerism testing detected 90% donor cells consistent with GVHD. CD3+ T-lymphocyte chimerism testing yielded 100% donor cells. Bone marrow biopsy demonstrated hypocellular marrow ( > 20 years and degree of HLA mismatch) in the early OLT period are needed to determine if this can lead to better patient outcomes.

Evaluation of the Impact of Stool Bacterial Cultures on Clinical Management on Patients Admitted With a Primary Diagnosis of Diarrhea

Introduction: Most cases of acute diarrhea are self-limited and due to viral or baterial infections. Stool cultures only test for the specific enteroinvasive bacteria, including Campylobacter jejuni, Salmonella species, Shigella species, Escherichia coli, which represent a small fraction of the infectious agents that can cause acute diarrhea. Previous studies have shown these organisms are positive in approximately 0.2 to 1.8% of cultures. We evaluated the effect of stool culture results on the management of inpatients with acute diarrhea. Methods: The database from the inpatient electronic medical records system at a university hospital was queried for stool bacterial cultures performed on inpatients from June 2010 through June 2014. Chart review was performed to assess the impact of stool culture results on clinical management and was limited to patients with an admitting diagnosis of acute diarrhea.Table 1: Stool Culture DistributionTable 2: Stool Culture DistributionFigure 1Figure 2Results: A total of 4576 stool cultures were evaluated within the study period. Of these stool cultures, 527 (11.5%) were positive, the most common organisms being: Candida sp. (n=282, 6.16%), Staphylococcus aureus (n=88, 1.92%), Campylobacter jejuni (n=25, 0.55%), Salmonella sp. (n=22, 0.48%), Shigella sp. (n=13, 0.28%). Escherchia coli 0157:H7 was not isolated in any cultures. Candida and S. aureus were considered contaminants and did not impact clinical management. This left 54 positive stool cultures for analysis, excluding duplicate cultures and those taken from patients without diarrhea. Seven cultures (15.5%) resulted in a change of the patient's management. Management changes included initiating antibiotics (n=4, 7.4%) and changing to narrower spectrum antibiotics (n=3, 5.6%). Results from 33 of the positive cultures (61%) were obtained after the patient was discharged with improved symptoms (with or without empiric antibiotic treatment). Results from the remaining 14 stool cultures (26%) were obtained during the patient's admission, but did not result in a change in management. Conclusion: In this large single center retrospective analysis, we demonstrate that bacterial stool cultures have a low rate of positivity, and positive culture results are of limited utility in guiding clinical management in patients admitted with acute diarrhea. Clinical judgment as to the benefits of culture results in guiding management should be considered prior to collecting them, and may enhance high value care and cost effectiveness.

Comparison of time-motion analysis of conventional stool culture and the BD MAX™ Enteric Bacterial Panel (EBP).

BackgroundConventional bacterial stool culture is one of the more time-consuming tests in a routine clinical microbiology laboratory. In addition, less than 5 % of stool cultures yield positive results. A molecular platform, the BD MAX™ System (BD Diagnostics, Sparks, MD) offers the potential for significantly more rapid results and less hands-on time. Time-motion analysis of the BD MAX Enteric Bacterial Panel (EBP) (BD Diagnostics, Quebec, Canada) on the BD MAX System was compared to conventional stool culture in the microbiology laboratory of a tertiary care pediatric hospital.MethodsThe process impact analysis of time-motion studies of conventional cultures were compared to those of EBP with 86 stool specimens. Sample flow, hands-on time, processing steps, and overall turnaround time were determined and analyzed. Data were obtained and analyzed from both standard operating procedures and direct observation. A regression analysis was performed to ensure consistency of measurements. Time and process measurements started when the specimens were logged into the accessioning area of the microbiology laboratory and were completed when actionable results were generated.ResultsWith conventional culture, negative culture results were available from 41:14:27 (hours:minutes:seconds) to 54:17:19; with EBP, positive and negative results were available from 2:28:40 to 3:33:39.ConclusionsThis study supports the suggestion that use of the EBP to detect commonly encountered stool pathogens can result in significant time savings and a shorter time-to-result for patients with acute bacterial diarrhea.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Bacterial Gastroenteritis

Bacterial gastroenteritis is a disease that is pervasive in both the developing and developed worlds. While for the most part bacterial gastroenteritis is self-limiting, identification of an etiological agent by bacterial stool culture is required for the management of patients with severe or prolonged diarrhea, symptoms consistent with invasive disease, or a history that may predict a complicated course of disease. Importantly, characterization of bacterial enteropathogens from stool cultures in clinical laboratories is one of the primary means by which public health officials identify and track outbreaks of bacterial gastroenteritis. This article provides guidance for clinical microbiology laboratories that perform stool cultures. The general characteristics, epidemiology, and clinical manifestations of key bacterial enteropathogens are summarized. Information regarding optimal specimen collection, transport, and processing and current diagnostic tests and testing algorithms is provided. This article is an update of Cumitech 12A (P. H. Gilligan, J. M. Janda, M. A. Karmali, and J. M. Miller, Cumitech 12A, Laboratory diagnosis of bacterial diarrhea, 1992).

Point-of-Care Testing for Clostridium Difficile Infection: A Real-World Feasibility Study of a Rapid Molecular Test in Two Hospital Settings.

IntroductionIn the developed world, Clostridium difficile infection (CDI) is the most important cause of nosocomial infectious diarrhea. In addition to providing epidemiological data and helping to indicate that a local outbreak may be occurring, laboratory tests are used to augment clinical decisions on individual patients. Very rarely do diagnostic tests provide results at the point of decision making; in the intervening period between requesting investigations on a patient with suspected CDI and return of the laboratory result, decisions must be made regarding patient isolation and treatment.MethodsA 22-month, real-world feasibility study was conducted in patients with clinically significant diarrhea, in a London Hospital between March 2011 and January 2013, in three older persons’ wards and two intensive care units (ICUs) to determine acceptability, ease of use, change in turnaround time and clinical utility of a rapid, polymerase chain reaction (PCR)-based point-of-care test (POCT) (Cepheid GeneXpert®, Sunnyvale, California, USA) for diagnosis of Clostridium difficile. Nurses in the older persons’ ward and laboratory technicians in the ICU were trained to perform the test. Residual samples were sent to the centralized laboratory for parallel testing using a two-step algorithm.ResultsA total of 335 samples were tested using the POCT with a median turnaround time of 1.85 h compared with 18 h for the centralized laboratory test. Overall agreement with centralized laboratory testing was 98.1%. Discrepant samples were more frequent on elderly wards than ICU. Overall 20/335 (6%) processing errors were encountered and were highest in the first few months of the study. Significantly more processing errors occurred on the older persons’ wards 13/102 (12.7%) than on ICU 7/271 (2.6%). Older persons’ patients who had POCT were significantly less likely to have a test requested for bacterial stool culture (3.1% vs. 10.9% p = 0.044). This difference was not observed in the ICU patients. No other differences in ancillary test requesting, mortality or length of stay were observed.ConclusionsThe majority of users reported that the POCT was easy to perform and was an acceptable part of their job. POCT using this system is feasible and acceptable to nursing staff and technicians working within these two hospital-based settings.Electronic supplementary materialThe online version of this article (doi:10.1007/s40121-014-0038-6) contains supplementary material, which is available to authorized users.

Indirect Protection of Adults From Rotavirus by Pediatric Rotavirus Vaccination

Pediatric vaccination has resulted in declines in disease in unvaccinated individuals through decreasing pathogen circulation in the community. About 2 years after implementation of pediatric rotavirus vaccination in the United States, dramatic declines in rotavirus disease were observed in both vaccinated and unvaccinated children. Whether this protection extends to adults is unknown. The prevalence of rotavirus, as determined by Rotaclone enzyme immunoassay, in adults who had stools submitted for bacterial stool culture (BSC) between February to May to Northwestern Memorial Hospital, Chicago, was compared between the prepediatric impact era (2006-2007) and the pediatric impact era (2008-2010). Isolates were genotyped and clinical characteristics of those with rotavirus were compared. Of the 5788 BSC sent, 4725 met inclusion criteria and 3530 of these (74.7%) were saved for rotavirus testing. The prevalence of rotavirus among adults who had stool sent for BSC declined from 4.35% in 2006-2007 to 2.24% in 2008-2010 (a relative decline of 48.4%; P = .0007). The decline in the prevalence of rotavirus was of similar significant magnitude in both outpatients and inpatients. Marked year-to-year variability was observed in circulating rotavirus genotypes, with strain G2P[4] accounting for 24%; G1P[8], 22%; G3P[8], 11%; and G12P[6], 10% overall. About 30% of adults from whom rotavirus was isolated were immunocompromised and this remained constant. Pediatric rotavirus vaccination correlated with a relative decline of almost 50% in rotavirus identified from adult BSC during the peak rotavirus season, suggesting that pediatric rotavirus vaccination protects adults from rotavirus.

Evaluation of intrapartum antibiotic prophylaxis for the prevention of early-onset group B streptococcal infection

We retrospectively assessed the medical records of pregnant women who delivered at Asahikawa Kosei Hospital during a period of 3years between January 2009 and December 2011 and their neonates. Our prophylactic measures against group B Streptococcus (GBS) infection are based on the Japanese guidelines. More specifically, we performed screening by examining bacterial cultures of vaginal-perianal swabs from pregnant women between gestational weeks 33 and 37. Then, sulbactam/ampicillin (SBT/ABPC) was given at a dose of 1.5g through a drip intravenous infusion at delivery if pregnant women were screened positive for GBS. For neonates born to GBS carrier women, bacterial cultures of pharyngeal swabs, vernix caseosa, stool, and gastric juice were performed at birth. There were 2,399 deliveries and 2,499 births at our hospital. In 169 of the deliveries (175 of the births), GBS was isolated from specimens obtained from gestational weeks 33-37. According to delivery mode, there were 42 cases of cesarean section (45 births) and 127 cases of vaginal delivery (130 births). The GBS-positive neonates accounted for 4.1% of all deliveries in pregnant women who tested positive for GBS at gestational weeks 33-37. In neonates born by vaginal delivery, the GBS-positive rate was 5.5%. Of the 2,499 neonates born at our hospital during a period of 3years, early-onset GBS infection occurred in 1 neonate. The incidence of early-onset GBS infection was 0.40 per 1,000 live births. From 1997 to 2001 (routine GBS screening of mothers was not performed), there were 2,097 deliveries and 2,166 births. Early-onset GBS infection occurred in 1 neonate during this period; thus, the incidence of early-onset GBS infection was 0.46 per 1,000 live births. There were no significant differences in the two periods. The present prophylactic measures such as screening of maternal GBS carriers and intrapartum antibiotic administration are inadequate to decrease the occurrence of early-onset GBS infection.

Survey of Physician Diagnostic and Treatment Practices for Patients with Acute Diarrhea in Guangdong Province, China

Although international clinical guidelines generally recommend performing bacterial stool culture in patients with acute diarrhea and fever and discourage routine antibiotic prescribing, clinical practice varies. Understanding practice patterns can help health officials assess the sensitivity of laboratory-based enteric infection surveillance systems and the need to improve antibiotic prescribing practices. We surveyed physicians in Guangdong province, China, to measure their practices for patients with acute diarrhea. A standardized questionnaire was used to interview physicians working in hospitals participating in a Salmonella surveillance system in Guangdong, China. The questionnaire asked physicians about their routine practice for patients with diarrhea, including how they managed the last patient they had seen with acute diarrhea. We calculated the odds ratio and 95% confidence interval for factors associated with ordering a stool culture and for prescribing antibiotics. We received surveys from 237 physicians across 22 hospitals in Guangdong. For the last patient with diarrhea whom they had evaluated, 134 (57%) reported ordering a stool culture. The most common reasons for not ordering a stool culture included that it takes too long to receive the result, that the patient is not willing to pay for the test, and that the patient's illness was too mild to warrant testing. Most physicians prescribed at least one medication for the last patient with diarrhea whom they had evaluated. Of the 237 physicians surveyed, 153 (65%) prescribed antibiotics, 135 (57%) probiotics, and 115 (49%), a gastric mucosal protective drug. In conclusion, physicians in Guangdong, China, reported high rates of ordering bacterial stool cultures from patients with diarrhea, possibly associated with their hospital's participation in a special surveillance project. The high rate of antibiotic prescribing suggests that efforts to promote judicious antibiotic use, such as physician education, are needed.

Rotavirus in adults requiring hospitalization

To determine the prevalence and epidemiological characteristics of rotavirus among adults admitted to the hospital with diarrhea that have bacterial stool cultures sent. The prevalence of rotavirus was determined by Rotaclone EIA in samples submitted for bacterial stool culture from adults requiring hospitalization at Northwestern Memorial Hospital, Chicago from December 01, 2005-November 30, 2006. Rotavirus was detected in 2.9% of eligible bacterial stool cultures. A bacterial pathogen (e.g., Salmonella, Shigella, Campylobacter) was identified in 3.3%. Bacterial stool pathogens were more common from June-October while rotavirus was 2.4 times more common than all bacterial pathogens from February-May. Adults in whom rotavirus was detected were older (p<0.05) and more often immunosuppressed (p<0.02), particularly with HIV (p<0.04) compared to individuals from whom bacteria were isolated. The duration of hospitalization and the number of invasive procedures performed in those with rotavirus and bacterial diarrhea were comparable. In the era immediately prior to widespread rotavirus vaccination of children, rotavirus was as commonly detected from adults admitted to the hospital with diarrhea as are the bacterial gastroenteritis pathogens. Rotavirus is particularly prevalent from February-May (as in children) and in immunosuppressed or older adults.

What Have We Learnt from Bacterial Stool Culture Results? a Retrospective Study of Hospitalised Gastroenteritis Cases in a Regional Hospital in Hong Kong

BackgroundStool culture is one of the common investigations done for patients with gastroenteritis, and fluoroquinolones have been used frequently for suspected bacterial gastroenteritis.ObjectiveTo study the yield of bacterial pathogens in stool culture in a local regional hospital for in‐patients with gastroenteritis and the individual pathogens identified. Also, the value of stool culture and the prescription of fluoroquinolones as empirical antibiotics were reviewed.MethodsThis was a retrospective study. All in‐patients with the principal diagnosis of “gastroenteritis” in the year 2007 were reviewed. We excluded pregnant patients and patients under 18 years of age. Patients were divided into two age groups and data were analysed including demographics, clinical findings, admission time and culture results. Antibiotics prescription behaviour was also analysed.ResultsA total of 837 adult patients fulfilled the criteria. Among them, 562 cases had their stool saved and sent for bacterial culture. Eighty‐nine cases were found to have their stool cultures positive for bacteria. The identified pathogens were namely Vibrio parahaemolyticus (38.2%), Salmonella species (34.8%), Campylobacter species (11.2%), Plesiomonas species (10.1%) and Aeromonas species (3.4%) respectively. The yield of positive stool culture was 15.8%.ConclusionVibrio parahaemolyticus and Salmonella species were still the most common pathogens for bacterial gastroenteritis among hospitalized patients in Hong Kong, especially in the young and middle aged. Their occurrence followed a seasonal pattern. Physicians had a tendency to prescribe fluoroquinolones for cases with fever and travel history. Also, the problem of antibiotic resistance did exist. It is important for practitioners to follow local guidelines before ordering microbiological investigations on stool and prescribing empirical antibiotic treatment.