Case report: isolation of Hydrogenophaga from septic blood culture following near-death drowning in lakewater.

A patient suffered a non-fatal wet drowning in a freshwater lake and developed bacteraemia several days later. Blood culture grew a Gram-negative rod that could not be identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). 16S ribosomal RNA sequencing of the isolate identified the microbe as Hydrogenophaga laconesensis - an environmental microbe commonly found in freshwater. The recovery of multiple pathogenic micro-organisms (although not H. laconesensis ) from culture of respiratory specimens prompted the initiation of antibiotic therapy with cefepime and, later, vancomycin. The patient's clinical course gradually improved over the course of 2 weeks and she was ultimately discharged home with minimal sequelae. To our knowledge, this is the first evidence of human infection with bacteria in the genus Hydrogenophaga . Hydrogenophaga may be considered in cases of freshwater near-drowning, and MALDI-TOF MS databases should be updated to include H. laconesensis .

Diagnostic and Therapeutic Utility of Positive Intravascular Catheter Tip Cultures.

This study evaluated the performance and clinical utility of performing intravascular catheter tip cultures (CTC). A retrospective chart review was conducted over a 2.5 year period on all patients who demonstrated growth of at least one organism on CTC. There were a total of 391 CTC performed. 88 (23%) grew at least one organism, while 303 (77%) had no growth. Of the positive CTC, 81 (92%) had blood cultures (BC) collected within 14 days, whereas 7 (8%) did not. Of the positive CTC with BC, 67 (83%) were BC-positive, whereas 14 (17%) were negative. For cases with growth on both CTC and BC, the organisms identified were concordant for 46 (69%) cases and discordant for 21 (31%). Of the concordant cases, 43 (93%) were clinically considered to be bacterial bloodstream infections that were secondary to a catheter infection. For all of the positive CTC cases total, there was no change in the antibiotics or management, with the exceptions of 2 out of 88 (2%) cases. Catheters were removed and cultured for an average of 38.6 h (range: -98 to 288 h) after positive BC results were available. Most CTC are negative, and for the CTC that are positive, most are concordant with BC results. CTC results are generally only available several days after positive BC results are known. The CTC results did not alter the antibiotic therapy or management, with the exceptions of rare cases. As such, this study concludes that CTC do not contribute diagnostic or therapeutic value. Therefore, current guidelines by the Infectious Diseases Society of America on catheter-related bloodstream infection diagnosis should be revised to exclude CTC collection. IMPORTANCE In patients with intravascular catheters who are febrile or have positive blood cultures and no other obvious sources of infection, catheter tip cultures are often obtained to evaluate potential catheter-related bloodstream infections. However, previous studies reported that the management of catheter-related bloodstream infection cases is entirely based on blood culture growth and susceptibilities and that catheter tip cultures have low diagnostic positive predictive value. Our study represents the largest contemporary evaluation that includes chart reviews on all positive catheter tip culture cases. We found that positive cultures led to no changes in antibiotics or management, except for in two cases. Furthermore, 92% of positive catheter tip cultures were associated with blood culture collections, and catheter cultures were generally available only several days after the blood culture results were known. Thus, our study supports the claim that positive catheter tip cultures add limited diagnostic and therapeutic value in suspected catheter-related bloodstream infections.

Clinical Significance of BD Bactec FX Blood Culture Incubation Beyond 96 Hours (4 Days).

Blood cultures (BC) for bacteria and yeast have traditionally been incubated for 5 days using modern instruments. Many organisms may grow sooner, and the need for the full 5-day incubation period has been questioned. This study evaluated the clinical significance of isolates recovered beyond 96 h. A retrospective chart review was conducted on all positive BC (+BC) performed via BD Bactec FX with >96 h of incubation from 5/2019 to 1/2022 at the UW Health University Hospital clinical microbiology laboratory. A total of 59,958 BC were performed; 6,031 (10%) were +BC. Of +BC, 104 (2%) demonstrated growth >96 h. The 104 cultures were from 89 patients and included 12 (12%) Staphylococcus aureus (1 MRSA), 9 (9%) yeast (8 Candida sp.), 8 (8%) Escherichia coli and 7 (7%) Enterococcus sp. (1 VRE) isolates. Fifty-six percent (n = 50) of the 89 +BC >96 h cases were clinically significant, and 26% (n = 13) resulted in antibiotic adjustments based on the +BC; 4 of these had previous positive cultures. Of the remaining 37 clinically significant +BC >96 h for which no antibiotic changes were made, 32 patients had previous positive cultures. The majority (98%) of BC bottles were positive before 96 h. For isolates that required >96 h, most (56%) were considered clinically significant, including S. aureus and E. coli cultures. Changes to antibiotic therapy were made in a minority (26%) of clinically significant cases. Based on these findings, under routine conditions, laboratories using BD Bactec FX should maintain a 120 h incubation period.

Clinical Utility of Dual Anterior Nares and Oropharynx MRSA Screening PCR for Patients with Suspected Pneumonia.

We reviewed the electronic health records of 1,419 inpatients with anterior nares (AN) and oropharynx (OP) MRSA PCR tests. Concordance was 96.5%. In discordant cases, AN negative-OP positive results increased detection of probable MRSA pneumonia by only 0.3%. A dual testing approach has limited utility in detecting MRSA pneumonia and increases resource utilization.

Prevalence of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Asymptomatic Infections in 2 Large Academic Health Systems in Wisconsin.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) asymptomatic infections may play a critical role in disease transmission. We aim to determine the prevalence of asymptomatic SARS-CoV-2 infection at 2 hospital systems in 2 counties in Wisconsin. The SARS-CoV-2 prevalence was 1% or lower at both systems despite the higher incidence of coronavirus disease 2019 (COVID-19) in Milwaukee County.

Utilization and Results of Repeat SARS-CoV-2 RT-PCR Testing in a Presumptive Low Prevalence Population.

INTRODUCTION: Early reports have raised concerns regarding the clinical sensitivity of nasopharyngeal SARS-CoV-2 reverse transcriptase-polymerase chain reaction (RT-PCR) testing for patients with COVID-19 symptoms, which has led to requests for repeat testing at our institution. However, to our knowledge, there are no reports to date of the utilization or results of repeat testing to help guide this practice. METHODS: The authors searched the institutional laboratory information system for consecutive patients who were tested for SARS-CoV-2 by RT-PCR of a nasopharyngeal specimen over a 1-month period. Characteristics and results of patients who received a single or multiple tests were documented and analyzed. RESULTS: Six thousand three (6003) tests were performed on 5757 patients; 272 (4.7%) patients were positive based on their initial test results. Two hundred thirty-six (4%) patients were tested more than once, with 226 (96%) tested twice. The largest proportion of these patients (n=160, 71%) were those who had an initial negative test followed by a repeat test for persistent symptoms. This group included all 7 patients who had discordant positive results on their second test; the result concordance rate within this group was 96%. CONCLUSION: In a population of patients with a low positive rate for SARS-CoV-2 by nasopharyngeal RT-PCR testing, repeat nasopharyngeal testing of negative patients who have persistent symptoms still yields a negative result in 96% of the cases.

Utility of Repeat Nasopharyngeal SARS-CoV-2 RT-PCR Testing and Refinement of Diagnostic Stewardship Strategies at a Tertiary Care Academic Center in a Low-Prevalence Area of the United States.

BACKGROUND: Multiple factors have led to an extremely high volume of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) testing. Concerns exist about sensitivity and false-negative SARS-CoV-2 RT-PCR testing results. We describe a retrospective observational study examining the utility of repeat nasopharyngeal (NP) SARS-CoV-2 RT-PCR testing at an academic center in a low-prevalence setting. METHODS: All patients within our health system with >1 NP SARS-CoV-2 RT-PCR test result were included. SARS-CoV-2 RT-PCR testing was performed according to 1 of 4 validated assays. Key clinical and demographic data were collected, including whether the patient was inpatient or outpatient at time of the test and whether the test was performed as part of a person under investigation (PUI) for possible coronavirus disease 2019 or for asymptomatic screening. RESULTS: A total of 660 patients had >1 NP SARS-CoV-2 PCR test performed. The initial test was negative in 638. There were only 6 negative-to-positive conversions (0.9%). All 6 were outpatients undergoing a PUI workup 5-17 days after an initial negative result. In >260 inpatients with repeat testing, we found no instances of negative-to-positive conversion including those undergoing PUI or asymptomatic evaluation. CONCLUSIONS: In a low-prevalence area, repeat inpatient testing after an initial negative result, using a highly analytically sensitive SARS-CoV-2 RT-PCR, failed to demonstrate negative-to-positive conversion. The clinical sensitivity of NP RT-PCR testing may be higher than previously believed. These results have helped shape diagnostic stewardship guidelines, in particular guidance to decrease repeated testing in the inpatient setting to optimize test utilization and preserve resources.

Comparative study of Revogene GBS LB assay and GeneXpert GBS LB assay for the detection of group B Streptococcus in prenatal screening samples.

BACKGROUND: Group B Streptococcal (GBS) infections in the United States are a leading cause of meningitis and sepsis in newborns. The CDC therefore recommends GBS screening for all pregnant women at 35-37 weeks of gestation and administration of intrapartum prophylaxis (in those that tested positive) as an effective means of controlling disease transmission. Several FDA approved molecular diagnostic tests are available for rapid and accurate detection of GBS in antepartum women. METHOD: In this study, we report a clinical comparison of the Xpert GBS LB assay and a novel FDA-cleared test, Revogene GBS LB assay. A total of 250 vaginal-rectal swabs from women undergoing prenatal screening were submitted to the University of Wisconsin's clinical microbiology laboratory for GBS testing. RESULTS: We found 96.8% of samples were concordant between the two tests, while 3.2% were discordant with a positive percent agreement of 98.0% and a negative percent agreement of 96.5% between the Revogene GBS LB assay and the GeneXpert GBS LB assay. CONCLUSION: Overall, we report that both assays perform well for the detection of GBS colonization in pregnant women.

Bordetella pertussis in a four-time kidney transplant recipient: A call for immunization programs at transplant centers.

Pertussis, or whooping cough, is a highly contagious respiratory illness caused most frequently by Bordetella pertussis. Clinical presentation ranges in severity, but life-threatening illness disproportionately affects children and immunocompromised individuals. Acellular vaccines for pertussis have been available for decades, and they are recommended throughout the lifespan. A patient who had received a kidney transplant presented with respiratory distress and dry cough as manifestations of co-infection with B pertussis and Bordetella parapertussis/bronchiseptica. The goal of this case report was to highlight the importance of immunization programs at transplant centers, which are in the unique position to care for patients both with end-stage organ disease and in the post-transplant setting.

Streptococcus agalactiae Strains with Chromosomal Deletions Evade Detection with Molecular Methods.

Surveillance of circulating microbial populations is critical for monitoring the performance of a molecular diagnostic test. In this study, we characterized 31 isolates of Streptococcus agalactiae (group B Streptococcus [GBS]) from several geographic locations in the United States and Ireland that contain deletions in or adjacent to the region of the chromosome that encodes the hemolysin gene cfb, the region targeted by the Xpert GBS and GBS LB assays. PCR-negative, culture-positive isolates were recognized during verification studies of the Xpert GBS assay in 12 laboratories between 2012 and 2018. Whole-genome sequencing of 15 GBS isolates from 11 laboratories revealed four unique deletions of chromosomal DNA ranging from 181 bp to 49 kb. Prospective surveillance studies demonstrated that the prevalence of GBS isolates containing deletions in the convenience sample was <1% in three geographic locations but 7% in a fourth location. Among the 15 isolates with chromosomal deletions, multiple pulsed-field gel electrophoresis types were identified, one of which appears to be broadly dispersed across the United States.

In vitro evaluation of meropenem-vaborbactam against clinical CRE isolates at a tertiary care center with low KPC-mediated carbapenem resistance.

The in vitro activity of meropenem-vaborbactam was examined against clinical carbapenem-resistant Enterobacteriaceae isolates collected over 3 years at our medical center. Only 3 KPC-producers were identified. Susceptibility to meropenem-vaborbactam was noted in 15/16 (94%) isolates (MIC90 2 mg/L) that were nonsusceptible to meropenem. Meropenem-vaborbactam may have utility at centers where non-KPC-producers are more frequent.

Comparison of turnaround time and total cost of HIV testing before and after implementation of the 2014 CDC/APHL Laboratory Testing Algorithm for diagnosis of HIV infection.

BACKGROUND: Updated recommendations for HIV diagnostic laboratory testing published by the Centers for Disease Control and Prevention and the Association of Public Health Laboratories incorporate 4th generation HIV immunoassays, which are capable of identifying HIV infection prior to seroconversion. OBJECTIVES: The purpose of this study was to compare turnaround time and cost between 3rd and 4th generation HIV immunoassay-based testing algorithms for initially reactive results. STUDY DESIGN: The clinical microbiology laboratory database at Mayo Clinic, Rochester, MN was queried for 3rd generation (from November 2012 to May 2014) and 4th generation (from May 2014 to November 2015) HIV immunoassay results. All results from downstream supplemental testing were recorded. Turnaround time (defined as the time of initial sample receipt in the laboratory to the time the final supplemental test in the algorithm was resulted) and cost (based on 2016 Medicare reimbursement rates) were assessed. RESULTS: A total of 76,454 and 78,998 initial tests were performed during the study period using the 3rd generation and 4th generation HIV immunoassays, respectively. There were 516 (0.7%) and 581 (0.7%) total initially reactive results, respectively. Of these, 304 (58.9%) and 457 (78.7%) were positive by supplemental testing. There were 10 (0.01%) cases of acute HIV infection identified with the 4th generation algorithm. The most frequent tests performed to confirm an HIV-positive case using the 3rd generation algorithm, which were reactive initial immunoassay and positive HIV-1 Western blot, took a median time of 1.1 days to complete at a cost of $45.00. In contrast, the most frequent tests performed to confirm an HIV-positive case using the 4th generation algorithm, which included a reactive initial immunoassay and positive HIV-1/-2 antibody differentiation immunoassay for HIV-1, took a median time of 0.4 days and cost $63.25. Overall median turnaround time was 2.2 and 1.5 days, and overall median cost was $63.90 and $72.50 for 3rd and 4th generation algorithms, respectively. CONCLUSIONS: Both 3rd and 4th generation HIV immunoassays had similar total numbers of tests performed and positivity rates during the study period. A greater proportion of reactive 4th generation immunoassays were confirmed to be positive, and the 4th generation algorithm identified several cases of acute HIV infection that would have been missed by the 3rd generation algorithm. The 4th generation algorithm had a more rapid turnaround time but higher cost for confirmed positive HIV infections and overall, compared to the 3rd generation algorithm.

Clinical significance of coryneform Gram-positive rods from blood identified by MALDI-TOF mass spectrometry and their susceptibility profiles - a retrospective chart review.

With the advent of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), most Gram-positive rods (GPRs) are readily identified; however, their clinical relevance in blood cultures remains unclear. Herein, we assessed the clinical significance of GPRs isolated from blood and identified in the era of MALDI-TOF MS. A retrospective chart review of patients presenting to the Mayo Clinic, Rochester, MN, from January 1, 2013, to October 13, 2015, was performed. Any episode of a positive blood culture for a GPR was included. We assessed the number of bottles positive for a given isolate, time to positivity of blood cultures, patient age, medical history, interpretation of culture results by the healthcare team and whether infectious diseases consultation was obtained. We also evaluated the susceptibility profiles of a larger collection of GPRs tested in the clinical microbiology laboratory of the Mayo Clinic, Rochester, MN from January 1, 2013, to October 31, 2015. There were a total of 246 GPRs isolated from the blood of 181 patients during the study period. 56% (n = 101) were deemed contaminants by the healthcare team and were not treated; 33% (n = 59) were clinically determined to represent true bacteremia and were treated; and 8% (n = 14) were considered of uncertain significance, with patients prescribed treatment regardless. Patient characteristics associated with an isolate being treated on univariate analysis included younger age (P = 0.02), identification to the species level (P = 0.02), higher number of positive blood culture sets (P < 0.0001), lower time to positivity (P < 0.0001), immunosuppression (P = 0.03), and recommendation made by an infectious disease consultant (P = 0.0005). On multivariable analysis, infectious diseases consultation (P = 0.03), higher number of positive blood culture sets (P = 0.0005) and lower time to positivity (P = 0.03) were associated with an isolate being treated. 100, 83, 48 and 34% of GPRs were susceptible to vancomycin, meropenem, penicillin and ceftriaxone, respectively.

Utility of PCR, Culture, and Antigen Detection Methods for Diagnosis of Legionellosis.

The goal of this retrospective study was to evaluate the performance of different diagnostic tests for Legionnaires' disease in a clinical setting where Legionella pneumophila PCR had been introduced. Electronic medical records at the Cleveland Clinic were searched for Legionella urinary antigen (UAG), culture, and PCR tests ordered from March 2010 through December 2013. For cases where two or more test methods were performed and at least one was positive, the medical record was reviewed for relevant clinical and epidemiologic factors. Excluding repeat testing on a given patient, 19,912 tests were ordered (12,569 UAG, 3,747 cultures, and 3,596 PCR) with 378 positive results. The positivity rate for each method was 0.4% for culture, 0.8% for PCR, and 2.7% for UAG. For 37 patients, at least two test methods were performed with at least one positive result: 10 (27%) cases were positive by all three methods, 16 (43%) were positive by two methods, and 11 (30%) were positive by one method only. For the 32 patients with medical records available, clinical presentation was consistent with proven or probable Legionella infection in 84% of the cases. For those cases, the sensitivities of culture, PCR, and UAG were 50%, 92%, and 96%, respectively. The specificities were 100% for culture and 99.9% for PCR and UAG.

Does cumulative prostate cancer length (CCL) in prostate biopsies improve prediction of clinically insignificant cancer at radical prostatectomy in patients eligible for active surveillance?

OBJECTIVES: To evaluate if cumulative prostate cancer length (CCL) on prostate needle biopsy divided by the number of biopsy cores (CCL/core) could improve prediction of insignificant cancer on radical prostatectomy (RP) in patients with prostate cancer eligible for active surveillance (AS). PATIENTS AND METHODS: Patients diagnosed with prostate cancer on extended (≥10 cores) biopsy with an initial prostate-specific antigen (iPSA) level of <15 ng/mL, clinical stage (cT) ≤ 2a, and highest biopsy Gleason score 3 + 3 = 6 or 3 + 4 = 7 with <3 positive cores who underwent RP were included in the study. The CCL/core and presence of insignificant cancer (organ-confined, volume <0.5 mL, Gleason score at RP ≤6) were recorded. pT2 prostate cancer with RP Gleason score ≤3 + 4 = 7 and volume <0.5 mL were categorised as low-tumour-volume organ-confined disease (LV-OCD). RESULTS: In all, 221 patients met the inclusion criteria: the mean age was 59 years and the median iPSA level was 4.5 ng/mL. The clinical stage was cT1 in 86% of patients; biopsy Gleason score was 3 + 3 = 6 in 67% (group 1) and 3 + 4 = 7 in 33% of patients (group 2). The maximum percentage of biopsy core involvement was <50 in 85%; the median CCL/core was 0.15 mm. Insignificant cancer was found in 27% and LV-OCD in 44% of patients. Group 2 was associated with higher number of positive cores, maximum percentage core involvement, total prostate cancer length, and CCL/core. Group 1 was more likely to have insignificant cancer (39%) or LV-OCD (54%) than group 2 (3% and 23%, respectively). Group 2 had significantly higher RP Gleason score and pathological stage. Univariate analysis of group 1 showed that the iPSA level, maximum percentage core involvement, prostate cancer length, and CCL/core were all significantly associated with insignificant cancer and LV-OCD. For group 2, the number of positive cores (1 vs 2) was also significantly associated with LV-OCD. On multivariate logistic regression analysis, maximum percentage core involvement of <50, and number of positive cores (1 vs 2) were independent predictors of insignificant cancer in group 1; biopsy Gleason score, maximum percentage core involvement of <50 and prostate cancer length of <3 mm or CCL/core of <0.2 mm were all independent predictors of LV-OCD in the whole population. The maximum percentage of core involvement of <50 and prostate cancer length of <3 mm or CCL/core of <0.2 mm were also independent predictors of LV-OCD in group 1 patients. CONCLUSION: In patients eligible for AS, a CCL/core of <0.20 mm was significantly associated with insignificant cancer and LV-OCD. However, when parameters of cancer burden were considered, CCL/core did not independently add any additional value for predicting insignificant cancer in patients with biopsy Gleason score 6. The CCL/core was an independent predictor of LV-OCD in the whole population and in group 1 patients, although the model including prostate cancer length showed slightly higher area under the receiver operating characteristic curve.

Evaluation of simultaneous muscle and nerve biopsies for the diagnosis of neuromuscular diseases.

Skeletal muscle and peripheral nerve are occasionally simultaneously biopsied with the goal of increasing diagnostic yield in patients with an uncertain clinical diagnosis or in cases where the pathology is known to be focal or multifocal (eg, vasculitis or amyloidosis). The purpose of the present study is to evaluate the diagnostic utility of performing simultaneous muscle and nerve biopsies. A surgical pathology database was searched from 1993 to 2011 to identify patients who had concomitant skeletal muscle and peripheral nerve biopsies. Demographic and pathologic findings were recorded for all cases. Two hundred eighty-seven patients were included for study. There were 161 (56%) males and 126 (44%) females with a mean age at the time of biopsy of 51 years. The most commonly sampled sites were gastrocnemius muscle (n=186, 65%) and sural nerve (n=264, 92%). Most cases (n=166, 58%) were found to have a definitive diagnosis in either muscle or nerve. Of the cases with definitive diagnoses, 44 (27%) were based off the muscle only, 100 (60%) off the nerve only, and 22 (13%) had a definitive diagnosis in both the muscle and nerve. The most common diagnoses made on muscle biopsy alone were denervation atrophy (n=34) and inflammatory myopathy (n=7). The most common diagnosis made on nerve biopsy alone was a moderate or greater degree of axonal loss (n=82). Vasculitis was found in muscle in 2 cases, in the nerve in 14 cases, and both muscle and nerve in 4 cases. Amyloidosis was exclusive to muscle in no cases, was seen in nerve only in 1 case, and was found in both muscle and nerve in 4 cases. Performing simultaneous muscle and nerve biopsies can improve diagnostic yield (from 8% to 58% in the current study).

Cavernous angiomas in chronic epilepsy associated with focal cortical dysplasia.

Both cavernous angiomas and focal cortical dysplasia (FCD) are well recognized causes of pharmacoresistant epilepsy. Anecdotal cases of FCD adjacent to cavernous angiomas have been documented in the literature. This study systematically reviews a series of cavernous angiomas in epilepsy patients, looking for evidence of coexistent FCD. 146 patients were diagnosed with cavernous angiomas on resection specimens from January 1989 to May 2011; 18 cases also had epilepsy and had ample tissue excised to assess for FCD. FCD was classified according to criteria outlined by Palmini et al. [12]. Patients included 10 females (55.6%); the mean age of study patients was 38.5 years (range 21 - 51 years) at the time of resection. All patients had a history of epilepsy (median 11 years) prior to surgery. 17 cavernomas were located in the temporal lobe and 1 in the occipital lobe. Adjacent FCD was identified in 13 out of the 18 cases (72.2%): Type Ia (n = 8; 61.5%), Type Ib (n = 4; 30.8%), and Type IIa (n = 1; 7.7%). After resection, a majority of the patients experienced resolution of their epilepsy (n = 14; 77.8%). Of the 4 patients that did not experience seizure resolution, 2 had evidence of adjacent FCD (Type Ia = 1, Type Ib = 1) and 2 did not. FCD is frequently present in association with cavernous angiomas in patients with chronic epilepsy. The type of FCD seen adjacent to these lesions varies, but most are Palmini et al. Type I. Resection of the cavernous angiomas and adjacent FCD often results in a resolution of the epilepsy.