Emergence of Erythromycin-Resistant Invasive Group A Streptococcus, West Virginia, USA, 2020-2021.

Clindamycin and ß-lactam antibiotics have been mainstays for treating invasive group A Streptococcus (iGAS) infection, yet such regimens might be limited for strains displaying MLSB phenotypes. We investigated 76 iGAS isolates from 66 patients in West Virginia, USA, during 2020-2021. We performed emm typing using Centers for Disease Control and Prevention guidelines and assessed resistance both genotypically and phenotypically. Median patient age was 42 (range 23-86) years. We found 76% of isolates were simultaneously resistant to erythromycin and clindamycin, including all emm92 and emm11 isolates. Macrolide resistance was conferred by the plasmid-borne ermT gene in all emm92 isolates and by chromosomally encoded ermA, ermB, and a single mefA in other emm types. Macrolide-resistant iGAS isolates were typically resistant to tetracycline and aminoglycosides. Vulnerability to infection was associated with socioeconomic status. Our results show a predominance of macrolide-resistant isolates and a shift in emm type distribution compared with historical reports.

Prevalence of erythromycin-resistant emm92-type invasive group A streptococcal infections among injection drug users in West Virginia, United States, 2021-23.

BACKGROUND: Increasing incidence of invasive group A Streptococcus (iGAS) disease has been reported in Europe and the USA over the past several years. Coupled with this are observations of higher rates of resistance to erythromycin and clindamycin. OBJECTIVES: To characterize iGAS and pharyngitis isolates from West Virginia (WV), a US state outside of the national Active Bacteria Core surveillance purview, where risk factors associated with iGAS infections are prevalent. METHODS: Seventy-seven invasive group A Streptococcus isolates were collected from 67 unique patients at the J.W. Ruby Memorial Hospital Clinical Microbiology Laboratory in WV from 2021 to 2023. Invasive isolates and 20 unique pharyngitis isolates were tested for clindamycin and erythromycin susceptibility in the clinical laboratory. Patient demographic and clinical information was retrieved from patient electronic health records. Isolates were further characterized based on emm subtype and detection of MLSB resistance determinants. RESULTS: Twenty-six (39%) isolates were of a single emm92 type. All emm92 isolates were uniformly erythromycin/clindamycin resistant with inducible or constitutive MLSB resistance imparted by the plasmid-borne erm(T) gene. The majority of emm92 infections were associated with adult patients who reported IV drug use, whereas no pharyngitis infections were caused by an emm92 strain. Overall, 51 (76%) of the 67 iGAS isolates were determined to carry MLSB resistance. CONCLUSIONS: Isolates of emm92 type (clonal subtype emm92.0) were associated with iGAS infections in adult IV drug users, but not with paediatric pharyngitis, and were uniformly resistant to erythromycin and clindamycin.

Prospective assessment of Clostridioides (formerly Clostridium) difficile colonization and acquisition in hematopoietic stem cell transplant patients.

BACKGROUND: Patients undergoing hematopoietic stem cell transplant (HSCT) possess numerous risk factors for Clostridioides (formerly Clostridium) difficile infection (CDI) and experience a high rate of diarrhea. Colonization rates of Clostridium difficile vary greatly among subgroup analyses with recent studies demonstrating colonization rates in the blood and marrow transplant units up to nine times that of the general population. METHODS: The primary objectives of this study were to identify the rate of C difficile colonization and acquisition in HSCT patients admitted to the blood and marrow transplant unit. This was a prospective study that included all adult patients admitted for hematopoietic stem cell transplantation. Stool specimens were routinely collected on admission and weekly thereafter for a maximum of six samples per patient. RESULTS: Forty-two patients met inclusion criteria and had baseline samples available for analysis. The rate of C difficile colonization on admission was 24%, and an additional 9% of patients acquired the organism during admission. Twelve percent of patients developed CDI that was diagnosed clinically. Univariate analysis showed an increased risk of colonization for patients with three or more prior chemotherapy cycles. CONCLUSIONS: Given high colonization rates coupled with high risk of CDI in this population, providers must be judicious when testing for CDI and interpreting test results for HSCT patients.

Vertebral osteomyelitis due to Candida species.

OBJECTIVE: We have noted an increased number of cases of vertebral osteomyelitis secondary to Candida species over the past few years at our facility. Our aim was to identify and review these cases to elucidate risk factors, treatment regimens and outcomes. METHODS: We performed a retrospective chart review using our electronic medical record and microbiology laboratory database to identify cases of vertebral osteomyelitis due to Candida at a single teaching hospital from 2006-2018. RESULTS: We found 15 cases of Candida vertebral osteomyelitis. The majority of cases were due to Candida albicans and affected either the lumbar or the thoracic spine. Injection drug use and previous spine surgery were the two most common risk factors identified. Treatment was largely with intravenous antifungal induction followed by prolonged therapy with oral fluconazole. There was no short-term mortality though we lacked long-term follow-up on most patients. CONCLUSIONS: The number of vertebral infections due to Candida may be increasing. This may be partially driven by both a rise in intravenous drug use as well as the growing rate of spine surgery. Management following currently available guidelines seems favorable, though further studies are necessary to determine the optimal treatment regimen.

Quantitative fecal lactoferrin in toxin-positive and toxin-negative Clostridium difficile specimens.

Quantitative fecal lactoferrin was measured in 112 patients tested for toxigenic Clostridium difficile using glutamate dehydrogenase (GDH) and toxin immunoassays combined with tcdB PCR. Lactoferrin levels were higher in the GDH-positive/toxin-positive group (79 µg/ml) than in the GDH-positive/toxin-negative/PCR-positive (21 µg/ml) and the GDH-negative groups (13 µg/ml). Differences in fecal lactoferrin levels suggest variable presence or severity of C. difficile infection among toxin-positive and toxin-negative patients.

Aspergillus collagen-like genes (acl): identification, sequence polymorphism, and assessment for PCR-based pathogen detection.

The genus Aspergillus is a burden to public health due to its ubiquitous presence in the environment, its production of allergens, and wide demographic susceptibility among cystic fibrosis, asthmatic, and immunosuppressed patients. Current methods of detection of Aspergillus colonization and infection rely on lengthy morphological characterization or nonstandardized serological assays that are restricted to identifying a fungal etiology. Collagen-like genes have been shown to exhibit species-specific conservation across the noncollagenous regions as well as strain-specific polymorphism in the collagen-like regions. Here we assess the conserved region of the Aspergillus collagen-like (acl) genes and explore the application of PCR amplicon size-based discrimination among the five most common etiologic species of the Aspergillus genus, including Aspergillus fumigatus, A. flavus, A. nidulans, A. niger, and A. terreus. Genetic polymorphism and phylogenetic analysis of the aclF1 gene were additionally examined among the available strains. Furthermore, the applicability of the PCR-based assay to identification of these five species in cultures derived from sputum and bronchoalveolar fluid from 19 clinical samples was explored. Application of capillary electrophoresis on nanogels was additionally demonstrated to improve the discrimination between Aspergillus species. Overall, this study demonstrated that Aspergillus acl genes could be used as PCR targets to discriminate between clinically relevant Aspergillus species. Future studies aim to utilize the detection of Aspergillus acl genes in PCR and microfluidic applications to determine the sensitivity and specificity for the identification of Aspergillus colonization and invasive aspergillosis in immunocompromised subjects.

Retrospective comparison of false-positive result frequencies of 3 syphilis serology screening tests in pregnant and nonpregnant patients at an academic medical center in Appalachia.

OBJECTIVE: This study retrospectively compared false-positive result frequencies of 3 syphilis serology screening tests and assessed whether false positivity was associated with pregnancy and age. METHODS: Results for 3 screening tests were retrieved from the laboratory database, including rapid plasma reagin (RPR) assay between October 2016 and September 2019, BioPlex 2200 Syphilis Total immunoassay between May 2020 and January 2022, and Alinity i Syphilis TP assay between February 2022 and April 2023. The false-positive result frequencies were calculated based on testing algorithm criteria. RESULTS: False-positive result frequency for BioPlex was 0.61% (90/14,707), significantly higher than 0.29% (50/17,447) for RPR and 0.38% (55/14,631) for Alinity (both P < .01). Patients with false-positive results were significantly older than patients with nonreactive results for RPR (median age: 36 vs 28, P < .001), but not for BioPlex or Alinity. For all 3 tests, the positive predictive values in pregnant women were lower than those in nonpregnant women or men. However, pregnant women did not exhibit a higher false-positive result frequency. CONCLUSION: Although false-positive result frequencies were low overall for all 3 syphilis serology tests, there is a significant difference between different tests. Pregnancy was not associated with more false-positive results for all 3 tests.

Candida dubliniensis endophthalmitis: first case in North America.

To report an unusual case of endogenous fungal endophthalmitis due to Candida dubliniensis. Interventional case report of a 27-year-old immunocompetent male with loss of vision, dense vitritis, and chorioretinal infiltrates, who underwent a diagnostic pars plana vitrectomy. Microbiology cultures obtained by a diagnostic vitrectomy were positive for the growth of C. dubliniensis. This infectious process was then appropriately treated with intravitreal amphotericin B and systemic fluconazole with resolution of the endophthalmitis. Endogenous fungal endophthalmitis is a condition that can masquerade other more common causes of endophthalmitis. Atypical cases of endophthalmitis may benefit from diagnostic pars plana vitrectomy for prompt diagnosis and treatment.

Stimulated innate resistance of lung epithelium protects mice broadly against bacteria and fungi.

Pneumonia is a serious problem worldwide. We recently demonstrated that innate defense mechanisms of the lung are highly inducible against pneumococcal pneumonia. To determine the breadth of protection conferred by stimulation of lung mucosal innate immunity, and to identify cells and signaling pathways activated by this treatment, mice were treated with an aerosolized bacterial lysate, then challenged with lethal doses of bacterial and fungal pathogens. Mice were highly protected against a broad array of Gram-positive, Gram-negative, and class A bioterror bacterial pathogens, and the fungal pathogen, Aspergillus fumigatus. Protection was associated with rapid pathogen killing within the lungs, and this effect was recapitulated in vitro using a respiratory epithelial cell line. Gene expression analysis of lung tissue showed marked activation of NF-kappaB, type I and II IFN, and antifungal Card9-Bcl10-Malt1 pathways. Cytokines were the most strongly induced genes, but the inflammatory cytokines TNF and IL-6 were not required for protection. Lung-expressed antimicrobial peptides were also highly up-regulated. Taken together, stimulated innate resistance appears to occur through the activation of multiple host defense signaling pathways in lung epithelial cells, inducing rapid pathogen killing, and conferring broad protection against virulent bacterial and fungal pathogens. Augmentation of innate antimicrobial defenses of the lungs might have therapeutic value for protection of patients with neutropenia or impaired adaptive immunity against opportunistic pneumonia, and for defense of immunocompetent subjects against a bioterror threat or epidemic respiratory infection.

Emergence of linezolid-resistant coagulase-negative Staphylococcus in a cancer centre linked to increased linezolid utilization.

OBJECTIVES: The prevalence of linezolid-resistant coagulase-negative Staphylococcus (CoNS) in the MD Anderson Cancer Center rose from 0.6% in 2007 to 5.5% in 2009. The aim of our study was to analyse the relationship between linezolid use and an outbreak of linezolid-resistant CoNS. PATIENTS AND METHODS: We retrospectively identified 27 infection or colonization events. Eleven isolates were available for supplemental investigation; species identification, clonal relatedness and linezolid resistance mutation analysis. The medical records of the affected patients were reviewed and linezolid utilization data were obtained from the pharmacy. RESULTS: Available isolates were confirmed as clonally related Staphylococcus epidermidis. Partial 23S rRNA gene sequencing found a G2576T mutation in all of the isolates tested. All patients received linezolid within 3 months prior to an event. Patients without a prior hospitalization had a longer time from admission to event; 29 versus 3.5 days (P = 0.002). The outbreak was preceded by a 51% increase in inpatient linezolid utilization and 64% of affected patients belonged to the leukaemia service, which had a utilization rate 3.1 times that of the other services (95% confidence interval: 2.96-3.23). CONCLUSIONS: Increased linezolid utilization preceded the appearance of a linezolid-resistant CoNS clone. Patients probably acquired the clonal strain nosocomially, given the longer time from admission to event among patients with no previous admission to the MD Anderson Cancer Center. Linezolid administration then selected this strain, since all patients received linezolid prior to an event. A linezolid utilization rate of >or=13 defined daily doses/100 patient-days was similar to that reported in two other outbreaks and may be the threshold required to generate an outbreak.

Burkholderia collagen-like protein 8, Bucl8, is a unique outer membrane component of a putative tetrapartite efflux pump in Burkholderia pseudomallei and Burkholderia mallei.

Bacterial efflux pumps are an important pathogenicity trait because they extrude a variety of xenobiotics. Our laboratory previously identified in silico Burkholderia collagen-like protein 8 (Bucl8) in the hazardous pathogens Burkholderia pseudomallei and Burkholderia mallei. We hypothesize that Bucl8, which contains two predicted tandem outer membrane efflux pump domains, is a component of a putative efflux pump. Unique to Bucl8, as compared to other outer membrane proteins, is the presence of an extended extracellular region containing a collagen-like (CL) domain and a non-collagenous C-terminus (Ct). Molecular modeling and circular dichroism spectroscopy with a recombinant protein, corresponding to this extracellular CL-Ct portion of Bucl8, demonstrated that it adopts a collagen triple helix, whereas functional assays screening for Bucl8 ligands identified binding to fibrinogen. Bioinformatic analysis of the bucl8 gene locus revealed it resembles a classical efflux-pump operon. The bucl8 gene is co-localized with downstream fusCDE genes encoding fusaric acid (FA) resistance, and with an upstream gene, designated as fusR, encoding a LysR-type transcriptional regulator. Using reverse transcriptase (RT)-qPCR, we defined the boundaries and transcriptional organization of the fusR-bucl8-fusCDE operon. We found exogenous FA induced bucl8 transcription over 80-fold in B. pseudomallei, while deletion of the entire bucl8 locus decreased the minimum inhibitory concentration of FA 4-fold in its isogenic mutant. We furthermore showed that the putative Bucl8-associated pump expressed in the heterologous Escherichia coli host confers FA resistance. On the contrary, the Bucl8-associated pump did not confer resistance to a panel of clinically-relevant antimicrobials in Burkholderia and E. coli. We finally demonstrated that deletion of the bucl8-locus drastically affects the growth of the mutant in L-broth. We determined that Bucl8 is a component of a novel tetrapartite efflux pump, which confers FA resistance, fibrinogen binding, and optimal growth.

Rate of surface contamination in the operating suite during revision total joint arthroplasty.

BACKGROUND: This study estimated operating room surface contamination rates during aseptic vs septic total joint arthroplasty and evaluated the similarity between clinically infecting organisms and those isolated from contaminated surfaces. METHODS: Patients undergoing total hip and knee revision arthroplasties were identified, and surface and tissue samples were collected. Cases were classified aseptic or septic based on Musculoskeletal Infection Society criteria for prosthetic joint infection. Positive surface cultures were compared with intraoperative tissue cultures. Positive cultures were speciated and tested for antimicrobial sensitivity. RESULTS: Samples were collected from 31 aseptic and 18 septic cases. Patients had similar demographics and time to explantation. Surface contamination rates for septic revisions were greater than those for aseptic revisions (77% vs 13%). During septic revisions, when intraoperative tissue cultures were positive, the surgical field was contaminated in 14 of 15 cases. The kappa correlation statistic for positive surgical cultures matching the surface sample was 0.9 (95% confidence interval: 0.78-1). CONCLUSIONS: Septic revisions had a significantly higher rate of surgical field contamination than aseptic revisions. Cultures suggest that bacteria contaminating the septic revision surgical field likely originated from the infected joint. Although this observation seems obvious, it is an important piece of information when discussing best practices during a single-stage exchange revision. Further clinical studies will demonstrate the use of a preparation and reset period during a single-stage revision to remove contaminated surfaces.

Prospective comparison of R-mix shell vial system with direct antigen tests and conventional cell culture for respiratory virus detection.

BACKGROUND AND OBJECTIVES: Conventional cell culture (CC) has limited clinical utility as a result of the extended incubation period often required for virus isolation. Alternative methodologies have been introduced in an effort to improve turnaround times. One such system, the R-mix shell vial is discussed herein. The study objectives were: (a) to establish R-mix testing parameters as compared to direct antigen testing (DAT) and CC, and (b) to assess technical aspects and cost of R-mix in a high volume clinical virology laboratory. STUDY DESIGN: A prospective analysis of respiratory samples submitted to the clinical virology laboratory between November 2004 and April 2005 was performed. All specimens were inoculated onto R-mix shell vials (SV) and CC tubes; and a subset also underwent DAT for influenza A and B and/or RSV. A retrospective estimated cost analysis was made. RESULTS: A total of 563 samples were included in the study, which collectively revealed a total of 207 viruses. Sensitivity of R-mix for seven major respiratory viruses ranged from 45% to 83% compared to CC and DAT, while mean time to detection (TTD) varied from 1.1 to 1.4 days. In addition to these viruses, 23 picornaviruses, 11 CMV isolates and 5 HSV isolates were detected by CC alone. CONCLUSIONS: The R-mix system has similar sensitivity as CC for the detection of parainfluenza 1-3 and influenza A/B while dramatically reducing the TTD. Furthermore, it is significantly more sensitive and produces more timely results for RSV than CC; yet, neither method offers a diagnostic benefit over rapid DAT for RSV detection. The sensitivity of R-mix for adenovirus appears to be significantly lower than that of CC. Lastly, methodologies other than R-mix must remain in place under circumstances where identification of other potential viral respiratory pathogens, including herpesviruses and picornaviruses, is desired.

Multidisciplinary performance improvement team for reducing health care-associated Clostridium difficile infection.

Clostridium difficile is the most frequent cause of health care-associated diarrhea and is a significant cause of morbidity and mortality. It is also associated with a considerable financial burden. A concerted multidisciplinary approach is required for prevention.

Invasive Exserohilum sinusitis in a patient with aplastic anemia.

A case of acute, invasive, sinusitis caused by the dematiaceous mold Exserohilum rostratum is presented. Herein we examine the subtypes of fungal sinusitis and briefly discuss some characteristics, pathologic and microbiologic differential diagnoses and management strategies of Exserohilum sinus infection in an immunocompromised patient.

Nocardiosis in 132 patients with cancer: microbiological and clinical analyses.

OBJECTIVES: To correlate the microbiological and clinical features of infections caused by Nocardia species. METHODS: We determined the species and drug susceptibility of 138 Nocardia strains isolated from 132 patients at the University of Texas M. D. Anderson Cancer Center (Houston, TX) from 2002 through 2012 and analyzed the clinical features. RESULTS: The 132 patients included 82 men and 50 women with a mean age of 59.1 years. All except two had underlying cancer, and 47 (35.6%) also received a stem cell transplant. These patients experienced 136 episodes of Nocardia infection, including pulmonary infection, abscess of deep skin and soft tissue, bacteremia and dissemination, and brain abscess. The 138 Nocardia strains involved 27 species, of which 20 species have been described since 2000. Common species included Nocardia nova, Nocardia cyriacigeorgica, Nocardia farcinica, and Nocardia abscessus, together accounting for 59.4%. N nova caused most bacteremia cases, whereas N farcinica caused most of the skin and brain infections. Infections with a few recent species likely represented first confirmation or report of human infections. Antimicrobial susceptibility tests of 117 strains showed that they were all susceptible to trimethoprim-sulfamethoxazole and linezolid but variably susceptible to other drugs depending on species. Most patients who were treated for the infection showed improvement or resolution. CONCLUSIONS: Diverse Nocardia species can cause secondary infections in patients with cancer. Timely species identification and antimicrobial susceptibility tests may guide treatment.

Pathology consultation on detection of Clostridium difficile.

Laboratory methods for detecting Clostridium difficile have undergone considerable evolution since the organism's etiologic association with antibiotic-associated diarrhea and colitis was established. Clearly, familiarity with the advantages and shortcomings of the various assays is essential for the laboratory director when choosing among these tests. For the consulting pathologist, furthermore, an understanding of the laboratory's role in securing a diagnosis of C difficile infection (CDI) is also required to identify requests for unnecessary testing that may be costly and potentially misleading. The purpose of this article is to highlight the major differences in laboratory test methods for CDI and to review a few commonly encountered provider ordering scenarios.

Comparison of analytical and clinical performance of three methods for detection of Clostridium difficile.

CONTEXT: Diagnostic laboratory testing for Clostridium difficile infection has undergone considerable and rapid evolution during the last decade. The ideal detection method(s), which should exhibit high analytical and clinical sensitivity and specificity, remains undefined. OBJECTIVE: We sought to evaluate the analytical and clinical performance characteristics of three methods for the laboratory detection of C difficile. DESIGN: This study used 114 consecutive stool samples to compare three methods of C difficile detection: an enzyme immunoassay (EIA) for toxins A/B, a lateral flow membrane immunoassay for glutamate dehydrogenase (GDH), and a qualitative real-time polymerase chain reaction (PCR) assay. Medical records of all patients having ≥1 positive test result were reviewed to estimate the clinical likelihood of C difficile infection. RESULTS: Based upon laboratory result consensus values, analytical sensitivity was significantly higher for GDH (94%) and PCR (94%) assays than for toxin EIA (25%). Analytical specificity was significantly higher for PCR (100%) and EIA (100%) than for GDH assay (93%). In contrast, assay performance based upon clinical probability of C difficile infection suggested lower discriminatory power (ie, clinical specificity) of the more analytically sensitive methods. CONCLUSIONS: Higher rates of C difficile detection will be realized upon implementation of GDH assay and/or real-time PCR-based testing algorithms than by testing with EIA alone. Further study is required to elucidate potential downstream costs for higher detection rates.