Mehreen Arshad

Hepatitis C virus infection during pregnancy and the newborn period--are they opportunities for treatment?

Summary.  The worldwide prevalence of hepatitis C virus (HCV) infection in pregnant women is estimated to be between 1 and 8% and in children between 0.05% and 5%. While parenteral transmission is still common in children living in developing countries, perinatal transmission is now the leading cause of HCV transmission in developed countries. The absence of an HCV vaccine or approved therapy during pregnancy means that prevention of vertical transmission is still not possible. However, a low vertical transmission rate of 3–5%, a high rate of spontaneous clearance (25–50%) and delayed morbidity have resulted in HCV being overlooked in pregnant women and their infants. Yet a study of the natural history in mothers and children demonstrates that the prognosis of HCV can vary greatly and should be taken seriously. Factors known to increase the risk of perinatal transmission include HIV coinfection and higher maternal viral loads, while elective C‐section and withholding breastfeeding have not been demonstrated to reduce vertical transmission. Current guidelines for the diagnosis of persistent perinatal infection require a positive anti‐HCV test in infants born to infected mothers after 12 months or two positive HCV RNA tests at least 6 months apart. Current HCV treatment options using pegylated interferon and ribavirin are both unsuitable for use in pregnancy and infancy. However, new agents currently in preclinical phases of development, along with the recently identified association between single‐nucleotide polymorphisms within the IL28 gene and treatment response, may serve to create a therapeutic window for these patients.

Urinary Tract Infections in the Infant

Urinary tract infection (UTI) in an infant may be the first indication of an underlying renal disorder. Early recognition and initiation of adequate therapy for UTI is important to reduce the risk of long-term renal scarring. Ampicillin and gentamicin are traditionally the empiric treatment of choice; however, local antibiotic resistance patterns should be considered. Maternal antibiotics during pregnancy also increase the risk of resistant pathogens during neonatal UTI. Long-term management after the first UTI in infants remains controversial because of lack of specific studies in this age group and the risk-benefit issues for antibiotic prophylaxis between reduced recurrent disease and emergent antibiotic resistance.

Lifting the Mask: Identification of New Small Molecule Inhibitors of Uropathogenic Escherichia coli Group 2 Capsule Biogenesis

Uropathogenic Escherichia coli (UPEC) is the leading cause of community-acquired urinary tract infections (UTIs), with over 100 million UTIs occurring annually throughout the world. Increasing antimicrobial resistance among UPEC limits ambulatory care options, delays effective treatment, and may increase overall morbidity and mortality from complications such as urosepsis. The polysaccharide capsules of UPEC are an attractive target a therapeutic, based on their importance in defense against the host immune responses; however, the large number of antigenic types has limited their incorporation into vaccine development. The objective of this study was to identify small-molecule inhibitors of UPEC capsule biogenesis. A large-scale screening effort entailing 338,740 compounds was conducted in a cell-based, phenotypic screen for inhibition of capsule biogenesis in UPEC. The primary and concentration-response assays yielded 29 putative inhibitors of capsule biogenesis, of which 6 were selected for further studies. Secondary confirmatory assays identified two highly active agents, named DU003 and DU011, with 50% inhibitory concentrations of 1.0 µM and 0.69 µM, respectively. Confirmatory assays for capsular antigen and biochemical measurement of capsular sugars verified the inhibitory action of both compounds and demonstrated minimal toxicity and off-target effects. Serum sensitivity assays demonstrated that both compounds produced significant bacterial death upon exposure to active human serum. DU011 administration in mice provided near complete protection against a lethal systemic infection with the prototypic UPEC K1 isolate UTI89. This work has provided a conceptually new class of molecules to combat UPEC infection, and future studies will establish the molecular basis for their action along with efficacy in UTI and other UPEC infections.

Threading the needle: small molecule targeting of a xenobiotic receptor to ablate Escherichia coli polysaccharide capsule expression without altering antibiotic resistance

BACKGROUND Uropathogenic Escherichia coli (UPEC), a leading cause of urinary tract and invasive infections worldwide, is rapidly acquiring multidrug resistance, hastening the need for selective new anti-infective agents. Here we demonstrate the molecular target of DU011, our previously discovered potent, nontoxic, small-molecule inhibitor of UPEC polysaccharide capsule biogenesis and virulence. METHODS Real-time polymerase chain reaction analysis and a target-overexpression drug-suppressor screen were used to localize the putative inhibitor target. A thermal shift assay quantified interactions between the target protein and the inhibitor, and a novel DNase protection assay measured chemical inhibition of protein-DNA interactions. Virulence of a regulatory target mutant was assessed in a murine sepsis model. RESULTS MprA, a MarR family transcriptional repressor, was identified as the putative target of the DU011 inhibitor. Thermal shift measurements indicated the formation of a stable DU011-MprA complex, and DU011 abrogated MprA binding to its DNA promoter site. Knockout of mprA had effects similar to that of DU011 treatment of wild-type bacteria: a loss of encapsulation and complete attenuation in a murine sepsis model, without any negative change in antibiotic resistance. CONCLUSIONS MprA regulates UPEC polysaccharide encapsulation, is essential for UPEC virulence, and can be targeted without inducing antibiotic resistance.

Clinical and Genomic Characterization of Recurrent Enterococcal Bloodstream Infection in Patients with Acute Leukemia

Abstract Background Rates and risk factors for recurrent enterococcal bloodstream infection (R-EBSI) and whether the same genetic lineage causes index EBSI and R-EBSI are unknown in patients with acute leukemia (AL) receiving chemotherapy. Methods Ninety-two AL patients with EBSI from 2010 to 2015 were included. Enterococcal bloodstream infection was defined by 31 positive blood cultures for Enterococcus faecium or Enterococcus faecalis and fever, hypotension, or chills. Clearance was defined by 31 negative cultures 324 hours after last positive culture and defervescence. Recurrent enterococcal bloodstream infection was defined by a positive blood culture for Enterococcus 324 hours after clearance. Categorical variables were reported as proportions and compared by the χ2 test. Continuous variables were summarized by median and interquartile range (IQR) and compared by the Wilcoxon-Mann-Whitney Test. P values <.05 were considered significant. Whole-genome sequencing was performed on available paired BSI isolates from 7 patients. Results Twenty-four patients (26%) had 31 episodes of R-EBSI. Median time to R-EBSI (IQR) was 26 (13–50) days. Patients with R-EBSI had significantly longer durations of fever and metronidazole exposure during their index EBSI. Thirty-nine percent of E. faecium R-EBSI isolates became daptomycin-nonsusceptible Enterococcus (DNSE) following daptomycin therapy for index EBSI. Whole-genome sequencing analysis confirmed high probability of genetic relatedness of index EBSI and R-EBSI isolates for 4/7 patients. Conclusions Recurrent enterococcal bloodstream infection and DNSE are common in patients with AL and tend to occur within the first 30 days of index EBSI. Duration of fever and metronidazole exposure may be useful in determining risk for R-EBSI. Whole-genome sequencing analysis demonstrates that the same strain causes both EBSI and R-EBSI in some patients.

Update on Associated Risk Factors, Diagnosis, and Management of Recurrent Urinary Tract Infections in Children

Recurrent urinary tract infection (rUTI) continues to challenge pediatric care providers. The diagnosis of an rUTI can be difficult, especially in young febrile children. Antibiotic resistance rates continue to rise, which limits oral treatment options. Prophylactic antibiotics are used commonly to manage rUTI, but their use increases the risk of rUTI with antibiotic-resistant strains without significantly reducing renal scarring. Alternative therapies for rUTI include probiotics and anthocyanidins (eg, cranberry extract) to reduce gut colonization by uropathogens and prevent bacterial adhesion to uroepithelia, but efficacy data for these treatments are sparse. The future of rUTI care rests in addressing the following contemporary issues: best diagnostic practices, risk factors associated with rUTI, and the prevention of recurrent infection. In this review, we summarize the state of the art for each of these issues and highlight future studies that will aim to take an alternative approach to managing rUTI.

Utility of Autopsy among Pediatric Allogeneic Hematopoietic Stem Cell Transplant Recipients: One Last Chance to Learn?

Autopsy may confirm clinical diagnoses or identify conditions that were not suspected prior to a patients death. Previous studies evaluating the utility of autopsy in hematopoietic stem cell transplant (HSCT) recipients yielded conflicting results. We conducted a retrospective cohort study of children (<18 years of age) undergoing allogeneic HSCT at Duke University who died of any cause between January 1, 1995, and December 31, 2016. We evaluated associations between patient characteristics and autopsy performance using chi-square or Fisher exact tests. We reviewed autopsy reports to determine the concordance between preautopsy causes of death and pathological diagnoses identified on autopsy. We classified unexpected diagnoses on autopsy using criteria developed by Goldman et al. We evaluated for temporal changes in the autopsy consent rate and the frequency of unexpected diagnoses on autopsy using Cochran-Armitage tests. During the 22-year study period, 475 patients died and had data available on autopsy performance, and 130 (27%) of these patients underwent autopsy. The autopsy consent rate declined over time (P < .0001), with autopsies being performed for 40% of deaths in 1995 to 1999 and 17% of deaths in 2009 to 2016. White patients were more likely to undergo autopsy than nonwhite patients (P = .03). There were no associations between autopsy performance and patient age, sex, HSCT indication, or HSCT donor. Unexpected diagnoses were identified in 31 (24%) autopsies. The proportion of autopsies with an unexpected diagnosis did not change during the study period (P = .45). However, infectious diagnoses that would have led to a change in management were more frequently identified on autopsies in 1995 to 2003 than in 2004 to 2016 (20% versus 0%; P = .001). The autopsy consent rate for pediatric HSCT recipients at our institution has declined substantially over the past several decades. The utility of autopsy in this patient population remains high despite a reduction in the identification of unexpected infections.

Copper Influences the Antibacterial Outcomes of a β-Lactamase-Activated Prochelator against Drug-Resistant Bacteria

The unabated rise in bacterial resistance to conventional antibiotics, coupled with collateral damage to normal flora incurred by overuse of broad-spectrum antibiotics, necessitates the development of new antimicrobials targeted against pathogenic organisms. Here, we explore the antibacterial outcomes and mode of action of a prochelator that exploits the production of β-lactamase enzymes by drug-resistant bacteria to convert a nontoxic compound into a metal-binding antimicrobial agent directly within the microenvironment of pathogenic organisms. Compound PcephPT (phenylacetamido-cephem-pyrithione) contains a cephalosporin core linked to 2-mercaptopyridine N-oxide (pyrithione) via one of its metal-chelating atoms, which minimizes its preactivation interaction with metal ions and its cytotoxicity. Spectroscopic and chromatographic assays indicate that PcephPT releases pyrithione in the presence of β-lactamase-producing bacteria. The prochelator shows enhanced antibacterial activity against strains expressing β-lactamases, with bactericidal efficacy improved by the presence of low-micromolar copper in the growth medium. Metal analysis shows that cell-associated copper accumulation by the prochelator is significantly lower than that induced by pyrithione itself, suggesting that the location of pyrithione release influences biological outcomes. Low-micromolar (4-8 μg/mL) minimum inhibitory concentration (MIC) values of PcephPT in ceftriaxone-resistant bacteria compared with median lethal dose (LD50) values greater than 250 μM in mammalian cells suggests favorable selectivity. Further investigation into the mechanisms of prochelators will provide insight for the design of new antibacterial agents that manipulate cellular metallobiology as a strategy against infection.