Point-of-Care Ultrasound by Nonexpert Operators Demonstrates High Sensitivity and Specificity in Detecting Gallstones: Data from the Samoa Typhoid Fever Control Program

Approximately 90% of chronic typhoid carriers with persistent Salmonella enterica serovar Typhi (S. Typhi) gallbladder infection have gallstones. In Samoa, where typhoid fever has been endemic for many decades, risk factors predisposing to the development of gallstones are increasing among adults. The Samoa Typhoid Fever Control Program dispatches a “Typhoid Epidemiologic SWAT Team” to perform a household investigation of every blood culture-confirmed case of acute typhoid fever. Investigations include screening household contacts to detect chronic carriers. Following limited training, two nonexpert ultrasound operators performed point-of-care ultrasound (POCUS) on 120 Samoan adults from August to September 2019 to explore the feasibility of POCUS to detect individuals with gallstones during household investigations and community screenings. POCUS scans from 120 Samoan adults in three cohorts (28 food handlers, two typhoid cases and their 18 household contacts, and 72 attendees at an ambulatory clinic) were reviewed by a board-certified radiologist who deemed 96/120 scans (80%) to be interpretable. Compared with the radiologist (gold standard), the nonexpert operators successfully detected 6/7 Samoans with gallstones (85.7% sensitivity) and correctly identified 85/89 without gallstones (95.5% specificity). The proportion (24/120) of uninterpretable scans from this pilot that used minimally trained clinicians (who are neither radiologists nor ultrasound technicians) indicates the need for additional training of POCUS operators. Nevertheless, this pilot feasibility study engenders optimism that in the Samoan setting nonexperts can be trained to use POCUS to diagnose cholelithiasis, thereby helping (along with stool cultures and Vi serology) to identify possible chronic S. Typhi carriers.

Intestinal Transgene Delivery with Native E. coli Chassis Allows Persistent Physiological Changes

Live bacterial therapeutics (LBT) could reverse disease by engrafting in the gut and providing persistent beneficial functions in the host. However, attempts to functionally manipulate the gut microbiome of conventionally-raised (CR) hosts have been unsuccessful, because engineered microbial organisms (i.e., chassis) cannot colonize the hostile luminal environment. In this proof-of-concept study, we use native bacteria as chassis for transgene delivery to impact CR host physiology. Native Escherichia coli isolated from stool cultures of CR mice were modified to express functional bacterial (bile salt hydrolase) and eukaryotic (Interleukin-10) genes. Reintroduction of these strains induces perpetual engraftment in the intestine. In addition, engineered native E. coli can induce functional changes that affect host physiology and reverse pathology in CR hosts months after administration. Thus, using native bacteria as chassis to knock-in specific functions allows mechanistic studies of specific microbial activities in the microbiome of CR hosts, and enables LBT with curative intent.

Clinical Significance of Toxigenic Clostridioides difficile Growth in Stool Cultures during the Era of Nonculture Methods for the Diagnosis of C. difficile Infection

The importance of detecting toxins or toxin genes when diagnosing Clostridioides difficile infections (CDIs) or predicting the severity and outcomes of CDI has been emphasized in recent years. Although the yielding of C. difficile from stool cultures might implicate higher bacterial loads in fecal samples, in an era of nonculture methods for the standard diagnosis of CDIs, clinical significance of positive stool cultures of toxigenic C. difficile was analyzed in this study.

An outbreak of salmonellosis among Filipinos in a private camp, Saudi Arabia

In October 1994, 19 Filipino professional staff of a large company in Damman city were hospitalized with acute febrile gastroenteritis. All ate three daily meals at the company cafeteria. A case-control investigation was begun to determine the cause of the outbreak. We searched the compound for any resident with a diarrhoeal illness. Both cases and controls were asked where and when foods were eaten during the three days before onset. Stool cultures were done for all patients and all 25 kitchen employees. Food cooking, handling and storage procedures were reviewed

Coinfection of the intestinal tract with Aeromonas hydrophila, Clostridium difficile and Rotavirus - a case report

Most cases of acute diarrhea in adults are of infectious etiology, likely viral and self-limited. Among those with severe diarrhea, however, bacterial causes are responsible for most cases. Apart from the standard stool cultures, to increase the positive yield a novel multiplex molecular test can be performed simultaneously. The authors present a patient with recurrent diarrhea and detection of Aeromonas hydrophila by culturing and Rotavirus and Clostridioides difficile by multiplex molecular test. They discuss and justify which is the most likely actionable pathogen. Good communication between the physicians and interpretation on the multiple positive results in the context of clinical picture and the test employed were important for a better management and favourable outcome of the patient.

Prospective Study in Children with Complicated Urinary Tract Infection Treated with Autologous Bacterial Lysates

Antimicrobial bacteria resistance is an important problem in children with recurrent urinary tract infections (rUTI), thus it is crucial to search for alternative therapies. Autologous bacterial lysates (ABL) may be a potential treatment for rUTI. Twenty-seven children with rUTI were evaluated for one year, urine and stool cultures were performed, 10 colonies of each culture were selected and those identified as Escherichia coli were characterized by serology. For patients who presented ≥105 UFC/mL, an ABL was manufactured and administered orally (1 mL/day) for a month. Twelve children were monitored for ≥1-year, 218 urine and 11 stool samples were analyzed. E. coli (80.5%) was the main bacteria isolated from urine and feces (72%). E. coli of classical urinary serotypes (UPEC), O25:H4, O75:HNM, and O9:HNM were identified in patients with persistent urinary infection (pUTI). In 54% of patients treated with ABL, the absence of bacteria was observed in urine samples after 3 months of treatment, 42% of these remained without UTI between 10–12 months. It was observed that the use of ABL controlled the infection for almost 1 year in more than 60% of the children. We consider it necessary to develop a polyvalent immunogen for the treatment and control of rUTI.

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

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.

P689 Aeromonas infection and Inflammatory Bowel Disease: a single tertiary center analysis

Background Aeromonas genus consists of gram-negative rods known to cause a spectrum of diseases in humans. Inflammatory bowel disease (IBD) is an idiopathic complex condition where multiple factors contribute to its development and progression. The association of Aeromonas infection with IBD manifestation have been proposed by other authors and is still largely unknown. We aim to look for the significance of Aeromonas infection and for significant differences between IBD and non-IBD patients. Methods A retrospective observational data retrieval and analysis was performed of all patients positive for Aeromonas in stool cultures, during a 10-year period, from a Portuguese tertiary and university setting hospital. Results Fifty patients, 56% of male sex and with a mean age of 42.1 years-old were included. Thirty-eight (76%) were non-IBD and 12 (24%) were IBD patients. IBD patients were more frequently under immunosuppressors. Two patients were asymptomatic and 44% develop mild, 44% moderate and 16.7% severe infection. The main Aeromonas strains isolated were Aeromonas hydrophila/caviae. Co-isolation with other bacteria was found in 4 non-IBD patients and histological findings compatible with Cytomegalovirus were found in 2 IBD patients. Non-IBD patients presented more frequently with fever and IBD patients with bloody diarrhea and abdominal pain. There was higher tendency for severe infection rate in IBD patients with higher antimicrobial therapy use. Steroids were exclusively used in IBD group. No significant differences were observed for isolation of Aeromonas resistant strains. From the IBD, 4 patients had the diagnosis of Ulcerative Colitis and 9 of Crohn’s Disease with colonic involvement. Of them 5 patients received the diagnosis after the acute episode of Aeromonas infection. Conclusion Clinical presentation of Aeromonas infection differ between IBD and non-IBD patients. Non-IBD patients had milder severity of infection with less use of antibiotics. Aeromonas infection seem to play an important role on the contribution of IBD manifestation.