An Unusual Case of Perirenal Abscess Caused by Campylobacter and Peptostreptococcus Species

Intra-abdominal abscesses mostly derive from the intra-abdominal viscera. Campylobacter spp. are Gram-negative rods which are known to cause oral infections but rarely have been documented to cause extra-intestinal infections resulting in abscesses. We report an atypical case of Campylobacter rectus (C. rectus) and Peptostreptococcus spp. bacteria isolated from a perinephric abscess presenting as abdominal pain. Abscesses originating from outside the gastrointestinal tract have been reported in other similar case reports infecting the head, brain, and thoracic wall amongst others. The potential source and development of such a Campylobacter infection could be due to multiple hypotheses. This is a first case report of perinephric abscess development. Studies have suggested person-to-person (fecal-oral) transmission along with insects serving as primary reservoirs. Seeding of bacteria through infections in the oral cavity or through infections in the bowel microperforations has also been considered as plausible reasons. Since C. rectus has been isolated in such rare instances, it should be kept in mind when considering differential diagnosis of potential causative agents for extra-oral infections such as invasive abscess formations.

Candida glabrata MSH2 deletion increases antifungal tolerance in vitro and during intra-abdominal candidiasis (IAC), it does not impact pathogenesis of peritonitis or intra-abdominal abscesses

Background: IAC is the second most common type of invasive Candidiasis, but its pathogenesis is poorly understood. We have shown that Candida albicans DNA damage response genes are strongly induced within intra-abdominal abscesses. Deletion of C. glabrata MSH2, A DNA mismatch repair (MMR) gene, results in a mutator phenotype that facilitates multidrug resistance in vitro and in mouse gastrointestinal tracts. Our goal was to determine if CGMSH2 Contributed to pathogenesis or resistance to the new antifungal rezafungin during IAC. Methods: We createdΔMSH2 in BG2 using SAT-Flipper, and tested virulence and rezafungin responses in a mouse model of IAC. Results: ΔMSH2 displayed no growth defects at 30°C in liquid (YPD, Ypglycerol) or solid media (YPD+0.02% MMS, 1MM H2O2, 1M NACL, 20 UG/ML CW, 250 UG/ML OR 0.02% SDS). ΔMSH2 longevity in YPD was comparable to BG2. Caspofungin-, Rezafungin- and Fluconazole-resistant mutants arose 24-, 16- and 3-fold more often, respectively, for ΔMSH2 than BG2 (108-106 CFU overnight in YPD, selected on 8XMIC-Containing plates). However, respective minimum inhibitory concentrations (MICS) were not different, nor were rezafungin time-kills.ΔMSH2 was comparable to BG2 in peritonitis and abscess burdens in mouse IAC.ΔMSH2 demonstrated significantly greater caspofungin- and fluconazole-tolerance than BG2 in abscesses. Rezafungin reduced peritonitis and abscess burdens ofΔMSH2,BG2 ANDFKS mutant strains to similar extents. Conclusions: CgMSH2 deletionincreased the frequency of spontaneously-arising echinocandin- and fluconazole-resistant colonies in vitro and tolerance in intra-abdominal abscesses, but it did not attenuate virulence or rezafungin responses during IAC.

An Alarming Mimicry of Intra-Abdominal Infections: Acute Appendiceal Diverticulitis

A 65-year-old woman presented with three days of colicky abdominal pain. Abdominal imaging illustrated small bowel enteritis, ascites in both paracolic gutters, and incidental hepatic steatosis. Although ascites fluid demonstrated high neutrophil count consistent with peritonitis and the patient received adequate antibiotics, she clinically deteriorated. Subsequent exploratory laparotomy revealed necrotic appendix and multiple intra-abdominal abscesses. Histopathology showed acute suppurative appendicitis with multiple other intact small diverticula, indicating likely perforation of inflamed appendiceal diverticula with subsequent abscess formation and abdominal peritonitis. This case highlights the importance of ascites fluid analysis and continued clinical correlation, especially in cases of rare entities with atypical presentations.

88. Effect of an MDR Enterobacterales Screening Tool on Antibiotic Prescribing for Abdominal Infections Caused by Mixed Bacteria

Background Background: Choosing antibiotics for infections caused by mixed Enterobacterales is challenging. Our microbiology lab implemented a multi-drug resistance (MDR) screen for cultures with mixed gram-negative to direct clinicians to use 3rd generation cephalosporins for screen neg. pathogens, and to use broader beta-lactams for screen-pos. pathogens. Here we report the effect of MDR screen on final antibiotic choice. Methods Methods: We retrospectively reviewed cases with abdominal infections caused by mixed bacteria at UNC Medical Center between August and November 2020. Cultures with non-Enterobacteraeles gram negatives were excluded. MDR screen was done by plating mixed Enterobacterales on HardyCHROM™ ESBL agar. Screen-pos. cases were updated “MDR Enterobacterales present” and pathogens were identified with full susceptibilities. Screen-neg. cases were labeled “MDR Enterobacterales not present”. Definitely covering antibiotics were defined by the use of 3rd generation cephalosporins for screen neg. cases, or based on susceptibilities in case of screen pos. organisms or concomitant bacteremia. Possibly covering antibiotics included regimens whose susceptibility could not be predicted based on the screen (e.g., amox/clav or quinolone+metronidazole). Results Results: 51 cases were identified. Median age was 51 years (range 10 to 87). 54.9% were female and 45.1% male. Infections included intra-abdominal abscesses (n =35), perirectal or scrotal abscesses (10), abdominal wound infections (4), perineal necrotizing fasciitis (1), and cholecystitis (1). Sample types were abscess fluid (43), wound purulence (4) or tissue (3). MDR screen was pos. in 7.8%. Antibiotics were adjusted in 17.6% as a result of the screen report. 31.5% of final antibiotics definitely covered the isolated bacteria, 56.9% possibly covered, and 5.9% did not have an active antibiotic. Among screen pos. cases, final antibiotics definitely covered in 75% and possibly in 25%. Conclusion Conclusions: The MDR Enterobacterales screening tool for abdominal infections had limited impact on final antibiotic choice, but was useful when positive. Further directions include assessment of provider understanding of the MDR screen results and investigation of utility of screen in other infection types. Disclosures All Authors: No reported disclosures

Genomic Features of Salmonella enterica Subspecies houtenae Serotype 45:g,z51:- Isolated from Multiple Abdominal Abscesses of an African Fat-Tailed Gecko, United States, 2020

Salmonella enterica subsp. houtenae (S. houtenae) is a common subspecies in reptiles and has been implicated as a source of serious and life-threatening diseases in humans. Although occurrence and significance of S. houtenae infections have been extensively studied, the genetic features of S. houtenae have remained unknown due to a lack of available high-quality genome sequences. We obtained the complete genome sequence of S. houtenae 45:g,z51:- strain 20-369 isolated from multiple abdominal abscesses of an African fat-tailed gecko (Hemitheconyx caudicinctus) using Nanopore and Illumina sequencing technologies and generated the 4.65Mbp complete genome sequence of the S. houtenae str. 20-369. We annotated and analyzed the genome sequence with the aim to gain a deeper understanding of the genome characteristics associated with its pathogenicity. Overall, this study found several interesting genomic features such as pseudogene formation, virulence gene profile, and novel genomic islands. This study provides basis for an understanding possible genetic mechanism underlying pathogenicity of S. houtenae 45:g,z51:- as well as a high-quality genome reference for future comparison studies.

EP.TH.1029Surgery for retained gallstones: A single centre experience

Aims Lost spilled gallstones during laparoscopic cholecystectomy is a rare inadvertent complication results in recurrent delayed sepsis. Diagnosis is made via retrospective review of operative notes. 2 cases of retained gallstones were removed surgically, following several years after the initial laparoscopic cholecystectomy. Conclusion 2 cases presented with delayed symptoms of abdominal pain, sepsis with intra-abdominal collections. Intra-abdominal abscesses treated with percutaneous USS guided drainage & antibiotics. Abscesses arise in right subphrenic space, right anterior abdominal wall & iliacus as a result of gallstone migration. Diagnosis of “spilled lost gallstones” was delayed until confirmation of retained gallstones on radiological imaging. Combination of USS, CT and MRI scan enabled to detect retained gallstones (radiolucent or radio-opaque) within an abscess cavity. Multi-disciplinary approach allowed a more concerted management i.e. diagnosis of retained gallstones & planning surgical exploration for retained gallstones. Ultimately, abscesses should be drained (percutaneously or surgically), and retained stones should be removed. Ideally this is done via minimally invasive techniques, but open surgery is often required. Use of laparoscopy enables exploration of the peritoneal cavity and any abscess cavity. This exploration will extract any fragment of gallstone that could be a nidus for continuous infection.

661 Improving Antibiotic Prescribing in a District General Hospital: A Closed Loop Audit

Aim Broad-spectrum antibiotics are effective in decreasing wound infection and postoperative intra-abdominal abscesses for patients undergoing appendicectomy. Compliance with local hospital antibiotic guidelines is important in ensuring antibiotic efficacy and reducing potential for toxicity and antibiotic resistance. The aim was to assess the impact of educational interventions on the adherence to local antibiotic guidelines in patients undergoing appendicectomy at a Scottish district general hospital. Method Preoperative antibiotic prescribing in consecutive adult patients aged ≥ 16 years undergoing appendicectomy were audited against hospital guidelines over a four-month period between March 2019 and July 2019. We implemented change through antibiotic prescribing teaching for doctors in the surgical team and anaesthetic team. This change was subsequently evaluated through a re-audit over a three-month period between December 2019 and February 2020. Results The baseline audit demonstrated 68.8% (n = 11/16) compliance to local antibiotic guidelines among patients undergoing appendicectomy. The remaining patients had the correct choice of antibiotics, but gentamicin was prescribed in different doses. Gaps in prescriber awareness of antibiotic guidelines were identified. Following departmental teaching sessions regarding antibiotic prescribing and use of the gentamicin dosing calculator, the re-audit showed 93.8% (n = 15/16) compliance with local antibiotic guidelines among prescribers in the surgical team and anaesthesic team. Conclusions Education interventions were instrumental in improving adherence to antibiotic prescribing guidelines. This highlights the importance of regular audit and prescriber education in the promotion of antibiotic stewardship in hospitals.

Severe pneumonia caused by Parvimonas micra: a case report

Background Parvimonas micra (P. micra) is a gram-positive anaerobic coccus that is detected widely on the skin, in the oral mucosa and in the gastrointestinal tract. In certain circumstances, P. micra can cause abdominal abscesses, bacteraemia and other infections. To the best of our knowledge, there have been no case reports describing the biological characteristics of P. micra-related pneumonia. These bacteria do not always multiply in an aerobic organ, such as the lung, and they could be easily overlooked because of the clinical mindset. Case presentation A 35-year-old pregnant woman was admitted to the emergency department 4 weeks prior to her due date who was exhibiting 5 points on the Glasgow coma scale. A computed tomography (CT) scan showed a massive haemorrhage in her left basal ganglia. She underwent a caesarean section and brain surgery before being admitted to the ICU. She soon developed severe pneumonia and hypoxemia. Given that multiple sputum cultures were negative, the patient’s bronchoalveolar lavage fluid was submitted for next-generation sequencing (NGS) to determine the pathogen responsible for the pneumonia; as a result, P. micra was determined to be the causative pathogen. Accordingly the antibiotic therapy was altered and the pneumonia improved. Conclusion In this case, we demonstrated severe pneumonia caused by the anaerobic organism P. micra, and the patient benefited from receiving the correct antibiotic. NGS was used as a method of quick diagnosis when sputum culture failed to distinguish the pathogen.