Primary sternal osteomyelitis due to Peptostreptococcus anaerobius

Peptostreptococcus anaerobius: Pathogenicity, identification, and antimicrobial susceptibility. Review of monobacterial infections and addition of a case of urinary tract infection directly identified from a urine sample by MALDI-TOF MS

Peptostreptococcus anaerobius is a gram-positive anaerobic coccus (GPAC) found in the gastrointestinal and vaginal microbiota. The organism is mainly found in polymicrobial and scarcely in monobacterial infections such as prosthetic and native endocarditis. Anaerobic bacteria have rarely been reported as the cause of urinary tract infection (UTI). Although GPAC are susceptible to most antimicrobials used against anaerobic infections, P. anaerobius has shown to be more resistant. Herein, we report a case of UTI caused by P. anaerobius from a 62-year-old man with a history of urological disease. Surprisingly, the microorganism was directly identified by Matrix-Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) from the urine sample. The isolate was successfully identified by phenotypic methods, MALDI-TOF MS, and 16S rRNA gene sequencing. P. anaerobius showed no β-lactamase-producing activity, was resistant to penicillin, ampicillin, ciprofloxacin and levofloxacin, and displayed intermediate susceptibility to ampicillin-sulbactam and amoxicillin-clavulanic acid. Successful treatment was achieved with oral amoxicillin-clavulanic acid. Antimicrobial susceptibility testing (AST) should be performed on P. anaerobius isolates due to their unpredictable AST patterns and because empirically administered antimicrobial agents may not be active. This report shows that MALDI-TOF MS, directly used in urine specimens, may be a quick option to diagnose UTI caused by P. anaerobius or other anaerobic bacteria. This review is a compilation of monobacterial infections caused by P. anaerobius published in the literature, their pathogenicity, identification, and data about the antimicrobial susceptibility of P. anaerobius.

Clinical and microbiological features of anaerobic implant-related infection in 80 patients after orthopedic surgery

OBJECTIVES

Implant-related infection is a common complication after orthopedic surgery, but there is limited research focused on anaerobic infections. We retrospectively analyzed data from 80 patients with anaerobic implant-related infections in order to investigate the clinical features, bacterial distribution and antimicrobial resistant characteristics of this disease.

METHODS

80 patients who underwent implant-related infections with anaerobes were included. Pathogens were isolated and identified by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry with verification of 16s rRNA sequencing. Antimicrobial susceptibility testing (AST) was performed using Epsilometric test (E-test).

RESULTS

Among the 80 patients, 61.2% (49/80) were infected with anaerobes alone, while 38.8% (31/80) were co-infected with anaerobes and other bacteria. Early infection cases involving anaerobe-alone infections were significantly higher compared to the co-infection group (P < 0.001), also exhibiting lower levels of neutrophils (P = 0.033) and ESR (P = 0.046). Anaerobe-alone infections in the prosthetic joint infection group represented a higher proportion compared with other implant-related infections (P = 0.031). Among all species of anaerobes identified, the top 3 were Cutibacterium acnes, Finegoldia magna and Peptostreptococcus anaerobius. Low MIC values to vancomycin was recorded in C. acnes strains and for amoxicillin/clavulanic acid and piperacillin/tazobactam in most F. magna strains. One of the C. acnes and F. magna strains appeared multi-drug resistant except to vancomycin.

CONCLUSIONS

Anaerobe-alone infections have later first onset times and lower infection biomarker levels compared to co-infected patients. The first choice against C. acnes is vancomycin, while amoxicillin/clavulanic acid and piperacillin/tazobactam are recommended for F. magna.

Primary Sternal Osteomyelitis caused by Staphylococcus aureus in an Immunocompetent Adult

Primary sternal osteomyelitis (PSO) is a rare condition that may develop without any contiguous focus of infection. Due to the rarity of the disease, early diagnosis and appropriate treatment are often delayed. Herein, we describe a patient with PSO caused by Staphylococcus aureus that presented with chest pain and fever. The patient had no predisposing factors for sternal osteomyelitis. The chest pain was thought to be non-cardiogenic, as electrocardiography and cardiac enzyme did not reveal ischemic changes when he visited the emergency room. After blood culture revealed the presence of S. aureus, every effort was made to identify the primary focus of infection. Bone scan and magnetic resonance imaging revealed osteomyelitis with soft tissue inflammation around the sternum. After 8 weeks of antibiotics treatment, the patient recovered without any complications.

Ruminococcus gnavus total hip arthroplasty infection in a 62-year-old man with ulcerative colitis

We report the case of a total hip arthroplasty infection caused by Ruminococcus gnavus in a 62-year-old man with ulcerative colitis. The bacterium was perfectly identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry.

Surgical site infections among high-risk patients in clean-contaminated head and neck reconstructive surgery: concordance with preoperative oral flora

BACKGROUND

Salivary contamination of surgical wounds in clean-contaminated head and neck surgery with free flap reconstruction remains a major cause of infection and leads to significant morbidity. This study investigates the correlation between intraoral flora and surgical site infections (SSIs) among high-risk head and neck cancer patients undergoing resection and free flap reconstruction.

METHODS

One hundred twenty-nine patients were identified as being at high risk for infective complications based on cancer stage, tumor size, comorbid factors, and extent of reconstruction. All patients had intraoral swab cultures before surgery. Patients with culture-confirmed SSI after surgery were chosen for analysis, using the κ index and its 95% confidence interval for concordance analysis. All patients received clindamycin and gentamicin for antibiotic prophylaxis for 5 days. Antibiotic susceptibility testing of all isolates was obtained and analyzed.

RESULTS

Thirty-seven patients experienced SSI, or an infection rate of 28.3%, occurring at a mean of 9.3 postoperative days. The overall concordance between oral flora and SSI was fair to moderate (κ index of 0.25), but detailed analysis shows a higher concordance for known and opportunistic pathogens, such as Pseudomonas aeruginosa and Enterococcus faecalis, compared to typical oral commensals. Antibiotic susceptibility tests show rapid and significant increases in resistance to clindamycin, indicating a need for a more effective alternative.

CONCLUSIONS

Predicting pathogens in SSI using preoperative oral swabs did not demonstrate a good concordance in general for patients undergoing clean-contaminated head and neck surgery, although concordance for certain pathogenic species seem to be higher than for typical intraoral commensals. The rapid development of resistance to clindamycin precludes its use as a prophylactic agent.