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Moraxella osloensis has been reported in the literature as a human pathogen, particularly among immunocompromised adults. In contrast to the adult population, most pediatric cases are among patients with no underlying immunological defect; however, no patient underwent further investigation and no data about the long-term follow-up are available. We report the case of a 2-month-old previously healthy girl infected with Moraxella osloensis. Here, we review case reports and case series of children and adults with Moraxella osloensis infection and compare them with our experience. On the basis of our findings, we recommend further investigations (immunological or other underlying diseases) when a child is found to be infected with these bacteria. [ABSTRACT FROM AUTHOR]

Introduction Moraxella osloensis is a gram-negative coccobacillus, that is saprophytic on skin and mucosa, and rarely causing human infections. Reported cases of human infections usually occur in immunocompromised patients. Presentation of case We report the second case of M. osloensis-caused-osteomyelitis in literature, occurring in a young healthy man. The organism was identified by sequencing analysis of the 16S ribosomal RNA gene. Our patient was treated successfully with surgical debridement and intravenous third-generation cephalosporins. Discussion M. osloensis has been rarely reported to cause local or invasive infections. Our case report is the second case in literature and it is different from the previously reported case in that our patient has no chronic medical problems, no history of trauma, with unique presentation and features on the MRI and intraoperative finding. Conclusion Proper diagnosis is essential for appropriate treatment of osteomyelitis. RNA gene sequence analysis is the primary method of M. osloensis diagnosis. M. osloensis is usually susceptible to simple antibiotics. [ABSTRACT FROM AUTHOR]

A-26-year-old man was admitted to our hospital with diffuse abdominal pain, nausea, and vomiting. He had a history of malignant nephrosclerosis, for which he had been receiving peritoneal dialysis (PD) for the past 14 months. His PD effluent was cloudy and turbid (white blood cell count, 10,528/μL; neutrophils 95.2%). A Gram-negative coccobacillus was isolated from peritoneal fluid culture. However, the organism could not be identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) (Vitek MS, bioMérieux), but was identified as Moraxella osloensis by the 16S rRNA gene sequencing. He was successfully treated with intraperitoneal cefazolin therapy for 3 weeks without removing the intra-abdominal catheter. A literature review revealed three previous case reports all of which were diagnosed by MALDI Biotyper (Bruker Daltonics), suggesting that the identification of M. osloensis may vary depending on the type of MALDI-TOF MS system. In conclusion, we experienced a case of M. osloensis infection in a PD patient, which was successfully treated by antibiotic treatment, without removing the PD catheter. [ABSTRACT FROM AUTHOR]

Abstract: A series of repeated exposures to γ-radiation with intervening outgrowth of survivors was used to develop radioresistant cultures of Moraxella osloensis that have been recognized as potential pathogenic microorganism. The D 10 value of the radiation-resistant strain, 5.903±0.006kGy, was increased by four-fold compared to the parent wild-type strain, 1.637±0.004kGy. Since most strains of M. osloensis are sensitive to penicillin, we have surveyed the sensitivity of radiation-resistant strain to this antibiotic. When the optical density was monitored after the addition of penicillin G, the radioresistant strain appeared to be more resistant to only a low concentration of penicillin G (0.5U/ml) than the parent strain. Interestingly, however, there was no apparent difference in the number of viable cells between both strains. Scanning electron microscope data showed that the resistance cells were generally larger than the parent cells, suggesting that this increase in size may cause a higher optical density of radioresistant cells. In conclusion, radiation mutation does not affect the penicillin resistance of M. osloensis. [Copyright &y& Elsevier]

Abstract: We present an unusual case of septic arthritis of the ankle due to Moraxella osloensis. The implications of a diplococcus culture are discussed, including notification of the disease, the suggestion of sexual impropriety and drug-induced side effects for the treating doctors and other contacts. The case is of a 56-year-old man presenting with a past medical history of gout (great hallux) and increasing pain in his ankle. Systemic examination revealed a low-grade pyrexia and lateral malleolar swelling with evidence of an effusion. Initial gram stain revealed a raised WBC. Laboratory evaluation showed a raised CRP, ESR and urate. The patient was commenced on intravenous antibiotics. Initial blood cultures suggested a possibility of Neisseria meningitidis and primary contacts were commenced on rifampicin. The cultures were later confirmed as the rather unusual penicillin sensitive, gram-negative, aerobic Moraxella oseloensis. Antibiotics were discontinued at 6 weeks and the patient discharged at 3 months. The recognition of septic arthritis, obtaining systemic blood cultures, joint aspirates followed by prompt treatment with a suitable antibiotic regime will reduce morbidity and mortality. Recognition of any potential pathogens that may be harmful to health professionals or other close contacts is also of vital importance. [Copyright &y& Elsevier]