Gram-negative osteomyelitis: clinical and microbiological profile

INTRODUCTION: Despite the growing interest in the study of Gram-negative bacilli (GNB) infections, very little information on osteomyelitis caused by GNB is available in the medical literature. OBJECTIVES AND METHODS: To assess clinical and microbiological features of 101 cases of osteomyelitis caused by GNB alone, between January 2007 and January 2009, in a reference center for the treatment of high complexity traumas in the city of São Paulo. RESULTS: Most patients were men (63 percent), with median age of 42 years, affected by chronic osteomyelitis (43 percent) or acute osteomyelitis associated to open fractures (32 percent), the majority on the lower limbs (71 percent). The patients were treated with antibiotics as inpatients for 40 days (median) and for 99 days (median) in outpatient settings. After 6 months follow-up, the clinical remission rate was around 60 percent, relapse 19 percent, amputation 7 percent, and death 5 percent. Nine percent of cases were lost to follow-up. A total of 121 GNB was isolated from 101 clinical samples. The most frequently isolated pathogens were Enterobacter sp. (25 percent), Acinetobacter baumannii (21 percent) e Pseudomonas aeruginosa (20 percent). Susceptibility to carbapenems was about 100 percent for Enterobacter sp., 75 percent for Pseudomonas aeruginosa and 60 percent for Acinetobacter baumannii. CONCLUSION: Osteomyelitis caused by GNB remains a serious therapeutic challenge, especially when associated to nonfermenting bacteria. We emphasize the need to consider these agents in diagnosed cases of osteomyelitis, so that an ideal antimicrobial treatment can be administered since the very beginning of the therapy.

Carbapenem stewardship: positive impact on hospital ecology

INTRODUCTION: Excessive group 2 carbapenem use may result in decreased bacterial susceptibility. OBJECTIVE: We evaluated the impact of a carbapenem stewardship program, restricting imipenem and meropenem use. METHODS: Ertapenem was mandated for ESBL-producing Enterobacteriaceae infections in the absence of non-fermenting Gram-negative bacilli (GNB) from April 2006 to March 2008. Group 2 carbapenems were restricted for use against GNB infections susceptible only to carbapenems and suspected GNB infections in unstable patients. Cumulative susceptibility tests were done for nosocomial pathogens before and after restriction using Clinical and Laboratory Standards Institute (CLSI) guide-lines.Vitek System or conventional identification methods were performed and susceptibility testing done by disk diffusion according to CLSI.Antibiotic consumption (t-test) and susceptibilities (McNemar's test) were determined. RESULTS: The defined daily doses (DDD) of group 2 carbapenems declined from 61.1 to 48.7 DDD/1,000 patient-days two years after ertapenem introduction (p = 0.027). Mean ertapenem consumption after restriction was 31.5 DDD/1,000 patient-days. Following ertapenem introduction no significant susceptibility changes were noticed among Gram-positive cocci. The most prevalent GNB were P. aeruginosa, Klebsiella pneumoniae, and Acinetobacter spp. There was no change in P. aeruginosa susceptibility to carbapenems. Significantly improved P. aeruginosa and K. pneumoniae ciprofloxacin susceptibilities were observed, perhaps due to decreased group 2 carbapenem use. K. pneumoniae susceptibility to trimethoprim-sulfamethoxazole improved. CONCLUSION: Preferential use of ertapenem resulted in reduced group 2 carbapenem use, with a positive impact on P. aeruginosa and K. pneumoniae susceptibility.

Atualização em infecções em próteses articulares / Update on infections in articular prosthesis

O implante de próteses articulares, principalmente de quadril e joelho, vem se tornando cada vez mais frequente, representando significante redução no desconforto e imensurável melhora na mobilidade dos pacientes. As revisões da literatura mundial revelam que 1 a 5 por cento destas próteses tornam-se infectadas, sendo importante lembrar que, conforme cresce o número de cirurgias para implantação destas próteses, cresce também o número de casos deste tipo de infecção. As bactérias gram-positivas são predominantes nas contaminações das próteses articulares, em especial o Staphylococcus aureus e o Staphylococcus epidermidis. As infecções causadas por bacilos gram-negativos e fungos como Candida sp vêm sendo relatadas com maior frequência em todo o mundo. As infecções de próteses articulares apresentam sinais característicos que podem ser divididos em manifestações agudas (dor severa, febre alta, toxemia, calor, rubor e secreção na ferida operatória) e crônicas (dor progressiva, formação de fístulas cutâneas, com drenagem de secreção purulenta, sem febre). O diagnóstico definitivo da infecção deve ser realizado através do isolamento em cultura do micro-organismo obtido a partir da punção do líquido articular, secreção da ferida cirúrgica e materiais colhidos durante desbridamento cirúrgico. É fundamental a cobertura de S.aureus meticilino-resistente, visto a importância epidemiológica deste agente nessas infecções. O tempo total da antibioticoterapia varia de seis semanas a seis meses, sendo que o tratamento deve ser readequado quando necessário, com base nos resultados das culturas colhidas.

The implantation of artificial joints, especially the hip and knee, is becoming increasingly common, representing a significant reduction in discomfort and an immeasurable improvement in patient mobility. Reviews of the global literature indicate that 1-5 percent of these grafts become infected, though it is important to remember that, as the number of surgeries for implantation of these prosthesis grows, so will the number of cases of this type of infection. Gram-positive bacteria predominate in the contamination of joint prosthesis, in particular Staphylococcus aureus and Staphylococcus epidermidis. Infections caused by gram-negative bacilli and fungi such as Candida sp have been reported with increased frequency throughout the world. Infections of joint prosthesis have characteristic signals that can be divided into acute (severe pain, high fever, toxemia, heat, redness, and wound secretion) and chronic (progressive pain, cutaneous fistula formation, with pus drainage, no fever) manifestations. The definitive diagnosis of the infection should be made through the isolation in culture of the micro-organism obtained from the puncture of the joint fluid, surgical wound secretion, and material collected during surgical debridement. It is essential to cover methicillin-resistant Staphylococcus aureus, given the epidemiological importance of this agent in these infections. The total time of antibiotic therapy varies from six weeks to six months, and that treatment should be adjusted as needed, based on the results of culturing.