Challenges in recognition and diagnosis of yaws in children in Papua New Guinea

A global resurgence of yaws in developing countries highlights the need for reliable diagnostic criteria for this neglected infection. We conducted a clinical and serologic survey of 233 children less than 15 years of age who had clinically suspected yaws. A total of 138 (59%) cases were confirmed serologically, and 10 of 12 primary stage cases showed positive results for Treponema pallidum by a polymerase chain reaction assay that has not yet been validated for identification of yaws. A high proportion of cases (46%) were in the secondary stage; 92% of them had osteoarticular involvement, and only 24% had a Venereal Disease Research Laboratory titer greater than 1:32.

Daptomycin, fosfomycin, or both for treatment of methicillin-resistant Staphylococcus aureus osteomyelitis in an experimental rat model

The in vivo activities of daptomycin, fosfomycin, and a combination of both antibiotics against a clinical isolate of methicillin-resistant Staphylococcus aureus (daptomycin MIC, 0.25 μg/ml; fosfomycin MIC, 0.5 μg/ml) were evaluated in a rat model of osteomyelitis. A total of 37 rats with experimental osteomyelitis were treated for 4 weeks with either 60 mg/kg of body weight of daptomycin subcutaneously once daily, 75 mg/kg fosfomycin intraperitoneally once daily, a combination of both drugs, or a saline placebo. After the completion of treatment, animals were euthanized, and the infected tibiae were processed for quantitative bacterial culture. Bone cultures were found to be positive for methicillin-resistant S. aureus in 9 of 9 (100%) animals of the placebo group, in 9 of 9 (100%) animals treated with daptomycin, in 1 of 10 (10%) fosfomycin-treated rats, and in 1 of 9 (22.2%) rats comprising the combination group. Results of bacterial counts in the bone samples were expressed as log(10) CFU/g of bone and analyzed by using the Mann-Whitney U test followed by Bonferroni's multiple-comparison test. Based on bacterial counts, treatment with daptomycin was significantly superior to placebo, although it remained inferior to treatment with fosfomycin. No synergistic or antagonistic effect was observed for the combination therapy. No development of resistance against daptomycin or fosfomycin was observed after the 4-week treatment period.

Osteomyelitis: an update for hospitalists

Osteomyelitis is a common and challenging condition for hospitalists to manage. The 3 main types of osteomyelitis that are commonly seen in the hospital setting are 1) contiguous spread from decubitus or diabetic ulcers, 2) hematogenous spread, such as in vertebral or long bone metaphyses, and 3) infections associated with a prosthetic joint. In patients with diabetes, osteomyelitis is the underlying cause of about 20% of foot infections, and greatly increases the chance that the patient will eventually need an amputation and be subject to perioperative risks. Osteomyelitis from hematogenous spread is increasing. The prevalence of vertebral osteomyelitis is also increasing, particularly in intravenous drug users and patients treated with immune-modulating agents. Prosthetic joint infections are perhaps the most challenging type to treat, and require hospitalists, orthopedic surgeons, and infectious disease specialists to work closely together to plan for effective treatment. Due to increasing antibiotic resistance, the microorganisms involved are also proving more difficult to treat. Emerging resistance to the commonly used antibiotics is resulting in changes in treatment choices. Community-acquired methicillin-resistant Staphylococcus aureus is commonly seen, and there is increasing concern about emerging vancomycin resistance. Treatment of osteomyelitis is still based largely on expert opinion rather than evidence from controlled studies.

Treating osteomyelitis: antibiotics and surgery

BACKGROUND

Osteomyelitis is an inflammatory disorder of bone caused by infection leading to necrosis and destruction. It can affect all ages and involve any bone. Osteomyelitis may become chronic and cause persistent morbidity. Despite new imaging techniques, diagnosis can be difficult and often delayed. Because infection can recur years after apparent "cure," "remission" is a more appropriate term.

METHODS

The study is a nonsystematic review of literature.

RESULTS

Osteomyelitis usually requires some antibiotic treatment, usually administered systemically but sometimes supplemented by antibiotic-containing beads or cement. Acute hematogenous osteomyelitis can be treated with antibiotics alone. Chronic osteomyelitis, often accompanied by necrotic bone, usually requires surgical therapy. Unfortunately, evidence for optimal treatment regimens or therapy durations largely based upon expert opinion, case series, and animal models. Antimicrobial therapy is now complicated by the increasing prevalence of antibiotic-resistant organisms, especially methicillin-resistant Staphylococcus aureus. Without surgical resection of infected bone, antibiotic treatment must be prolonged (≥4 to 6 weeks). Advances in surgical technique have increased the potential for bone (and often limb) salvage and infection remission.

CONCLUSIONS

Osteomyelitis is best managed by a multidisciplinary team. It requires accurate diagnosis and optimization of host defenses, appropriate anti-infective therapy, and often bone débridement and reconstructive surgery. The antibiotic regimen must target the likely (or optimally proven) causative pathogen, with few adverse effects and reasonable costs. The authors offer practical guidance to the medical and surgical aspects of treating osteomyelitis.

Short- versus long-term antimicrobial treatment for acute hematogenous osteomyelitis of childhood: prospective, randomized trial on 131 culture-positive cases

BACKGROUND

Considerable uncertainty exists on the optimal duration of antimicrobials for acute hematogenous osteomyelitis (AHOM) in children. Often they are administered for 1 to 2 months, the first 1 to 2 weeks intravenously, and decompressive surgery is usually added. No prospective, randomized, sufficiently powered comparative trial has been available.

METHODS

Children aged 3 months to 15 years with culture-positive AHOM were randomly assigned to receive clindamycin or a first-generation cephalosporin for 20 or 30 days, including an intravenous phase for the first 2 to 4 days. Surgery was kept at minimum. Illness was monitored with preset criteria. Antimicrobial was discontinued once most signs had subsided and serum C-reactive protein decreased ≤20 mg/L. The primary end point was full recovery without need for further antimicrobial therapy because of an osteoarticular indication during the 12 months after the primary therapy.

RESULTS

Of the 131 cases, 18% also involved the adjacent joint. Staphylococcus aureus caused 89% of cases, and all strains were methicillin susceptible. The median duration of treatment was 20 days for 67 children, and 30 days for 64 children. Most children underwent only the diagnostic percutaneous aspiration or drilling, and 24% had no surgery. Except for 1 mild sequela in both treatment groups, all patients recovered entirely.

CONCLUSIONS

Most cases of childhood AHOM can be treated for 20 days, including a short period intravenously, with large doses of a well-absorbed antimicrobial such as clindamycin or a first-generation cephalosporin, provided the clinical response is good and C-reactive protein normalizes within 7 to 10 days. Extensive surgery is rarely needed.

Bone penetration of amoxicillin and clavulanic acid evaluated by population pharmacokinetics and Monte Carlo simulation

Amoxicillin (amoxicilline)-clavulanic acid has promising activity against pathogens that cause bone infections. We present the first evaluation of the bone penetration of a beta-lactam by population pharmacokinetics and pharmacodynamic profiling via Monte Carlo simulations. Twenty uninfected patients undergoing total hip replacement received a single intravenous infusion of 2,000 mg/200 mg amoxicillin-clavulanic acid before surgery. Blood and bone specimens were collected. Bone samples were pulverized under liquid nitrogen with a cryogenic mill, including an internal standard. The drug concentrations in serum and total bone were analyzed by liquid chromatography-tandem mass spectrometry. We used NONMEM and S-ADAPT for population pharmacokinetic analysis and a target time of the non-protein-bound drug concentration above the MIC for > or = 50% of the dosing interval for near-maximal bactericidal activity in serum. The median of the ratio of the area under the curve (AUC) for bone/AUC for serum was 20% (10th to 90th percentile for between-subject variability [variability], 16 to 25%) in cortical bone and 18% (variability, 11 to 29%) in cancellous bone for amoxicillin and 15% (variability, 11 to 21%) in cortical bone and 10% (variability, 5.1 to 21%) in cancellous bone for clavulanic acid. Analysis in S-ADAPT yielded similar results. The equilibration half-lives between serum and bone were 12 min for amoxicillin and 14 min for clavulanic acid. For a 30-min infusion of 2,000 mg/200 mg amoxicillin-clavulanic acid every 4 h, amoxicillin achieved robust (> or = 90%) probabilities of target attainment (PTAs) for MICs of < or = 12 mg/liter in serum and 2 to 3 mg/liter in bone and population PTAs above 95% against methicillin-susceptible Staphylococcus aureus in bone and serum. The AUC of amoxicillin-clavulanic acid was 5 to 10 times lower in bone than in serum, and amoxicillin-clavulanic acid achieved a rapid equilibrium and favorable population PTAs against pathogens commonly encountered in bone infections.

Penetration of moxifloxacin into bone evaluated by Monte Carlo simulation

Moxifloxacin is a fluoroquinolone with a broad spectrum of activity and good penetration into many tissues, including bone. Penetration of moxifloxacin into bone has not yet been studied using compartmental modeling techniques. Therefore, we determined the rate and extent of bone penetration by moxifloxacin and evaluated its pharmacodynamic profile in bone via Monte Carlo simulation. Twenty-four patients (10 males, 14 females) undergoing total hip replacement received 400 mg moxifloxacin orally 2 to 7 h prior to surgery. Blood and bone specimens were collected. Bone samples were pulverized under liquid nitrogen by a cryogenic mill, including an internal standard. Drug concentrations were analyzed by high-performance liquid chromatography. We used ADAPT II (results reported), NONMEM, and WinBUGS for pharmacokinetic analysis. Monte Carlo simulation was performed to reverse engineer the necessary area under the free concentration-time curve fAUC(SERUM)/MIC in serum and total AUC(BONE)/MIC in bone for a successful clinical or microbiological outcome. The median (10% to 90% percentile for between-subject variability) of the AUC in bone divided by the AUC in serum (AUC(BONE)/AUC(SERUM)) was 80% (51 to 126%) for cortical bone and 78% (42 to 144%) for cancellous bone. Equilibration between serum and bone was rapid. Moxifloxacin achieved robust (> or = 90%) probabilities of target attainment (PTAs) in serum, cortical bone, and cancellous bone up to MICs of < or = 0.375 mg/liter based on the targets fAUC(SERUM)/MIC > or = 40 and AUC(BONE)/MIC > or = 33. Moxifloxacin showed high bone concentrations and a rapid equilibrium between bone and serum. The favorable PTAs compared to the 90%-inhibitory MIC of Staphylococcus aureus warrant future clinical trials on the effectiveness of moxifloxacin in the treatment of bone infections.