Treatment of bone, joint, and soft-tissue infections with oral ciprofloxacin

Cell migration, DNA fragmentation and antibacterial properties of novel silver doped calcium polyphosphate nanoparticles

To combat infections, silver was used extensively in biomedical field but there was a need for a capping agent to eliminate its cytotoxic effects. In this study, polymeric calcium polyphosphate was doped by silver with three concentrations 1, 3 or 5 mol.% and were characterized by TEM, XRD, FTIR, TGA. Moreover, cytotoxicity, antibacterial, cell migration and DNA fragmentation assays were done to assure its safety. The results showed that the increase in silver percentage caused an increase in particle size. XRD showed the silver peaks, which indicated that it is present in its metallic form. The TGA showed that thermal stability was increased by increasing silver content. The antibacterial tests showed that the prepared nanoparticles have an antibacterial activity against tested pathogens. In addition, the cytotoxicity results showed that the samples exhibited non-cytotoxic behavior even with the highest doping concentration (5% Ag-CaPp). The cell migration assay showed that the increase in the silver concentration enhances cell migration up to 3% Ag-CaPp. The DNA fragmentation test revealed that all the prepared nanoparticles caused no fragmentation. From the results we can deduce that 3% Ag-CaPp was the optimum silver doped calcium polyphosphate concentration that could be used safely for medical applications.

Pseudomonas aeruginosa: Infections and novel approaches to treatment "Knowing the enemy" the threat of Pseudomonas aeruginosa and exploring novel approaches to treatment

Pseudomonas aeruginosa is an aerobic Gram-negative rod-shaped bacterium with a comparatively large genome and an impressive genetic capability allowing it to grow in a variety of environments and tolerate a wide range of physical conditions. This biological flexibility enables the P. aeruginosa to cause a broad range of infections in patients with serious underlying medical conditions, and to be a principal cause of health care associated infection worldwide. The clinical manifestations of P. aeruginosa include mostly health care associated infections and community-acquired infections. P. aeruginosa possesses an array of virulence factors that counteract host defence mechanisms. It can directly damage host tissue while utilizing high levels of intrinsic and acquired antimicrobial resistance mechanisms to counter most classes of antibiotics. P. aeruginosa co-regulates multiple resistance mechanisms by perpetually moving targets poses a significant therapeutic challenge. Thus, there is an urgent need for novel approaches in the development of anti-Pseudomonas agents. Here we review the principal infections caused by P. aeruginosa and we discuss novel therapeutic options to tackle antibiotic resistance and treatment of P. aeruginosa infections that may be further developed for clinical practice.

The Microbiological Etiology of Fracture-Related Infection

Purpose

Fracture-related infection (FRI) is an important complication related to orthopaedic trauma. Although the scientific interest with respect to the diagnosis and treatment of FRI is increasing, data on the microbiological epidemiology remains limited. Therefore, the primary aim of this study was to evaluate the microbiological epidemiology related to FRI, including the association with clinical symptoms and antimicrobial susceptibility data. The secondary aim was to analyze whether there was a relationship between the time to onset of infection and the microbiological etiology of FRI.

Methods

FRI patients treated at the University Hospitals of Leuven, Belgium, between January 1st 2015 and November 24th 2019 were evaluated retrospectively. The microbiological etiology and antimicrobial susceptibility data were analyzed. Patients were classified as having an early (<2 weeks after implantation), delayed (2-10 weeks) or late-onset (> 10 weeks) FRI.

Results

One hundred ninety-one patients with 194 FRIs, most frequently involving the tibia (23.7%) and femur (18.6%), were included. Staphylococcus aureus was the most frequently isolated pathogen, regardless of time to onset (n=61; 31.4%), followed by S. epidermidis (n=50; 25.8%) and non-epidermidis coagulase-negative staphylococci (n=35; 18.0%). Polymicrobial infections (n=49; 25.3%), mainly involving Gram negative bacilli (GNB) (n=32; 65.3%), were less common than monomicrobial infections (n=138; 71.1%). Virulent pathogens in monomicrobial FRIs were more likely to cause pus or purulent discharge (n=45;54.9%; p=0.002) and fistulas (n=21;25.6%; p=0.030). Susceptibility to piperacillin/tazobactam for GNB was 75.9%. Vancomycin covered 100% of Gram positive cocci.

Conclusion

This study revealed that in early FRIs, polymicrobial infections and infections including Enterobacterales and enterococcal species were more frequent. A time-based FRI classification is not meaningful to estimate the microbiological epidemiology and cannot be used to guide empiric antibiotic therapy. Large multicenter prospective studies are necessary to gain more insight into the added value of (broad) empirical antibiotic therapy.

Physiologically Based Population Pharmacokinetic Modeling Approach for Ciprofloxacin in Bone of Patients Undergoing Orthopedic Surgery

Ciprofloxacin is highly active against bacteria that commonly cause bone infections. However, the time-course of ciprofloxacin in bone has not been characterized using population pharmacokinetic modeling. Thirty-nine patients received a 1-h infusion of 400 mg of ciprofloxacin before orthopedic surgery. Blood and bone samples were collected at 0.5 to 20 h following the start of the infusion. Bone samples were separated into cortical and cancellous bone and pulverized under liquid nitrogen using a cryogenic mill. Ciprofloxacin in plasma, and cortical and cancellous bone was quantified by liquid chromatography-tandem mass spectrometry. A physiologically based pharmacokinetic modeling approach was utilized to describe the concentration-time profiles in plasma and bone. Ciprofloxacin concentrations ranged from 0.176 to 5.98 mg/L (median, 1.67; density, 1.99 g/cm³) in cortical, and 0.224 to 14.6 mg/L (median, 1.22; 1.92 g/cm³) in cancellous bone. The average observed cortical bone/plasma concentration ratio was 0.67 at 0.5 to 2 h (n = 7) and 5.1 at 13 to 20 h (n = 9). For cancellous bone the respective average ratios were 0.77 and 4.4. The population PK model included a central (blood) compartment, two peripheral tissue compartments, and compartments for the organic and inorganic (hydroxyapatite) matrix in cortical and cancellous bone. The population mean ciprofloxacin clearance was 20.7 L/h. The estimated partition coefficients of the organic bone matrix were 3.39 for cortical and 5.11 for cancellous bone. Ciprofloxacin achieved higher concentrations in bone than plasma. Slow redistribution from bone to plasma may have been due to binding to the inorganic bone matrix. The developed model presents a step toward optimized antibiotic dosing in osteomyelitis.

Treatment of Infection and Colonization Caused by Methicillin-Resistant Staphylococcus aureus

The mechanism of methicillin resistance confers resistance to all available B-lactam antibiotics; consequently, B-lactam antibiotics have no role in therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin remains the drug of choice. Teicoplanin and daptomycin are two investigational antibiotics related to vancomycin in structure and in spectrum of activity. In clinical trials employing relatively low doses, neither was as effective as vancomycin. Trials at higher doses are on-going. Quinolones, ciprofloxacin in particular, have been used successfully to treat infections caused by MRSA; however, the usefulness of quinolones may be limited by the tendency of resistance to emerge during therapy. Quinolones probably should be used only in combination with another active agent, such as rifampin, when treating serious infections caused by MRSA. Other agents may be active in vitro against MRSA, but clinical data showing their effectiveness are lacking. Rifampin combination regimens appear most effectively to eradicate colonization with MRSA.

Home iv antibiotic therapy through a medical day care unit

An out-patient parenteral antibiotic therapy program provided through a medical day care unit was evaluated in a tertiary care hospital. From July 11, 1988 to December 31, 1990, 122 patients were treated either on site at the unit or at home with self-administered intravenous antibiotics. In all, 142 courses of parenteral antibiotics (mostly cephalosporins and clindamycin) were given for a total of 124 infections, mostly bone and soft tissue infections (67 of 124, 54%). The duration of out-patient therapy ranged from two to 62 days with a mean duration of 9.4 days if treated at the unit, or 13.2 days in the home care model (1476 patient-days). Vein access was peripheral and catheters remained functional for an average of 4.9 days (range 0.5 to 22 days). Only two patients experienced adverse drug reactions that necessitated modification of treatment. One other case was readmitted to the hospital for surgical debridement. The average cost per patient-day was $66 compared with $375 for in-hospital therapy. This program proved to be safe, efficient, and cost-effective.

Systemic antibiotic therapy for chronic osteomyelitis in adults

The standard recommendation for treating chronic osteomyelitis is 6 weeks of parenteral antibiotic therapy. However, oral antibiotics are available that achieve adequate levels in bone, and there are now more published studies of oral than parenteral antibiotic therapy for patients with chronic osteomyelitis. Oral and parenteral therapies achieve similar cure rates; however, oral therapy avoids risks associated with intravenous catheters and is generally less expensive, making it a reasonable choice for osteomyelitis caused by susceptible organisms. Addition of adjunctive rifampin to other antibiotics may improve cure rates. The optimal duration of therapy for chronic osteomyelitis remains uncertain. There is no evidence that antibiotic therapy for >4-6 weeks improves outcomes compared with shorter regimens. In view of concerns about encouraging antibiotic resistance to unnecessarily prolonged treatment, defining the optimal route and duration of antibiotic therapy and the role of surgical debridement in treating chronic osteomyelitis are important, unmet needs.

Remission after treatment of osteoarticular infections due to Pseudomonas aeruginosa versus Staphylococcus aureus: a case-controlled study

PURPOSE

Osteoarticular infections due to methicillin-susceptible Staphylococcus aureus (MSSA) or its methicillin-resistant variant (MRSA) are feared due to treatment failures. According to clinical experience, Pseudomonas aeruginosa may reveal less long-term remission than S. aureus.

METHODS

A case-controlled study comparing outcomes of osteoarticular infections due to P. aeruginosa vs S. aureus was performed at Geneva University Hospitals.

RESULTS

A total of 111 S. aureus (including 37 MRSA) and 20 P. aeruginosa osteoarticular infections were analysed in 131 patients: arthroplasties (n = 38), fracture fixation devices (n = 56), native joint arthritis (n = 7) and osteomyelitis without implant (n = 30). The median active follow-up time was 4 years. The patients underwent a median number of two surgical interventions for P. aeruginosa infections compared to two for S. aureus (two for MRSA), while the median duration of antibiotic treatment was 87 days for P. aeruginosa and 46 days for S. aureus infections (58 days for MRSA) (all p > 0.05). Overall, Pseudomonas-infected patients tended towards a lower remission rate than those infected with S. aureus (12/20 vs 88/111; p = 0.06). This was similar when P. aeruginosa was compared with MRSA alone (12/20 vs 30/37; p = 0.08). In multivariate logistic regression analyses adjusting for case mix, odds ratios (OR) for remission were as follows: P. aeruginosa vs S. aureus [OR 0.4, 95% confidence interval (CI) 0.1-1.2], number of surgical interventions (OR 0.6, 95% CI 0.5-1.0) and duration of antibiotic treatment (OR 1.0, 95% CI 1.0-1.0).

CONCLUSIONS

Despite a similar number of surgical interventions and longer antibiotic treatment, osteoarticular infections due to P. aeruginosa tended towards a lower remission rate than infections due to S. aureus in general or MRSA in particular.

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.

Streptococcus salivarius bacteremia and spontaneous bacterial peritonitis in liver transplantation candidates

Bacterial infections are a serious complication of end-stage liver disease (ESLD) that occurs in 20% to 60% of patients. We retrospectively reviewed medical records of patients with ESLD who were identified by our microbiology laboratory as having Streptococcus salivarius bacteremia. Of 592 patients listed for transplantation between January 1998 and January 2006, 9 (1.5%) had 10 episodes of S salivarius bacteremia. Of 2 patients already receiving quinolone prophylaxis for spontaneous bacterial peritonitis (SBP), 1 later presented with a second episode. The male-to-female ratio was 1:1.2. Medians for age, Model for End-Stage Liver Disease score, and Child-Turcotte-Pugh score were 50 years, 17, and 10, respectively. Presenting symptoms and signs in 10 episodes of infection were ascites (in 8 episodes), elevated temperature (6), abdominal pain (5), and encephalopathy (4). Median laboratory values included: white blood cell count, 15.1 x 10(9)/L; creatinine, 0.9 mg/dL; albumin, 3.1 gm/dL; aspartate aminotransferase, 64 U/L; alanine aminotransferase, 52.5 U/L; ammonia, 67 mug/dL; and prothrombin time, 17.3 seconds. Ascitic fluid in patients with peritonitis showed a median white blood cell count of 466 cells/mm(3) (range, 250-12,822 cells/mm(3)), with 66% polymorphs, protein of 0.9 gm/dL, and albumin of 0.4 gm/dL. S salivarius may cause primary bacteremia and SBP in liver transplantation candidates despite quinolone prophylaxis.

Treatment of brucella spondylitis: lessons from an impossible meta-analysis and initial report of efficacy of a fluoroquinolone-containing regimen

Although spondylitis is the most common of the complications of brucellosis, and is often debilitating and difficult to treat, there is no consensus on the preferred combination of antibiotics used. We attempted to perform a meta-analysis based on series on brucellar spondylitis published in the last 22 years. Meta-analysis was aborted largely due to insufficient data recorded in most series. However, useful conclusions could be drawn, such as the importance of prolonged treatment, usually more than 12 weeks. No antibiotic combination was proven to be superior, but 14 different regimens were used in the series studied. The authors propose the use of a combination of doxycycline and ciprofloxacin for a period of 3 months, and report the successful use of such a combination in five patients with brucellosis and spondylitis.

The battle against emerging antibiotic resistance: should fluoroquinolones be used to treat children?

Inappropriate use of antibiotic drugs in humans and animals has led to widespread resistance among microbial pathogens. Resistance is the phenotypic expression corresponding to genetic changes caused by either mutation or acquisition of new genetic information. In some cases, multidrug resistance occurs. Streptococcus pneumoniae is one of the most important respiratory pathogens, playing a major role in both upper and lower respiratory tract infections. Pneumococcal resistance to antimicrobials may be acquired by means of horizontal transfer followed by homologous recombination of genetic material from the normal flora of the human oral cavity or by means of mutation. Resistance to penicillins and macrolides has been increasing for some time, but, recently, fluoroquinolone resistance has become an issue as well. We are concerned that, if fluoroquinolones are approved for use in children, their widespread use will result in rapid emergence of pneumococcal resistance, because children are more often colonized in the nasopharynx with high-density populations of pneumococci than are adults.

Bacterial skin infections in the elderly: diagnosis and treatment

Skin and soft tissue infections are quite common in elderly people. A number of special conditions and circumstances need to be considered in the diagnosis and therapy. It is important to try to establish the causative organism, exclude other cutaneous disorders and identify precipitating factors. Treatment modalities include antiseptics, topical and systemic antibacterials, dressings and biotherapy. Skin infections presenting with erythema, blisters, pustules, and ulcerations or in body folds are described in detail. Cellulitis and infected ulcers are the most commonly encountered cutaneous infections in the elderly. Accurate and quick diagnosis and treatment are imperative to prevent significant morbidity and mortality. Appropriate antibacterials, antiseptics and dressings are necessary depending on the severity of the clinical presentation and resistance patterns. Laboratory tests, such as skin swabs, to establish the exact pathogen take time and the results might represent colonisation rather than infection of the skin. Cellulitis should be clinically distinguished from erysipelas and necrotising fasciitis. The latter is a life-threatening condition, which in the majority of cases requires surgical debridement of the infected tissue. Blisters and honey-coloured crusts are typical features of impetigo. It is very contagious and close contacts should be examined. Folliculitis is a commonly seen skin infection, which often responds to the use of antiseptics and topical antibacterials. More severe pustular skin eruptions, such as furunculosis and carbunculosis, usually require treatment with systemic antibacterials. Intertrigo and erythrasma have a predilection for the body folds, especially the axillae and groin, and topical therapy is usually sufficient. Secondary skin infections are often the result of persistent pruritus associated with increasing dryness of the aging skin. Emollients and antihistamines are useful measures. Primary cutaneous disorders and systemic diseases should be excluded with the aid of appropriate investigations, such as blood tests and skin biopsy. Staphylococcus aureus and beta-haemolytic streptococci are the most common causative organisms of cutaneous infections.

Characterization of crosslinked high amylose starch matrix implants. 2. In vivo release of ciprofloxacin

The purpose of this study was to develop a crosslinked high amylose starch (CLHAS) matrix implant as a sustained antimicrobial delivery system for local prevention and/or treatment of osteomyelitis. Implants (200 mg) of CLHAS containing 2.5% (5 mg), 7.5% (15 mg), 15.0% (30 mg) and 20.0% (40 mg) of ciprofloxacin (CFX), were prepared by direct compression of dry blends. Rabbits were administered six 2.5, two 7.5, one 15.0 or one 20.0%-CFX implants along the femur between the quadriceps and biceps femoris muscles to determine systemic (serum) versus local (muscle and bone) CFX concentrations over 1 month. Blood samples were taken throughout the study for CFX assay. Muscle and femur were collected at 3, 7, 14, 21 and 28 days after implantation for host response evaluation and CFX assay. Residual polymer was explanted to determine the remaining dose of CFX. All animals remained healthy during the study. Local tissue reaction was mild and limited to the implantation site. Serum CFX concentrations remained low regardless of implant loading. Increased drug loading resulted in a higher and longer release of CFX in muscle and in bone. Local CFX concentrations were detected largely in excess of the MIC over 28 days with 20.0%-CFX implants. More residual CFX in polymer was detected over a longer period of time at high loading. These results strongly support the development of CLHAS implants for local antibacterial therapy.

Pharmacotherapy of lower limb diabetic ulcers

OBJECTIVE

To discuss the pathophysiology, microbiology, and pharmacotherapy of lower extremity (LE) diabetic ulcers.

DATA SOURCES

A MEDLINE search from 1966 to April 1999 was conducted. The search was limited to humans and English-language journals. Key search words included "diabetic ulcer," "fluoroquinolones," "beta-lactam," "hyperbaric oxygen," "diabetes mellitus," "diabetic foot," and "growth factor."

STUDY SELECTION

Randomized and nonrandomized studies were selected for review. Results of randomized, placebo-controlled studies were emphasized more than nonrandomized results.

DATA SYNTHESIS

LE ulcers are a common cause of hospitalization, and cause significant morbidity and mortality. Staphylococcus aureus is the most common pathogen in non-limb-threatening infections; Gram-negative bacteria and anaerobes are most prevalent in limb-threatening and life-threatening infections. Oral antibiotic therapy may be used in non-limb-threatening infections, if adequate response is achieved in 24-48 hours; otherwise, intravenous antibiotics should be started. Intravenous antibiotics should be the initial therapy for limb-threatening or life- threatening ulcers. Antimicrobial therapy of at least 10-14 days has been effective in treating LE ulcers in the absence of osteomyelitis. Growth factors offer another treatment alternative, although only becaplermin is currently approved for diabetic ulcers.

CONCLUSION

Antibiotic therapy has been effective for the treatment of LE diabetic ulcers. However, further studies are required to identify optimal antibiotics and dosage regimens. Growth factors may have a role but additional research is needed to determine when best to initiate this therapy.

A retrospective analysis of pharmacokinetic/pharmacodynamic indices as indicators of the clinical efficacy of ciprofloxacin

A retrospective analysis of the relationship between estimated pharmacokinetic/pharmacodynamic indices and the reported efficacy of ciprofloxacin has been carried out using different correlation models. f1.gif" BORDER="0">, T(ss) > MIC, f2.gif" BORDER="0"> and AUIC(ss) were calculated for each clinical case included in the study, from simulated plasma level curves corresponding to the dosage regimen administered. A univariate correlation analysis was performed considering efficacy (%) as the dependent variable and indices as the independent variables according to linear and non-linear pharmacokinetic-pharmacodynamic models (PK-PD models). The results prove that log-transformation of the independent variable improves the data fitting to linear model. The four estimated indices show a log-linear relationship with outcome, T(ss) > MIC and AUIC(ss) being the parameters best correlated with percentage efficacy. The E(max) model with intrinsic response is an additional correlation strategy for T(ss) > MIC, leading to estimated values of E(max) and E(0) of 100.34 +/- 25.09% and 24.40 +/- 11.7%, respectively. The wide range of bacteria responsible for the infections considered, including Gram-positive pathogens such as staphylococci, might explain the good correlation between T(ss) > MIC and percentage efficacy found for ciprofloxacin in this study.

Ciprofloxacin, lomefloxacin, or levofloxacin as treatment for chronic osteomyelitis

The efficacy and safety of three oral fluoroquinolones (lomefloxacin, levofloxacin, and ciprofloxacin) for the treatment of chronic osteomyelitis were analyzed. Twenty-seven patients had documented infections with quinolone-sensitive organisms and received either lomefloxacin, levofloxacin, or ciprofloxacin. Levofloxacin was effective therapy for 9 of 15 (60%) patients. Lomefloxacin was effective therapy for five of seven (71%) patients, and ciprofloxacin was effective therapy for two of five patients (40%). Average follow-up was 11.8 months for patients who completed the course of therapy, and the average duration of therapy was 60.6 days. Gram-positive bacteria were isolated from 18 patients, and 11 patients were cured. Oral fluoroquinolones can be safe, effective therapy if they are given for a prolonged course as treatment for infections caused by susceptible gram-positive as well as gram-negative organisms and in combination with adequate surgical debridement.

Use of quinolones in osteomyelitis and infected orthopaedic prosthesis

The present review provides an updated critical analysis of the use of quinolones in osteomyelitis and orthopaedic prosthetic infections. Only papers published in peer-reviewed journals and related to the following areas were selected: experimental osteomyelitis, penetration of quinolones into human bone, and clinical use in comparative and noncomparative studies. Local drug carriers impregnated with quinolones allow high local antibiotic concentrations to be achieved in experimental systems. Considerable clinical experience has been gained mostly with ciprofloxacin and ofloxacin. Cumulated results in clinical trials show clinical success rates of more than 90% in osteomyelitis caused by Enterobacteriaceae. The combination of quinolones and rifampicin for the treatment of staphylococcal osteomyelitis as well as orthopaedic prosthetic infections appears very promising in clinical studies with a small number of patients. However, further comparative studies using quinolones as single agents or in combination (versus standard parenteral therapy) remain necessary in osteomyelitis due to Staphylococcus aureus or Pseudomonas aeruginosa. In particular, studies with the newer quinolones should be strongly encouraged in acute or chronic osteomyelitis and in more complicated situations such as diabetic osteomyelitis or foreign-body infection.

Efficacy of levofloxacin for experimental aortic-valve endocarditis in rabbits infected with viridans group streptococcus or Staphylococcus aureus

Levofloxacin is among the more active fluoroquinolones against streptococci and staphylococci. It is effective against moderately severe infections caused by these organisms, but its efficacy in the treatment of bacteremia and serious infections such as endocarditis is not well defined. We compared the efficacy of levofloxacin to those of standard agents in the rabbit model of aortic-valve endocarditis caused by fluoroquinolone-susceptible strains including a penicillin-susceptible strain of Streptococcus sanguis, a penicillin-resistant strain of Streptococcus mitis, a methicillin-resistant strain of Staphylococcus aureus, and a methicillin-susceptible strain of S. aureus. Levofloxacin administered intramuscularly at dosages of 20 to 40 mg/kg of body weight twice daily (b.i.d.) was completely ineffective against the penicillin-susceptible strain, with mean vegetation titers after 3 days of therapy not statistically significantly different from those for controls. Levofloxacin was no more effective than penicillin against the penicillin-resistant strain. Levofloxacin administered for 4 days at a dosage of 20 mg/kg b.i.d. was at least as effective as vancomycin administered intravenously at a dosage of 25 mg/kg b.i. d. against the methicillin-resistant S. aureus strain and was as effective as nafcillin administered intramuscularly at 100 mg three times daily against the methicillin-susceptible strain. Emergence of resistance to levofloxacin in vitro was less likely to occur than resistance to ciprofloxacin, and resistance to levofloxacin was not observed in vivo. Levofloxacin-rifampin combinations were antagonistic in vitro and in vivo. Levofloxacin was highly effective as a single agent against experimental staphylococcal endocarditis but was surprisingly ineffective against streptococcal endocarditis, suggesting that it has a potential role as treatment for serious S. aureus but not viridans group streptococcal infections in humans.

No benefit of long-term ciprofloxacin treatment in patients with reactive arthritis and undifferentiated oligoarthritis: a three-month, multicenter, double-blind, randomized, placebo-controlled study

OBJECTIVE

To investigate the effect of long-term antibiotic treatment in patients with reactive arthritis (ReA) and undifferentiated oligoarthritis.

METHODS

One hundred twenty-six patients were treated with ciprofloxacin (500 mg twice a day) or placebo for 3 months, in a double-blind, randomized study. Of these patients, 104 (48 treated with ciprofloxacin and 56 treated with placebo) were valid for clinical evaluation: 55 were diagnosed as having ReA with a preceding symptomatic urogenic or enteric infection and 49 as having undifferentiated oligoarthritis. These 2 groups were randomized separately. The triggering bacterium was sought by serology and/or culture. The percentage of patients in remission after 3 months of treatment was chosen as the primary efficacy parameter.

RESULTS

A triggering bacterium could be identified in 52 patients (50%): Chlamydia trachomatis in 13, Yersinia in 14, and Salmonella in 25. No patient was positive for Campylobacter jejuni or for Shigella. No difference in outcome was found between treatment with ciprofloxacin or placebo in the whole group or in subgroups of patients with ReA or undifferentiated oligoarthritis. No difference was seen in patients with a disease duration <3 months. Ciprofloxacin was not effective in Yersinia- or Salmonella-induced arthritis but seemed to be better than placebo in Chlamydia-induced arthritis. This difference was not significant, however, which might be due to the small sample size.

CONCLUSION

Long-term treatment of ReA with ciprofloxacin is not effective; however, it might be useful in the subgroup of patients who have Chlamydia-induced arthritis. This has to be proven in a bigger study focusing on patients with Chlamydia-induced arthritis.

Killing effects of antibiotics and two-fold antimicrobial combinations on proliferating and non growing staphylococci

Antimicrobial agents are generally tested against bacteria in the log phase of multiplication to produce the maximal bactericidal effect. In case of foreign body infections, bacteria may multiply less optimally. We examined the effects of several classes of lipophilic antistaphylococcal agents to determine their antimicrobial activity towards coagulase-positive and coagulase-negative staphylococci during the non-growing and slowly growing phases. Only two-fold combinations containing rifampicin were bactericidal (3-log kill) against Staphylococcus aureus. This was in contrast to growing bacteria in the log phase, in which a variety of antibiotics produced relevant killing. Concerning the staphylococci examined, antibiotic killing was greatly dependent on the growth rate. Most of the two-fold combinations containing rifampicin showed additive and synergistic antibacterial activity both in growth and stationary states as measured by the killing kinetics. The theoretical and clinical implications of delayed killing by chemotherapeutic agents for established bacterial infections and infections involving foreign bodies are discussed. Antimicrobial combinations including rifampicin and a second lipophilic antistaphylococcal drug may be most promising and appropriate as coating substances for intravascular devices or for clinical application in cases of implant infections.

Outpatient parenteral antimicrobial therapy for osteomyelitis

OPAT for osteomyelitis is effective, safe, and well-established. There are particular considerations with osteomyelitis, however, that relate to patient selection and the plans of therapy. Orthopedic infections may impose physical considerations that need to be considered. Concomitant medical problems, such as diabetes, must be considered and may be good reasons for hospital care aside from the infection. Further investigations of treatment of osteomyelitis are clearly needed, with OPAT patients being good subjects to study.

Methicillin resistance in staphylococci: molecular and biochemical basis and clinical implications

Methicillin resistance in staphylococci is determined by mec, composed of 50 kb or more of DNA found only in methicillin-resistant strains. mec contains mecA, the gene for penicillin-binding protein 2a (PBP 2a); mecI and mecR1, regulatory genes controlling mecA expression; and numerous other elements and resistance determinants. A distinctive feature of methicillin resistance is its heterogeneous expression. Borderline resistance, a low-level type of resistance to methicillin exhibited by strains lacking mecA, is associated with modifications in native PBPs, beta-lactamase hyperproduction, or possibly a methicillinase. The resistance phenotype is influenced by numerous factors, including mec and beta-lactamase (bla) regulatory elements, fem factors, and yet to be identified chromosomal loci. The heterogeneous nature of methicillin resistance confounds susceptibility testing. Methodologies based on the detection of mecA are the most accurate. Vancomycin is the drug of choice for treatment of infection caused by methicillin-resistant strains. PBP 2a confers cross-resistance to most currently available beta-lactam antibiotics. Investigational agents that bind PBP 2a at low concentrations appear promising but have not been tested in humans. Alternatives to vancomycin are few due to the multiple drug resistances typical of methicillin-resistant staphylococci.

Quinolones

Fluoroquinolones represent a major advance in antimicrobial chemotherapy. Currently, there are five fluoroquinolones approved by the FDA, and many more quinolones are expected to become available in years to come. Although their clinical utility is constantly expanding, they have been best studied in complicated urinary tract infections, chronic osteomyelitis caused by gram-negative bacilli, bacterial gastrointestinal infections such as traveler's diarrhea and typhoid fever, and uncomplicated gonococcal infections and in the prophylaxis of bacterial infections in patients with neutropenia. These agents have the convenience of oral administration, favorable pharmacokinetic properties, and low toxicity profiles but should be used advisedly because indiscriminate use may result in the early emergence of resistance.

Quinolones and osteomyelitis: state-of-the-art

The present review provides a critical quantitative analysis of the use of quinolones in osteomyelitis. Only papers published in peer-reviewed journals and related to the following areas were selected: experimental osteomyelitis, penetration of quinolones into human bone and clinical use in comparative and non-comparative studies. Cumulated results show clinical success rates of more than 90% in osteomyelitis caused by Enterobacteriaceae, after prolonged oral use of ciprofloxacin. However, further comparative studies using oral quinolones as single agents or in combination (versus standard parenteral therapy) are required in osteomyelitis due to S. aureus or P. aeruginosa, or in more complicated situations such as diabetic osteomyelitis or foreign body infection.

In vitro elution of ciprofloxacin from polymethylmethacrylate cement beads

The use of antibiotic-impregnated polymethylmethacrylate (PMMA) cement beads for the local delivery of antibiotics in the treatment of chronic osteomyelitis has become a standard orthopaedic practice. The increasing resistance to antibiotics of organisms associated with orthopaedic infections has led to interest in the incorporation of more effective antibiotics into PMMA cement. Ciprofloxacin, a synthetic fluoroquinolone, is potent against a broad spectrum of bacteria associated with osteomyelitis. In this study, strands of ciprofloxacin-impregnated PMMA cement beads were prepared with 0.2, 0.5, or 1.0 g of ciprofloxacin per 40 g of PMMA. The elution concentration of ciprofloxacin was at least 1-2 mcg/ml for 7 days (0.2 g), 30 days (0.5 g), and 42 days (1.0 g). This concentration is equivalent to the minimum inhibitory concentration for the common pathogens associated with osteomyelitis. Concurrent systemic and local ciprofloxacin therapy appears to be a method for the treatment of chronic osteomyelitis.

In vitro activity of sparfloxacin, ciprofloxacin, ofloxacin, and other antibiotics against bloodstream isolates of gram-positive cocci

The in vitro activity of sparfloxacin was compared with the activities of ciprofloxacin, ofloxacin, and six other antimicrobial agents against 323 bloodstream isolates of staphylococci (both oxacillin susceptible and resistant) enterococci, and pneumococci. Sparfloxacin was more active than both ciprofloxacin and ofloxacin against all the isolates tested. Its activity (MIC for 90% of strains tested < or = 0.10 microgram/ml) against oxacillin-susceptible staphylococci was superior to that of ciprofloxacin and ofloxacin by at least fourfold. Sparfloxacin was also more potent against pneumococci. However, fluoroquinolone resistance was noted among oxacillin-resistant strains of Staphylococcus aureus and coagulase-negative staphylococci.

Lomefloxacin concentrations in bone after a single oral dose

We studied the penetration characteristics of lomefloxacin in bone in 30 patients with osteoarthritis undergoing total hip replacement. Patients were given a single oral 400 mg dose at various times from 1 to 12 hours prior to removal of bone samples. The peak plasma and bone (subchondral bone from femoral head) concentrations reached approximately 4.0 micrograms/mL at 2 hours post-dose and 3.0 micrograms/mL at 3 hours post-dose, respectively. At 12 hours post-dose both plasma and bone concentrations were still greater than 1.0 microgram/mL. Two hours after dosing the average bone-to-plasma ratio was greater than 0.6. These data indicate that a single 400 mg oral dose of lomefloxacin attains bone concentrations that are above its usual minimum inhibitory concentrations for susceptible organisms.

Successful therapy of experimental chronic foreign-body infection due to methicillin-resistant Staphylococcus aureus by antimicrobial combinations

We compared the efficacy of a long-duration (3-week) therapy of vancomycin, fleroxacin, fleroxacin plus rifampin, and vancomycin plus fleroxacin and rifampin in a recently developed rat model of chronic staphylococcal foreign-body infection. Subcutaneous tissue cages containing polymethylmethacrylate coverslips were infected with 1 x 10(5) to 5 x 10(5) CFU of methicillin-resistant Staphylococcus aureus. Three weeks later, a quantitative culturing of the fluid that had accumulated in the cages was done (mean, 6.72 log10 CFU/ml; n = 110) and treatment was initiated after randomization. The CFUs in the cage fluid were counted on days 11 and 22 and 1 week after the termination of treatment; in addition, a final culture of coverslips (surface-bound microorganisms) was performed. The three-drug therapy was significantly superior to the other treatments on day 11 (a 5.16 log10 decrease of bacterial counts versus a 2.12 log10 to 2.94 log10 decrease for vancomycin, fleroxacin, and fleroxacin plus rifampin; P less than 0.01). On day 22, count decreases were 4.16 log10 for vancomycin, 4.91 log10 for fleroxacin (vancomycin versus fleroxacin, not significant), 6.14 log10 for two-drug therapy, and 6.34 log10 for three-drug therapy (vancomycin-fleroxacin-rifampin versus fleroxacin-rifampin, not significant; fleroxacin-rifampin versus monotherapies, P less than 0.01); the numbers of CFU in most cage fluids were under the detection limit (20 CFU/ml) in combination groups. One week after the end of treatment, 92% of fluids and coverslips (detection limit, 1 CFU) were culture negative with tritherapy, 88% of fluids and 41% of coverslips were negative with bitherapy, and less than 12% of fluids and coverslips were negative with single drugs (for coverslips, P was <0.01 for vancomycin-fleroxacin-rifampin versus fleroxacin-rifampin and P was <0.001 for fleroxacin-rifampin versus the monotherapies). No mutants resistant to rifampin or fleroxacin were detected. In conclusion, antimicrobial combinations were highly effective and superior to single drugs in treating a chronic staphylococcal foreign-body infection for 3 weeks. The three-drug therapy decreased bacterial counts more rapidly than the two-drug therapy under study and appeared to be curative in most cases.

The fluoroquinolones

The fluoroquinolone class of antibiotics promises to become as diverse and as important as beta-lactam agents. The fluoroquinolones inhibit bacterial DNA gyrase and are bactericidal. All fluoroquinolones have potent activity against most gram-negative bacteria; ciprofloxacin is the most active against Pseudomonas aeruginosa. Activity against gram-positive organisms is variable; methicillin-resistant Staphylococcus aureus has acquired resistance to the fluoroquinolones at an alarming rate. Currently available quinolones do not have, but new quinolone agents likely will have, substantial activity against anaerobic bacteria. Some quinolones are also active against Mycobacterium, Chlamydia, and Mycoplasma organisms. All fluoroquinolones have excellent absorption after oral administration; however, this process can be impaired by the presence of aluminum- or magnesium-containing antacids and by zinc, iron, or calcium supplements. Ciprofloxacin is also available for intravenous use. Although most fluoroquinolones do not achieve adequate cerebrospinal fluid levels, penetration into other tissues is excellent. Dosage adjustments for renal and hepatic dysfunction vary among the quinolones. Although side effects are rare, concomitant use of caffeine or theophylline with some quinolones may cause toxicity to the central nervous system. Because they may affect the development of cartilage, all fluoroquinolones are contraindicated in children, adolescents, and pregnant or breast-feeding women.

Treatment of infection and colonization caused by methicillin-resistant Staphylococcus aureus

The mechanism of methicillin resistance confers resistance to all available beta-lactam antibiotics; consequently, beta-lactam antibiotics have no role in therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections. Vancomycin remains the drug of choice. Teicoplanin and daptomycin are two investigational antibiotics related to vancomycin in structure and in spectrum of activity. In clinical trials employing relatively low doses, neither was as effective as vancomycin. Trials at higher doses are on-going. Quinolones, ciprofloxacin in particular, have been used successfully to treat infections caused by MRSA; however, the usefulness of quinolones may be limited by the tendency of resistance to emerge during therapy. Quinolones probably should be used only in combination with another active agent, such as rifampin, when treating serious infections caused by MRSA. Other agents may be active in vitro against MRSA, but clinical data showing their effectiveness are lacking. Rifampin combination regimens appear most effectively to eradicate colonization with MRSA.

Fluoroquinolones. New miracle drugs?

Fluoroquinolones are the newest antibiotics for treatment of some infections caused by highly resistant bacteria (eg, Pseudomonas aeruginosa). Clinically sound indications for these drugs include resistant infections of the urinary, intestinal, and respiratory tracts; otitis externa; osteomyelitis; foot infections in diabetic patients; and late infections complicating burns. Fluoroquinolone therapy is not indicated in children younger than 12 years old and patients with foreign bodies, abscesses, pelvic inflammatory disease, or infections requiring a prophylactic antibiotic. Drug interactions with antacids or theophylline may occur.

Treatment of experimental foreign body infection caused by methicillin-resistant Staphylococcus aureus

A novel model of experimental foreign body infection was developed in rats: four perforated Teflon tissue cages per animal were implanted subcutaneously and 3 to 4 weeks later were infected with 0.5 x 10(5) to 2 x 10(5) CFU of methicillin-resistant Staphylococcus aureus. After 2 weeks, the number of CFU in the cage fluid was determined [day 1 mean, (7.25 +/- 0.79) log10 CFU/ml], and treatment with vancomycin (50 mg/kg twice a day [BID]), fleroxacin (50 mg/kg BID), or fifampin (25 mg/kg BID), alone and in combination, was initiated for a duration of 6 days. Concentrations of antibiotics in cage fluids were in the range of those encountered in clinical conditions. Eighteen hours after the last injection (day 7), the number of CFU in the cage fluid was determined and the difference between day 1 and day 7 values was calculated. Rifampin, alone and in combination with fleroxacin or vancomycin, was the most effective regimen in reducing the bacterial counts in the tissue cage fluids [(1.87 +/- 1.44, 2.18 +/- 1.02, and 2.55 +/- 1.09 log10) CFU/ml, P less than 0.001, respectively]. After treatment, cage fluids and cages were analyzed for resistant bacteria. Resistance to rifampin occurred in 15 of 19 cages in animals treated with rifampin alone and in 4 of 25 in animals treated with rifampin plus vancomycin. We detected no development of resistance to rifampin in animals treated with rifampin plus fleroxacin or to fleroxacin in animals treated with this antimicrobial agent. In conclusion, regimens including rifampin alone or in combination with vancomycin or fleroxacin were an effective treatment of foreign body infection due to methicillin-resistant S. aureus in reducing bacteria counts, but rifampin monotherapy was compromised by significant emergence of resistance. The combined therapy of fleroxacin with rifampin prevent development of resistance to rifampin.

Comparative in vitro activities of sparfloxacin (CI-978; AT-4140) and other antimicrobial agents against staphylococci, enterococci, and respiratory tract pathogens

The in vitro activity of sparfloxacin (CI-978; AT-4140) was compared with those of other antimicrobial agents against isolates of staphylococci, enterococci, and various respiratory tract pathogens. Sparfloxacin was the most active drug tested against staphylococci (MIC for 90% of the strains tested [MIC90], 0.125 micrograms/ml) and enterococci (MIC90, 1.0 microgram/ml). It was also active against Haemophilus influenzae (MIC90, less than or equal to 0.06 microgram/ml), Moraxella (Branhamella) catarrhalis (MIC90, 0.125 microgram/ml), Streptococcus pneumoniae (MIC90, 0.5 microgram/ml), and Streptococcus pyogenes (MIC90, 1.0 microgram/ml).

Oral ciprofloxacin treatment of Pseudomonas aeruginosa osteomyelitis

Twenty-two adult patients with osteomyelitis due to Pseudomonas aeruginosa were enrolled in an open, prospective cooperative study to determine the efficacy of oral ciprofloxacin therapy in a dosage of 750 mg twice a day. Twenty patients received a complete course of treatment and could be assessed for efficacy. There were 12 men and 8 women, with a mean age of 55 years. Six patients had undergone previous, unsuccessful attempts at therapy. Eight patients had clinically important underlying conditions. The most common sites of infection were the sternum (six patients), hip (four patients), vertebrae (four patients), and tibia (two patients). Initial surgical debridement was performed in 18 of the 20 assessable patients. The mean duration of treatment was 2.85 months (range, 1 to 4 months), and that of the follow-up was 27 months (range, 6 to 52 months). Cure was achieved in 19 of the 20 (95%) patients. The only significant adverse effect (which prompted discontinuation of therapy) was severe nausea in one case. Oral ciprofloxacin coupled with adequate debridement is an effective, convenient, and safe therapy in patients with acute and subacute P. aeruginosa osteomyelitis.

Ciprofloxacin drug utilization review and prospective drug use evaluation

Ciprofloxacin is a fluoroquinolone antimicrobial with activity against both gram-negative and -positive bacteria including pseudomonal and staphylococcal species. It is the only available oral agent possessing this unique spectrum of activity that achieves serum concentrations adequate to treat a variety of systemic infections. A retrospective drug utilization review and a prospective drug use evaluation of ciprofloxacin were performed to determine if the agent was being used for appropriate indications, to ensure correct dosing and appropriate monitoring, and to determine whether its use is cost effective at the Veterans Administration Medical Center, Cleveland (VAMCC). For the retrospective review, 40 patients' charts were randomly chosen for review from computerized inpatient and outpatient prescription records. Drug use review criteria were developed by the Pharmacy Service and Infectious Disease Section. For the prospective evaluation, data were collected for all inpatient and outpatient requests for ciprofloxacin during a six-month period (May to November 1988) using the same criteria as in the retrospective study. Cost analysis was performed by identification and cost comparison of alternative therapy and by estimating the number of days saved by using appropriate oral therapy. All charts from the retrospective review were found to meet criteria for appropriate use. All patients for whom documented follow-up was performed had microbiologic or clinical cures. In the prospective evaluation, 168 patients were started on ciprofloxacin. Ninety-five percent of patients had appropriate justification for use according to criteria. Drug cost savings for the six-month period was +14,962.54 or +29,925.08/year. This covered drug and minibag acquisition costs only. An estimated 127 hospital days were saved (shortened length of +71,717.00 or +143,434.00/year.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical utility of new quinolones in treatment of osteomyelitis and lower respiratory tract infections

In the eight major clinical studies published on use of oral quinolones in therapy of contiguous osteomyelitis, clinical and microbiologic cure/improvement rates were 75% and 73%, respectively, when drug therapy was combined with appropriate surgical debridement. This included many cases of polymicrobial osteomyelitis, as well as infection caused by recalcitrant pathogens such as Pseudomonas aeruginosa. In contrast, the response of staphylococcal osteomyelitis to oral quinolones, especially in cases caused by methicillin-resistant strains, appeared suboptimal. Quinolones appear to have a limited role in the treatment of community-acquired pneumonia, since other established antibiotic regimens have been proven effective in such situations. Quinolones may play an important role in the treatment of nosocomially acquired aerobic gram-negative bacillary pneumonia, either as primary parenteral therapy or as transitional oral therapy when affected patients become outpatients. In cystic fibrosis-associated acute exacerbations of chronic pseudomonal pneumonitis, the outcome of oral ciprofloxacin therapy was very satisfactory in the six major studies reported (approximately 85% improvement rates). In three comparative studies oral quinolone treatment of such pulmonary exacerbations resulted in clinical response rates equivalent to those for aminoglycoside plus beta-lactam therapy given intravenously. Quinolone-resistant Pseudomonas aeruginosa strains were commonly isolated from sputum during treatment; however, such patients continued to respond clinically to quinolone treatment, and sputum became rapidly repopulated with quinolone-susceptible Pseudomonas aeruginosa strains after discontinuation of therapy.

Synergistic effect of quinolones and oxacillin on methicillin-resistant Staphylococcus species

Various combinations of antistaphylococcal antimicrobial agents have been tested against 17 selected Staphylococcus isolates, including methicillin-susceptible and methicillin-resistant strains of S. aureus and coagulase-negative Staphylococcus species. With the checkerboard technique the following combinations were tested: oxacillin-ofloxacin, oxacillin-temafloxacin, oxacillin-fleroxacin, vancomycin-fleroxacin, gentamicin-fleroxacin, and rifampin-fleroxacin. Against methicillin-resistant staphylococci the combination oxacillin-quinolone tested at 35 degrees C always showed a fractional inhibitory concentration (FIC) index of less than 0.75, which is interpreted as synergistic or additive. Equal or more synergistic effects were observed at 30 degrees C. In contrast, when methicillin-susceptible Staphylococcus species were tested, the FIC for the combination oxacillin-quinolone was always 1 or 2, which is considered to be indifferent. For the other mentioned combinations the FICs were also 1 or 2. Killing kinetics showed synergistic or additive bactericidal activity for the combination oxacillin-ofloxacin against methicillin-resistant Staphylococcus species, killing 1.5 to 2.8 log10 CFU more of these per ml than did the most active drug after 24 h of incubation. This difference was not observed for methicillin-susceptible strains. In vitro evidence for the potential clinical use of quinolones in treating infections due to methicillin-resistant staphylococci in combination with a beta-lactamase-resistant penicillin is provided.