P. Baiocchi

Conservative Medical Therapy of Infections Following Osteosynthesis: a Retrospective Analysis of a Six-Year Experience

Abstract The conventional therapeutic approach to bone infection associated with osteosynthesis is based on the idea that microbial eradication is most readily achieved by removal of the foreign material together with adequate antimicrobial therapy. This strategy usually requires implantation of external fixation devices with additional discomfort to the patient. We report our experience with conservative medical and antimicrobial therapy without removal of the osteosynthesis until adequate bone callus deposition is documented by bone radiography scan. Twenty patients with infections associated with intramedullary nailing (9 patients), screws and plate (9 patients) or screws (2 patients) were treated between 1995 to 2000. Osteosynthesis implantation sites were tibia (7 patients), femur (6 patients), femur and tibia (1 patient), humerus (1 patient), others (5 patients). Diagnosis of infection was based on clinical-microbiological evidence and confirmed by 99Tc-labeled leukocyte scan studies. Offending pathogens were Staphylococcus aureus 17 cases, Staphylococcus aureus + Escherichia coli, Staphylococcus epidermidis, unknown, 1 case each. Most infections were initially treated with intravenous or intramuscular teicoplanin ± ciprofloxacin or rifampin followed by oral antimicrobial therapy usually with ciprofloxacin or minocycline plus rifampin. Mean duration of antimicrobial therapy was 27.7 weeks (range 12-64 weeks). All patients (100%) were cured, and none complained of side-effects requiring antibiotic therapy discontinuation. We conclude that conservative medical therapy is feasible for osteosynthesis-associated bone infection.

Sternal wound infection revisited

Abstract.Sternal wound infections (SWIs) can be subdivided into two types, superficial or deep, that require different treatments. The clinical diagnosis of superficial SWI is normally easy to perform, whereas the involvement of deep tissues is frequently difficult to detect. Therefore, there is a need for an imaging study that permits the assessment of SWIs and is able to distinguish between superficial and deep SWI. The present work was a prospective study aiming to evaluate the role of technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) labelled leucocyte scan in SWI management. Twenty-eight patients with suspected SWIs were included in the study. On the basis of clinical examination they were subdivided into three groups: patients with signs of superficial SWI (group 1), patients with signs of superficial SWI and suspected deep infection (group 2) and patients with suspected deep SWI without superficial involvement (group 3). Ten patients previously submitted to median sternotomy, but without suspected SWI, were also included in the study as a control group (group 4). All patients with suspected SWI had bacteriological examinations of wound secretion, if present. In addition 99mTc-HMPAO labelled leucocyte scan was performed in all patients. The patients of groups 1, 2 and 3 were treated on the basis of the clinical signs and microbiological findings, independently of the scintigraphic results. The patients of group 4 did not receive treatment. The final assessment of infection was based on histological and microbiological findings or on long-term clinical follow-up. Sensitivity, specificity, accuracy and positive and negative predictive values for scintigraphic and non-scintigraphic results were calculated. In the diagnosis of superficial and deep SWI, clinical and microbiological examination (combined) yielded, respectively, a sensitivity of 68.7% and 100%, a specificity of 77.3% and 80.8%, an accuracy of 73.7% and 86.8%, a positive predictive value of 68.7% and 70.6% and a negative predictive value of 77.3% and 100%. The scintigraphic results obtained in superficial SWI yielded a sensitivity of 56.2%, a specificity of 90.9%, an accuracy of 76.3%, a positive predictive value of 81.8% and a negative predictive value of 74.1%, while, by contrast, in deep SWI all of these values were 100%. Therefore, one can conclude that 99mTc-HMPAO labelled leucocyte scan permits accurate diagnosis of deep SWI, solving the main clinical problem in this field. In the present study the categorisation of patients without taking into account 99mTc-HMPAO labelled leucocyte planar scan findings caused a non-negligible number of cases of superficial SWI to be treated as though they were deep SWI. This ”overestimation” led to unnecessary surgery, increased and prolonged use of antibiotics with more (higher) toxicity and additional expense.

High rate of oxacillin-resistant Staphylococcus aureus isolates in an Italian University Hospital.

We reviewed our routine clinical laboratory records from January 1990 to March 1993 to evaluate the rate of oxacillin-resistance among nosocomial isolates of Staphylococcus aureus. Of 265 clinically significant isolates, 174 (65%) were oxacillin-resistant S. aureus (ORSA). Most of these strains were obtained from surgery patients and/or were isolated from surgical wounds. The isolations of S. aureus increased during the study period: 45 in 1990, 50 in 1991, 130 in 1992 and 40 in the first trimester of 1993. The annual rates of ORSA among S. aureus isolated varied from 62 to 68% through these years. Most ORSA isolates proved resistant to ciprofloxacin, gentamicin and rifampicin, and susceptible to vancomycin, netilmicin and cotrimoxazole. Based on these results, the need for a stringent application of infection control measures is outlined.

Potential of clindamycin in addition to vancomycin for the treatment of oxacillin-resistant Staphylococcus aureus septicemia persisting under vancomycin therapy

We observed seven patients with persistent fever and staphylococcemia under vancomycin-containing antimicrobial regimens who promptly improved as clindamycin was added to the initial antibiotics. Moreover, in all these patients a striking increase in peak and trough serum inhibitory activity (SIR) and serum bactericidal activity (SBA) levels was observed after addition of clindamycin. SIA and SBA levels after administration of a single dose of vancomycin (500 mg), clindamycin (600 mg) or vancomycin + clindamycin were also measured in three healthy volunteers against six ORSA isolates. Unsatisfactory peak SBA levels (0% of cases 1:8) were obtained after vancomycin administration. Vice versa, peak SBA levels 1:8 were obtained in 94% of the cases after clindamycin and in 100% of cases after vancomycin + clindamycin. Time-kill studies showed a borderline or incomplete bactericidal activity of vancomycin against three ORSA isolates from infections that manifested poor or slow response to vancomycin therapy. The combination with clindamycin did not result in a synergistic interaction between the two drugs. It is concluded that addition of clindamycin may be useful in some cases of ORSA septicemia that show poor or slow response to vancomycin therapy. The recommendation for a wider use of this combination of antibiotics requires further documentation of efficacy.

Alterations of coagulase-negative staphylococcal flora in cardiac surgery patients: comparative study between cefamandole and pefloxacin perioperative prophylaxis.

The changes in coagulase-negative staphylococcal flora induced by cefamandole prophylaxis were compared with those induced by pefloxacin prophylaxis among patients undergoing heart valve surgery. Twenty-five patients (15 receiving cefamandole prophylaxis and 10 receiving pefloxacin prophylaxis) were included in the study. In the pefloxacin group, colonization rates in anterior nares and in chest skin or wound that were 60% and 50% respectively before surgery, became 50% and 20% respectively after surgery. In the cefamandole group, colonization rates in anterior nares and chest skin or wound were 53.3% and 60% respectively before surgery and became 53.3% and 40% respectively after surgery. Cefamandole did not appear to induce the emergence of oxacillin or pefloxacin resistant coagulase-negative staphylococcal colonization in any cultured site. On the other hand pefloxacin appeared somewhat more efficacious than cefamandole in eradicating staphylococcal flora of anterior nares and chest skin or wound. Pefloxacin and oxacillin resistant strains were found in the perianal area in 0% of patients before pefloxacin prophylaxis and in 70% of patients after pefloxacin prophylaxis. However, further studies are necessary to confirm the emergence of antibiotic resistant coagulase-negative staphylococci in the intestinal microflora after quinolone administration. The clinical implications of such apparently disturbing phenomenon remain to be evaluated.

The role of preoperative Tc-99m HMPAO-labeled leukocyte total-body scans in aortic prosthetic reconstruction.

Purpose This study was performed to evaluate the utility of Tc-99m HMPAO-labeled leukocyte total-body scans (TBLS) for detecting remote septic foci before operation in patients undergoing aortofemoral vascular surgery. Materials and Methods Fifty-eight patients were screened before operation for inflammatory or infective disease, and a clinical score was assigned to each patient. Each patient had TBLSs. The relation between the clinical score and the TBLS result was determined. Patients with positive results of the TBLSs were examined, and the causes of these findings were treated before surgery. Results Ten of the 58 (17%) patients had a positive result of TBLSs. Of 31 patients with a clinical score of zero, 3 had positive findings of TBLS. No TBLS was positive in the 13 patients with a clinical score of 1. TBLS findings were positive in 7 of 14 of the combined patients with clinical scores of 2, 3, or 4. None of the patients showed signs of prosthetic vascular graft infection during the postoperative follow-up period. Conclusions In conclusion, TBLSs can be used before aortofemoral vascular surgery, but only in patients with high clinical scores for inflammatory or infective disease to identify relevant infective foci that could cause vascular graft infection.

STAPHYLOCOCCUS AUREUS MEININGITIS IN NEUROSURGERY ADULT PATIENTS: RETROSPECTIVE CLINICAL AND MICROBIOLOGIC ANALYSIS

We reviewed 12 cases of Staphylococcus aureus meningitis occurring over a 5-year period in five neurosurgery divisions at the Policlinico Umberto I. Six patients had an intraventricular shunt, five had craniotomy, and one had spinal surgery. All patients had one or more underlying causes other than surgery that might have predisposed to infection. Clinical presentation and cerebrospinal fluid (CSF) laboratory findings did not distinguish this form of meningitis from other acute bacterial meningitides. Gram stain of centrifuged CSF showed gram-positive cocci in 83% of cases. Blood cultures were positive in 25% of cases. Overall mortality was 50%. Eight CSF isolates were simultaneously resistant to oxacillin and rifampicin. Six of 10 patients treated with a glycopeptide were cured or improved. The remaining two patients with an oxacillin-susceptible S. aureus infection were cured: one was treated with cefamandole, the other one with ciprofloxacin and rifampicin.

The activity ‘in vitro’ of trospectomycin against high-level antibiotic-resistant enterococci

Trospectomycin, a new aminocyclitol antibiotic, was uniformly active against 69 isolates of enterococci with high-level resistance to steptomycin (54 isolates), gentamicin (27 isolates), ampicillin (19 isolates), ciprofloxacin (17 isolates), vancomycin (3 isolates), or teicoplanin (3 isolates). In time-killing studies, trospectomycin alone demonstrated no bactericidal activity. No synergistic interaction was demonstrated when trospectomycin was combined with ampicillin, vacomycin or ciprofloxacin.

Intravenous ciprofloxacin for the treatment of severe infections.

Intravenous ciprofloxacin at a daily dosage of 400 mg divided in two doses was administered to 19 patients with severe infections caused by ciprofloxacin-susceptible bacteria. These infections included: 11 surgical would infections, 5 soft tissue infections, 2 respiratory tract infections, 1 urinary tract infection. The offending pathogens were: 8 coagulase-negative staphylococci, 3 Staphylococcus aureus, 3 Pseudomonas aeruginosa, 2 Proteus spp., 1 Escherichia coli, 1 Branhamella catarrhalis, 1 Klebsiella ozenae and 1 Serratia liquefaciens. Overall, 17 of 19 infections (89%) showed a satisfactory clinical response to trial therapy (15 cures and 2 improvements). Microbiological eradication was observed in 17 out of 20 isolated pathogens. Emergence of resistance to ciprofloxacin occurred in 1 coagulase-negative Staphylococcus and was associated with clinical failure. No side effects were observed. We conclude that intravenous ciprofloxacin may represent efficacious and safe therapy of severe infections; however close microbiological monitoring seems to be necessary to evaluate the emergence of resistance during quinolone therapy.

Early Markers of Cardiovascular Risk in Autosomal Dominant Polycystic Kidney Disease

Background/Aims: Cardiovascular disease is the most frequent cause of morbidity and mortality in autosomal dominant polycystic kidney disease (ADPKD) patients, often before the onset of renal failure, and the pathogenetic mechanism is not yet well elucidated. The aim of the study was to identify early and noninvasive markers of cardiovascular risk in young ADPKD patients, in the early stages of disease. Methods: A total of 26 patients with ADPKD and 24 control group, matched for age and sex, were enrolled, and we have assessed inflammatory indexes, mineral metabolism, metabolic state and markers of atherosclerosis and endothelial dysfunction (carotid intima media thickness (IMT), ankle brachial index (ABI), flow mediated dilation (FMD), renal resistive index (RRI), left ventricular mass index (LVMI)) and cardiopulmonary exercise testing (CPET), maximal O2 uptake (V’O2max), and O2 uptake at lactic acid threshold (V’O2@LT). Results: The ADPKD patients compared to control group, showed a significant higher mean value of LVMI, RRI, homocysteine (Hcy), Homeostasis Model Assessment-insulin resistance (HOMA-IR), serum uric acid (SUA), Cardiac-troponinT (cTnT) and intact parathyroid hormone (iPTH) (p<0.001, p<0.001, p<0.001, p<0.001, p<0.001, p=0.007, p=0.019; respectively), and a lower value of FMD and 25-hydroxyvitaminD (25-OH-VitD) (p<0.001, p<0.001) with reduced parameters of exercise tolerance, as V’O2max, V’O2max/Kg and V’O2max (% predicted) (p<0.001, p<0.001, p=0.018; respectively), and metabolic response indexes (V’O2@LT, V’O2 @LT%, V’O2@LT/Kg,) (p<0.001, p=0.14, p<0.001; respectively). Moreover, inflammatory indexes were significantly higher in ADPKD patients, and we found a positive correlation between HOMA-IR and C-reactive protein (CRP) (r=0.507, p=0.008), and a negative correlation between HOMA-IR and 25-OH-VitD (r=-0.585, p=0.002). Conclusion: In our study, ADPKD patients, in the early stages of disease, showed a greater insulin resistance, endothelial dysfunction, inflammation and mineral metabolism disorders, respect to control group. Moreover, these patients presented reduced tolerance to stress, and decreased anaerobic threshold to CPET. Our results indicate a major and early cardiovascular risk in ADPKD patients. Therefore early and noninvasive markers of cardiovascular risk and CPET should be carried out, in ADPKD patients, in the early stages of disease, despite the cost implication.