Gentamicin-loaded strontium-containing hydroxyapatite bioactive bone cement--an efficient bioactive antibiotic drug delivery system

Modified strontium-containing hydroxyapatite (Sr-HA) bone cement was loaded with gentamicin sulfate to generate an efficient bioactive antibiotic drug delivery system for treatment of bone defects. Gentamicin release and its antibacterial property were determined by fluorometric method and inhibition of Staphylococcus aureus (S. aureus) growth. Gentamicin was released from Sr-HA bone cement during the entire period of study and reached around 38% (w/w) cumulatively after 30 days. Antibacterial activity of the gentamicin loaded in the cements is clearly confirmed by the growth inhibition of S. aureus. The results of the amount and duration of gentamicin release suggest a better drug delivery efficiency in Sr-HA bone cement over polymethylmethacrylate bone cement. Bioactivity of the gentamicin-loaded Sr-HA bone cement was confirmed with the formation of apatite layer with 1.836 ± 0.037 μm thick on day 1 and 5.177 ± 1.355 μm thick on day 7 after immersion in simulated body fluid. Compressive strengths of the gentamicin-loaded Sr-HA cement reached 132.60 ± 10.08 MPa, with a slight decrease from the unloaded groups by 4-9%. Bending moduli of Sr-HA cements with and without gentamicin were 1.782 ± 0.072 GPa and 1.681 ± 0.208 GPa, respectively. On the contrary, unloaded Sr-HA cement obtained slightly larger bending strength of 35.48 ± 2.63 MPa comparing with 33.00 ± 1.65 MPa for loaded cement. No statistical difference was found on the bending strengths and modulus of gentamicin-loaded and -unloaded Sr-HA cements. Sr-HA bone cement loaded with gentamicin was proven to be an efficient drug delivery system with uncompromised mechanical properties and bioactivity.

Rationality of administered gentamicin dose in cerebral coma patients treated in an intensive care unit

Gentamicin is still widely used in the treatment of patients in an intensive care unit (ICU). The efficacy of aminoglycosides correlates with the peak serum concentration (Cmax), and the toxicity with the minimum serum concentration (Cmin). The aim of this study was to determine Cmax and Cmin in serum of cerebral coma ICU patients when a dosage of gentamicin of 5 mg/kg body weight was administered once daily; to evaluate the rationality of mentioned dose; and to identify factors associated with these concentrations. Material and METHODS. A total of 24 ICU patients suffering from cerebral coma were included into this analysis. A dosage of gentamicin of 5 mg/kg body weight was administered once a day. Gentamicin concentrations were tested twice after the first dose infusion (immediately and 5 hours after 1-hour infusion). Cmax, Cmin, volume of distribution (Vd), and elimination half-life (T1/2) were obtained. RESULTS. The mean Cmax was 17.96 (SD, 4.31) µg/mL (range, 10.30-27.87 µg/mL). The desirable Cmax (≥ 20 µg/mL) was reached only in 6 patients (25%). Cmin was calculated using a special pharmacokinetic program "Kinetica." Cmin of 0.5 µg/mL was not exceeded in any patient. A correlative analysis indicated a significant inverse direct correlation between Cmax and Vd and between Cmax and treatment duration in the ICU. An inverse correlation was observed between Cmin and T1/2, evaluation of coma according to the Glasgow coma scale, and creatinine clearance. CONCLUSIONS. A dosage of 5 mg/kg body weight once a day was not sufficient in cerebral coma ICU patients. This dose was not associated with the nephrotoxic effect of gentamicin (additional risk factors were absent). It is recommended to obtain gentamicin concentration at two time points following administration of the first dose (e.g., immediately after 1-hour infusion and 5 hours later), and using a special pharmacokinetic software, to calculate a necessary dose and interval of administration.

Local application of gentamicin collagen implants in the prophylaxis of surgical site infections following gastrointestinal surgery: a review of clinical experience

BACKGROUND

Surgical site infection (SSI) is a common type of healthcare-associated infection in gastrointestinal (GI) surgical procedures, which often has major consequences for patient recovery and increased healthcare costs due to prolonged hospital stay. This article provides an overview of the efficacy and safety of prophylactic application of resorbable gentamicin-containing collagen implants (GCI) in the prevention of SSI following high-risk GI surgical procedures.

METHOD

Nine publications were identified using the PubMed online database and search terms 'gentamicin collagen implant' plus 'surgical site infection', 'wound infection' and 'gastrointestinal surgery'.

RESULTS

Data from 483 patients treated prophylactically have demonstrated that GCI can reduce the wound infection rate in high-risk GI surgical procedures and improve wound healing after pilonidal sinus excision. In a study of 221 patients who underwent colorectal surgery, the wound infection rate was reduced to 5.6% in the GCI group compared to 18.4% in the control group (P < 0.01). GCI also positively influences the post-operative course for patients undergoing particularly risky procedures e.g. abdominoperineal resection (APR) combined with neoadjuvant radiotherapy. In one such patient series, GCI reduced the wound infection rate by over 70% and the length of hospital stay by 40%. Few side effects of GCI were noted in the 9 clinical studies.

CONCLUSIONS

This review demonstrates that GCI can have a positive effect on wound infection rates in high-risk GI surgery and can also improve wound healing after pilonidal sinus excision.

Antimicrobial-resistant enterococci in animals and meat: a human health hazard?

Enterococcus faecium and Enterococcus faecalis belong to the gastrointestinal flora of humans and animals. Although normally regarded harmless commensals, enterococci may cause a range of different infections in humans, including urinary tract infections, sepsis, and endocarditis. The use of avoparcin, gentamicin, and virginiamycin for growth promotion and therapy in food animals has lead to the emergence of vancomycin- and gentamicin-resistant enterococci and quinupristin/dalfopristin-resistant E. faecium in animals and meat. This implies a potential risk for transfer of resistance genes or resistant bacteria from food animals to humans. The genes encoding resistance to vancomycin, gentamicin, and quinupristin/dalfopristin have been found in E. faecium of human and animal origin; meanwhile, certain clones of E. faecium are found more frequently in samples from human patients, while other clones predominate in certain animal species. This may suggest that antimicrobial-resistant E. faecium from animals could be regarded less hazardous to humans; however, due to their excellent ability to acquire and transfer resistance genes, E. faecium of animal origin may act as donors of antimicrobial resistance genes for other more virulent enterococci. For E. faecalis, the situation appears different, as similar clones of, for example, vancomycin- and gentamicin-resistant E. faecalis have been obtained from animals and from human patients. Continuous surveillance of antimicrobial resistance in enterococci from humans and animals is essential to follow trends and detect emerging resistance.

Comparison of gentamicin distribution in the inner ear following administration via the endolymphatic sac or round window

OBJECTIVE/HYPOTHESIS

The distribution of gentamicin in the inner ear via the endolymphatic sac (ES) or round window (RW) routes was investigated.

STUDY DESIGN

Experimental study.

METHODS

A fluorescent gentamicin-Texas Red conjugate (GTTR) was adopted to visualize the gentamicin. Adult guinea pigs were treated with GTTR applied to the ES or RW, the animals were allowed to recover for 3 days, then confocal microscopy was used to observe and quantify GTTR distributions in cochlear and vestibular sensory epithelium.

RESULTS

When GTTR was applied via the ES, strong GTTR labeling was observed in the vestibule while little GTTR was detected in the cochlea (P < .0001). However, distinct GTTR fluorescence was observed in the cochlea and vestibule following RW application (P = .7967). There was less GTTR labeling in cochlea via ES application than through RW administration (P < .0001).

CONCLUSIONS

ES drug application may be preferable for the treatment of intractable Meniere's disease. Laryngoscope, 2010.

Gentamicin-collagen sponge for infection prophylaxis in colorectal surgery

BACKGROUND

Despite the routine use of prophylactic systemic antibiotics, surgical-site infection continues to be associated with significant morbidity and cost after colorectal surgery. The gentamicin-collagen sponge, an implantable topical antibiotic agent, is approved for surgical implantation in 54 countries. Since 1985, more than 1 million patients have been treated with the sponges.

METHODS

In a phase 3 trial, we randomly assigned 602 patients undergoing open or laparoscopically assisted colorectal surgery at 39 U.S. sites to undergo either the insertion of two gentamicin-collagen sponges above the fascia at the time of surgical closure (the sponge group) or no intervention (the control group). All patients received standard care, including prophylactic systemic antibiotics. The primary end point was surgical-site infection occurring within 60 days after surgery, as adjudicated by a clinical-events classification committee that was unaware of the study-group assignments.

RESULTS

The incidence of surgical-site infection was higher in the sponge group (90 of 300 patients [30.0%]) than in the control group (63 of 302 patients [20.9%], P=0.01). Superficial surgical-site infection occurred in 20.3% of patients in the sponge group and 13.6% of patients in the control group (P=0.03), and deep surgical-site infection in 8.3% and 6.0% (P=0.26), respectively. Patients in the sponge group were more likely to visit an emergency room or surgeon's office owing to a wound-related sign or symptom (19.7%, vs. 11.0% in the control group; P=0.004) and to be rehospitalized for surgical-site infection (7.0% vs. 4.3%, P=0.15). The frequency of adverse events did not differ significantly between the two groups.

CONCLUSIONS

Our large, multicenter trial shows that the gentamicin-collagen sponge is not effective at preventing surgical-site infection in patients who undergo colorectal surgery; paradoxically, it appears to result in significantly more surgical-site infections. (Funded by Innocoll Technologies; ClinicalTrials.gov number, NCT00600925.)

Once-daily gentamicin administration for community-associated methicillin resistant Staphylococcus aureus in an in vitro pharmacodynamic model: preliminary reports for the advantages for optimizing pharmacodynamic index

PURPOSE

Community-associated methicillin resistant Staphylococcus aureus (CAMRSA) infections are increasing. Although gentamicin (GEN) is usually susceptible against CA-MRSA, GEN is rarely considered for treatment as monotherapy. We employed an in vitro pharmacodynamic model (IVPDM) to compare efficacies of GEN against CA-MRSA with two dosing regimens [thrice-daily (TD), once-daily (OD)].

MATERIALS AND METHODS

Using two strains of CA-MRSA, we adopted IVPDM comprised of two-compartments with a surface-to-volume ratio of 5.34 cm(-1). GEN regimens were simulated with human pharmacokinetic data of TD and OD. Experiments were performed over 48 hours in triplicate for each strain and dosing regimen.

RESULTS

MICs of GEN for YSSA1 and YSSA15 were 1 and 2 mg/L, respectively. In OD, indices of peak/MIC were > 8.6 at least, in contrast to < 6.4 in TD. A > or = 3-log(10) reduction in CFU/mL was demonstrated prior to 4 hours in TD and OD, and continued until 8 hours for both strains. However, reductions in the colony counts at 24 and 48 hours were significantly larger for OD compared to TD in both strains (p < 0.001). During TD, resistance developed in YSSA1 and small colony variants (SCVs) were documented in YSSA15. No resistance or SCVs were observed during OD in both strains.

CONCLUSION

TD and OD showed the same killing slopes until 8 hours. After the 24 hours of experiments, OD of GEN would be advantageous not only in having more reductions in colony counts, but also suppressing the development of resistance or SCVs for 48 hours.

Competitive antagonism of fluorescent gentamicin uptake in the cochlea

Aminoglycosides enter inner ear hair cells via apical endocytosis, or mechanoelectrical transduction channels, implying that, in vivo, aminoglycosides enter hair cells from endolymph prior to exerting their cytotoxic effect. If so, circulating aminoglycosides likely cross the strial blood-labyrinth barrier and enter marginal cells prior to clearance into endolymph. We characterized the competitive antagonism of unconjugated aminoglycosides on the uptake of fluorescent gentamicin (GTTR) in the stria vascularis and kidney cells at an early time point. In mice, uptake of GTTR by kidney proximal tubule cells was competitively antagonized by gentamicin at all doses, but only weakly by kanamycin (mimicking in vitro data). GTTR fluorescence was approximately 100-fold greater in proximal tubule cells than in the stria vascularis. Furthermore, only high molar ratios of aminoglycosides significantly reduced strial uptake of GTTR. Thus, gentamicin antagonism of GTTR uptake is more efficacious in proximal tubules than in the stria vascularis. Competitive antagonism of GTTR uptake is indicative of specific cell-regulatable uptake mechanisms (e.g., ion channels, transporters) in the kidney. Strial uptake mechanisms have lower specific affinity for gentamicin, and/or density (compared to the kidney), yet may be critical to transport gentamicin across the strial blood-labyrinth barrier into marginal cells.

Effect of an implantable gentamicin-collagen sponge on sternal wound infections following cardiac surgery: a randomized trial

CONTEXT

Despite the routine use of prophylactic systemic antibiotics, sternal wound infection still occurs in 5% or more of cardiac surgical patients and is associated with significant excess morbidity, mortality, and cost. The gentamicin-collagen sponge, a surgically implantable topical antibiotic, is currently approved in 54 countries. A large, 2-center, randomized trial in Sweden reported in 2005 that the sponge reduced surgical site infection by 50% in cardiac patients.

OBJECTIVE

To test the hypothesis that the sponge prevents infection in cardiac surgical patients at increased risk for sternal wound infection.

DESIGN, SETTING, AND PARTICIPANTS

Phase 3 single-blind, prospective randomized controlled trial, 1502 cardiac surgical patients at high risk for sternal wound infection (diabetes, body mass index >30, or both) were enrolled at 48 US sites between December 21, 2007, and March 11, 2009.

INTERVENTION

Single-blind randomization to insertion of 2 gentamicin-collagen sponges (total gentamicin of 260 mg) between the sternal halves at surgical closure (n = 753) vs no intervention (control group: n = 749). All patients received standardized care including prophylactic systemic antibiotics and rigid sternal fixation.

MAIN OUTCOME MEASURES

The primary end point was sternal wound infection occurring through 90 days postoperatively as adjudicated by a clinical events classification committee blinded to study treatment group. The primary study comparison was done in the intent-to-treat population. Secondary outcomes included (1) superficial wound infection (involving subcutaneous tissue but not extending down to sternal fixation wires), (2) deep wound infection (involving the sternal wires, sternal bone, and/or mediastinum), and (3) score for additional treatment, presence of serous discharge, erythema, purulent exudate, separation of the deep tissues, isolation of bacteria, and duration of inpatient stay (ASEPSIS; minimum score of 0 with no theoretical maximum).

RESULTS

Of 1502 patients, 1006 had diabetes (67%) and 1137 were obese (body mass index >30) (76%). In the primary analysis, there was no significant difference in sternal wound infection in 63 of 753 patients randomized to the gentamicin-collagen sponge group (8.4%) compared with 65 of 749 patients randomized to the control group (8.7%) (P = .83). No significant differences were observed between the gentamicin-collagen sponge group and the control group, respectively, in superficial sternal wound infection (49/753 [6.5%] vs 46/749 [6.1%]; P = .77), deep sternal wound infection (14/753 [1.9%] vs 19/749 [2.5%]; P = .37), ASEPSIS score (mean [SD], 1.9 [6.4] vs 2.0 [7.2]; P = .67), or rehospitalization for sternal wound infection (23/753 [3.1%] vs 24/749 [3.2%]; P = .87).

CONCLUSION

Among US patients with diabetes, high body mass index, or both undergoing cardiac surgery, the use of 2 gentamicin-collagen sponges compared with no intervention did not reduce the 90-day sternal wound infection rate.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00600483.

Gentamicin dosing for pediatric patients with congenital heart disease

Pediatric patients with congenital heart disease can have physiologies that alter the pharmacokinetics of certain medications, such as aminoglycosides. Currently, no literature describes the appropriate dosing of aminoglycoside antibiotics for infants and children with congenital heart disease. Patients were identified through the pharmacy and laboratory computer systems. Patients were included in the study if they were younger than 18 years, received gentamicin on the acute-care (nonintensive care) cardiology floor at the authors' institution, had structural congenital heart disease, and had a peak and trough level obtained at about the third dose or later. Cohort achievement of therapeutic peak and trough concentrations based on standard dosing guidelines was evaluated. The inclusion criteria were met by 48 patients (31 boys). Eight patients (17%) had baseline cyanosis. Cardiac surgery was performed for 23 patients (48%) during the same admission at which aminoglycoside therapy was initiated. A total of 27 patients (56%) received at least one other nephrotoxic medication at the time of aminoglycoside therapy. Six patients had undetectable serum trough levels. A therapeutic peak concentration was not achieved by 16.7% of the cohort, and 7.1% of the cohort did not achieve a therapeutic trough concentration. Pediatric patients with congenital heart disease may require alterations in gentamicin dosing. Close pharmacokinetic monitoring of aminoglycoside therapy for these patients is warranted to ensure attainment of goal concentrations.

Antibiotic lock solutions for the prevention of catheter-related bacteraemia in haemodialysis patients

OBJECTIVE

To investigate the effect of antibiotic lock solutions for preventing catheter-related bacteraemia in patients receiving haemodialysis.

DESIGN

Retrospective study.

SETTING

University teaching hospital, Hong Kong.

PATIENTS

Consecutive patients from March 2006 to April 2007 who had central venous catheter insertion for haemodialysis in our centre were included in this historically controlled study. In all, 75 patients had catheters with heparin solution alone and 74 had catheters with a gentamicin antibiotic lock. The majority of catheters were non-tunnelled (95%). Cumulative catheter survival free of catheter-related bacteraemia in the two groups was compared.

RESULTS

Baseline characteristics in the two groups were similar apart from a slightly lower serum albumin level in those with gentamicin locks. There were 18 and five catheter-related bacteraemia episodes before and after recourse to gentamicin antibiotic locks, respectively. Staphylococcus aureus contributed to over half (65%) of the total bacteraemia episodes. Use of gentamicin antibiotic locks significantly reduced catheter-related bacteraemia episodes per 1000 catheter days from 4.6 to 1.5 (P=0.002). Kaplan-Meier survival analysis using the log rank test showed significantly better bloodstream infection-free survival associated with using gentamicin antibiotic locks (P=0.032). A similar survival advantage was associated with gentamicin antibiotic locks when the analysis was restricted to non-tunnelled catheters. There was no significant association of catheter-related bacteraemia with patient age, obesity, gender, baseline serum albumin level, or diabetes mellitus. No serious adverse events were attributable to the use of gentamicin antibiotic locks.

CONCLUSION

Use of gentamicin lock solutions effectively reduced catheter-related bacteraemia in haemodialysis patients, including those with non-tunnelled catheters.

Ridge preservation following tooth extraction: a comparison between atraumatic extraction and socket seal surgery

OBJECTIVE

To evaluate whether alveolar ridge resorption following tooth extraction could be prevented or reduced using absorbable collagen material impregnated with gentamicin and sealed with an autogenous soft tissue graft to stabilize the extraction clot, and to compare this with natural healing by clot formation using a classic extraction technique.

METHOD AND MATERIALS

A total of 125 patients providing 173 extraction sites were included in the study. Three extraction protocols were compared: atraumatic extraction (group A, n = 101 extraction sites), atraumatic extraction sealing the socket with autogenous soft tissue graft (group B, n = 39), and atraumatic extraction with socket seal surgery and collagen matrix impregnated with gentamicin (group C, n = 33). Silicone impressions were made before and 3 months after extraction. Casts were used to measure the width of the alveolar bone at the extraction area using the incisal edge of the adjacent teeth as a reference point.

RESULTS

The clinical measurement 3 months after extraction revealed a loss of bone width of 0.3 +/- 0.5 mm in group A, 0.8 +/- 0.7 mm in group B, and 0.1 +/- 0.1 mm in group C. There was no significant difference in bone resorption in extraction sites among the groups (P > .05). However, the difference between group A and group C was borderline significant (P = .07). After 10 days, 31 grafts from group C and 30 grafts from group B remained vital.

CONCLUSIONS

It seems that extraction technique affects alveolar bone resorption, regardless of whether the socket is treated with free gingival graft or bone graft. Further, the local application of gentamicin presented more vascular ingrowth in the blood clot and granulation tissue beneath the graft, thereby supplying better nourishment during the initial healing phase of the graft.

Release of gentamicin sulphate from biodegradable PLGA-implants produced by hot melt extrusion

For a long-term local treatment of osteomyelitis biodegradable poly(lactic-co-glycolic acid) (PLGA) implants loaded with gentamicin sulphate (GS) were prepared, analysed and compared to the marketed product Septopal (Biomet, Darmstadt, Germany), which consists of polymethylmethacrylate (PMMA) beads loaded with the same active ingredient. The implants were manufactured by hot melt extrusion with a twin screw extruder. In order to decrease the processing temperature and to improve the drug release behaviour, polyethylene glycol 400 (PEG 400) was added as plasticizer in different concentrations. The glass transition temperature of PLGA measured by differential scanning calorimetry declined in the same manner as the extrusion temperature with increasing PEG 400 concentration. The extrudates of all batches exhibited good encapsulation efficiency between 85% and 115% of the specified content. The behaviour of the implants during exposure to a release medium were characterised by scanning electron microscopy, gravimetric analysis and finally in vitro drug release studies. The results suggest that drug liberation is not affected by the addition of PEG 400, and depends on the drug-PLGA ratio only. Extrudates with 25% GS showed a release pattern with an initially higher drug release followed by a zero order kinetic for about four weeks and showed release profiles equivalent to Septopal.

The effectiveness of the controlled release of gentamicin from polyelectrolyte multilayers in the treatment of Staphylococcus aureus infection in a rabbit bone model

While the infection rate of orthopedic implants is low, the required treatment, which can involve six weeks of antibiotic therapy and two additional surgical operations, is life threatening and expensive, and thus motivates the development of a one-stage re-implantation procedure. Polyelectrolyte multilayers incorporating gentamicin were fabricated using the layer-by-layer deposition process for use as a device coating to address an existing bone infection in a direct implant exchange operation. The films eluted about 70% of their payload in vitro during the first three days and subsequently continued to release drug for more than four additional weeks, reaching a total average release of over 550 microg/cm(2). The coatings were demonstrated to be bactericidal against Staphylococcus aureus, and degradation products were generally nontoxic towards MC3T3-E1 murine preosteoblasts. Film-coated titanium implants were compared to uncoated implants in an in vivo S. aureus bone infection model. After a direct exchange procedure, the antimicrobial-coated devices yielded bone homogenates with a significantly lower degree of infection than uncoated devices at both day four (p < 0.004) and day seven (p < 0.03). This study has demonstrated that a self-assembled ultrathin film coating is capable of effectively treating an experimental bone infection in vivo and lays the foundation for development of a multi-therapeutic film for optimized, synergistic treatment of pain, infection, and osteomyelitis.

In vitro assessment of the antibiotic efficacy of contrast media and antibiotics and their combinations at various dilutions

Discography is a controversial diagnostic procedure involving the injection of radiographic contrast medium (RCM) into the intervertebral disc. Iatrogenic bacterial discitis is a rare but serious complication. The intervention has been increasingly performed in our patients here in the United Arab Emirates. Prophylactic intravenous antibiotic administration can reduce post-interventional discitis; however, this may favour the development of bacterial resistance. Direct intradiscal injection of an antibiotic together with the RCM is a potential alternative. To date, there has been only one study on the efficacy of antibiotics added to an RCM. Equally, there are only limited data regarding the potential direct effect of RCM on bacterial growth. The purpose of this study was to determine whether the efficacy of antibiotics is affected when RCM are added. In an in vitro study, the effect of non-ionic RCM on the growth of five laboratory bacterial strains, alone and in combination with three broad-spectrum antimicrobials, was tested. Bacterial growth was assessed in the absence and the presence of RCM, antibiotics and their combinations. All three RCM alone demonstrated some inhibition of bacterial growth at high concentrations. In the presence of the RCM, all three antibiotics retained their inhibitory effect on bacterial growth. In conclusion, our in vitro experiments did not reveal any changes in the antimicrobial efficacy of the three antibiotics in the presence of the three tested RCM. Subsequent clinical trials will need to assess whether intradiscal antibiotic administration may be a suitable substitute for, or a supplement to, prophylactic systemic antibiotics before discography.

Use of povidone-iodine drop instead of sub-conjunctival injection of dexamethasone and gentamicin combination at the end of phacoemulsification cataract surgery

To evaluate the use of 5% povidone-iodine drop with subconjunctival injection of dexamethasone and gentamicin combination at the completion of phacoemulsification cataract surgery. This prospective randomized study was conducted at the department of Ophthalmology, Bangabandhu Sheikh Mujib Medical University (BSMMU), Dhaka, Bangladesh during the period of July, 2005 to June 2006. Senile & pre-senile cataract patients undergoing phacoemulsification cataract surgery were included in the study. Thirty patients were randomly included in Group A, receiving sub-conjunctival injection of dexamethasone and gentamicin combination and 30 patients in Group- B, receiving 5% povidone-iodine drop at the end of phacoemulsification surgery. Protocol for pre-operative medications, phacoemulsification technique and post-operative medications were similar in both groups. All patients were followed for 6 months post-operatively. Outcome measures were i) patients experience of pain and discomfort post-operatively ii) grade of inflammation post-operatively and iii) visual outcome. Difference of data between two groups was analyzed by unpaired 't' test and chi-square test. In Group A, mean age were 56.86+/-10.25 (SD) years and in Group B, mean age was 57.70+/-10.25 (SD) years. In Group A, 18(60%) patients were male and 12(40%) were female. In Group B, 16(53.33%) were male and 14(46.67%) were female. Pain and discomfort perceived by patients were measured by VAS at the end of operation, on 1st POD and after 7 days post-operatively. Mean VAS score was 5.7 in Group A and 2.7 in Group B at the end of surgery, 2.5 in Group A and 2.2 in Group B on 1st POD and 0.7 in Group A and 0.6 in Group B on 7th POD. Post-operative inflammation was assessed by slit lamp considering conjunctival congestion, chemosis, corneal striation, corneal oedema, cells and flare in anterior chamber. No significant difference was observed between two groups. Mean visual acuity was 0.16+/-0.12 in Group A and 0.15+/-0.13 in Group B. Anti-inflammatory, anti-infective effects and visual outcome are similar in both groups. But sub-conjunctival injection resulted more pain and hence less acceptable to patients.

[Treatment of chronic osteomyelitis of rabbit with liposomal gentamicin-impregnated allogeneic cortical bone]

OBJECTIVE

It is difficult to treat chronic osteomyelitis due to the formation of the Staphylococcus aureus biofilms. Liposomal gentamicin-impregnated allogeneic cortical bone can inhibit the formation of the Staphylococcus aureus biofilms. To explore the treatment of chronic osteomyelitis of rabbit by liposomal gentamicin-impregnated allogeneic cortical bone.

METHODS

The liposomal gentamicin, liposomal gentamicin-impregnated allogeneic cortical bone and gentamicin-impregnated allogeneic cortical bone were produced. Then the chronic Staphylococcus aureus osteomyelitis models of rabbit were made in left lower limbs of 40 6-month-old rabbits and the right lower limbs were used as controls. After 2 weeks, the observations of gross and X-ray were done. Four rabbits died within 10 days after the models were made and other 36 rabbits were divided into 6 groups: group A (no antibiotics), group B (intravenous injection of gentamicin), group C (intravenous injection of liposomal gentamicin), group D (implantation of gentamicin-impregnated allogeneic cortical bone), group E (implantation of liposomal gentamicin-impregnated allogeneic cortical bone), and group F (implantation of allogeneic cortical bone). After 2 weeks of treatment, the bacterial culture, X-ray and HE staining were done.

RESULTS

The chronic Staphylococcus aureus osteomyelitis model of rabbit was made successfully. The X-ray showed dissolution of bone and periosteal reaction in groups A, B, C, and F, and no obvious dissolution of bone and periosteal reaction in groups D and E. The Norden scores were (2.5 +/- 0.3), (2.1 +/- 0.2), (1.5 +/- 0.3), (1.5 +/- 0.2), (0.9 +/- 0.3), and (2.7 +/- 0.3) points in groups A-F, respectively; showing significant differences between group A and groups B-E (P < 0.05), between groups B, E, F and other groups (P < 0.05). The results of blood and marrow cultures for Staphylococcus aureus were positive in groups A and F, and negative in other 4 groups; the results of bone marrow culture for Staphylococcus aureus were positive in 6 rabbits of group B, 4 rabbits of group C and 3 rabbits of group D; and the results were negative in group E. HE staining showed: in groups A and F, abscess and dead bone formed, and no new bone formation were observed; in groups B and C, different degrees of neutrophil accumulation was seen; in group D, some neutrophil accumulation occurred, and osteoprogenitor cells and osteoclasts were seen around implanted bone; and in group E, no neutrophil accumulation was observed, a lot of granulation tissues formed, and osteoprogenitor cells and osteoclasts were seen around implanted bone.

CONCLUSION

Implantation of liposomal gentamicin-impregnated allogeneic cortical bone has remarkably better effect in treating chronic osteomyelitis than intravenous injection of liposomal gentamicin and implantation of gentamicin-impregnated allogeneic cortical bone.

[Septic pylephlebitis associated with Enterobacter cloacae septicemia]

Septic pylephlebitis or purulent thrombosis of the portal venous system generally results from a progressive extension of suppurated thrombophlebitis, secondary to an intrabdominal infection. Germs most often found are Escherichia coli and Streptococcus, isolation of Enterobacter cloacae is unusual. We report a particular observation of septic pylephlebitis associated with E. cloacae bacteremia, without biliary, digestive or pancreatic lesion on the CT-scan. The antibiotic sensitivity pattern of the isolated germ and the negative epidemiologic investigation pled in favour of community acquired infection. The infection resolved with antibiotics and anticoagulation, followed by total repermeation of the portal system.

[Antibiotic resistance of bacteria Campylobacter sp]

Campylobacter is recognized as a major cause of human acute bacterial enteritis. The incidence of human Campylobacter infection has increased markedly in both developed and developing countries and, more significantly, so has rapid emergence of antibiotic-resistant Campylobacter strains. It is caused by improper applying antibiotics in treating people and too frequent applying these substances in the animal husbandry. In this review, the patterns of emerging resistance to the antimicrobial agents useful in treatment of the disease are presented and the mechanisms of resistance to these drugs in Campylobacter spp. are discussed.

High-dose intratympanic gentamicin instillations for treatment of Meniere's disease: long-term results

CONCLUSIONS

Administration of high-dose gentamicin for intractable Meniere's disease appears to be effective in achieving long-term control of vertigo. However, the safety of this route of administration with respect to the patient's hearing has not yet been sufficiently established.

OBJECTIVES

The study aimed to analyze the long-term results of patients receiving high-dose intratympanic gentamicin (ITG) instillation for refractory Meniere's disease.

PATIENTS AND METHODS

Fourteen patients with Meniere's disease according to 1995 American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) guidelines who had failed medical (12 subjects) or surgical (2 subjects) treatment were included. Intratympanic injections of 27 mg/ml gentamicin were performed three times daily for 4 days. Vertigo control, the patients' functional level, and their hearing threshold were all analyzed. Criteria described in 1995 by AAO-HNS were used.

RESULTS

The overall successful vertigo control rate was 92.9% over the 2-year follow-up and 85.7% at long-term follow-up (average 10 years). Hearing level as pure-tone average was worse in four patients (28.5%) after 2 years follow-up and in six patients (42.8%) after long-term follow-up, respectively. Profound sensorineural hearing loss occurred as a result of gentamicin injection in one patient (7%).

Empyema necessitans and acute osteomyelitis associated with community-acquired methicillin-resistant Staphylococcus aureus in an infant

Staphylococcus aureus is a well recognized pathogen with global distribution. In recent years community-associated, methicillin-resistant S. aureus has emerged as an increasing cause of severe infections among adults and children. Herein, a case is reported of a previously healthy, 19-month-old male, who presented with empyema necessitans and acute osteomyelitis due to a community-associated, methicillin-resistant, S. aureus strain. This report highlights the evolving epidemiology of S. aureus, as important pathogen in the community as well as the hospital setting, and the importance of establishing appropriate guidelines for diagnosis, management and surveillance of this public health problem.

Vestibular function and vertigo control after intratympanic gentamicin for Ménière's disease

The aim of this study was to correlate long-term vertigo control with reduction in vestibular function after intratympanic (IT) gentamicin therapy for unilateral Ménière's disease. IT gentamicin injections were given as needed to control vertigo attacks. Vertigo frequency and changes in angular vestibulo-ocular reflex (AVOR) gain (measured using magnetic search coils and manual head thrusts) and caloric weakness were assessed before and after treatment. Better vertigo control after treatment was found with >or=60% reduction in quantitative ipsilateral horizontal semicircular canal AVOR gain from pre-treatment values and/or with caloric unilateral weakness (UW) >50%. However, no correlations were found between the continuous variables of vertigo control and either gain or gain recovery, nor between gain and UW because of the large variability in vertigo control in subjects with lesser reductions in these measures.

[The self-protective effect of low dosage of gentamicin]

AIM

To approach the protective effect of low dose gentamicin against high ototoxic dose of gentamicin.

METHODS

The guinea pigs were randomly divided into four groups: control group, low dose group, low dose protective group and high dose group. Each group received multiple intraperitoneal injections of gentamicin sulphate within different durations. Auditory brain stem response (ABR) was examined one day previous to the first and 24 h after the final injection respectively. The bulla was taken out so that the content of NO, MDA and the activity of LDH in cochlear were determined.

RESULTS

The threshold of ABR was significantly lower in low dose protective group compared with high dose group (P < 0.01). The content of NO (15.86 +/- 1.98 nmol/mg pro) and MDA (19.14 +/- 0.96 nmol/mg pro) in homogenate of high dose group was significantly higher than that of control group, low does group and low does protective group (P < 0.01). The increase of the content of NO and MDA induced by high dose GM could be significantly decreased by low dose GM administration previous to high dose injection (P < 0.01). The activity of LDH in homogenate of high dose group was significantly higher compared with control group, low dos group and low dos protective group (P < 0.01). There was no statistically significant difference of content of NO and MDA among control group, low does group and low does protective group.

CONCLUSION

The protective effects resulting from previous low dose administration to high dose injection of GM may be related to the decrease of content of NO and MDA and activity of LDH both of which induced by high dose GM.

The video head impulse test: diagnostic accuracy in peripheral vestibulopathy

BACKGROUND

The head impulse test (HIT) is a useful bedside test to identify peripheral vestibular deficits. However, such a deficit of the vestibulo-ocular reflex (VOR) may not be diagnosed because corrective saccades cannot always be detected by simple observation. The scleral search coil technique is the gold standard for HIT measurements, but it is not practical for routine testing or for acute patients, because they are required to wear an uncomfortable contact lens.

OBJECTIVE

To develop an easy-to-use video HIT system (vHIT) as a clinical tool for identifying peripheral vestibular deficits. To validate the diagnostic accuracy of vHIT by simultaneous measures with video and search coil recordings across healthy subjects and patients with a wide range of previously identified peripheral vestibular deficits.

METHODS

Horizontal HIT was recorded simultaneously with vHIT (250 Hz) and search coils (1,000 Hz) in 8 normal subjects, 6 patients with vestibular neuritis, 1 patient after unilateral intratympanic gentamicin, and 1 patient with bilateral gentamicin vestibulotoxicity.

RESULTS

Simultaneous video and search coil recordings of eye movements were closely comparable (average concordance correlation coefficient r(c) = 0.930). Mean VOR gains measured with search coils and video were not significantly different in normal (p = 0.107) and patients (p = 0.073). With these groups, the sensitivity and specificity of both the reference and index test were 1.0 (95% confidence interval 0.69-1.0). vHIT measures detected both overt and covert saccades as accurately as coils.

CONCLUSIONS

The video head impulse test is equivalent to search coils in identifying peripheral vestibular deficits but easier to use in clinics, even in patients with acute vestibular neuritis.

A rare case of infective endocarditis complicated by Trichosporon asahii fungemia treated by surgery

The patient was a 58-year-old male. He consulted our hospital because of weight loss and fever. Computed tomography (CT) revealed renal infarction. Nine days after admission, CT showed hemorrhagic cerebral infarction in the right frontal lobe. A blood culture revealed streptococcus oralis, and echocardiography revealed vegetation in the mitral and aortic valves, suggesting infective endocarditis (IE). Fever (39 degrees C or higher) was noted 23 days after admission. A blood culture revealed Trichosporon asahii (T. asahii), suggesting T. asahii fungemia. An intravenous drip of fluconazole at 400 mg/day was initiated, and two-valve replacement was performed 34 days after admission. Following surgery, the patient became negative for beta-D glucan and was discharged 85 days after admission. We report the present case of IE complicated by T. asahii fungemia, which is rare in patients other than malignant blood disease or tumor patients, showing a poor prognosis in which survival was achieved by surgery.

Simplified dosing of gentamicin for treatment of sepsis in Bangladeshi neonates

Extended-interval dosing of gentamicin has several advantages over conventional multiple-daily dosing for the treatment of sepsis. The study was conducted to evaluate the pharmacokinetics of gentamicin for the treatment of neonatal sepsis in predetermined doses at 24- or 48-hour intervals, according to weight category, and to develop a simplified protocol for use in peripheral healthcare settings in developing countries. This prospective observational study was conducted among 59 neonates admitted to the Special Care Nursery at Dhaka Shishu Hospital, Bangladesh, with suspected sepsis and treated with antibiotics, including gentamicin. Intravenous dosing of gentamicin according to weight category was: 10 mg every 48 hours if the infant weighed < 2,000 g (n = 23), 10 mg every 24 hours if the infant weighed 2,000-2,249 g (n = 12), or 13.5 mg every 24 hours if the infant weighed 2,500-3,000 g (n = 24). Peak and trough concentrations of gentamicin and the presence of signs of nephrotoxicity and ototoxicity were determined. The mean +/- standard deviation peak concentration of gentamicin was 12.3 +/- 3.7 microg/mL in infants weighing < 2,000 g, 9.6 +/- 3.1 microg/mL in infants 2,000-2,249 g, and 10.0 +/- 3.4 microg/mL in infants 2,500-3,000 g. Initial peak concentration of gentamicin was > 12 microg/mL in 28.8% and initial trough concentration was > 2 microg/mL in 6.8% of the subjects. No signs of nephrotoxicity or ototoxicity were detected. Favourable pharmacokinetic parameters found with the simplified dosing regimen suggest that it is safe for the treatment of neonatal sepsis.

[A rare case of endocarditis due to Moraxella catarrhalis in an immunocompetent patient]

Moraxella catarrhalis is a gram-negative, catalase and oxidase positive diplococcus. While it causes otitis media, sinusitis, bronchitis and conjunctivitis in children and adults, it has a tendency to cause lower respiratory tract infections in older ages. More severe clinical pictures with the range of sepsis to endocarditis are also seen in immunocompromised patients. In this report, a case of M. catarrhalis endocarditis in an immunocompetent host who needed valve replacement has been presented. Forty three years old female patient was admitted to our hospital with the complaints of fever, nausea, night sweating and arthralgia for 20 days. Physical examination revealed systolic murmurs on the apex, and vegetation on the atrial surface of mitral valve was detected by transthoracic echocardiography. Intravenous (IV) ampicillin (4 x 3 g/day) and gentamicin (3 x 80 mg/day) treatment was started empirically with prediagnosis of infective endocarditis. The treatment was modified to IV ceftriaxone (1 x 2 g/day) and gentamicin (3 x 80 mg/day) due to the reporting of gram-negative bacilli in blood culture (BacT/ALERT 3D, bioMérieux, France) on the next day. Gram-negative cocobacilli/diplococci were detected with Gram stain on the smear prepared from the blood culture bottle. Simultaneous subcultures to blood agar and eosin methylene blue agar yielded white colored, S-type, non-hemolytic colonies on only blood agar. Catalase and oxidase tests were positive, while beta-lactamase activity was negative. The isolate was identified as M. catarrhalis by using API NH (bioMérieux, France) identification strips. M. catarrhalis was isolated from five different blood culture specimens of the patient. The focus for bacteremia could not be detected. The patient underwent mitral valve replacement operation as an emergency since the vegetation exhibited rapid growth on the fifth day of medical treatment. Antibacterial therapy was completed for 6 weeks. Control echocardiography revealed that artificial mitral valve was open and functional, thus the patient recovered completely without sequela. In conclusion, M. catarrhalis should be considered as a possible cause of infective endocarditis even in immunocompetent patients.

Multifunctional implant coatings providing possibilities for fast antibiotics loading with subsequent slow release

The possibility to fast-load biomimetic hydroxyapatite coatings on surgical implant with the antibiotics Amoxicillin, Gentamicin sulfate, Tobramycin and Cephalothin has been investigated in order to develop a multifunctional implant device offering sustained local anti-bacterial treatment and giving the surgeon the possibility to choose which antibiotics to incorporate in the implant at the site of surgery. Physical vapor deposition was used to coat titanium surfaces with an adhesion enhancing gradient layer of titanium oxide having an amorphous oxygen poor composition at the interface and a crystalline bioactive anatase TiO(2) composition at the surface. Hydroxyapatite (HA) was biomimetically grown on the bioactive TiO(2) to serve as a combined bone in-growth promoter and drug delivery vehicle. The coating was characterized using scanning and transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The antibiotics were loaded into the HA coatings via soaking and the subsequent release and antibacterial effect were analyzed using UV spectroscopy and examination of inhibition zones in a Staphylococcus aureus containing agar. It was found that a short drug loading time of 15 min ensured antibacterial effects after 24 h for all antibiotics under study. It was further found that the release processes of Cephalothin and Amoxicillin consisted of an initial rapid drug release that varied unpredictably in amount followed by a reproducible and sustained release process with a release rate independent of the drug loading times under study. Thus, implants that have been fast-loaded with drugs could be stored for ~10 min in a simulated body fluid after loading to ensure reproducibility in the subsequent release process. Calculated release rates and measurements of drug amounts remaining in the samples after 22 h of release indicated that a therapeutically relevant dose could be achieved close to the implant surface for about 2 days. Concluding, the present study provides an outline for the development of a fast-loading slow-release surgical implant kit where the implant and the drug are separated when delivered to the surgeon, thus constituting a flexible solution for the surgeon by offering the choice of quick addition of antibiotics to the implant coating based on the patient need.

Cost effectiveness of local collagen-gentamicin as prophylaxis for sternal wound infections in different risk groups

OBJECTIVES

In a randomized trial addition of local collagen-gentamicin in the sternal wound reduced the rate of sternal wound infection (SWI) to about 50% compared to intravenous prophylaxis alone. The aim of the present study was to evaluate the economic rationale for its use in every-day clinical practice. This includes the question whether high-risk groups that may have particular benefit should be identified.

DESIGN

For each patient with SWI in the trial the costs attributable to the SWI were calculated. Risk factors for SWI were identified and any heterogeneity of the effect of the prophylaxis examined.

RESULTS

The mean cost of a SWI was about 14500 Euros. A cost effectiveness analysis showed that the prophylaxis was cost saving. The positive net balance was even higher in risk groups. Assignment to the control group, overweight, diabetes, younger age, mammarian artery use, left ventricular ejection fraction <35% and longer operation time were independent risk factors for infection.

CONCLUSION

The addition of local collagen-gentamicin to intravenous antibiotic prophylaxis was dominant, i.e. resulted in both lower costs and fewer wound infections.

Residue depletion of gentamicin in swine tissues after intramuscular administration

A sensitive and robust high-performance liquid chromatographic method with fluorescence detection (HPLC-FLD) was developed for the determination of gentamicin (GEN) residues in swine tissues. The limit of quantification (LOQ) of the method was 50 ng/g for muscle and 100 ng/g for liver and kidney. Mean recoveries at all fortification levels ranged from 82.34 to 93.20% with coefficient of variation (CV) below 5.39%. Residue depletion study of GEN in swine was performed after intramuscular injections twice daily at a dose of 4 mg/kg of bw with 12 h intervals for 5 consecutive days. The concentrations of GEN were determined in injection site, muscle, liver, and kidney by the HPLC-FLD method. The highest GEN concentration was measured in kidney, indicating that kidney was the primary target tissue for GEN residue. GEN concentrations in all examined tissues were below the maximum residue limit (MRL) recommended by the European Union (EU) at 50 days post-treatment.

[Selective decontamination of the digestive tract: repercussions on microbiology laboratory workload and costs, and antibiotic resistance trends]

INTRODUCTION

This study determines the workload and cost of implementing selective digestive decontamination in the microbiology laboratory, and reports the impact on microbial flora and bacterial resistance trends in the intensive care unit (ICU).

METHODS

The total microbiological workload and cost were quantified, as well as the part charged to the petitioning service, in the year before and the year after introducing the procedure. Changes in microbial flora were evaluated and bacterial resistance trends were analyzed over 12 years in 21 sentinel antimicrobial/microorganism combinations.

RESULTS

The workload ascribed to the ICU increased by 10% and cost increased by 1.8% in the period after introduction of the procedure (non-significant differences). The increased workload resulting from epidemiological surveillance cultures was compensated by significant reductions in quantitative endotracheal aspirate cultures, blood cultures, exudate cultures, identification tests with antibiograms, and serologies. The procedure has been associated with a significant decrease in Acinetobacter isolates and a significant increase in Enterococcus. Three significant trends of increased resistance were detected, all of them in Pseudomonas aeruginosa (imipenem, tobramycin, and ciprofloxacin).

CONCLUSIONS

In our hospital, implementation of selective digestive decontamination did not cause a significant increase in the workload or costs in the microbiology laboratory. Selective digestive decontamination was associated with a significant decrease in Acinetobacter, an increase in Enterococcus, and higher resistance to imipenem, tobramycin and ciprofloxacin in P. aeruginosa.

Assessing low-dose gentamicin-induced kidney injury in rats by analysis of urine

INTRODUCTION

Gentamicin is an important aminoglycoside antibiotic used in clinics to combat infections from especially gram negative bacteria. A frequent side-effect of aminoglycoside antibiotics is a kidney injury consisting of necrosis of proximal tubular cells. It is important both in clinics and in research directed to eliminate or ameliorate this side-effect that a method is available for detection of injury at an early stage.

METHODS

We have therefore compared the sensitivity of four methods currently used in animal models to assess kidney injury induced by aminoglycoside antibiotics by applying them to the analysis of urine from male rats treated with low doses of gentamicin.

RESULTS

Excretion of phospholipids was significantly increased in contrast to excretion of N-acetyl-beta-glucosaminidase (NAG), neutrophil gelatinase-associated lipocalin (NGAL) and protein. Assessment of phospholipiduria thus is the more sensitive noninvasive way to monitor initial renal injury induced by aminoglycoside antibiotics. A protocol is given for the serial analysis of urinary phospholipids allowing a considerable number of determinations to be carried out in the course of 2-3 days.

DISCUSSION

It is well known that all four considered methods do detect kidney damage induced in rats by high gentamicin doses far above doses used in clinics. The present investigation shows that only the analysis of the urinary phospholipids will detect damage induced by low doses of gentamicin. The method is relevant for animal model studies but will require considerable and innovative development for use in clinics.

Cure of persistent, post-appendectomy Klebsiella pneumoniae septicaemia with continuous intravenous administration of meropenem

A 15-year-old girl developed a persistent bacteraemia with Klebsiella pneumoniae accompanied by systemic symptoms including high fever and rigors after appendectomy. Extensive laboratory and imaging work-up, including tests for an intra-vascular source of infection, did not reveal the origin of the persistent bacteraemia. The Klebsiella pneumoniae isolates were susceptible to gentamicin and colistin and intermediately susceptible to meropenem. The septicaemia persisted despite the intravenous administration of meropenem 1 g and later 2 g every 8 h in combination with intravenous gentamicin and later colistin. The patient was cured only after the continuous intravenous administration of meropenem of 6 g/d.

Chronopharmacokinetic Study of Gentamicin in Dogs

The purpose of this experiment was to determine whether the time of day of single intravenous doses of gentamicin affects the drug's pharmacokinetics in dogs maintained under a 12 h light (08:00 to 20:00 h), 12 h dark (20:00 to 08:00 h) cycle. Using a crossover design, 6 mixed-breed male dogs received a single dose of 2 mg/kg of gentamicin at 8:00 or 20:00 h. Serial blood samples were collected and pharmacokinetic parameters were calculated following each timed dose. The concentration of the antibiotic was lower following the 08:00 h compared to the 20:00 h administration. When gentamicin was administered at 20:00 h, the initial concentration, mean residence time, and area under the disposition curve were significantly higher (p < 0.05) and the apparent volume of distribution of the central compartment, apparent volume of distribution, apparent volume of distribution at steady-state, and total body clearance (1.73+/-0.55 at 20:00 h versus 3.31+/-0.67 L/min/kg at 08:00 h) were significantly lower than for the 08:00 h administration (p < 0.05). Our results show that the pharmacokinetics of gentamicin exhibits significant temporal variation when administered to dogs at different times of day.

Once daily dose gentamicin in neonates - is our dosing correct?

AIM

The aim of this paper is to study the safety and efficacy (measured by therapeutic level) of once daily gentamicin in neonates >or=32 weeks of gestation and <or=7 days of age.

SETTING

Level II neonatal intensive care unit.

SUBJECTS

Neonates >or=32 weeks of gestation and <or=7 days of age treated with gentamicin for presumed sepsis.

METHODS

Gentamicin was administered by intravenous injection at 4 mg/kg/day once daily. Peak and trough gentamicin levels were measured at the third dose.

RESULTS

In neonates with gestational age between 32 and 36 weeks, 14 out of 65 (22%) had trough serum concentration >2 mg/L. Only 39 (60%) had peak and trough levels within the therapeutic range. All babies who had audiometric evaluation (62 out of 65) had normal hearing. Out of the 65 babies, 60 had paired serum creatinine levels estimated and none had evidence of renal dysfunction. Among term neonates, only 2 out of 50 had the trough serum concentration of >2 mg/L. In 38 (76%) of the 50 neonates, the trough serum gentamicin concentration was <2.0 mg/L and the peak level was <10 mg/L. Forty-eight babies had audiometric evaluation which was normal.

CONCLUSION

A dose of 4 mg/kg/day produces serum gentamicin levels outside the therapeutic range in two-fifths of neonates between 32 and 36 +/- 6 weeks. A single dose of 4 mg/kg/day of gentamicin is appropriate for term babies and probably excessive for 32-36 weeks' neonates.

Amoxicillin/clavulanate (Augmentin) resistant Escherichia coli in bacterial peritonitis after abdominal surgery--clinical outcome in ICU patients

Bacterial resistance to antimicrobial agents is of great concern to clinicians. Patient outcome after infection is mainly dependent on the sensitivity of the bacterium to the agent used. We retrospectively studied 89 postoperative intensive care unit (ICU) patients with proven Escherichia coli peritonitis and investigated the clinical consequences of the E. coli resistance to amoxicillin/clavulanate. Significantly increased mortality, days of ventilation and ICU stay were noted in the co-amoxicillin/clavulanate resistant group. Furthermore, our results demonstrate that the sensitivity of E. coli to amoxicillin/clavulanate in the postoperative ICU setting has decreased in recent years. We can conclude that the current antibiotic regimen for the empirical treatment of ICU patients with peritonitis, as used in our hospital, needs to be changed. A switch, for instance, to ceftriaxone (Rocephin) in combination with metronidazole and gentamicin, instead of the present regimen of amoxicillin/clavulanate in combination with gentamicin, seems preferable.

Elution of gentamicin and vancomycin from polymethylmethacrylate beads and hip spacers in vivo

BACKGROUND AND PURPOSE

Late infections after total hip arthroplasty are still a problem. Treatment procedures include resection arthroplasty with implantation of antibiotic-loaded beads or implantation of an antibiotic-impreganted spacer. However, little is known about antibiotic elution from bone cement beyond the first 2-3 postoperative days in humans.

METHODS

17 hip spacers (80 g PMMA, 1g gentamicin, and 4 g vancomycin) and 11 chains (40 g PMMA, 0.5 g gentamicin, and 2 g vancomycin) in 28 patients were studied. The release of both agents was measured in the drainage fluid on a daily basis. The drains were left in situ until less than 50 mL was produced per day. The elution of both antibiotics was determined by fluorescence polarization immunoassay. Systemic antibiotics were given postoperatively according to antibiogram. If possible, no gentamicin or vancomycin was given.

RESULTS

Peak mean concentrations from beads and spacers were reached for gentamicin (1,160 (12-371) microg/mL and 21 (0.7-39) microg/mL, respectively) and for vancomycin (80 (21-198) microg/mL and 37 (3.3-72) microg/mL) on day 1. The last concentrations to be determined were 3.7 microg/mL gentamicin and 23 microg/mL vancomycin in the beads group after 13 days, and 1.9 microg/mL gentamicin and 6.6 microg/mL vancomycin in the spacer group after 7 days. Between the fifth and seventh day, an intermittent increase in elution of vancomycin from both beads and spacers and of gentamicin from spacers was noticed. No renal or hepatic dysfunction was observed.

INTERPRETATION

Beads showed higher elution characteristics in vivo than the spacers due to their larger surface area; however, a great amount of inter-subject variability was seen for both beads and spacers. The inferior elution properties of spacers emphasize the importance of additional systemic antibiotics for this treatment procedure during the postoperative period. Future studies should clarify whether the dose of antibiotics or length of antibiotic therapy may be reduced in the case of bead implantation, without jeopardizing the control of infection.