Reduction in cytokine release from human monocytes by modifications in cell wall structure of Staphylococcus aureus induced by subinhibitory concentrations of oxacillin

Whole bacterial cells of Staphylococcus aureus as well as purified staphylococcal peptidoglycan (PG) have been demonstrated to stimulate human monocytes to release cytokines. Hypothesising that the phenomenon of changes induced by beta-lactam antibiotics in cell-wall composition may alter the immunological properties of the intact cell wall as well as of purified cell-wall components, this study assessed whether cytokine release by human monocytes is altered if cells from strains grown in the presence or absence of sub-minimal inhibitory concentrations of oxacillin are used as stimuli. Whole bacterial cells and isolated PG from these strains, grown in the presence of oxacillin, showed a significantly reduced stimulation of tumour necrosis factor-alpha, interleukin (IL)-1beta and IL-6 release by human monocytes in a concentration-dependent fashion. The serum-induced potentiation of cytokine production by human monocytes in response to PG with modified cross-linking was also reduced. These observations may have particular relevance for staphylococcal infections, in which clinically achievable beta-lactam concentrations do not suppress staphylococcal growth yet may alter and possibly enhance virulence.

MR of staphylococcal myelitis of the cervical spinal cord

A homogeneously enhancing cervical cord lesion and multiple ring-enhancing brain lesions were detected with MR imaging in a 41-year-old woman with a staphylococcal septicemia. The brain and spinal cord lesions diminished in size after antibiotic therapy. Although no biopsy was performed, we believe, on the basis of the clinical outcome, that the spinal cord lesion represented a bacterial myelitis and that the lesion was prevented from developing into an abscess by early antibiotic therapy.

Oral antibiotic treatment of right-sided staphylococcal endocarditis in injection drug users: prospective randomized comparison with parenteral therapy

PURPOSE

To compare the efficacy and safety of inpatient oral antibiotic treatment (oral) versus standard parenteral antibiotic treatment (intravenous) for right-sided staphylococcal endocarditis in injection drug users.

PATIENTS AND METHODS

In a prospective, randomized, non-blinded trial, febrile injection drug users were assigned to begin oral or intravenous (IV) treatment on admission, before blood culture results were available. Oral therapy consisted of ciprofloxacin and rifampin. Parenteral therapy was oxacillin or vancomycin, plus gentamicin for the first 5 days. Antibiotic dosing was adjusted for renal dysfunction. Administration of other antibacterial drugs was not permitted during the treatment or follow-up periods. Bacteremic subjects having right-sided staphylococcal endocarditis received 28 days of inpatient therapy with the assigned antibiotics. Test-of-cure blood cultures were obtained during inpatient observation 6 and 7 days after the completion of antibiotic therapy, and again at outpatient follow-up 1 month later. Criteria for treatment failure and for drug toxicity were prospectively defined.

RESULTS

Of 573 injection drug users who were hospitalized because of a febrile illness and suspected right-sided staphylococcal endocarditis, 93 subjects (16.2%) had two or more sets of blood cultures positive for staphylococci; 85 of these bacteremic subjects (14.8%) satisfied diagnostic criteria for at least possible right-sided staphylococcal endocarditis (no other source of bacteremia was apparent) and entered the trial. Forty-four (oral, 19; IV, 25) of these 85 subjects completed inpatient treatment and evaluation including test-of-cure blood cultures. There were four treatment failures (oral, 1 [5.2%]; IV, 3 [12.0%]; not significant, Fisher's exact test). Drug toxicity was significantly more common in the parenterally treated group (oral, 3%; IV, 62%; P < 0.0001), consisting largely of oxacillin-associated increases in liver enzymes.

CONCLUSIONS

For selected patients with right-sided staphylococcal endocarditis, oral ciprofloxacin plus rifampin is effective and is associated with less drug toxicity than is intravenous therapy.

Cervicofacial Actinomyces viscosus infection in a Brazilian fila: a case report and literature review

A five-month-old, male Brazilian fila presented with a three-day history of a focal swelling in the left superior palpebra and a focal, subcutaneous swelling over the dorsal cervical region. Both lesions initially responded to warm compresses and a two-week course of oral amoxicillin-clavulanic acid therapy. The eyelid swelling recurred after discontinuation of the oral antibiotic therapy. The lesion was progressive and was refractory to trimethoprim-sulfadiazine therapy. Culture and sensitivity performed from a surgical biopsy sample of the eyelid mass identified Actinomyces viscosus and other bacterial genera. A combination of surgical debulkment, Penrose drain placement, and a one-month course of oral oxacillin therapy has resulted in clinical regression of the lesion at a six-month postoperative evaluation.

Antibiotic penetration into cervical discs

Antibiotics are frequently prophylactically administered in surgical procedures to reduce the incidence of infection. The penetration of antibiotics into lumbar discs has been studied with mixed results, but penetration into cervical discs has not been reviewed. In this study, we examined the penetration of two commonly used antibiotics, oxacillin and cefazolin, into cervical discs. Eighteen patients with a total of 30 discs removed were studied. Two groups, each consisting of four patients with five discs removed, received either 1 g of oxacillin or 1 g of cefazolin by a single, preoperative intravenous infusion. Two other groups, each consisting of five patients with 10 discs removed, received either 2 g of oxacillin or 2 g of cefazolin, also by a single, preoperative intravenous infusion. A blood specimen, from which serum antibiotic levels were determined, was obtained from each patient simultaneously with each discectomy. The time interval between the antibiotic infusion and discectomy/phlebotomy was also recorded. Antibiotic levels were detected in all discs removed but were quantifiable in only 12. Nine of these 12 had been exposed to cefazolin. Of these nine discs, one was from a patient who had received 1 g whereas the other eight were from patients who had received 2 g of cefazolin. This represents 80% of the removed discs exposed to 2 g of cefazolin (10 discs total) and 20% exposed to 1 g (5 discs total). The remaining three discs with quantifiable antibiotic levels had been exposed to 2 g of oxacillin, which represents 30% of the discs (10 total) exposed to that dose of oxacillin. Although cervical disc space infections are rare, they are serious.(ABSTRACT TRUNCATED AT 250 WORDS)

Antimicrobial therapy for children with chronic suppurative otitis media without cholesteatoma

This study was designed to determine the middle ear bacterial pathogens, the frequency of serum immunoglobulin deficiency and the efficacy of medical management in patients with chronic suppurative otitis media without cholesteatoma. This was an open noncomparative clinical trial performed at the National Children's Hospital, San Jose, Costa Rica, and included 186 patients older than 2 months of age with a confirmed diagnosis of chronic suppurative otitis media without cholesteatoma. Middle ear cultures and serum for immunoglobulin determinations were obtained on admission. The first 40 patients were treated only with ceftazidime and from patient 41 and up, if a Gram-positive organism was cultured, oxacillin was added to (for combined infection) or replaced ceftazidime. Parenteral antibiotics and suction twice daily were continued until three days after the middle ear became dry. Trimethropimsulfamethoxazole prophylaxis was administered during the follow-up period. Middle ear bacterial cultures were positive in 166 patients. Pseudomonas sp. (35.6%), enteric Gram-negative organisms (28.7%) and Gram-positive cocci (26%) were the most common organisms. Immunoglobulin determinations were below normal in 3 of 69 (4.3%) evaluable patients. Dryness of the ear was achieved in 174 patients (93.5%) including 130 of 139 patients treated with ceftazidime, 28 of 28 patients treated with oxacillin and 14 of 14 patients treated with ceftazidime and oxacillin. Recurrent otorrhea developed in 39 (23.4%) patients. Twice-daily canal aspiration and parenteral ceftazidime for Gram-negative organisms and/or oxacillin for Gram-positive bacteria for 3 days after dryness of the middle ear followed by prophylactic oral antimicrobials are effective for treatment of most chronic suppurative otitis media without cholesteatoma patients.

Single-dose antibiotic prophylaxis in maxillofacial surgery

The clinical efficacy of short-term antimicrobial prophylaxis with either one shot of ceftriaxone (1 g) or a course of 3 injections of a fixed combination of mezlocillin (2 g) and oxacillin (1 g) administered over 24 h was studied in a prospective randomized clinical study of 100 patients undergoing elective maxillofacial surgery. Tissue and plasma concentrations of the antibiotics were determined by high-pressure liquid chromatography in 6 tumor surgery patients from each treatment group. Statistical analysis showed the treatment group to be comparable both demographically and with respect to the types of surgery performed and the durations of the procedures. Only 1 patient in each group developed a postoperative wound infection. It is concluded that 1 g ceftriaxone given 30 min preoperatively meets the pharmacokinetic requirements for perioperative antimicrobial prophylaxis in maxillofacial surgery.

[The dynamics of the nonspecific immunity indices during the lymphotropic therapy of children with acute pyelonephritis]

The comparison of the effect obtained in children with primary acute pyelonephritis treated with lymphotropic ampiox plus lidase against oral or intramuscular ampiox showed more rapid induction of clinical remission and more pronounced tendency to normalization of immunological indices in the patients on lymphotropic ampiox. In addition, the lymphotropic route made it possible to decrease the drug dose and number of its injections which is of importance in pediatric practice. The above advantages say in favour of wide application of indirect lymphotropic therapy for pyelonephritis in children.

Activity of ampicillin-sulbactam and oxacillin in experimental endocarditis caused by beta-lactamase-hyperproducing Staphylococcus aureus

Using a rat model of aortic valve infective endocarditis, we previously found that oxacillin was equally effective against an oxacillin-susceptible strain of Staphylococcus aureus and a beta-lactamase-hyperproducing borderline oxacillin-susceptible strain of S. aureus; also, ampicillin-sulbactam was less effective than oxacillin against both isolates and at low doses was less effective against the borderline-susceptible strain than against the fully oxacillin-susceptible strain (C. Thauvin-Eliopoulos, L. B. Rice, G. M. Eliopoulos, and R. C. Moellering, Jr., Antimicrob. Agents Chemother. 34:728-732, 1990). In the present study, we extended this work, using alternative treatment schedules and additional bacterial strains. Extending treatment with low doses of ampicillin-sulbactam (500 and 250 mg/kg of body weight per day, respectively) to 6.5 days resulted in equalization of effectiveness against the previously studied strains BOSSA-1 and OSSA-1 (3.75 +/- 1.61 log10 and 4.71 +/- 1.79 log10 CFU of residual viable bacteria per g, respectively). Against the borderline oxacillin-susceptible strain BOSSA-1, increasing the sulbactam dosage from 500 to 2,000 mg/kg/day while maintaining a fixed dose of ampicillin (1,000 mg/kg/day) by continuous infusion resulted in lower bacterial counts (4.93 +/- 1.84 log10 versus 3.65 +/- 1.26 log10 CFU of residual viable bacteria per g, respectively), but this difference was of only borderline significance; differences in efficacy between the low-dose and high-dose sulbactam regimens were exaggerated when intermittent intravenous administration was used (6.19 +/- 1.90 log10 versus 3.37 +/- 1.41 log10 CFU/g, respectively; P < 0.001). However, for any individual sulbactam dosage, the model of administration (continuous versus intermittent infusion) did not affect the activity of the regimen. When additional strains were used in the model, oxacillin and ampicillin-sulbactam (1,000 plus 2,000 mg/kg/day) were equally effective against both oxacillin-susceptible and borderline oxacillin-resistant strains of S. aureus. These results support the predictions that oxacillin would be clinically effective in the treatment of infections caused by borderline oxacillin-susceptible strains of S. aureus and that, except at very low doses, ampicillin-sulbactam would also be as effective against borderline-susceptible strains as against fully oxacillin-susceptible strains of S. aureus.

[Excretion of beta-lactam antibiotics in human parotid saliva]

We investigated the penetration of beta-lactam antibiotics into parotid saliva after intravenous administration. Neither mezlocillin nor oxacillin could be detected in parotid saliva, but cefotaxime (CTX) and cefotiam (CTM) penetrated parotid saliva very well. While salivary CTM concentrations reached peak values (9.52 +/- 3.4 mg/l) within 30 min of the end of infusion, the highest CTX concentrations in parotid saliva (5.84 +/- 2.6 mg/l) were observed after 90 min. After 300 min the salivary CTM levels were below the limit of detection, while the mean CTX concentration even 360 min after the end of infusion was 2.27 +/- 1.23 mg/l. Both CTX and CTM achieve salivary concentrations that are inhibitory against the prevailing pathogens causing suppurative parotitis, and thus promise to be effective for the treatment of this disease. Furthermore, the excretion of comparatively high concentrations of both drugs into the mouth achieves a selective decontamination of the mucosal surfaces of the upper aerodigestive tract so that they are suitable for perioperative prophylaxis in head and neck surgery.

[Perioperative preventive use of antibiotics in neurosurgery. Experience with a fixed antibiotic combination of mezlocillin and oxacillin (optocillin)]

We report a retrospective account of 200 patients who have been surveyed after having undergone neurosurgical intervention. They received as perioperative antibiotic prophylaxis a combination of Mezlocillin and Oxacillin in a ratio of 2:1 (Optocillin) in their management. The clinical and bacteriological efficacy including the side effects was examined with standardisation of sterility measures in the operating theatre, careful standardised operative procedures and ward after care. No problems in wound healing were found. There was no certain evidence of side effects.

Antibiotic prophylaxis during prolonged clean neurosurgery. Results of a randomized double-blind study using oxacillin

The efficacy of oxacillin as a prophylaxis for infection was analyzed in a 27-month randomized double-blind study of 400 patients who had undergone clean neurosurgical interventions lasting longer than 2 hours. Four neurosurgeons took part in the study and 356 patients were eligible for final analysis. Among the 171 patients treated with oxacillin, there was one case of infection (0.6%), compared to nine (4.9%) of the 185 patients given a placebo. The difference between the two groups was statistically significant (p = 0.0398). This study, together with others (randomized or not), clearly demonstrates the efficacy of antibiotic prophylaxis in prolonged clean neurosurgery.

Efficacy of oxacillin and ampicillin-sulbactam combination in experimental endocarditis caused by beta-lactamase-hyperproducing Staphylococcus aureus

Optimal therapy of infections caused by borderline oxacillin-susceptible, beta-lactamase-hyperproducing Staphylococcus aureus has not been established. We used a rat model of aortic valve endocarditis to examine efficacies of antibiotic regimens against a borderline oxacillin-susceptible strain as compared with a fully susceptible S. aureus strain. Animals were treated with oxacillin alone or in combination with sulbactam or with ampicillin-sulbactam combinations at two dose levels. Infections caused by the borderline susceptible and fully susceptible strains responded equally well to oxacillin alone, with residual bacterial titers in vegetations falling to 4.8 +/- 1.6 and 4.4 +/- 1.7 (mean +/- standard deviation) log10 CFU/g, respectively. Addition of sulbactam to oxacillin (1:2) did not enhance the efficacy of oxacillin against either strain in the animal model. A high-dose regimen of ampicillin-sulbactam (2:1) yielding mean (+/- standard deviation) levels in serum of 16.8 +/- 7.4 and 9.5 +/- 1.1 micrograms/ml, respectively, proved equally effective against both strains (bacterial titers, 6.6 log10 CFU/g). However, at lower doses (8.3 +/- 2.6 and 5.9 +/- 2.4 micrograms/ml, the combination showed greater efficacy against the fully susceptible strain, with residual titers of 7.1 +/- 2.0 versus 9.0 +/- 1.6 log10 CFU/g (P less than 0.05). In vitro studies revealed that the beta-lactamase inhibitor sulbactam was also a potent inducer of staphylococcal beta-lactamase at clinically relevant concentrations. Based on this short-term in vivo therapy study, oxacillin would be predicted to be clinically effective in the therapy of infections caused by borderline oxacillin-susceptible strains of S. aureus, while the combination of ampicillin with sulbactam appears to be inferior to oxacillin alone against such infections.

[Perioperative preventive use of antibiotics in thoracic surgery--results of a controlled randomized study with optocillin]

There seems to be general agreement that antibiotic prophylaxis should be provided for patients undergoing resections of the lung. In order to obtain further information about the extent of resection beyond which this is necessary, and also to establish the type of prophylaxis that is meaningful over the long term, we carried out a controlled study involving two groups of 100 patients each. In the first group, who received minor resections, ultrashort-term prophylaxis was compared with an 0 group. We were able to show that in high-risk patients with prior pulmonary diseases, prophylaxis is indeed meaningful. In the second group of patients undergoing major resections, antibiotic prophylaxis must be provided; a one-day administration suffices, and long-term administration fails to offer any further advantages.

[Early complications following stapedectomy--surgical or conservative treatment?]

The incidence of sensorineural hearing loss after stapedectomy ranges from 0.6% to 5%. There is evidence that reparative granuloma is a major cause: most authors report that it requires urgent surgery, but this view is not universally accepted. This study analyses 14 stapedectomies that resulted in a sudden or gradual sensorineural hearing loss, often combined with vertigo, and presenting between 1 and 6 weeks after an initial hearing improvement. All patients were treated immediately with a combined infusion of an antibiotic, a corticosteroid and a plasma expander. The sensorineural hearing loss began to improve compared with pre-operative values 9 days later. Thus drug therapy might be sufficient in most cases of sensorineural hearing loss early after stapedectomy, and surgery can be restricted to patients with perilymph fistulae.

[Bacterial infections in cancer patients without neutropenia. Comparison between 2 antibiotic combinations (aztreonam and oxacillin versus cefoxitin and tobramycin)]

In the treatment of infections arisen in neoplastic patients without neutropenia, 2 antibiotic combinations (aztreonam + oxacillin vs tobramycin + cefoxitin), have been compared with regard to therapeutic effectiveness and tolerability. Twenty patients (age: 30-75) have been studied. Tolerability of both combinations was excellent. Results of this study showed a lower percentage of superinfections and a higher percentage of cure in patients treated with the combination aztreonam + oxacillin, even if the data were not statistically significant.

Oxacillin and tobramycin serum levels during cardiopulmonary bypass

Antibiotic prophylaxis in cardiac surgery is recommended to combat acquired infections caused by staphylococci and gram-negative bacilli. Prophylaxis seems effective provided blood levels are greater than minimal inhibitory concentrations (MIC). In this study, two doses of antibiotics were compared in 45 patients with normal renal function during cardiopulmonary bypass (CPB). All patients received 50 mg/kg of oxacillin. Group 1 (30 patients) also received 1 mg/kg of tobramycin, while group 2 (15 patients) received 2 mg/kg of tobramycin. Blood samples were taken after the administration of antibiotics, as well as at the onset and conclusion of CPB. Additional samples were taken before and after heparin injection before CPB, and from the arterial and venous cannulae of the bubble oxygenator during CPB. In both groups, oxacillin serum levels were constantly greater than MIC for susceptible bacteria. In group 1, tobramycin levels less than 2 micrograms/mL (MIC for most susceptible bacteria) occurred in four patients before CPB, in 14 patients at the onset of CPB, and in 19 patients at the conclusion of CPB. These low levels were not explained by heparin administration or absorption onto the CPB circuit, but were the result of hemodilution. In group 2, in which all the tobramycin levels were higher than 2 micrograms/mL, serum levels decreased from 9.9 +/- 3.4 (mean +/- SD) to 3.7 +/- 0.7 micrograms/mL throughout the procedure. Plasma creatinine did not change significantly in either group. It is concluded that in patients with normal renal function, doses as high as 50 mg/kg of oxacillin and 2 mg/kg of tobramycin may be necessary before CPB to provide adequate serum levels throughout CPB.

[In vivo bactericidal activity of an oxacillin-netilmicin combination against Staphylococcus aureus. Influence of the rhythm of netilmicin administration]

The bactericidal activity of two regimens of netilmicin (8 mg/kg/day) given intravenously once a day (od) or thrice daily (tid) both alone and in combination with oxacillin (200 mg/kg/day) was compared using a model of fibrin clots infected with a strain of Staphylococcus aureus (10(7) CFU/g) sensitive to methicillin and netilmicin (clinical isolate) and implanted subcutaneously in rabbit. This study shows that: 1) Netilmicin given alone as both single and divided doses results in early bacterial killing but does not exert a bactericidal effect after 24 hours because of a significant late increase of the number of bacterial. 2) The netilmicin-oxacillin combinations are more bactericidal at 1 h, 2 h and 24 h than oxacillin alone (P less than 0.001). 3) The oxacillin-netilmicin combination appears to be better for bacterial killing when netilmicin is given thrice daily (P less than 0.001). It is hard to draw a clinical inference from such an experimental study but it seems that 8-hour divided doses intervals should be better for administration of netilmicin than single daily dose during the acute period of staphylococcal infections.

Control of prosthetic bacterial infection: evaluation of an easily incorporated, tightly bound, silver antibiotic PTFE graft

Despite the use of prophylactic antibiotics in vascular surgery, prosthetic infection rate remains 2-5%. Antibiotics bound to vascular prostheses can control experimentally induced infection but prolonged antibacterial activity has not been achieved. This study evaluates the in vivo efficacy and antibiotic retention of an easily prepared silver-antibiotic prosthesis. Prostheses were prepared by combining silver with oxacillin or amikacin using an organic solvent. After evaporation of the solvent, the graft was left impregnated with the antibiotic complex. In vivo retention studies were performed by implanting PTFE 110Ag-oxacillin prostheses in four canine abdominal aortas. When prostheses were explanted at 1 week, mean antibiotic retention was found to be 20% of original activity, higher than the mean inhibitory concentration for Staphylococcus aureus. In three groups of five dogs, 20 X 7-mm prostheses of PTFE alone, PTFE silver-oxacillin, or PTFE silver-amikacin were implanted in the abdominal aorta and the grafts were inoculated with 10(7) S. aureus of a known bacteriophage type, in a closed retroperitoneal pocket. The animals were sacrificed at 1 week and the prostheses were excised for quantitative bacterial culture. PFTE silver-oxacillin, and PTFE silver-amikacin prostheses had 1.7 X 10(2) and 2.0 X 10(2) colonies, respectively, significantly less (P less than 0.05) than controls (1.3 X 10(6) colonies). These data suggest that antibiotic prostheses can be easily prepared without binding agents. They retain the bound antibiotic for a prolonged period and are effective in reducing graft infection in a stringent direct contamination model.