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S Saavedra

Publications and source records attributed to S Saavedra.

26 records · Page 2Linked to original sources
PubMed1986

Susceptibility of aerobic gram-negative bacilli to aminoglycosides. Effects of 45 months of amikacin as first-line aminoglycoside therapy.

Amikacin was instituted as the primary empiric aminoglycoside at the San Juan Veterans Administration Medical Center in January 1982; at that time, 16 percent of the strains at the hospital were gentamicin-resistant. A prospective surveillance study was designed to correlate detection of bacterial resistance with aminoglycoside use. In the current report, the baseline period, during which gentamicin was the first-line aminoglycoside, accounting for 61 percent of overall aminoglycoside use, is compared with the period from January 1982 to September 1985, during which the first-line aminoglycoside was amikacin, accounting for 85 percent of overall use. This study is ongoing. During the two periods, the patient population did not differ with regard to aminoglycoside therapy, indications, or overall aminoglycoside use (541 versus 680 patient days per month). Among the gram-negative bacilli isolated, the percent of strains resistant to amikacin was as follows: pre-baseline period/baseline period, 0.8/0.2 percent; amikacin-usage period, 3.6 percent. Resistance to gentamicin and tobramycin during the period of amikacin use decreased from 16 to 11 percent for gentamicin and from 17 to 11 percent for tobramycin. The decrease in resistance of the gram-negative bacilli to gentamicin varied among strains: the resistance of Escherichia coli decreased from 8 to 4 percent; that of Proteus mirabilis, from 12 to 5 percent; that of indole-positive Proteus, from 19 to 12 percent; that of Acinetobacter, from 57 to 23 percent; that of Citrobacter, from 15 to 7 percent; and that of Pseudomonas aeruginosa, from 24 to 16 percent. During the amikacin-usage period, amikacin resistance was unchanged for most strains, with the exception of P. aeruginosa, the resistance of which increased from 4.5 to 7.8 percent. Of the 4,795 strains isolated, 174 were resistant to amikacin; of these, 29 Pseudomonas strains were studied for all mechanisms of resistance. Changes in permeability were exhibited by 11 of the 29 strains; 14 strains exhibited the AAC(6')-I enzyme, 10 strains exhibited the APH(3')-II enzyme, and two strains exhibited ANT(2") in addition to some other unidentified mechanism. Multiple enzyme production was found in 15 of the strains. The use of amikacin as a first-line aminoglycoside is associated with a decrease in resistance to other aminoglycosides and a slight increase in overall resistance to amikacin among aerobic gram-negative bacilli. The usefulness of amikacin has not been affected at our institution.

Acetyltransferases↗
PubMedDate not supplied

Comparison of empiric aztreonam and aminoglycoside regimens in the treatment of serious gram-negative lower respiratory infections.

An open-label, controlled, randomized study was performed to assess the efficacy and safety of combination regimens using either aztreonam or an aminoglycoside control regimen as empiric therapy for suspected aerobic gram-negative bacillary pneumonia or purulent bronchitis. Eighty-four patients, 42 in each arm of the study, were randomly assigned to one of two treatment regimens. The combination aztreonam regimen included aztreonam, 2 gm every 8 hours (q8h), plus either clindamycin, 600 to 900 mg q8h, or nafcillin, 1.5 gm to 2 gm every 6 hours (q6h). The control regimen was one of the following depending on the combination therapy that was designated standard at each of the three study institutions: amikacin, 5 mg/kg q8h, plus cefazolin, 1 gm q8h; amikacin, 500 mg every 12 hours plus mezlocillin, 4 gm q6h; or kinetically dosed tobramycin plus ticarcillin, 3 gm to 4 gm q4h. The two groups were well matched in terms of demographics and clinical characteristics. Among the 84 patients, organisms from the Enterobacteriaceae family accounted for the largest proportion of isolates (44%) including Escherichia coli (13%), Klebsiella species (14%), and Serratia species (9%). Other commonly identified organisms were Pseudomonas aeruginosa (19%), Haemophilus influenzae (15%), Streptococcus pneumoniae (12%), and Staphylococcus aureus (8%). Results of this trial included clinical response rates of 83% in both groups (P = 0.951) and a microbiologic cure rate of 75% in the aztreonam group and 63% in the control group (P = 0.291). In the 59 patients with documented aerobic gram-negative pneumonia, microbiologic eradication rates were 72% in the aztreonam group versus 57% in the control group (P = 0.359). Duration of treatment tended to be shorter in the aztreonam group than in the control group, with a median 10 days of therapy versus 12 days of therapy (P = 0.095), respectively. In addition, the percentage of patients requiring nonstudy antimicrobial agents tended to be lower in the aztreonam group than the control group, involving 21% of patients in the aztreonam group compared with 36% of patients in the control group (P = 0.086). All regimens were well tolerated, and no patient was withdrawn because of adverse reactions to the study medications. Two patients, both in the control group, required dose reduction, which was necessitated by possible aminoglycoside-induced nephrotoxicity. This trial shows that aztreonam is an effective agent with an excellent safety profile when used in combination regimens for the empiric treatment of pneumonia. A well-controlled trial is needed to verify the trend toward shorter hospital stays and a reduced need for additional antimicrobial agents seen with the aztreonam regimen when compared with those receiving aminoglycoside-combination regimens.

Adolescent↗
PubMedDate not supplied

Bacillary angiomatosis: microbiology, histopathology, clinical presentation, diagnosis and management.

Bacillary angiomatosis is known to be caused by a rickettsial organism; Rochalimaea henselae. This causative agent has been compared with different microorganisms and clinical conditions that appear in similar settings buy have been clearly differentiated from them; e.i. Cat-scratch disease (Afipia felis), Bartonella bacilliformis, other Rochalimaea sp., Kaposi's sarcoma, Lobular capillary hemangioma, Angiosarcoma, and Epithelioid hemangioma. Clinically the bacillary angiomatosis (BA) skin lesions vary from a single lesion to thousands. The cutaneous lesion appears as a bright-red round papule, subcutaneous nodule, or as a cellulitic plaque. When the lesion is biopsied it tends to blanch-out, bleed, and cause pain. The patient might present with signs and symptoms of chills, headaches, fever, malaise, and anorexia with or without weight loss. The extracutaneous lesions found in BA tend to be from multiple organs affecting from the oral lesions to anal mucosal lesions to widespread visceral lesions. The sites of preference for BA lesion manifestation tend to be the liver, spleen, lymph nodes, and bone. To diagnose bacillary angiomatosis the physician should prepare a differential diagnosis based primarily on its histopathological and clinical characteristics. To confirm the results from the stain, electron microscopy can identify the bacillus and pin-point the diagnosis of bacillary angiomatosis. The lesions presented by BA respond well to therapy with erythromycin 500 mg four times daily for a duration of 2 weeks to 2 months. In case of intolerance to erythromycin the second line of drug that successfully treats the BA bacillus is doxycyline. If relapses of the BA lesion recur, then a prolonged antibiotic therapy is necessary and in AIDS patients the duration may be extended as life-long suppressive therapy.

Angiomatosis, Bacillary↗
PubMedDate not supplied

Bacillary angiomatosis: microbiology, histopathology, clinical presentation, diagnosis and management.

Bacillary angiomatosis is known to be caused by a rickettsial organism; Rochalimaea henselae. This causative agent has been compared with different microorganisms and clinical conditions that appear in similar settings but that have been clearly differentiated from them; e.i. Cat-scratch disease (Afipia felis), Bartonella bacilliformis, other Rochalimaea sp., Kaposi;s sarcoma, Lobular capillary hemangioma, Angiosarcoma, and Epithelioid hemangioma. Clinically the bacillary angiomatosis (BA) skin lesions vary from a single lesion to thousands. The cutaneous lesion appears as a bright-red round papule, subcutaneous nodule, or as a cellulitic plaque. When the lesion is biopsied it tends to blanch-out, bleed, and cause pain. The patient might present with signs and symptoms of chills, headaches, fever, malaise, and anorexia with or without weight loss. The extracutaneous lesions found in BA tend to be from multiple organs affecting from the oral lesions to anal mucosal lesions to widespread visceral lesions. The sites of preferences for BA lesion manifestation tend to be the liver, spleen, lymph nodes, and bone. To diagnose bacillary angiomatosis the physician should prepare a differential diagnosis based primarily on its histopathological and clinical characteristics. To confirm the results from the stain, electron microscopy can identify the bacillus and pin-point the diagnosis of bacillary angiomatosis. The lesions presented by BA respond well to therapy with erythromycin 500mg four times daily for a duration of 2 weeks to 2 months. In case of intolerance to erythromycin the second line of drug that successfully treats the BA bacillus is doxycycline. If relapses of the BA lesion recur, then a prolonged antibiotic therapy is necessary and in AIDS patients the duration may be extended as life-long suppressive therapy.

Angiomatosis, Bacillary↗