Maxwell Finland

METHICILLIN - RESISTANT STAPHYLOCOCCUS AUREUS AT BOSTON CITY HOSPITAL. BACTERIOLOGIC AND EPIDEMIOLOGIC OBSERVATIONS

Abstract Twenty-two isolates of methicillin-resistant Staphylococcus aureus were obtained from 18 patients; 21 of the strains were phage nontypable, exhibited methicillin resistance to other penicillins and cephalosporins tested, and had characteristics similar to those of previously reported methicillin-resistant strains. These staphylococci were isolated from patients on seven of the 42 hospital wards. Fifteen of the 18 patients acquired their infection in the hospital. Thirteen of the 22 isolates were from the sputum of 12 patients with pulmonary superinfection, and four from the urine of two patients with catheter-associated urinary-tract infections. Evidence of patient-to-patient spread of infection was found during a ward outbreak involving four clinical cases and a nurse who was a nasopharyngeal carrier.

Effect of Inoculum and of Beta-Lactamase on the Anti-Staphylococcal Activity of Thirteen Penicillins and Cephalosporins

Because there are few persuasive data for selecting one semisynthetic penicillin or cephalosporin over another for treatment of serious staphylococcal infections, 118 recent clinical isolates of Staphylococcus aureus were studied to determine to what extent the presence of β-lactamase affected the relative anti-staphylococcal activity of six penicillins and seven cephalosporins. In addition, the effect of inoculum was studied for its possible effect on the anti-staphylococcal activity of the 13 β-lactam antibiotics. By all criteria, methicillin and nafcillin were clearly more resistant to both the inoculum effect and the production of staphylococcal β-lactamase, whereas benzylpenicillin and cephaloridine (especially benzyl-penicillin) were the most susceptible to these effects. Cephazolin was clearly more susceptible to staphylococcal β-lactamase and heavy inocula than the other cephalosporins (with the exception of cephaloridine), whereas cephalothin was the most resistant cephalosporin to these factors. The minimal inhibitory concentration for benzylpenicillin for tests with undiluted inoculum, compared to results with inoculum diluted 10−4, differed by a factor up to 16,384, whereas with methicillin and nafcillin the differences were rarely more than twofold. Ratios for the other 10 antibiotics fell between these extremes. These results suggest that methicillin or nafcillin is most stable to staphylococcal β-lactamase, and that benzylpenicillin and cephaloridine are the most susceptible.

Changing Etiology of Bacterial Endocarditis in the Antibacterial Era: Experiences at Boston City Hospital 1933-1965

Abstract During 12 selected years from 1933 to 1965, 337 patients were documented as having bacterial endocarditis at Boston City Hospital, 43 of them with 2 organisms and 10 with 3 in their blood,...

PERSISTENCE OF ANTIBIOTICS IN BLOOD OF PATIENTS WITH ACUTE RENAL FAILURE. III. PENICILLIN, STREPTOMYCIN, ERYTHROMYCIN AND KANAMYCIN

In the preceding papers, one dealing with tetracycline and chlortetracycline (2) and the other with chloramphenicol (3), the circumstances under which these drugs would be expected to accumulate in the blood of patients with renal failure were indicated. Dosage regimens were outlined which took into account the limitations imposed by renal disease on the elimination of these drugs. The present report presents the results of studies on the persistence of four additional antibiotics; penicillin, streptomycin, erythromycin and kanamycin, following their administration to patients with severe renal failure. Since anuria may be considered to represent the maximumimpairment of renal function as seen in man, emphasis was placed on the study of patients in this state in determining the maximum contribution of nonrenal factors toward the elimination or inactivation of these drugs under the physiological limitations of uremia. The findings should prove helpful in delineating the optimum dosage regimens for these drugs in patients with markedly impaired renal function.

Comparative studies of antibacterial activity in vitro and absorption and excretion of lincomycin and clinimycin.

The antibacterial spectrum of clinimycin (7-chloro-7-deoxy-lincomycin) and that of lincomycin were found to be identical. Both were highly active against recent isolates of Staphylococcus aurcus, pneumococci and streptococci other than enterococci, but clinimycin was 8 to 16 times more active than lincomycin against S. aurcus and pneumococci. Neither drug was highly active against Ncisseria meningitidis, N. gonorrhocac, or Hemophilus influenzac and both were essentially inactive against the commonly encountered pathogenic gram-negative rods. Strains of Staph. aurcus resistant to erythromycin were as sensitive to both lincomycin antibiotics as were erythromycin-resistant strains. Both appear to be bactericidal against most strains of S. aurcus. Peak levels of clinimycin in serum were at least twice as high as those of lincomycin. Absorption of clinimycin was slightly delayed but not decreased by ingestion with food, which markedly decreased the absorption of lincomycin; the levels of the former remained higher for eight hours at which time all subjects still had significant serum levels of clinimycin. Bioactivity appeared in the urine in higher concentrations and more rapidly following clinimycin than after lincomycin. About one-eighth of the doses of clinimycin given either fasting or immediately after a meal were recovered as active drug in the urine in 24 hours, as compared with 9.3 and 2.6% of the fasting and postprandial doses, respectively, of lincomycin. Side effects were limited to mild gastrointestinal symptoms which were similar with both drugs.

Emergence of antibiotic-resistant bacteria.

Changes in Microflora during Antibiotic Administration The material presented thus far has dealt with clearly identifiable organisms, which, for the most part, are primary pathogens and the chief t...

Susceptibility of Staphylococcus aureus and Staphylococcus epidermidis to 65 Antibiotics

The susceptibilities of 36 recent isolates of Staphylococcus aureus and 35 recent isolates of Staphylococcus epidermidis were determined against each of 65 antimicrobial agents and against two of them in combination. Rifampin was the most active of all the agents tested against both S. aureus and S. epidermidis. Among the penicillins, cloxacillin, dicloxacillin, and nafcillin were most active, although benzylpenicillin and phenoxymethyl penicillin were more active against susceptible strains. Cephaloridine was the most active of the cephalosporins, and sisomicin was the most active aminoglycoside. Minocycline was more active than the other tetracycline analogues tested. Among the macrolide-lincomycin compounds in clinical use, clindamycin was more active, and lincomycin was less active than erythromycin. The synergy of trimethoprim-sulfamethoxazole was more striking against S. aureus than against S. epidermidis. The median minimal inhibitory concentrations of the penicillins, cephalosporins, and aminoglycosides were lower against S. aureus, whereas the minimal inhibitory concentrations of the tetracyclines were lower against S. epidermidis.

Changing Patterns of Susceptibility of Common Bacterial Pathogens to Antimicrobial Agents

Abstract Groups of strains of selected bacterial pathogens were collected at intervals from patients at Boston City Hospital and tested for susceptibility to antibiotics, using essentially the same...

Susceptibility of Nocardia asteroides to 45 Antimicrobial Agents In Vitro

A method for preparing uniformly dispersed cultures of Nocardia asteroides for use in tests for susceptibility to antimicrobial agents is described. The minimal inhibiting concentration (MIC) of 45 agents for cultures thus prepared was determined with the use of a replica-inoculating apparatus. Minocycline at a concentration of 3.1 μg or less/ml inhibited 90% of the strains tested, and all were inhibited by 6.3 μg/ml. An erythromycin concentration of 0.8 μg or less/ml inhibited 40% of the strains, but the MIC for most of the others was > 100 μg/ml. The other agents were generally less active. Chemically related analogues varied in activity to different degrees. Also, the MIC of each antibiotic against different strains generally varied over a wide range. Sulfonamides and trimethoprim were not active against most strains in the method used. The size of the inoculum markedly affected the MIC of sulfonamides and had variable effects on other agents. Marked synergy of erythromycin with ampicillin was demonstrated for nearly all strains tested.

Infections and Antibiotic Use among Patients at Boston City Hospital, February, 1967

Abstract In a survey of infections and antibiotic use at the Boston City Hospital in February, 1967, 26.3 per cent of the patients had infections considered to be community-acquired, and 15.5 per c...