The sensitivity to 12 antibiotics of 125 strains of Streptococcus group B isolated in a maternity home

Sensitivity of 125 strains of group B streptococci isolated from newborns, their mothers and personnel in a maternity home was studied with respect to 12 antibiotics: benzylpenicillin, ampicillin, methicillin, cephalotin, erythromycin, lincomycin, levomycetin (chloramphenicol), oxacillin, tetracycline, streptomycin, gentamicin and ristomycin. The method of serial dilutions in a solid medium was applied. All the strains were sensitive to ristomycin and erythromycin. The predominating number of the strains were sensitive to lincomycin, levomycetin and the beta-lactam antibiotics. Strains resistant or moderately resistant to benzylpenicillin, ampicillin, oxacillin, methicillin and cephalotin were detected. The majority of the strains were resistant to streptomycin, tetracycline and gentamicin. Multiple antibiotic resistance with 2-7 determinants was revealed in 11.2 per cent of the strains. The antibiotic sensitivity of the strains isolated from the newborns, their mothers and the personnel in the maternity home was on the whole similar or insignificantly differed.     

Antibiotic sensitivity of beta-hemolytic Streptococcus group A on a new nutrient medium for the cultivation of streptococci

Sensitivity of 167 strains of beta-hemolytic streptococci of group A was studied with the method of serial dilutions on a solid agar medium for cultivation of streptococci. The medium was developed at the I. I. Mechnikov Research Institute of Vaccines and Sera. It does not require addition of blood or serum. The strains were found to be highly sensitive to penicillin, cephalothin and erythromycin. The number of the strains resistant to tetracycline, streptomycin, gentamycin, levomycetin (chloramphenicol) and ristomycin amounted to 51, 36, 23, 1.8 and 1.8 per cent, respectively. One of the strains (0.6 per cent) was resistant to lincomycin. Strains with multiple resistance were isolated. The necessity of regular control of distribution of antibiotic resistance among staphylococci is indicated.     

Antimicrobial Susceptibility of Clostridium difficile from Different Sources

A total of 79 Clostridium difficile strains from healthy young and elderly adults, elderly patients without gastrointestinal disease, elderly patients receiving antibiotics without gastrointestinal complications, and elderly patients with antibiotic-associated diarrhea or pseudomembranous colitis were tested for their susceptibilities to 24 antimicrobial agents. All of the 79 strains were inhibited by low concentrations of rifampicin, metronidazole, fusidic acid, vancomycin, ampicillin, and penicillin G. The strains were highly resistant to aminoglycosides, trimethoprim, sulfamethoxazole, nalidixic acid, and cycloserine and often resistant to neomycin, cefoxitin, and cefalexin. Wide variations in the susceptibility of C. difficile strains to erythromycin, clindamycin, lincomycin, chloramphenicol, and tetracycline were found. Strains resistant to erythromycin, clindamycin, and lincomycin were more frequently found among strains isolated from elderly adults than those isolated from young adults, with particularly high frequency among strains isolated from elderly patients receiving antibiotics. None of the 23 strains isolated from healthy young adults was resistant to chloramphenicol. All of the 14 strains resistant to erythromycin, clindamycin, lincomycin, and chloramphenicol were sensitive to tetracycline and all of the 15 strains resistant to erythromycin, clindamycin, lincomycin, and tetracycline were sensitive to chloramphenicol. Only one out of 19 tetracycline-resistant strains was highly toxigenic, whereas 42 (70%) of 60 sensitive strains were highly toxigenic.     

Sensitivity of Mycoplasma hominis cultures isolated from clinical material to certain antibiotics]

Sensitivity to II antibiotics of 80 strains of M. hominis isolated from patients with various inflammatory processes of the urogenital tract was studied by the method of suppressing the metabolic activity. Inhibition of the arginine metabolism of mycoplasma was used as a test for determination of the growth suppression. All the strains tested were highly sensitive to tetracycline and lincomycin. Kanamycin and neomycin were less active against M. hominis. All the strains tested were resistant to erythromycin, oleandomycin, ristomycin, novobiocin and streptomycin. The inhibitory effect of tetracycline and lincomycin on M. hominis decreased by the 5th day.     

Drug Resistance of Staphylococci

Examination of cross resistance to macrolide antibiotics in erythromycin resistant staphylococcal strains isolated from clinical sources in the United States showed that there were two types of cross resistance, group A (13.4%) and group C (86.6%). Group A possessed multiple resistance to the macrolide antibiotics, erythromycin, oleandomycin, leucomycin and spiramycin, and was also resistant to lincomycin. In group C, resistance to erythromycin alone or to both erythromycin and oleandomycin could be induced by exposure to erythromycin.     

Comparative Inhibition of Methicillin-resistant Strains of Staphylococcus aureus by Lysostaphin and Otner Antibiotics

Sixteen methicillin-resistant strains of Staphylococcus aureus obtained from Europe were found to be sensitive to the lytic activity of lysotaphin. With only minor exceptions, the strains were found to be sensitive to novobiocin, erythromycin, fusidic acid, and lincomycin, and slightly less sensitive to vancomycin and chloramphenicol. All strains were resistant to tetracycline, penicillinase-sensitive penicillins (benzylpenicillin, ampicillin, and propicillin), penicillinase-resistant penicillins (methicillin, nafcillin, ancillin, oxacillin, cloxacillin, and dicloxacillin), and two cephalosporin antibiotics (cephalothin and cephaloridine).     

Sensitivity of methicillin-resistant Staphylococcus aureus strains to some antibiotics, antiseptics and disinfectants

The effects of antibiotics, antiseptics and disinfectants against some methicillin-resistant (MRSA) and methicillin-sensitive (MSSA) Staphylococcus aureus strains have been studied. The MRSA and MSSA strains were equally sensitive to phenols, esters of para(4)-hydroxybenzoic acid and chlorhexidine but MRSA strains were slightly more resistant to quaternary ammonium compounds and considerably more so to dibromopropamidine isothionate. Some MRSA strains were also resistant to phenylmercuric nitrate (but not another organomercurial, thiomersal), mercuric chloride and cadmium chloride. All MRSA strains produced beta-lactamase. Strains from the Royal Free Hospital, London were highly resistant to beta-lactam antibiotics, erythromycin, trimethoprim and tetracyclines but were sensitive to other antibiotics. One strain from the University Hospital of Wales, Cardiff was resistant to gentamicin but sensitive to tetracycline and trimethoprim.     

The incidence of inflammation among patients suffering from cervix cancer with positive beta haemolytic streptococci cultures from genital tract

AimThe main goal of this investigation was to evaluate the influence of positive beta haemolytic streptococci culture from the genital tract on patients receiving radiation therapy who suffer from cervical cancer. The other aim was to observe radiation therapy complications.BackgroundGroup B streptococci (GBS), group C streptococci (GCS) and group G streptococci (GGS) have been described as frequent invasive pathogens in elderly patients, often in association with underlying medical conditions including immunodeficiency and cancer.Materials and methodsIn the years 2006–2015, vaginal swabs from 452 patients were examined. A total of 118 women with positive beta haemolytic streptococci (BHS) groups A, B, C, F, G cultures were analysed, of whom 111 were diagnosed with cervix cancer of IB to IVA degree according to the FIGO 1988 clinical classification.ResultsOf the 452 patients suffering from cervix cancer 26.1% were positive for A, B, C, F or G group BHS isolated from the genital tract. All of the 114 examined strains were sensitive to beta-lactam antibiotics. The antimicrobials for which resistance was noted were erythromycin, clindamycin, ciprofloxacin and tetracycline.ConclusionsPositive cultures of BHS from the genital tract were demonstrated to occur in patients with cervix cancer. Complications were found during radiotherapy in 30 (27%) of these patients, including 20 (18%) patients suffering from clinical symptoms of inflammation. When beta-lactam antibiotics are not recommended because of allergy, sensitivity tests to other drugs are necessary.     

The pharyngeal beta-hemolytic streptococcal carrier state among blood donors

459 blood donors aged 18-50 years were examined in 1987-1988 in Moscow. Among them, carrier state with respect to beta-hemolytic streptococci was detected in 107 donors (23.3%). The number of carriers gradually decreased with the increase of age of the examined donors. Group C streptococci occurred least of all (6.9%). Group A beta-hemolytic streptococci were isolated in 16.7% of the carriers. The isolation rate of streptococci from blood achieved its maximum in autumn and winter months and did not depend on preceding diseases, unhealthy working conditions, the rhesus factor and, with the exception of group A streptococci, the blood group. Among tonsillectomized donors carrier state with respect to beta-hemolytic streptococci occurred 2.2 times less frequently than among donors who had not undergone tonsillectomy. Carrier state with respect to beta-hemolytic streptococci was accompanied by higher levels of salivary sIgA antibodies to polysaccharide A, serum antibodies to polysaccharide A and circulating polysaccharide A. All beta-hemolytic streptococci were sensitive to erythromycin. All groups of streptococci showed the highest percentage of cultures resistant to gentamicin and tetracycline. In 100% of cases group A streptococci were sensitive to benzylpenicillin, methicillin, ampicillin, erythromycin and lincomycin.     

Antibiotic sensitivity of Staphylococci populating the breast skin of nursing women

Sensitivity to penicillins, tetracycline, erythromycin and lincomycin was tested in 1513 staphylococcal strains isolated from the skin of various anatomic areas of the breast of nursing mothers. It was shown that 82.9, 78.4 and 33.9 per cent of the isolated cultures were highly sensitive to lincomycin, erythromycin and methicillin respectively. Sensitivity to tetracycline and benzylpenicillin was detected in 33.1 and 19.8 per cent of the cultures respectively. The study of the resistance spectra of 1343 strains resistant to certain antibiotics revealed that 498 cultures (37.1 per cent) were polyresistant. None of the tested antibiotics could be used for selective decontamination of the breast skin with respect to S. aureus in prophylaxis of lactic mastitis.     

Action of Lincomycin on Staphylococci

On a solid medium, 0.1 to 1 μg/ml of lincomycin hydrochloride had a bacteriostatic effect upon 95 of 100 strains of staphylococci. Using cellophane transfers, we observed a bactericidal effect upon 54 of these strains after 3 to 14 hr of contact with 1 μg/ml. Five staphylococcal strains resistant to 100 μg/ml of lincomycin were also resistant to penicillin G, streptomycin, erythromycin, tetracycline, chloramphenicol (three strains), and rovamycin (three strains). Other staphylococcal strains resistant to methicillin, ampicillin, tetracycline, streptomycin, chloramphenicol, and erythromycin were sensitive to lincomycin.     

Study of the sensitivity of the L-forms of group A Streptococcus to antibiotics in artificial nutrient media and in human cell cultures

Sensitivity of L-forms of group A streptococci to 5 antibiotics such as erythromycin, lincomycin, tetracycline, gentamicin and chloramphenicol was studied in an artificial nutrient medium and cell cultures i.e. human fibroblast diploid cells and transplantable human heart cells (Girardi). In vitro investigation of the antibiotic effect on the streptococcal L-forms revealed their sensitivity to erythromycin (MIC, 0.4 micrograms/ml), lincomycin (MIC, 0.08 microgram/ml) and tetracycline (MIC, 2 micrograms/ml). The streptococcal L-forms were slightly sensitive to gentamicin (MIC, 6 micrograms/ml) and chloramphenicol (MIC, 30 micrograms/ml). Complete inhibition of the growth of the L-forms in the Girardi cells on the 1st day of the experiment after the antibiotics administration in single doses was induced by lincomycin, 5 micrograms/ml, erythromycin, 10 micrograms/ml, and tetracycline, 100 micrograms/ml. In the diploid cells, the respective figures were 50, 100 and 200 micrograms/ml. Chloramphenicol and gentamicin had an inhibitory effect on the growth of the L-forms but produced no sanative effect.     

In-vitro Comparison of Erythromycin,Lincomycin, and Clindamycin

The in-vitro antibacterial activities of erythromycin, lincomycin, and clindamycin, a new derivative of lincomycin, were compared. Clindamycin was always more active than lincomycin, and was either as active as erythromycin or more so against betahaemolytic streptococci, Streptococcus viridans, Str. pneumoniae, and erythromycin-sensitive Staphylococcus aureus. It was also fully active against most erythromycin-resistant strains of Staph. aureus. On the other hand, it was somewhat less active than erythromycin against Haemophilus influenzae and considerably less active than erythromycin against Str. faecalis and Neisseria gonorrhoeae.Clinical trials seem to be justified in infections with sensitive organisms for which erythromycin might have been indicated.     

II. In vitro studies of antibacterial activity

One hundred and forty isolates of beta-hemolytic streptococcus cultured from patients with clinical pharyngitis were studied by disc diffusion for antibiotic sensitivity to lincomycin, erythromycin, cephalexin and penicillin and by agar dilution to cephalexin and penicillin. All isolates were sensitive to ≤ 0.1 μg./ml. penicillin and ≤ 1.56 μg./ml. cephalexin. The disc-diffusion test was reliable in predicting the sensitivities in vitro. One strain of group A betahemolytic streptococcus was resistant to erythromycin by disc diffusion. When compared to Lancefield grouping 18% of strains were incorrectly identified as group A by the bacitracin-disc test. Cephalexin was uniformly effective in vitro in inhibiting beta-hemolytic streptococci and the 30 μg. cephalexin disc was reliable in predicting these sensitivities.     

Conjugative R plasmids in Streptococcus agalactiae (group B).

Twenty-one drug-resistant clinical isolates of group B streptococci were investigated for drug-resistance transfer by conjugation. Six strains were resistant to tetracycline, two to chloramphenicol, one to both drugs, and twelve to macrolide antibiotics (erythromycin, oleandomycin and spiramycin), lincomycin, pristinamycin I, and/or chloramphenicol and tetracycline. Ten strains carried R plasmids which were transferable to group B and/or group D recipients by a conjugation-like phenomenon. Six plasmids were transferred at a high frequency (9 × 10^?2 to 4 × 10^?4) and four, at low frequency (5 × 10^?6 to 7 × 10^?8). The molecular weight of one plasmid (pIP501) was investigated after transfer into the new hosts and was found to be similar to that carried by the wild strain (19.8 × 10⁶).     

Antibiotic sensitivity of staphylococci isolated from the surface of the skin of the breasts in pregnant women

Nine hundred and fourty coagulase-positive and coagulase-negative strains of staphylococci isolated from the skin surface of the mammary glands of 94 pregnant women were tested by the disc agar diffusion method for their sensitivity to five antibiotics. The highest number of the isolates were sensitive to erythromycin and lincomycin (87.7 and 89.7 per cent, respectively). The highest number of moderately resistant strains were detected with respect to methicillin. 19 out of 42 cultures of Staph. aureus were resistant to benzylpenicillin and 24 cultures were resistant to tetracycline. Among staphylococci 130 strains or 13.8 per cent were polyresistant.     

Antibiotic sensitivity of plague microbe strains from foreign countries]

The method of serial dilutions on the Hottinger agar was applied to comparative assay of antibiotic sensitivity in 50 strains of the plague microbe isolated abroad and in 5 strains isolated in the plague focus in the Central Caucasus. The antibiotics used in the assay were the following: streptomycin, gentamicin, doxycycline, monomycin, kanamycin, tetracycline, erythromycin, ristomycin, lincomycin and polymyxin M. Irrespective of the origin, all the isolates were resistant to erythromycin, lincomycin and polymyxin M. The levels of the sensitivity to the other antibiotics were different. The data serve as a ground for the statement that there is no tendency to development of antibiotic resistance in the plague microbe in patients treated with high doses of the antibiotics and mainly streptomycin. Along with streptomycin, such antibiotics as gentamicin, tetracycline, doxycycline and kanamycin are useful in the therapy of plague and require further investigation.     

Pneumococci resistant to erythromycin.

Susceptibility to erythromycin was determined for all pneumococci isolated in one laboratory from clinical specimens between 1969 and 1977. All 4724 isolates examined prior to October 1973 were susceptible to erythromycin. From October 1973 to December 1977, 64 (0.71%) of 8995 pneumococcus isolates were resistant to erythromycin. The resistant strains were isolated from 38 patients living in six widely separated communities in Alberta. The erythromycin-resistant strains were of nine capsular types, including six that often cause bacteremic disease and five for which resistance to erythromycin has not been reported hitherto. Certain strains of type 33 and of type 15 were highly resistant, the minimum inhibitory concentration (MIC) of erythromycin being 2000 microgram/mL; these strains were also highly resistant to lincomycin and clindamycin. Resistance in strains of other types was much lower, the MIC of erythromycin being 0.6 to 20 microgram/mL, and all but one of these strains were susceptible to lincomycin and clindamycin. All the erythromycin-resistant pneumococci were suspectible to penicillin.     

Antimicrobial susceptibility of some streptococci strains of anginosus group isolated from oral and maxillofacial infections

Streptococci strains of the anginosus group isolated from various oral and maxillofacial infections (OMF) were screened for their susceptibility to the following antimicrobial agents: benzylpenicillin, ampicillin, oxacillin, cephalothin, ceftazidime, cefotaxime, cefuroxime, erythromycin, clindamycin, tetracycline, chloramphenicol, vancomycin and trimethoprime-sulphamethoxazole. The isolates were susceptable to: clindamycin, chloramphenicol, vancomycin and all beta-lactam antibiotics, except ceftazidime to which 54.5% of the strains showed intermediate susceptibility. Intermediate susceptibility to tetracycline was found in 11.3% of the strains, whereas resistance to the same antibiotic was demonstrated in 61.4%. Resistance to erythromycin and trimethoprime-sulphamethoxazole was of 2.3% for both. In conclusion, penicillin is the drug of choice in infections caused by streptococci of the anginosus group.     

Susceptibility of Coagulase-negative Staphylococci to Lysostaphin and Other Antibiotics

In general, coagulase-negative staphylococci were found to be relatively less susceptible to the lytic action of lysostaphin than coagulase-positive staphylococci. To achieve, arbitrarily, a lysis greater than 75%, it was necessary to use an increased concentration of enzyme or a longer incubation period than that usually required with coagulase-positive strains. For the most part, the cultures studied were sensitive to oxacillin, cloxacillin, dicloxacillin, nafcillin, ancillin, cephalothin, cephaloridine, fusidic acid, lincomycin, novobiocin, and neomycin [median minimal inhibitory concentrations (MIC) of 1.56 mug/ml or less]. Some degree of resistance (median MIC values of 12.5 mug/ml or greater) to benzylpenicillin, ampicillin, methicillin, tetracycline, chloretetracycline, erythromycin, ristocetin, and lysostaphin was found. Ten methicillin-resistant, coagulase-negative staphylococal strains were found to be cross-resistant to all nine of the penicillins tested, but much less resistant to the two cephalosporin analogues. In several instances, some of these strains seemed to be more sensitive to benzylpenicillin and to certain of the semisynthetic penicillins than to methicillin. Of the 18 antibiotics tested with the viable plate count method, the methicillin-resistant strains were found to be the most sensitive to lincomycin and novobiocin.