Clinical Evaluation of Co-trimoxazole and Furazolidone in Treatment of Shigellosis in Children

Co-trimoxazole (trimethoprim—sulphamethoxazole) was compared with furazolidone in the treatment of shigellosis in two groups of 33 and 30 patients respectively. Those treated with co-trimoxazole recovered more quickly; none had shigellae in the faeces four days after the start of treatment, whereas in the group given furazolidone eight still had positive stool cultures seven days after treatment.The susceptibility of 104 shigella strains to seven antimicrobial agents was studied by plate dilution technique. All agents but tetracycline and chloramphenicol were found highly effective against most of the strains tested. All shigella isolates were resistant to sulphamethoxazole, and 63% were sensitive to trimethoprim. Potentiation of trimethoprim by sulphamethoxazole was shown in that all strains tested became sensitive to the combination of trimethoprim and sulphamethoxazole in a ratio of 1:20.     

Duration of bacterial discharge in Sonne dysentery]

The authors report on the results of their observations during 3 epidemic outbreaks. Despite different intervals at which the bacteriological examinations were carried out comparable data were obtained: during 2 outbreaks when no chemotherapeutic agents were used in 78.0 and 79.9% of children shigella discharge ceased in 4 weeks. Daily bacteriological examinations carried out in the course of the 3rd outbreak showed the maximal intermittent bacterial discharge for up to 79 days in individual cases.     

A Three-Year Survey of the Antibacterial Spectra of the More Commonly Used Chemotherapeutic Agents

Eight major bacterial groups (25,000 strains) of gram-positive and gram-negative organisms which were isolated from a variety of clinical specimens were tested by the disc-plate and tube dilution procedure. The in vitro antibacterial spectra of 17 commonly used chemotherapeutic agents were recorded and evaluated statistically during a three-year period. Penicillin G, erythromycin and chloramphenicol were very effective against members of the diplococci and streptococci genera. The synthetic penicillins inhibited 99% of Staph. aureus whereas penicillin G was effective against only 45% of these strains. There was a significant increase in the number of tetracycline-resistant strains of both D. pneumoniae and the Lancefield Group A streptococci. A yearly increase in gram-negative pathogens was noted. These organisms (i.e. Escherichia, Aerobacter, Proteus, Pseudomonas) showed greater resistance to the majority of chemotherapeutic agents than did the gram-positive organisms. The percentage of susceptible strains for each bacterial group appears in the text.     

Antimicrobial biotypes and colicine types: potential epidemiological markers of Salmonella agona

With the purpose of characterizing epidemiologic markers, 240 strains of S. agona isolated from differents sources (man, food and environment) and obtained from five Brazilian States (Minas Gerais, S?o Paulo, Rio de Janeiro, Pernambuco and Rio Grande do Sul) were analysed. The susceptibility to 15 antimicrobial agents and numeric codification of the resistance profiles allowed us to recognize 56 antibiotic resistance biotypes, while 40 strains were able to produce colicine, belonging to the types: Ia (55%); B (32.5%); Ib (10%) and untypable (2.5%). The application of these elements into intra-serotype differentiation is discussed.     

Microbial resistance of Salmonella agona from various regions of Brazil

The object of the investigation was the evaluation of the susceptibility to antibiotic and chemotherapeutic agents of 240 strains of Salmonella agona isolated from different sources (human, food and environment) obtained from five Brazilian states (Minas Gerais, S?o Paulo, Rio de Janeiro, Pernambuco and Rio Grande do Sul). The presence of R factors in 26 representative strains of the sample was also determined.     

Effect of subinhibitory levels of selected antibiotics on susceptibility of Staphylococcus aureus strains to phagocytosis and killing by rabbit granulocytes

The aim of the study was to assess the of chosen antibiotics in subinhibitory concentrations (sub-MIC) on the sensitive of Staphylococcus aureus cells to phagocytosis and killing by rabbit granulocytes. The following antibiotics were used: cloxacillin, cefadroxil, cefuroxim, cefotaxim, gentamicin, netilmicin, lincomicin, doxycycline and riphamicin. A total of 144 S. aureus strains with varied sensitivity to these antibiotics were selected for the study. The experiment used granulocytes isolated from rabbit blood and S. aureus strains incubated for 18 h in TSB broth containing antibiotics in the concentrations of 0.1 MIC, 0.2 MIC and 0.5 MIC, and in the antibiotics-free medium. Phagocytosis was assessed by the method of differential staining with acridine orange and crystal violet, allowing simultaneous determination of phagocytised and killed S. aureus cell counts. The findings revealed that the culture of S. aureus in the presence of all the antibiotics used in subinhibitory concentrations increased significantly the susceptibility of most S. aureus strains to phagocytosis and killing by granulocytes. The above effect usually occurred in the concentrations of 0.1 MIC (54.2%), more seldom in 0.2 MIC (13%) and 0.5 MIC (15% of strains). Each group of S. aureus contained some which showed no change in susceptibility following culture with the chemotherapeutic agents in subinhibitory concentrations (26.3%). Insensitive strains to the subinhibitory effects were equally common among susceptible (27%), intermediate (23%) and resistant (26%) strains of S. aureus to the antibiotics used. No statistically significant reduction was noted in phagocytosis or killing by rabbit granulocytes. No correlation was observed between the susceptibility to the subinhibitory effects of the antibiotics involved and their biochemical mechanisms.     

Microbiological control of drug resistance of causative agents in suppurative-septic infections in newborn infants

Resistance of the main causative agents of purulent septic infections such as pneumonia, meningitis, sepsis, etc. to 11 chemotherapeutic drugs was studied. The pathogens were isolated from autopsies of 203 newborns who died within 1981 to 1987. Among 2978 isolates belonging to Enterobacteriaceae (2466 strains) and Pseudomonadaceae (512 strains) which constituted 88% of all the isolates, strains with multiple resistance predominated: 90% of the strains resistant to 4 or more antibiotics, 77% of the strains resistant to 6 or more antibiotics and 48% of the strains resistant to 8 or more antibiotics. The highest number of the isolates were resistant to 8 and 9 chemotherapeutics (19 and 20%, respectively). 84% of all the isolates belonged to 4 genera: Klebsiella (34%), Escherichia (21%), Serratia (14%) and Pseudomonas (15%). They were characterized by the highest resistance spectra. In all the cases massive colonization of the intestine by the strains with multiple resistance which caused purulent septic infections was observed. The most frequent variants of the drug resistance combination were determined. In the total frequency of the isolate with multiple resistance no significant differences were detected in 1981 and thereafter. In 1986-1987 the frequency of S. marcescens strains increased 3-5 times with simultaneous broadening of their drug resistance spectra. Strains of S. marcescens and K. pneumoniae with multiple drug resistance endemic for definite hospitals were detected.     

应用肠杆菌科诊断噬菌体检测志贺氏菌的评价

应用肠杆菌科诊断噬菌体对2280株疑似志贺氏菌进行了检测,同时进行了常规鉴定。结果表明,志贺氏菌属Sh噬菌体10³RTD对属内裂解率为100%,1RTD为99.9%;65株与志贺氏菌分型血清呈现凝集的非志贺氏菌,10³RTD裂解率为12.3%,1RTD为4.6%。裂解模式的测定表明,2215株志贺氏菌分属于7个裂解模式,仅模式3中3株鲍氏5型为文献[2,3]所未列入,余者完全一致。Sh10³RTD裂解的非志贺氏菌均可用1RTD和裂解模式排除     

Susceptibility to selected chemotherapeutics of Staphylococcus aureus strains resistant to methycyline isolated from clinical materials in the years 1991-1992 and 1997

The susceptibility to selected chemotherapeutic agents was determined in 100 strains of Staphylococcus aureus methicillin-resistant (MRSA) isolated from clinical materials in 1991-1992 (50 strains) and in 1997 (50 strains). Two methods were used for the determination: disc method and antibiotic dilution in agar. The minimal inhibitory concentration (MIC) was determined for vancomycin, teicoplanin, furazolidone, nitrofurantoin, ofloxacin, gentamicin, netilmicin and trimethoprim. The concentrations of the chemotherapeutics in the substrate ranged from 0.125 to 512 mg/l. The obtained results served for drawing of the following conclusions: all studied MRSA strains isolated in 1991-1992 and in 1997 were sensitive to glycopeptide antibiotics: vancomycin and teicoplanin, to nitrofurans: nitrofurantoin and furazolidone, and to fusidic acid. MRSA strains isolated in 1991-1992 were sensitive to ofloxacin, but in 1997 about 80% of the strains were resistant to that antibiotic, and this resistance was noted in S. aureus strains with homogeneous resistance to methicillin. Increasing frequency of resistance to mupirocin was found, in 1991-1992 4% of the strains were resistant, and in 1997 the resistance of MRSA to that antibiotic was found in 12%. No changes occurred in the sensitivity of staphylococci to trimethoprim/sulfamethoxazole (cotrimoxazole). About 94% of strains in 1991-1992 and 1997 were sensitive to that drug. The sensitivity to cotrimoxazole is connected with one of its components (trimethoprim), with 94% of MRSA strains sensitive to it.     

Microbiological External Quality Assurance Program (MEQAO)--evaluation of results obtained in 2001 of sanitary-epidemiological station laboratories

The aim of this study was to evaluate reliability of identification and determination of sensitivity to antibiotics and chemotherapeutics of some Enterobacteriaceae strains in 49 sanitary-epidemiological stations. All laboratories engaged in this study received 4 strains each (S. marcescens phenotype ESBL+, K. pneumoniae phenotype ESBL+, S. Typhimurium and S. Newport) previously identified in the Department of Bacteriology of National Institute of Hygiene. The laboratories included in the survey were asked to determine the genus (serovar) of each control strain using the lowest number of biochemical test recommended by Institute and to determine of the sensitivity of the identified strains to antibiotics in accordance with the guidelines of the NCCLS and domestic recommendations. Only in 2 participating laboratories the identification of one of studied strains (K. pneumoniae) was completely bad and in 9 laboratories the serological identification of S. Newport was incomplete or serological type was not correctly recognised. In the determination of the sensitivity of the control strains to chemotherapeutic agents abnormalities were found in the technique of antibiogram and test for ESBL performing and incorrect selection of disc for antibiograms as well as erroneous interpretation of the results.     

Cryofragility and other membrane characteristics of solid mouse tumors

The membrane fragility of Ridgway osteogenic sarcoma (ROS) was compared with that of other solid tumors in an attempt to explain its sensitivity to chemotherapeutic agents. The sensitivity of ROS to freezing, hypotonicity, and to the mechanical insult of homogenization was determined by bioassay. The results were compared with those obtained with an ROS subline resistant to cyclophosphamide (ROS/CPA), with melanoma B16 and the recently induced sarcoma S1976, the latter two being relatively drug-resistant tumors. Representative values of the viability as expressed by percent of tumor takes were: (a) after storage at ?78 °C for 24 hr in Earle's balanced salt solution without DMSO, for ROS 0%, ROS/CPA 11%, B16 82%, and S1976 100%; (b) after incubation at 37 °C for 2 hr in distilled water, for ROS 0%, ROS/CPA 0%, B16 42%, and S1976 80%; (c) after mechanical dispersion in a tissue grinder, for ROS 17%, ROS/CPA 28%, B16 100%, and S1976 100%. Relevant therapeutic indices for ROS, B16, and S1976 were: for single doses of cyclophosphamide 12, 3.1, 3.5, melphalan 3.5, 1.5, 1.5, medphalan 4.2, 1.5, 1.2 and for 6 daily doses of 5-fluorouracil 1.5, <1.0, <1.0, and 6-mercaptopurine 5.9, 1.4, 1.6. The marked membrane fragility of ROS may be related to its sensitivity to chemotherapeutic agents.     

Cytidine deamination assay to differentiate Staphylococcus aureus from other staphylococci

AIMS: Adoption of the property of cytidine (cytosine-beta-d-riboside) deamination in staphylococci to distinguish Staphylococcus aureus from other staphylococci. METHODS AND RESULTS: A total of 560 staphylococcal strains were examined. The test demonstrated a sensitivity of 97.1% and a specificity of 98.8%. Of the 249 S. aureus strains (115 oxacillin-resistant) 58 strains were coagulase-negative S. aureus and another 16 strains were clumping factor-negative S. aureus. The 74 deficient S. aureus strains were identified by 16S rRNA gene sequencing and further investigated by spa typing and 13 spa types were found. CONCLUSIONS: The cytidine deaminase test (CDT) is useful especially for distinguishing coagulase- and clumping factor-negative S. aureus from other staphylococci and the results correlated well with 16S rRNA sequencing and the polymerase chain reaction (PCR) amplification of the nuc gene. SIGNIFICANCE AND IMPACT OF THE STUDY: Cytidine deamination assay differentiates S. aureus from other staphylococci. This method is fast (6 h) and reliable in distinguishing between non-S. aureus and the defective (coagulase-negative, clumping factor-negative) S. aureus isolates which could have major consequences for therapy.     

Slime production and antibiotic susceptibility in staphylococci isolated from clinical samples

A total of 187 isolates from several clinical specimens were identified to species level as 129 Staphylococcus aureus strains and 58 coagulase-negative staphylococci (CNS) strains by the API Staph System (Biomerieux). Slime production was detected both by the conventional Christensen's method as well as by the Congo red agar method. Seventy-two strains of staphylococci isolates (38.5%) were found to be slime producers by Christensen's test tube method whereas 58 strains (31%) were slime positive with Congo red agar method. There was no statistically significant difference between the two methods for the detection of slime production (P > 0.05). Susceptibility of isolates against antimicrobial agents was tested by the disk diffusion method. Staphylococcal species had resistance to one or more antibiotics. Among the various antimicrobial agents, oxacillin (71.1%) and erythromycin (47.1%) showed higher resistance than most of the agents used against all isolates. Oxacillin resistant S. aureus (ORSA) and oxacillin resistant coagulase-negative staphylococci (ORCNS), 97 (75.2%) and 36 (62.1%) respectively were frequently observed in strains isolated from clinical materials. Among the ORSA strains, two strains were resistant to vancomycin. Moreover, 96 (74.4%) of 129 S. aureus strains were positive for beta-lactamase enzyme. However, 78 (81.25%) of 96 beta-lactamase positive S. aureus strains were beta-lactamase positive ORSA isolates, but none of them had vancomycin resistance.     

Occurrence of Clostridium difficile in feces of children with dysfunction of the digestive tract and other disorders

Thousand and six hundred ninety two fecal samples from children of few weeks old up to over ten years were tested for the presence of Clostridium difficile. Most of them were treated with antibiotics and showed diarrhea symptoms. Hundred and twenty three strains of C-difficile were submitted to serological typing and their sensitivity to 10 selected antibiotics and chemotherapeutic agents was determined. Among 109 strains of C. difficile tested for enterotoxin production by latex test 82 strains (75.2%) were positive. Almost half (48%) of the isolated strains belonged to serotype C. Most of the strains were resistant to cefoxitin (88%) and clindamycin (76%). Over 90% of strains were sensitive to vancomycin and azlocillin and 86% to chloramphenicol and metronidazole. In the majority of patients with positive C. difficile cultures diarrhea was present, however, it was difficult to find a direct link between these symptoms and antibiotic therapy.     

Antimicrobial resistance and presence of <Emphasis Type="Italic">ileS-2</Emphasis> gene encoding mupirocin resistance in clinical isolates of methicillin-resistant <Emphasis Type="Italic">Staphylococcus</Emphasis> sp.

Seventy-eight staphylococcal strains were isolated from surgical-site, blood-stream and other hospital-acquired infections. Eighteen isolates were determined as methicillin (MET)-resistant S. aureus (MRSA), while the remaining were MET-resistant coagulase-negative staphylococci (CoNS). Fifty percent of CoNS strains were multiresistant, while 10 % of isolates were resistant only to β-lactams. Clinical isolates of CoNS were generally more resistant to antimicrobial agents than S. aureus strains. Thirty-nine % of S. aureus strains were resistant only to β-lactams. None of the MRSA strains carried ileS-2 gene; this gene was found in two strains of S. epidermidis.     

Unique features of heat-stable enterotoxin of Shigella flexneri.

Sephadex G-100 fractions of ultrasonic lysate of Shigella felxneri were compared to the fractions of Escherichia coli lysates of Ent- , LT+ ST+, LT+ and ST+ strains. The range of molecular weight of S. flexneri ST fractions was the same as that of E. coli LT fractions. Rapid PF activity was associated with the ST peak in the case of S. flexneri, and followed the LT activity in the E. coli (LT+ ST+) fractions, and appeared in the same molecular weight range in the case of Ent- E. coli lysate. Cross neutralization could be demonstrated between S. flexneri ST and E. coli LT. Antigenic relationship between shigella ST and choleragen seemed to be less expressed and rather unilateral.     

Strategic down-regulation of DNA polymerase beta by antisense RNA sensitizes mammalian cells to specific DNA damaging agents.

Previously, mouse NIH 3T3 cells were stably transfected with human DNA polymerase beta (beta-pol) cDNA in the antisense orientation and under the control of a metallothionein promoter [Zmudzka, B.Z. and Wilson, S.H. (1990) Som. Cell Mol. Gen., 16, 311-320]. To assess the feasibility of enhancing the efficacy of chemotherapy by an antisense approach and to confirm a role for beta-pol in cellular DNA repair, we looked for increased sensitivity to DNA damaging agents under conditions where beta-pol is down-regulated in the antisense cell line. Such a sensitization is anticipated only where beta-pol is rate-limiting in a DNA repair pathway. A number of agents were tested: cis-diamminedichloroplatinum II (cisplatin); 1,3-bis(2-chloroethyl)-1- nitrosourea (BCNU); ionizing radiation and the radio-mimetic drug bleomycin; the bifunctional alkylating agents nitrogen mustard and L-phenylalanine mustard (melphalan); the monofunctional alkylating agent methyl methane sulfonate (MMS) and ultraviolet (UV) radiation. In the cases of cisplatin and UV radiation, a significant enhancement of cytotoxicity was observed. Damage as a result of both of these agents is thought to be repaired by the nucleotide excision repair (NER) pathway. The results suggest that, in this cell line, beta-pol is involved in and is rate-limiting in NER. We propose that down-regulation of beta-pol by antisense approaches might be used to enhance the cytotoxic effects of cisplatin and other DNA damaging chemotherapeutic agents.     

Investigation of the lytic ability of South African bacteriophages specific for Staphylococcus aureus,associated with bovine mastitis

Bovine mastitis is an infectious disease of the mammary glands of dairy cattle primarily causaled by the bacterium, Staphylococcus aureus subsp. aureus Rosenbach1884. Traditional control of this organism was through the use of antibiotics. However, S. aureus is developing resistance towards these chemotherapeutic agents faster than they are being developed. Bacteriophages can serve as an alternative control measure for the disease. This study investigated the prevalence of phages and S. aureus within the South African dairy environment, as well as infectivity of phage isolates against antibiotic-resistant S. aureus. The four S. aureus strains used in the study displayed resistance to representative antibiotics from both the β-lactamases and non-β-lactamases, macrolides, aminoglycosides and glycopeptides. Susceptibility was only noted towards the tetracycline antibiotics. Twenty-eight phages were isolated and screened against four strains of S. aureus. Only six phages showed biocontrol potential based on their wide host range, high titres and common growth requirements. Morphological and preliminary genomic analysis was carried out on the three best performing phages. At an optimal titre of between 6.2 × 10⁷ and 2.9 × 10⁸ pfu.ml^?1, the phages were able to reduce live bacterial cell counts between 64% and 95%. In addition, these six phages showed further infectivity towards S. aureus strains that were isolated from different milk-producing regions during a farm survey. The phages isolated in this study show reasonable potential for in vivo applications.     

In vitro susceptibility of 7.5-kb common plasmid-free Chlamydia trachomatis strains

Using a new plaque cloning technique, we obtained unique Chlamydia trachomatis strains which were confirmed to be free of the 7.5-kb common plasmid and glycogen in inclusions. The in vitro susceptibility of these strains to various chemotherapeutic agents was tested by comparison with their parent strains and clinical isolates possessing the common plasmid. No difference was detected for any of the agents tested, indicating that the 7.5-kb common plasmid is unrelated to the drug resistance of C. trachomatis.     

Classification and biological characteristics of coagulase-positive Staphylococci isolated from animals

A total of 165 coagulase-positive staphylococcal strains of different origin (142 S. aureus strains and 23 S. intermedius strains) were subjected to biological typing in accordance with the schemes of Hajek-Marsalek and Meyer-Witte. The former of these schemes permitted to identify 68% and the latter 18% of S. aureus strains. The cultures isolated from swine and chickens had the most uniform composition: 85-86% of the strains belonged to biotype B. 44% of the strains isolated from cows and sheep belonged to biotypes C (ecovars bovis and ovis) and A (ecovar hominis); the rest of the strains could not be identified. 96% of the strains isolated from minks were made up of S. intermedius, more than a half of them belonging to biotype E (ecovar canis). In 80% of S. aureus strains and 48% S. intermedius cultures protein A was detected. Only 9% of S. aureus strains of animal origin were found capable of producing enterotoxins (A-D). The expediency of working out a unified scheme for the biotyping of coagulase-positive staphylococci is discussed.