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[Salmonellosis in Dakar: bacteriological, clinical, epidemiological and therapeutic aspects. Ten years records (author's transl)].

A study on salmonellosis in Senegal has been carried out in Dakar at the University Hospital of Fann from 1966 to 1976. The authors describe the various methods of isolating the germs (mainly hemoculture and coproculture) and the techniques used for bacteriological research (antibiograms, tests on plasmidic resistance). The results of these investigations, which took the whole of 10 years, are presented below, in accordance with their different aspects: - bacteriological: 1 335 strains of Salmonella have been isolated. Significantly, S. typhi is predominant (56,6 p. 100). But 7 serotypes represent 90 p. 100 of the total strains which are now in existence in Dakar; - clinical: the aspects of these diseases vary: typhoïd fever, encephalitis, diarrheic syndrome, especially among infants, and purulent meningitis, which is generally severe; - therapeutic: 880 strains have been tested with 10 antibiotics. Two groups of Salmonella serotypes are opposed: those which are sensitive (S. typhi, S. typhi murium, S. enteritidis, S. paratyphi C), those which have become resistant (S. stanleyville, S. havana, S. ordonez). The most frequent antibiotype of this kind is ASKCTSu. This is a phenomenon of plasmidic resistance, demonstrated by in vitro experiments; - epidemiological: the lysotypes of 86 strains have been determined. Two epidemiological features must be described: either a stable endemic situation with sensitive strains - or epidemics, lasting several years, with resistant serotypes. Different therapeutic schemes can be used: chloramphenicol for typhoid fever, or sometimes cotrimoxazole, or ampicillin for meningitis. In diarrheic syndrome, symptomatic treatment is enough. Then, the authors give their comments on the special characteristics of salmonellosis in Dakar: - the influence of environment on the various clinical aspects of these diseases: very serious cases of meningitis, typhoid fever, which is more severe than in France, and complications when treatment has gone wrong at the beginning; - antibiograms, which are essential, in order to choose the adequate therapeutics; - and the different aspects of epidemillogy, which are linked to the sensitivity of the serotypes to the most active antibiotics. The existence of several resistant serotypes in Senegal is a real danger: plasmidic resistance could be transferred to S. typhi. In such a situation, epidemiological surveillance of salmonellosis is absolutely necessary, and control of enteric diseases, characterized by foecal transmission, must be carried out, with the techniques available in the country.

Anti-Bacterial Agents

Meningitis due to two serotypes of Escherichia coli. An infant who recovered.

A newborn infant with hyaline membrane disease and aspiration pneumonia developed purulent meningitis on day 19, three days after discontinuation of ampicillin sodium and gentamicin sulfate therapy. Therapy with gentamicin, both systemically and intrathecally, for two weeks was ineffective. During this time each of four specimens of cerebrospinal fluid contained two serotypes of Escherichia coli, namely, O83:H4 and O75:H5. The antibiograms of the two strains were identical, both being susceptible to gentamicin and ampicillin. Treatment with ampicillin resulted in prompt disappearance of the infecting microorganisms and recovery from the infection. One of the strains (O75:H5) produced an antigen cross-reacting with the capsular antigen of Haemophilus influenzae type B; the other did not. The patient developed O antibodies in substantial titers against E coli O83 but not against E coli O75.

Ampicillin

Correlation of minimum inhibitory concentration and beta-lactamase activity.

The beta-lactamase activity of 510 recently isolated Enterobacteriaceae was investigated with a quantitative photometric test. Beta-lactamase could be detected in 55 percent of the Enterobacteriaceae. At the same time minimal inhibition concentration (MIC) of beta-lactam antibiotics was determined. There was no correlation between MIC values and lactamase activity. For correct antibacterial therapy the clinician requires information on the lactamase activity of isolated bacteria in addition to the antibiogram. The qualitative test is useful for screening.

Amidohydrolases

Exacerbations of chronic bronchitis: exogenous or endogenous infection?

Six male patients with chronic bronchitis, who were known previously to have excreted Streptococcus pneumoniae and/or Haemophilus influenzae, both at the times of exacerbations and during remission, were studied for 43 to 52 months. Sputum was examined fortnightly and at the time of exacerbations. Strains of Strep. pneumoniae were serotyped and those of Haemophilus species were typed by antibiograms along with other supporting methods. Sera collected before or at the time of an exacerbation and seven and 30 days afterwards were examined by complement fixation tests against respiratory viruses and Mycoplasma pneumoniae. In 18 out of 25 exacerbations there was evidence of a new type of Strep. pneumoniae and/or Haemophilus spp. or of a current virus infection, suggesting exogenous infection in the majority of these cases. There was a possible reason for failure to detect a new pathogen in three of the seven cases in which none was found. In five further exacerbations adequate investigation was not possible.

Aged

Detection of Serratia outbreaks in hospital.

Infections due to Serratia marcescens were studied in 23 different hospitals. A retrospective study was done in 4 hospitals; all isolates were compared by serological typing, antibiograms, bacteriocin production, and bacteriocin sensitivity. 2 of the hospitals were having cross-infection problems due to antibiotic-resistant strains, but the other 2 had little or no cross-infection. Outbreaks were studied in 19 other hospitals. 9 of these outbreaks were classified as "common source" since contaminated "sterile solutions" were incriminated as the cause in each. One hospital had a "pseudo-outbreak," in which Serratia from E.D.T.A. blood-collecting tubes contaminated blood-cultures as they were collected. All 10 of these strains from common-source outbreaks were generally sensitive to antibiotics. Outbreaks in 9 other hospitals resulted from cross-infection and were caused by strains which were very resistant to antibiotics. Guidelines for detecting outbreaks are given and control measures are suggested.

Alabama

Four-year surveillance of major Gram-negative pathogens in a Saudi tertiary hospital: clinical distribution, comorbidity profiles, and antimicrobial resistance.

PURPOSE: To describe four-year diagnostic-distribution, burden, and antimicrobial-resistances of major Enterobacterales and Pseudomonas aeruginosa in a tertiary-care surveillance framework. PATIENTS AND METHODS: We retrospectively studied first non-duplicate-isolate per/patient/organism between 2022-2025 at a Saudi tertiary-care. Diagnostics used automated-platforms with GeneXpert-Carba-R employed parallel to cultures. Susceptibility interpretations used CLSI-breakpoints relevant to test-year. Annual-trends were assessed with grouped-binomial logistic-regression, and Benjamini-Hochberg false-discovery-rate correction was applied within prespecified analysis. RESULTS: Among 1,857 isolates, Klebsiella pneumoniae was most frequent (36.2%), followed by P.&#xa0;aeruginosa (33.4%), Escherichia coli (17.9%), and Enterobacter cloacae (12.3%). Mean patient age was 64.8&#x2009;years, 51.3% isolates were from intensive-care, 37.4% from urine, and 80.8% records had comorbidity. K.&#xa0;pneumoniae showed overall ESBL (76.6%), CRE (59.9%), MDR (69.3%), panel-defined XDR (64.7%), and panel-defined PDR (15.2%) frequencies. Enterobacterales ESBL-positivity increased (58.1% to 76.8%;q&#x2009;<0.001), whereas meropenem non-susceptibility decreased (52.6% to 33.2%;q&#x2009;<0.001). In P.&#xa0;aeruginosa, ceftazidime non-susceptibility increased (55.2% to 78.6%;q&#x2009;<0.001), meropenem decreased (46.8% to 32.9%;q&#x2009;=&#x2009;0.031), and tobramycin increased (22.2% to 45.7%;q&#x2009;=&#x2009;0.030). Crude-comorbidity differences remained insignificant after false-discovery-rate correction. CONCLUSION: We show a persistent species-specific Gram-negative resistance burden, led by K.&#xa0;pneumoniae and accompanied by substantial P.&#xa0;aeruginosa non-susceptibility. This supports organism-specific detections, antibiograms and continued multicenter-surveillance linked to antimicrobial exposure, genomic-data, and patient outcomes.

ESBL

Bacteriocin typing of Serratia marcescens. A simplified system.

The authors describe a simplified system for the detection of bacteriocin production by Serratia marcescens with the use of six indicator strains, which include Escherichia coli, Klebsiella pneumoniae, Citrobacter diversus, Enterobacter aerogenes (two strains), and Serratia rubidaea grown on arabinose minimal medium plates. Of the 64 possible bacteriocin types, 11 were observed; 66% of the isolates tested were found to be one of three types. Occasionally more than one bacteriocin type was observed in an individual specimen; however, serotyping or antibiograms, or both, also indicated this was a different strain. The marcescin types were stable markers. With the use of this technic, different endemic strains of Serratia were shown to predominate in various areas of the hospital. In addition, when urinary tract isolates were compared with respiratory tract isolates, significant differences were found in the predominate types. The typing of these isolates by bacteriocin production was supported by serotype and antibiotype findings. The results suggest that this simple system may be a useful tool in a general hospital.

Bacteriocins

Nosocomial infection due to Pseudomonas pseudomallei: two cases and an epidemiologic study.

Pseudomonas pseudomallei was recovered from urine specimens of two patients who acquired the organism after they were admitted to a hospital in a region in which it is endemic. Both patients were diabetic and both had urethral catheters passed while they were hospitalized. samples of soil taken from the hospital grounds yielded an isolate of P. pseudomallei that was identical biochemically and by antibiogram to the two isolates recovered from the urine specimens of the two patients. The two patients stayed in wards located in separate hospital blocks, which were geographically distinct but connected by a walkway. The relevant clinical histories of the two patients and the epidemiologic and microbiologic characteristics of the P. pseudomallei isolates were studied. Sera from both patients showed a significant rise in titers of antibody specific for P. pseudomallei. These two patients are considered to represent the first reported cases of hospital-acquired infection due to P. pseudomallei.

Aged

Pseudomonas species bacteremia caused by contaminated normal human serum albumin.

In May and June 1973, 11 patients on the surgical service at the University of Maryland Hospital had bacteremia caused by Pseudomonas species. Seven of the isolates recovered from blood cultures had the same antibiogram (sensitive only to chloramphenicol and tetracycline). Ten of the 11 patients were given 25% normal serum albumin (human) shortly before the onset of symptoms. In contrast, only two of seven patients with bacteremia due to Psuedomonas aeruginosa in May and June (P =0.013) and only nine of 20 patients located in surgical special care units during these months (P =0.014) were given this product. When cultured, the albumin in one of 54 previously unopened vials from the implicated lot yielded Pseudomonas cepacia sensitive only to chloramphenicol, tetracycline, and nalidixic acid. Subsequent investigation showed that five more patients in four other hospitals had symptoms of bacteremia shortly after the infusion of different lots of albumin from the same manufacturer, and in four cases P. cepacia was cultured from the suspect albumin. Since sterility testing by manufacturers may not detect low-frequency contamination, surveillance of nosocomial infections, investigation of unusual disease clusters, and prompt reporting of suspect reactions are essential in the control of such outbreaks.

Chloramphenicol

Relationship between antibiotic resistance, the production of "virulence factors", and virulence for experimental animals in Staphylococcus aureus.

Variants that had lost some of their antibiotic-resistance determinants were selected from a multiple-antibiotic-resistant strain of Staphylococcus aureus. When tested by subcutaneous injection into guinea-pigs, and measured as the number of cocci needed to produce a skin lesion of an arbitrarily chosen diameter, the virulence of strains fell progressively with loss of resistance determinants. When the staphylococci were injected intracutaneously into mice, however, the results were less easy to interpret, but loss of resistance appeared to be associated with a reduction of the slope of the dose-response line. There was no association between the antibiogram of the strains and their production of certain enzymes and haemolysins.

Animals

Physical characterization of ten R plasmids obtained from an outbreak of nosocomial Klebsiella pneumoniae infections.

Gentamicin resistance in Klebsiella pneumoniae involved in an outbreak at the Minneapolis Veterans Administration Hospital was due to a transmissible R plasmid. In addition to gentamicin, this plasmid conferred resistance to tobramycin, kanamycin, ampicillin, carbenicillin, cephalothin, chloramphenicol, and sulfathiazole. R plasmids which transferred this complex antibiogram were identified in several clinical isolates, including four different serotypes of K. pneumoniae, Escherichia coli, Enterobacter cloacae, and Proteus morganii. The covalently closed circular form of all R plasmids isolated had a sedimentation coefficient of 76S to 77S, corresponding to a molecular weight of 58 x 10(6). The possibility that a single R plasmid was responsible for the dissemination of multiple drug resistance among all of these different clinical strains was examined by characterizing the plasmids by using EcoRI restriction endonuclease. The same 15 fragments were obtained from each of the 10 plasmids analyzed. Their molecular weights ranged from 4 x 10(5) to 11 x 10(6). Thus, we conclude that each of the 10 plasmids present in the various clinical strains isolated from the hospital over a 7-month period originated from a common source and that R plasmid transfer was important in their spread.

Anti-Bacterial Agents

Ureolytic Escherichia coli of human origin: serological, epidemiological, and genetic analysis.

Forty-five strains of ureolytic Escherichia coli of human origin, isolated in the United States between 1956 and 1977, were characterized by geographical distribution, site of infection, serotype, resistance to antibiotics, and biochemical reactions. All strains were studied for the ability to generate clones of nonureolytic E. coli (segregants), and a subset of these were selected for plasmid analysis and a variety of bacterial matings. There did not appear to be a common geographical distribution, serotype, antibiogram, or other aberrant biochemical reactions other than the hydrolysis of urea among these strains. The predominance of urinary tract isolates (46.7% total) may reflect a relationship between urea hydrolysis and pathogenesis at this site. Ten of the strains (22.2%) did segregate nonureolytic E. coli colonies, and all possessed at least one common plasmid species with a molecular weight of about 65 X 10(6). Only strain 1138-77 serotype O16:H6 conjugally transfered the ability to hydrolyze urea, ferment sucrose, and resist inhibition by sulfadiazide simultaneously. The resulting, recombination-deficient E. coli K-12 tranconjugant was found to possess a plasmid with a molecular weight of about 80 X 10(6) to 90 X 10(6).

Anti-Bacterial Agents

Serotypes and antibiotic susceptibilities of Pseudomonas aeruginosa isolates from single sputa of cystic fibrosis patients.

A phenotypic characterization of Pseudomonas aeruginosa from single sputum samples of 21 typical cystic fibrosis patients indicated a high frequency of heterogeneity among isolates on the basis of differences in antibiotic resistance, colony morphology, pigmentation, and serotype. Two or more isolates with different but stable susceptibilities to carbenicillin, gentamycin, streptomycin, tetracycline, chloramphenicol, and sulfamethoxazole plus trimethoprim were detected in 38% of the sputa. Differences generally were independent of the mucoid state of the strain. O-antigen group determination with the Difco typing set showed that two or more serologically distinct strains were present in 10/21 sputum specimens. Nonmucoid derivatives of mucoid isolates almost always retained both the antibiotic susceptibilities and serotype of their parent strain. These data suggest that cystic fibrosis patients may be cocolonized/coinfected by different strains of P. aeruginosa more frequently than generally believed. Alternatively, phenotypically distinct strains from a single patient might arise as phenotypic dissociants from a single infecting strain. Because of the frequency and multiplicity of phenotypically distinct P. aeruginosa isolates which we obtained from our cystic fibrosis patients, it is important to select multiple isolates from sputum cultures for antimicrobial susceptibility testing so as to assess adequately the susceptibility of this organism to antibiotic therapy in cystic fibrosis. We recommend that several colonies of each distinguishable colony type of P. aeruginosa be pooled for the antibiogram.

Adolescent

Improving the performance of anaerobic bacteriology in a hospital laboratory.

A comparison was made of the performance of a newly established anaerobic section of a clinical laboratory and the routine diagnostic section in terms of isolation and identification of anaerobic bacteria. Both sections attempted to isolate obligate anaerobes from the same clinical specimens which were not transported in anaerobic containers. Anaerobic and diagnostic sections isolated anaerobes from 35% and 6% respectively of clinical specimens. The use of antibiograms greatly improved the identification of anaerobic organisms.

Anaerobiosis

New aid to management of septicaemia: rapid direct antibiotic susceptibility testing.

A rapid and reliable method of performing direct antibiotic susceptibility tests on positive blood cultures has been developed. A result is now available five hours after laboratory confirmation of septicaemia. An evaluation involving 55 blood-culture isolates demonstrated an over-all correlation of 97.8% when results obtained by the rapid direct Autobac l method were compared to those obtained by definitive testing procedures. The method is particularly applicable to isolates of Staphyloccus aureus, Pseudomonas aeruginosa, and the Enterobacteriaceae. It is especially significant because of the recent emergence of multiple antibiotic resistance amongst hospital strains of these bacteria with many isolates showing resistance to antibiotics frequently used in the empirical treatment of septicaemia. The rapid availability of a reliable antibiogram is important in allowing early appropriate chemotherapy and, hence, in the reduction of septicaemia-associated morbidity and mortality, and the length of stay in hospital.

Anti-Bacterial Agents

[Changes in time of the microbial flora in bronchopulmonary infections].

The authors carried out a study on 100 cases with broncho-pulmonary infections in two different periods: 1963--1964 and 1973--1974. Changes in the microbial flora were investigated, as well as the sensitivity of germs to antibiotics. An increase was noted in the number of chronic bronchitis and a decrease in the number of pneumonia cases. In the microbial flora there was a constant proportion of staphylococcus, streptococcus and coli strains. The proportion of micrococci decreased with time and pneumococci practically disappeared, being replaced by klebsiella germs. Sensitivity to penicilin remained almost identical while that to chloramphenicol decreased significantly, as well as sensitivity to tetracycline and neomycine. The practical conclusion is that in some cases the application of penicilin treatment, before the results of the antibiogram are available appears to be justified.

Anti-Bacterial Agents

[Clinical, radiological and bacteriological study of pulmonary tuberculosis with bacteria showing drug resistance].

The authors have investigated two groups of patients of young age suffering from tuberculosis with germs showing primary resistance to chemotherapeutic agents (61 cases), and with germs displaying sensitivity to these agents (64 cases). The following conclusions have been reached: tuberculosis with germs showing primary drug resistance did not display onset modalities, clinically and radiologically, that differed significantly from other types of tuberculosis; sputum conversion is more slow in patients with resistant germs than in those with sensitive germs in the first two months of treatment, but following application of the treatment according to the data resulting from the antibiogram, this differences quickly disappeared. The presence of a smaller number of complete recoveries and of a surplus of doubtful recoveries can be explained in the same way in this group of patients: the final results are similar in both groups of patients, evidencing that the treatment of pulmonary tuberculosis due to germs showing parimary drug resistance does not give rise to particular problems.

Adolescent