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Laboratory support for the diagnosis and treatment of sexually transmitted diseases has traditionally been within a patient-based diagnostic paradigm. Tests and interpretative criteria developed within this paradigm may not be appropriate for laboratories supporting population-based STD control programs. As STD control strategies expand to population-based levels, the present patient-based laboratory models will have to be modified to meet these increased demands.

We present an analysis of the complete nucleotide sequence of pLS88, a naturally occurring, 4.8-kb broad-host-range plasmid isolated from Haemophilus ducreyiand encoding resistance to sulfonamides, streptomycin, and kanamycin. Sequence analysis of the genes encoding sulfonamide and streptomycin resistance revealed homology to the RSF1010 sulIIand strAgenes. The sulII-strAintergenic region of pLS88 has a 38-bp deletion identical to that of the RSF1010-like plasmid pHD8.1, isolated from Actinobacillus pleuropneumoniae. The kanamycin resistance gene shows strong homology to Tn903, but lacks the inverted repeats of the transposon. No other genes have been identified. The region downstream of the kanamycin resistance gene shows homology to the RSF1010 oriVregion; however, this region is not essential to plasmid replication. The oriof pLS88 is contained within a 1060-bp region and does not appear to contain structures typical of plasmid origins. This region is flanked by DNA showing strong homology to regions both upstream and downstream of the Haemophilus influenzaeROB-1 β-lactamase gene. Because of the small size of the origin. pLS88 appears to resemble the structure of narrow-host-range plasmids, but replicates, via an as yet unidentified mechanism, as a broad-host-range plasmid.

Intravenous cefazolin and cefoxitin were compared in a prospective randomized trial in infections where the suspected pathogen was expected to be susceptible to both antibiotics. In the cefazolin group (12 patients) the diagnosis was pneumonia in 4, including 2 with pneumococcal bacteremia, soft tissue infection in 5, Staphylococcus aureusbacteremia in 1, acute pyelonephritis in 1, and disseminated gonococcal infection in 1. In the cefoxitin group (10 patients) the diagnosis was pneumonia in 4, including 2 with pneumococcal bacteremia, soft tissue infection in 4, acute pyelonephritis in 1, and disseminated gonococcal infection in 1. In the cefazolin group receiving an evaluable course of therapy, a good clinical response was seen in 10 of 11 patients, and a bacteriological response was seen in 5 of 7. Cefazolin failed to eradicate S. aureusbacteremia in 1 patient and S. aureusin a skin ulcer of another patient. All 10 cefoxitin patients had good clinical and bacteriological responses, but in 1 patient S. aureuscolonization of a postoperative wound recurred after discontinuation of the drug. Side effects in both groups included skin rash, phlebitis, and elevation of the serum alkaline phosphatase. Both cefoxitin and cefazolin appeared effective in infections caused by susceptible aerobic pathogens with the possible exception of S. aureus, although all 11 strains of S. aureusisolated in this study were susceptible in vitro to both antibiotics. Cefoxitin appeared to be equivalent to cefazolin in efficacy and occurrence of side effects.

Three of 19 strains of Haemophilus ducreyi, isolated during a recent outbreak of chancroid, were found to produce β-lactamase and to harbor a 6.0 × 106-dalton plasmid. Escherichia colitransformed with this plasmid acquired β-lactamase-mediated resistance to ampicillin. The guanine-plus-cytosine content of the plasmid was found to be 41 mol%. Restriction endonuclease digestion studies suggest that a relatively large portion of the Tn1translocon is carried by this plasmid. Whereas this plasmid could not be transferred to H. influenzaeby mating on membrane filters, a strain of H. ducreyiwas able to receive and donate a 30 × 106-dalton ampicillin resistance plasmid from H. influenzae. The ability of H. ducreyito receive and donate conjugative plasmids may result in the appearance of multiply resistant strains.

During the 19-month period from June 1976 to December 1977, 90 patients became colonized or infected with gentamicin-resistant Staphylococcus aureus(GRS). Of 63 adults, 56 had hospital-acquired GRS, whereas only 9 of 27 children had hospital-acquired GRS (P< 0.001). The other 7 adults and 18 children had GRS present on admission. More than half of those who acquired GRS in the hospital had received prior aminoglycoside therapy. Attack rates were higher in adults than in children and significantly higher on the plastic surgery service than on any other adult service. Phage typing revealed a single-strain outbreak on the plastic surgery ward involving 11 patients, whereas other isolates were of several phage types. Community-acquired GRS occurred more frequently in rural native communities (P< 0.02) and may be related to the use of topical gentamicin. Of 17 native children, 10 were from the same area but there was no common phage type. Agar dilution minimal inhibitory concentration (MIC) testing confirmed that all isolates were gentamicin resistant (MIC ≥ 8 μg/ml) and almost all were tobramycin resistant (MIC ≥ 8 μg/ml). Although the MIC distribution between gentamicin disk-susceptible and -resistant strains was significantly different, MIC's for 90% of gentamicin disk-resistant strains were ≤8 μg of amikacin per ml, and MIC's for 92% of the strains were ≤4 μg of netilmicin per ml.

A broth microdilution method was used to measure the minimal inhibitory concentrations (MICs) of the antibiotics most often recommended for treatment of listeriosis. The MICs of ampicillin, penicillin, erythromycin, and tetracycline for 175 strains of Listeria monocytogeneswere below the approximate MIC breakpoint for susceptible strains as recommended by the National Committee on Clinical Laboratory Standards. Inhibition diameters for 125 strains were measured by the standardized disk method (National Committee on Clinical Laboratory Standards) and compared with the appropriate MIC values. By both methods, strains were susceptible to the above four antibiotics, except for three strains, which were intermediate in susceptibility to penicillin by the disk method. Since the minimal bactericidal concentrations for ampicillin and penicillin significantly exceeded the MICs for these antibiotics, 45 strains were evaluated with ampicillin (5 μg/ml) and gentamicin (1 μg/ml) to compare the synergistic bactericidal effect of the two used in combination and singly. An increased kill of 100-fold was observed with the antibiotics combined in 19 strains after 4 to 6 h and in 40 strains after 24 h. A comparison of results with microdilution in Trypticase soy broth and agar dilution in Mueller-Hinton agar revealed that MICs for gentamicin, kanamycin, and streptomycin were strongly influenced by the media used. The MICs were consistently lower in Mueller-Hinton agar.

OBJECTIVE: To determine the demographic, clinical and microbiological characteristics of a representative Canadian obstetrical population.DESIGN: A one-year cohort study of all maternity patients who were followed to delivery, using detailed patient questionnaires containing more than 60 demographic and clinical variables, and three microbiological evaluations during gestation - first trimester, 26 to 30 weeks, and labour and delivery. Outcome measurements included birth weight and gestational age.SETTING: Labour and delivery suites of all office obstetrical practices affiliated with a single hospital.POPULATION STUDIED: A consecutive sample of pregnant women in the study practices during one year were eligible for enrolment; 2237 consecutive patients were approached for consent, 2047 enrolled and 1811 completed the study through delivery.RESULTS: The average patient was white, married and 29 years of age. Slightly more than half of the patients had postsecondary education, but 10% fell below the national poverty line for income. Frequency of factors linked to adverse pregnancy outcomes included cigarette smoking (19%), alcohol ingestion (18%), previously having had a premature infant (7%), and maternal diabetes (2%). Overall prevalence of genital microbes variously implicated in prematurity was 37% for ureaplasma, 11% for group B streptococcus and 4% for Mycoplasma hominis. Prevalence of bacterial vaginosis was 14%. The median gestational age for the cohort was 39 weeks, with 7% of infants born less than 37 weeks' gestation. Mean birth weight was 3415 g.CONCLUSIONS: The present clinical cohort represents demographic and medical characteristics of the Canadian obstetrical population. The birth outcomes are consistent with national data. This database provides valuable information about a general obstetrical population that is managed by a universal health care system.