Objectives: To examine susceptibilities of Bacillus anthracis and related species to 24 antimicrobials using and concurrently comparing two methods. cereus, three were resistant to clindamycin and one was resistant to clarithromycin and clindamycin. One B. mycoides was intermediately resistant to quinupristin/dalfopristin and meropenem and one was clindamycin-resistant. All B. pseudomycoides were clindamycin-resistant with one quinupristin/ dalfopristin-resistant. Two B. mycoides/pseudomycoides were intermediately resistant to quinupristin/ dalfopristin and clindamycin and a third was intermediately resistant to clindamycin alone. All isolates were susceptible to chloramphenicol, ciprofloxacin, gatifloxacin, gentamicin, levofloxacin, linezolid, moxifloxacin, rifampicin, streptomycin, tetracycline, tigecycline and vancomycin. MethodsConclusions: This paper expands the list of therapeutic or prophylactic antimicrobials potentially effective against B. cereus group isolates using two testing methods that produced comparable results.

The mefE gene codes for a membrane bound efflux protein, which confers resistance to macrolides, and has been identified in Streptococcus pneumoniae. A variety of gram-positive organisms were examined. Twenty-six isolates of S. pneumoniae carried mefE and were resistant to erythromycin (MIC of 2-16 mg/L). Two additional isolates of Emr S. pneumoniae carried both ermB and mefE(MIC of 16-128 mg/L). One Micrococcus luteus, one Corynebacterium jeikeium, three Corynebacterium spp., two viridans streptococci and seven Enterocccus spp. also carried mef genes. It was possible to move the mef gene from all 11 S. pneumoniae tested to susceptible S. pneumoniae and/or Enterococcus faecalis recipients. The addition of DNase (1 g/L) did not affect the gene transfer. It was also possible to move the mef gene from donor Enterococcus spp., viridans streptococci, M. luteus, C. jeikeium and Corynebacterium spp. to E. faecalis recipients. Transconjugant isolates were resistant to erythromycin (MIC = 16 mg/L). Hybridization with a labelled mef oligonucleotide probe against Southern blots and bacterial dot blots confirmed the presence of the mef genes. This is the first time that a mobile mef gene has been identified in four different genera, from three distinct geographical locations.

Bacillus anthracis, the cause of anthrax, has been used as a bioterrorism agent. Because the isolation and identification of B. anthracis by culture can take days, first response units (hazardous materials [HAZMAT], firemen, police, and hospital personnel) desire a quick and easy test that can be done in the field to detect possible B. anthracis contamination (1, 4). To our knowledge, there are no peer-reviewed published data on commercially available kits that could guide first responders in their search for such rapid detection methods. We tested three lateral flow immunoassay kits that are designed to test for B. anthracis at 10 4 to 10 5 spores per sample: (i) Anthrax BioThreat Alert (BTA) test strips (Tetracore, Gaithersburg, Md.), (ii) BioWarfare Agent Detection Devices (BADD) (Osborne Scientific, Lakeside, Ariz.), and (iii) Anthrax (spore) SMART II (New Horizons Diagnostics, Columbia, Md.). These tests require little technician time and training, and results are available within 15 min.This study was conducted at the Florida Department of Health Laboratory in Tampa, Fla., and employed B. anthracis Pasteur (CDC BC 3132) and Bacillus cereus and Bacillus thuringiensis from our culture collection. Spores were added to the buffer provided by the manufacturer to achieve 10 2 to 10 6 (B. anthracis) or 10 6 (B. cereus and B. thuringiensis) spores per sample. The range of 10 2 to 10 5 for B. anthracis spores was chosen in order to include the manufacturer's claims of sensitivity. We also tested 10 6 spores in order to achieve a clear, easy-to-read positive result. Because one of the kits did not consistently detect spores at the upper limit (10 5 ), we tested 10 6 spores more than once to see if detection was consistent. All tests were performed according to the manufacturer's instructions and were allowed to proceed for 15 min, although the positive results were recognized within 5 min. Spore concentrations were verified by viable plate counts on Trypticase soy agar (Remel, Lenexa, Kans.) in duplicate.

We screened 615 gram-positive isolates from 150 healthy children for the presence of the erm(A), erm(B), erm(C), erm(F), and mef(A) genes. The mef(A) genes were found in 20 (9%) of the macrolide-resistant isolates, including Enterococcus spp., Staphylococcus spp., and Streptococcus spp. Sixteen of the 19 gram-positive isolates tested carried the other seven open reading frames (ORFs) described in Tn1207.1, a genetic element carrying mef(A) recently described in Streptococcus pneumoniae. The three Staphylococcus spp. did not carry orf1 to orf3. A gram-negative Acinetobacter junii isolate also carried the other seven ORFs described in Tn1207.1. A Staphylococcus aureus isolate, a Streptococcus intermedius isolate, a Streptococcus sp. isolate, and an Enterococcus sp. isolate had their mef(A) genes completely sequenced and showed 100% identity at the DNA and amino acid levels with the mef(A) gene from S. pneumoniae.The normal flora is thought to act as a reservoir for many bacterial antimicrobial resistance genes, including those that confer macrolide resistance (12). In 1999, there were 20 different rRNA methylases described in the literature, which coded for macrolide-lincosamide-streptogramin B resistance, and 24 efflux and inactivating genes, which coded for one or more of the macrolide-lincosamide-streptogramin B complex of antimicrobials (14). However, relatively few of these 44 genes are found in the majority of macrolide-resistant grampositive bacteria (1, 2, 13). Resistance to macrolides in the absence of resistance to lincosamides and streptogramin B has been associated with the presence of the mef(A) gene in Streptococcus pneumoniae (17,18). The mef(A) gene has become more common than erm(B) in macrolide-resistant S. pneumoniae isolates from North America (7,15). We have shown that the mef(A) gene is present in macrolide-resistant oral Streptococcus spp. and Enterococcus spp. isolated in Seattle, Wash., and Micrococcus luteus and Corynebacterium spp. isolated in the United Kingdom (5), as well as in gram-negative Acinetobacter junii and Neisseria gonorrhoeae (6). All of these species have been able to conjugally transfer the mef(A) genes to a variety of recipients. Recently, two genetic elements, Tn1207.1 (16) and mega (3), have been characterized from macrolide-resistant S. pneumoniae. A highly related gene has been sequenced from Streptococcus pyogenes, while related genes have been identified in Lancefield group C and G streptococci from Finland (4).In this study, we examined randomly selected gram-positive isolates collected from healthy Portuguese children for the presence of the common macrolide resistance genes, erm(A), erm(B), erm(C), erm(F), and mef(A). Representative mef(A)genes were sequenced, and the presence of the other seven open reading frames (ORFs) from Tn1207.1 was investigated.(The data in Table 2 were presented in part at the First Annual Symposium on Resistant Gram-Positive Infections in San Antonio, Tex., 3 to 5 Dec. 2000.) MATERIALS AND METHODSBacterial isolates. A total of 615 rand...

The mef gene, originally described for gram-positive organisms and coding for an efflux pump, has been identified in clinical isolates of Acinetobacter junii and Neisseria gonorrhoeae. These strains could transfer the mef gene at frequencies ranging from 10 ؊6 to 10 ؊9 into one or more of the following recipients: gram-negative Moraxella catarrhalis, Neisseria perflava/sicca and Neisseria mucosa and gram-positive Enterococcus faecalis. Three Streptococcus pneumoniae strains could transfer the mef gene into Eikenella corrodens, Haemophilus influenzae, Kingella denitrificans, M. catarrhalis, Neisseria meningitidis, N. perflava/sicca, and N. mucosa at similar frequencies. The mef gene can thus be transferred to and expressed in a variety of gram-negative recipients.The mef gene encodes a membrane-bound efflux protein and confers resistance to macrolides but not to lincosamides or streptogramin B (24, 25). From geographically diverse areas, two gene variants with 90% nucleotide sequence identity, mefA and mefE, have been identified in gram-positive organisms, including Streptococcus pneumoniae, Streptococcus pyogenes, Corynebacterium spp., Enterococcus spp., Micrococcus luteus, and viridans group streptococci (2,5,9,20,(23)(24)(25). Both genes have now been combined as mef(A) (20).Recently, we have shown that both Neisseria gonorrhoeae and oral commensal Neisseria spp. carry known rRNA methylase genes (20). However, we have also identified several of these Neisseria spp. and oral gram-negative isolates that were macrolide resistant yet did not carry Erm determinants (ErmA, -B, -C, or -F) (21). We selected a gram-negative Acinetobacter junii strain and screened two groups of N. gonorrhoeae in order to determine if the mef gene was present. Because we have shown that the mef gene can be transferred by conjugation in various gram-positive genera, we also wanted to determine the mobility of the mef gene in these gram-negative isolates as well as the ability of gram-positive donors to move the mef gene to gram-negative species (9).(This work was presented, in part, at the 39th Interscience Conference on Antimicrobial Agents and Chemotherapy, 23 to 27 September 1999, San Francisco, Calif.) MATERIALS AND METHODSBacteria. Erythromycin-resistant (Ery r ) Acinetobacter junii strain 329 was isolated from the oral gumline of a child in Portugal (Table 1). The organism was identified by D. Stroman (Alcon Laboratories, Inc., Fort Worth, Tex.) by sequencing the 16S rRNA. Sixteen N. gonorrhoeae isolates with variable susceptibilities to erythromycin (MIC ϭ 0.25 to 4 g/ml) were collected from urethral specimens from adults in Seattle, Wash., and identified by the Neisseria Reference Laboratory at the University of Washington (Table 1). Thirteen N. gonorrhoeae isolates carrying the tetM 25.2-MDa plasmid were collected in Seattle and the eastern United States during 1983 through 1986 and have been previously described (7). Of the three Ery r S. pneumoniae strains carrying the mef gene, two (n011 and 970146) were isolated in Washington...