Identification of a putative infC-rpmI-rplT operon flanked by long inverted repeats in Mycoplasma fermentans (incognitus strain)

A specific 1542-bp DNA fragment was amplified from Mycoplasma fermentans (incognitus strain) using a unique 23-nucleotide (nt) synthetic deoxyribonucleotide (oligo) (5'-TCCAAAAAGTCCGGAATTTGGGG) as the primer pair in the polymerase chain reaction (PCR). The 23-nt sequence is part of the 29-bp terminal inverted repeat (IR) which forms the left potential stem-and-loop (s&l) structure of the previously identified M. fermentans insertion-sequence(IS)-like genetic element [Hu et al., Gene 93 (1990) 67-72]. The amplified DNA was cloned and sequenced. A pair of 27-bp IR containing the 23-nt synthetic oligo was identified at both termini. Between the IR, there are four potential open reading frames (ORFs) which are arranged adjacent to each other in the order, ORF-1, ORF-2, ORF-3 and ORF-4, with parts of ORF-1 and ORF-2 overlapping. The deduced amino acid (aa) sequences of ORF-2, ORF-3 and ORF-4 are 34 to 60% identical to the translation initiation factor IF3 (encoded by the infC gene), ribosomal proteins L35 (rpmI gene) and L20 (rplT gene) of Escherichia coli and Bacillus stearothermophilus, respectively. In bacteria, the infC-rpmI-rplT genes are organized to function as an operon. There are multiple sites with promoter-like sequences identified upstream from the putative infC gene in the mycoplasma closely resembling the gene arrangement in the bacterial operon. All three genes of ORF-2, ORF-3 and ORF-4 are preceded individually by a strong appropriately spaced (7 and 10 bp) putative Shine-Dalgarno sequence (5'-AAGGA).(ABSTRACT TRUNCATED AT 250 WORDS)

Detection and isolation of Mycoplasma fermentans from urine of human immunodeficiency virus type 1-infected patients

Mycoplasma fermentans (incognitus strain) has been linked with acquired immunodeficiency syndrome-associated nephropathy. Ten (23%) of 43 urine sediment specimens from 40 human immunodeficiency virus (HIV)-positive patients at different stages of acquired immunodeficiency syndrome disease tested positive in the polymerase chain reaction using a primer pair found in the insertion sequences specific to M fermentans. Mycoplasma fermentans was isolated from two HIV-positive patients' urine sediment specimens and on a repeated basis from one. All three culture-positive urine sediment specimens tested positive in the polymerase chain reaction. Fifty urine sediment specimens from age-matched HIV-negative healthy controls tested negative for M fermentans by polymerase chain reaction. Mycoplasma fermentans was not isolated from any of the control urine sediment specimens. Our results show a high prevalence of M fermentans in urine sediment specimens from HIV-positive patients but not from urine sediment specimens of HIV-negative healthy controls.

Acquired immunodeficiency syndrome-like illness associated with systemic Mycoplasma fermentans infection in a human immunodeficiency virus-negative homosexual man

A 35-year-old homosexual man developed a composite nodal Kaposi's sarcoma and peripheral T-cell lymphoma that were associated with a peripheral blood CD4-positive lymphocyte count of only 43/mm3. The patient subsequently developed Pneumocystis carinii pneumonitis and eventually died due to disseminated Cryptococcus neoformans. Numerous premortem tests for the presence of human immunodeficiency virus (HIV) types 1 and 2 were negative by the enzyme-linked immunosorbent assay, Western blot, viral isolation, and polymerase chain reaction techniques. Postmortem evaluations for HIV-1, HIV-2, human T-cell lymphotropic virus (HTLV)-I, and HTLV-II also were negative by polymerase chain reaction, immunofluorescence assays, and viral isolation. A systemic infection by Mycoplasma fermentans, however, was documented by immunohistochemistry and polymerase chain reaction in premortem and postmortem tissues. This recently recognized human pathogen has produced systemic infections in patients with the acquired immunodeficiency syndrome (AIDS) and in previously healthy non-AIDS patients who characteristically have a fulminant flu-like illness. Additionally, M fermentans has enhanced the cytopathic effect of HIV in in vitro studies and has produced fatal wasting illnesses with terminal lymphopenia in inoculated adult silvered leaf monkeys. This report is the first description of an association between M fermentans infection and an AIDS-like illness in an HIV-negative individual. The etiology of the severe immunosuppression in this patient and the associated role of M fermentans remain to be determined by further investigations.

[The inhibitory action of 6-azacytidine on Mollicutes and its proposed mechanism]

6-Azacytidine (6-AC) is shown to have an inhibitory effect on the Mollicutes of the different systematic position. The growth of type strains of Mollicutes (Acholeplasma laidlawii PG-8, Mycoplasma pneumoniae FH and M. fermentans PG-18) completely ceased in the nutrient medium at concentration of the above substance in it within the range of 125-250 micrograms/ml. 50% inhibiting concentration of 6-AC equaled: for M. fermentans PG-8: 23.43 micrograms/ml; M. pneumoniae FN: 46.8 micrograms/ml; Acholeplasma laidlawii PG-8: 62.5 micrograms/ml. 6-AC concentration 5 micrograms/ml decreased the process of DNA-dependent DNA synthesis in the in vitro system more than by 60%. 6-AC exerted less effect on the DNA-dependent RNA synthesis in the in vitro system: at different concentrations of 6-AC (up to 400 micrograms/ml) RNA synthesis decreased only by 20%. Translation on ribosomes of Mollicutes in the in vitro system completely ceased at 6-AC concentration 100 micrograms/ml. The results obtained indicate that for 6-AC in cells of Mollicutes and, possibly, for other microorganisms there are two targets: ribosomes and DNA-dependent DNA-polymerase. Total effect of blocking of the translation and replication processes by 6-azacytidine causes death of Mollicutes. Since 6-AC has no harmful effect on the human cells, it can be used as an efficient method for treatment of respiratory and urogenital diseases induced by Mollicutes.

Mycoplasma fermentans in individuals seropositive and seronegative for HIV-1

Mycoplasmas have been suggested as a co-factor to explain various puzzling features of infection by human immunodeficiency virus 1 (HIV-1). We sought Mycoplasma fermentans by means of a semi-nested polymerase chain reaction (PCR) in samples of peripheral-blood mononuclear cells (PBMC), throat swabs, and urine samples from 117 HIV-seropositive patients (of whom 114 were homosexual men). M fermentans was detected in 12 (10%) PBMC samples, 15 (23%) of 65 throat samples, and 4 (8%) of 55 urine samples from the seropositive subjects. The organism was detected in similar proportions among 73 HIV-seronegative patients recruited from a sexually transmitted diseases clinic (9%, 20%, and 6%, respectively); again, most of the men (40 of 50) in this group were homosexual. We found no association between infection by the mycoplasma and stage of disease, CD4 count, or HIV-1 load. These findings do not, however, eliminate the possibility that the mycoplasmal infection could affect the speed of disease progression.

Association of mycoplasma and human immunodeficiency virus infection: detection of amplified Mycoplasma fermentans DNA in blood

A cross-sectional study was undertaken to determine the prevalence of Mycoplasma fermentans infection in patients with human immunodeficiency virus (HIV) infection using polymerase chain reaction methodology. Targeted M. fermentans DNA sequences could be amplified from the DNA extracted from the blood of 6 (11%) of 55 HIV-seropositive patients but from none of 26 HIV-seronegative subjects at low risk for HIV infection (P = .17). There was no correlation between M. fermentans infection and HIV clinical stage. There was a nonsignificant trend toward an association between M. fermentans infection and a history of syphilis. Infection with M. fermentans may occur more commonly in HIV-infected patients; however, a role as a copathogen or opportunistic infection was not established in this study.

Selective detection of Mycoplasma fermentans by polymerase chain reaction and by using a nucleotide sequence within the insertion sequence-like element

A new assay using the polymerase chain reaction to amplify a 206-nucleotide specific gene sequence within the insertion sequence-like element of Mycoplasma fermentans has been developed. The unique insertion sequence-like element exists in multiple copies in the M. fermentans genome. The assay selectively amplifies DNA from all strains of M. fermentans tested. In contrast, DNA from other species of human and nonhuman mycoplasmas, common tissue culture-contaminating mycoplasmas, and bacteria, as well as human, monkey, and mouse tissues do not produce the amplified DNA products specific for M. fermentans.