Detection of Mycoplasma genitalium in women with laparoscopically diagnosed acute salpingitis.

OBJECTIVES: Mycoplasma genitalium has been associated with cervicitis, endometritis, and tubal factor infertility. Because the ability of this bacterium to ascend and infect the fallopian tube remains undefined, we performed an investigation to determine the prevalence of M genitalium in fallopian tube, endometrial, and cervical specimens from women laparoscopically diagnosed with acute salpingitis in Nairobi, Kenya. METHODS: Women presenting with pelvic inflammatory disease were laparoscopically diagnosed with salpingitis. Infection with M genitalium in genital specimens was determined by polymerase chain reaction (PCR). RESULTS: Of 123 subjects with acute salpingitis, M genitalium was detected by PCR in the cervix and/or endometrium in nine (7%) participants, and in a single fallopian tube specimen. In addition, those infected with M genitalium were more often HIV infected than women not infected by M genitalium (seven of nine (78%) v 42 of 114 (37%), p<0.03). CONCLUSIONS: M genitalium is able to ascend into the fallopian tube, but its association with tubal pathology requires further investigation.

An outbreak of Legionella micdadei pneumonia in transplant patients: evaluation, molecular epidemiology, and control.

PURPOSE: To describe a nosocomial outbreak of Legionella micdadei pneumonia in transplant patients and to characterize the source of the outbreak and the control measures utilized. SUBJECTS AND METHODS: We performed retrospective Legionella micdadei serologic testing to enhance case finding in transplant patients with pneumonia that lacked a documented microbial etiology, as well as prospective environmental surveillance of water sites and testing for Legionella in clinical specimens. RESULTS: During a 3-month period, 12 cases of Legionella micdadei pneumonia were identified either by culture or serologic testing among 38 renal and cardiac transplant patients. Legionella micdadei isolates from hot water sources were found by pulsed-field gel electrophoresis to have a DNA banding pattern that was identical to the isolates from the first 3 culture-positive cases and from 2 cases that occurred 16 months later. CONCLUSIONS: Hospitals caring for organ transplant recipients and other immunosuppressed patients must be aware of the possibility of environmental sources of outbreaks of Legionella infection. A first-line screen with the Legionella urine antigen test will identify Legionella pneumophila serogroup 1. However, specific cultures in outbreak situations should be considered to identify other Legionella pneumophila serotypes and the nonpneumophila Legionella species.

Use of the National Committee for Clinical Laboratory Standards guidelines for disk diffusion susceptibility testing in New York state laboratories.

Accurate antimicrobial susceptibility testing is vital for patient care and surveillance of emerging antimicrobial resistance. The National Committee for Clinical Laboratory Standards (NCCLS) outlines generally agreed upon guidelines for reliable and reproducible results. In January 1997 we surveyed 320 laboratories participating in the New York State Clinical Evaluation Program for General Bacteriology proficiency testing. Our survey addressed compliance with NCCLS susceptibility testing guidelines for bacterial species designated a problem (Staphylococcus aureus and Enterococcus species) or fastidious (Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria gonorrhoeae) organism. Specifically, we assessed compliance with guidelines for inoculum preparation, medium choice, number of disks per plate, and incubation conditions for disk diffusion tests. We also included length of incubation for S. aureus and Enterococcus species. We found overall compliance with the five characteristics listed above in 80 of 153 responding laboratories (50.6%) for S. aureus and 72 of 151 (47.7%) laboratories for Enterococcus species. The most common problem was an incubation time shortened to less than 24 h. Overall compliance with the first four characteristics was reported by 92 of 221 (41.6%) laboratories for S. pneumoniae, 49 of 163 (30.1%) laboratories for H. influenzae, and 11 of 77 (14.3%) laboratories for N. gonorrhoeae. Laboratories varied from NCCLS guidelines by placing an excess number of disks per plate. Laboratories also reported using alternative media for Enterococcus species, N. gonorrhoeae, and H. influenzae. This study demonstrates a need for education among clinical laboratories to increase compliance with NCCLS guidelines.

Phenotypic and ribosomal RNA characterization of Arcobacter species isolated from porcine aborted fetuses.

Aerotolerant organisms resembling Campylobacter, now designated as Arcobacter, have been described from aborted farm animals and from cases of human enteritis worldwide. The goals of this study were 1) to attempt to recover Arcobacter spp. from cases of porcine abortion, 2) to characterize these isolates by phenotype and ribotype, and 3) to compare the usefulness of ribotype and phenotype patterns for identifying Arcobacter butzleri and the DNA hybridization groups 1A and 1B of A. cryaerophilus. Isolates of Arcobacter spp. from North Carolina and Iowa were recovered from porcine tissues. In Iowa, Arcobacter spp. were recovered from 43% (13/30) of porcine abortion cases evaluated. Isolations were made from placenta (44%), kidney (44%), and stomach contents (12%), which were the only tissues examined. The most reliable biochemical tests for A. butzleri included growth in 1% glycine and in 1.5% NaCl, weak catalase activity, and resistance to cadmium chloride. Arcobacter cryaerophilus strains were characterized by strong catalase activity and sensitivity to cadmium chloride. The DNA hybridization groups 1A and 1B of A. cryaerophilus could not be distinguished by biochemical tests. This represents the first description of A. cryaerophilus DNA group 1A in animals within the United States.

Genotypic and phenotypic characterization of Helicobacter cinaedi and Helicobacter fennelliae strains isolated from humans and animals.

By DNA-DNA hybridization, we classified 26 human strains, 4 dog and cat strains, and 4 hamster strains putatively identified as Helicobacter cinaedi as well as 2 human strains and 2 animal strains of Helicobacter fennelliae. All but one human strain belonged to the same hybridization group as the type strain of H. cinaedi. The animal strains also appeared to belong to this hybridization group. Both human strains of H. fennelliae were shown to be H. fennelliae by DNA-DNA hybridization, but both animal strains were less than 15% related to the type strain. All strains were also characterized by plasmid profiles and ribotyping. Plasmids were found in 23% of the human strains, 100% of the hamster strains, and 33% of the dog and cat strains. Human strains were essentially identical by ribotyping, but were clearly differentiated from the hamster and dog and cat strains. Some strains may be difficult to culture on primary isolation; we found that our strains grew well on anaerobic CDC agar, brucella agar, and tryptic soy agar II. Our H. cinaedi and H. fennelliae strains differed from those previously described because some were resistant to cephalothin: some H. cinaedi strains were also resistant to nalidixic acid. All isolates were also characterized by antimicrobial susceptibility testing. We found that human strains of H. cinaedi were more resistant to clindamycin and erythromycin than were animal isolates; 19% of the human strains were resistant to ciprofloxacin. Therefore, we recommend that antimicrobial susceptibility results be obtained before initiating therapy for H. cinaedi and H. fennelliae infections.

Ribosomal RNA patterns identify additional strains of Campylobacter jejuni and C. coli among isolates serotyped by heat-stable and heat-labile antigens.

Heat-stable (HS, O-antigen) and heat-labile (HL) serotyping are the most common methods used to type Campylobacter jejuni and C. coli for epidemiologic purposes. In this study, we conducted RRNA analysis to differentiate strains of C. jejuni and C. coli that had been serotyped by use of the passive hemagglutination (heat-stable) and slide agglutination (heat-labile) methods. Ribotyping of isolates within HS and HL serotypes revealed further discrimination of strains. Four ribotypes were identified by Pvu II and Pst I digests of eight HS serotype-34 isolates. Ribotyping also differentiated strains within HL serotypes. Ribotyping also was conducted on 10 representative isolates of C. jejuni and C. coli isolated from an infant macaque. The eight ribotypes confirmed previous results of serotyping and other phenotypic analyses, which indicated that the infant was repeatedly reinfected with different strains of C. jejuni and C. coli. Results of the study indicated that ribotyping is a sensitive molecular marker for distinguishing strains of C. jejuni and C. coli. Furthermore, some isolates with similar ribotype patterns had variability in their HS and HL serotypes.

Helicobacter cinaedi-associated bacteremia and cellulitis in immunocompromised patients.

OBJECTIVE: To define the clinical spectrum of illness associated with Helicobacter cinaedi infection in the United States and to determine associated epidemiologic risk factors and optimal laboratory methods for recovery of H. cinaedi. DESIGN: A retrospective epidemiologic study of 23 patients with H. cinaedi-associated illness. PATIENTS: 23 patients with H. cinaedi infection identified between January 1982 and August 1990. Most isolates (22 of 23) were from blood; one was from stool. RESULTS: Ages ranged from 24 to 84 years (mean, 44 years). Eighty-three percent of patients were men; 17% were women. Clinical and laboratory data were obtained from 21 patients. Eighteen patients were febrile (15 required hospitalization); cellulitis was reported in 9 patients. Sixty percent were immunocompromised; 45% were reported to be seropositive for human immunodeficiency virus (HIV). For bacteremic patients, positive blood cultures were detected by a slightly elevated growth index in an automated blood culture system; many hospital laboratories had difficulty isolating the organism. CONCLUSIONS: Helicobacter cinaedi appears to cause recurrent cellulitis with fever and bacteremia in immunocompromised hosts. Blood cultures from immunocompromised patients with these symptoms may need special handling to isolate H. cinaedi.

Evaluation of ribotyping techniques as applied to Arcobacter, Campylobacter and Helicobacter.

Restriction fragment length polymorphisms of ribosomal DNA (ribotyping) of many bacterial species has been useful for both epidemiologic subtyping and species identification. However, the use of ribotyping has been confined to major research and reference laboratories due to two factors: (a) the procedure must be carefully optimized for each organism one wishes to investigate and (b) most currently available protocols use hazardous chemicals or radioisotopes. The purpose of this study is to suggest an overall scheme that a clinical or research microbiologist could apply to ribotyping of any organism. In general, we recommend using a guanidium extraction method for DNA extraction, careful optimization of restriction conditions, and hybridization with non-radioactive digoxigenin-labelled probes; these procedures do not use hazardous chemicals or radioisotopes.

Pathogens and predictors of fatal septicemia associated with human immunodeficiency virus infection in Ivory Coast, west Africa.

In East Africa, bacteremia is more common in hospitalized human immunodeficiency virus (HIV) type 1-positive than -negative patients. In 1991, blood cultures and clinical and laboratory data were obtained from 319 patients in Ivory Coast, where both HIV-1 and -2 infections occur. Forty-three bacterial, 10 mycobacterial, and 8 fungal pathogens were isolated from blood of 54 patients (17%). Pathogens isolated significantly (P < or = .05) more frequently from HIV-positive than -negative patients were nonmycobacterial bacteria, particularly Salmonella enteritidis; mycobacteria, particularly Mycobacterium tuberculosis-Mycobacterium bovis; and yeast or fungus. HIV-1 or -2 positivity was associated with a 3-fold increased risk for septicemia (P < .02). HIV-positive patients with fever or with lymphocyte counts < 1000 were more likely to be septicemic than those without these characteristics. Mortality increased significantly with HIV positivity (40% vs. 14%, P < .001) and, among HIV-positive patients, with having pathogens isolated from blood (63% vs. 33%, P < .001).

Arcobacter (Campylobacter) butzleri-associated diarrheal illness in a nonhuman primate population.

After DNA hybridization identified an isolate from an ill rhesus macaque (Macaca mulatta) as Arcobacter (Campylobacter) butzleri, we initiated a study to determine whether A. butzleri was associated with diarrheal disease in nonhuman primates at the Yerkes Primate Research Center. By using Campy-CVA medium incubated at 35 degrees C, 15 A. butzleri isolates were obtained from 14 macaques; 7 macaques were coinfected with Campylobacter coli and Campylobacter jejuni. A. butzleri was not isolated from normal feces, despite the fact that feces from 76 macaques were cultured at necropsy. Histologic evaluation of colonic specimens from three macaques from which A. butzleri had been isolated showed mild to moderately severe chronic, active colitis. Ribotype analysis of the 15 A. butzleri isolates revealed nine different strains; these data suggest that A. butzleri may be endemic in this primate population and that a point source of infection is unlikely. This is the first report of the presence of A. butzleri in juvenile and adult macaques with diarrhea, and it may present an opportunity to study the pathogenesis of this organism, which appears to be associated with persistent diarrhea in humans.

Uncommon Campylobacter species in infant Macaca nemestrina monkeys housed in a nursery.

Studies were conducted to characterize 18 isolates of Campylobacter spp. that could not be identified as either Campylobacter jejuni or C. coli. The isolates were cultured from specimens from 13 of 18 infant nonhuman primates during a prospective epidemiologic study reported previously. Phenotypic tests, DNA hybridization, and analysis of DNA coding for rRNA identified the isolates as C. butzleri (seven isolates), C. hyointestinalis (seven isolates), and C. fetus subsp. fetus or C. fetus subsp. fetus-like organisms (four isolates). Ribotype and polyacrylamide gel electrophoresis patterns indicated that there was heterogeneity among the isolates of C. butzleri and C. fetus subsp. fetus-like organisms.

In vitro susceptibilities of aerotolerant Campylobacter isolates to 22 antimicrobial agents.

We evaluated the in vitro activities of 22 antimicrobial agents against 78 human and animal isolates belonging to two aerotolerant Campylobacter species, C. cryaerophila and C. butzleri, using a broth microdilution technique. An additional 10 antimicrobial agents were included at concentrations found in selective Campylobacter media. Strains of C. cryaerophila belonged to two DNA hybridization groups: DNA hybridization group 1A, which includes the type strain of C. cryaerophila, and DNA hybridization group 1B. The aminoglycosides, fluoroquinolones, and one tetracycline (minocycline) demonstrated the most activity against all DNA hybridization groups (C. cryaerophila DNA groups 1A and 1B and C. butzleri). Most isolates were resistant to cephalosporin antibiotics, with the exception of cefotaxime, and were variably susceptible to trimethoprim-sulfamethoxazole. C. cryaerophila DNA hybridization group 1A isolates were generally susceptible to the tetracyclines, chloramphenicol, nalidixic acid, azithromycin, erythromycin, and roxithromycin and moderately susceptible to clindamycin, trimethoprim-sulfamethoxazole, ampicillin, and ampicillin-sulbactam. The MICs of tetracyclines were higher for C. butzleri and C. cryaerophila DNA hybridization group 1B isolates than for C. cryaerophila DNA hybridization group 1A isolates, but most strains were still susceptible to doxycycline and tetracycline; all isolates were susceptible to minocycline. C. butzleri and C. cryaerophila DNA hybridization group 1B isolates were generally resistant to the macrolide antibiotics (including erythromycin), chloramphenicol, clindamycin, nalidixic acid, ampicillin, and trimethoprim-sulfamethoxazole. Differences in antimicrobial susceptibility between aerotolerant Campylobacter species and more common Campylobacter species, e.g., C. jejuni, suggest that different treatment strategies may be necessary. Strains of all three DNA hybridization groups of aerotolerant Campylobacter isolates were susceptible to colistin, polymyxin B, and rifampin at concentrations commonly used in selective media. These results suggest that primary isolation methods for Campylobacter species may need to be modified to include aerotolerant Campylobacter strains.

Epidemiologic typing of Staphylococcus aureus by DNA restriction fragment length polymorphisms of rRNA genes: elucidation of the clonal nature of a group of bacteriophage-nontypeable, ciprofloxacin-resistant, methicillin-susceptible S. aureus isolates.

Analysis of DNA restriction fragment length polymorphisms of rRNA genes (ribotyping) was employed to assist in the epidemiologic investigation of the emergence and spread of ciprofloxacin-resistant Staphylococcus aureus at the Atlanta VA Medical Center because many isolates of interest were nontypeable by phages and harbored few plasmids useful as strain markers. Chromosomal DNAs of selected S. aureus isolates were digested initially with 20 different restriction enzymes. EcoRI appeared to give the best discrimination of hybridization banding patterns (ribotypes) and was used with all study isolates. Overall, 15 different ribotypes were seen among the 50 S. aureus isolates studied (7 ribotypes among 13 methicillin-susceptible S. aureus [MSSA] isolates and 9 ribotypes among 37 methicillin-resistant S. aureus [MRSA] isolates). Seven of eight ciprofloxacin-resistant MSSA (CR-MSSA) patient isolates had identical antibiograms, were nontypeable by phages, and had a single 22-MDa plasmid. Six of these seven CR-MSSA isolates had an identical ribotype pattern. Ribotyping distinguished this CR-MSSA strain or clone from MRSA and other MSSA isolates, including nontypeable isolates that contained a 22-MDa plasmid. Five ciprofloxacin-susceptible MSSA isolates studied had five ribotypes; one pattern was identical to the CR-MSSA clone. Twenty-three CR-MRSA isolates recovered from the Atlanta VA Medical Center had four different ribotypes. Ribotyping proved to be a useful molecular epidemiologic tool in the study of S. aureus because it differentiated isolates which were indistinguishable by more traditional methods. In addition, this technique demonstrated that at our institution, ciprofloxacin resistance emerged in multiple strains of MRSA, as opposed to primarily a single strain or clone of MSSA.

Molecular epidemiology of Yersinia enterocolitica O:3 infections: use of chromosomal DNA restriction fragment length polymorphisms of rRNA genes.

Yersinia enterocolitica is a major enteric pathogen associated with a wide variety of clinical and immunologic manifestations, including transfusion-associated disease, from which there is a high mortality. Although previously rare in the United States, in the late 1980s Y. enterocolitica O:3 emerged as the predominant serotype in the United States, as it has been in Canada, Europe, and Japan. Epidemiologic investigation of this serogroup has been hampered by the limited availability of a phage typing system and the fact that Y. enterocolitica harbors few plasmids that are useful as strain markers. We therefore analyzed whole-cell DNA restriction fragment length polymorphisms of rRNA genes (ribotyping) to study a group of 61 (50 human, 11 porcine) Y. enterocolitica isolates. Initially, 20 different restriction enzymes were used: NciI appeared to give the best discrimination of hybridization banding patterns (ribotypes) within Y. enterocolitica O:3. Ribotyping distinguished seven clones among all the study isolates and four clones within Y. enterocolitica O:3 (53 isolates studied) and clearly differentiated Y. enterocolitica O:3 from Y. enterocolitica O:9; O:1,2,3; O:20; and O:5,27. Most serogroup O:3 isolates belonged to two clones, ribotypes I and II, including 23 of 24 Y. enterocolitica O:3 (13 human, 11 porcine chitterling) isolates recovered from a recent outbreak of Y. enterocolitica in children in Atlanta associated with chitterling preparation and 3 transfusion-associated O:3 isolates from the United States. Y. enterocolitica O:3 ribotypes I and II were also isolated in Japan, ribotypes II and IV were isolated in Belgium, and ribotype I was isolated in Canada. Ribotype patterns I and II corresponded to phage types 9b and 8, respectively. Ribotyping was able to distinguish individual strains of Y. enterocolitica O:3, but suggests that a limited number of clones have disseminated within the United States and globally. The finding of identical ribotype patterns in chitterling and human specimens from the Atlanta outbreak supports epidemiologic evidence that swine were the source of infection and major reservoir for Y. enterocolitica O:3.

Restriction fragment length polymorphisms in rRNA operons for subtyping Shigella sonnei.

Shigella sonnei is the most frequent cause of shigellosis in the United States. Epidemiologic studies of this organism have been hampered by the lack of adequate typing procedures. Ribosomal DNA analysis (ribotyping), a method which analyzes restriction fragment length polymorphisms in the chromosomal genes that encode rRNA, has recently been shown to be useful for microbial species identification and subtyping. To determine whether ribotyping could be used to distinguish between S. sonnei isolates, we conducted Southern hybridization studies on isolates from 16 different geographic locations and from four recent outbreaks. S. sonnei genomic DNA fragments generated following digestion with SalI hybridized with Escherichia coli 16S and 23S rRNAs to produce six distinct patterns; strains with patterns 1, 2, and 3 were each further subdivided into two additional patterns by using PvuII, SmaI, and SstI, respectively. Epidemiologically related strains had identical patterns. Ribotyping appears to be a useful tool for epidemiologic studies of shigellosis caused by S. sonnei.

Restriction fragment length polymorphisms in the ribosomal genes for species identification and subtyping of aerotolerant Campylobacter species.

Whole-cell chromosomal digests of 84 strains of aerotolerant Campylobacter (AC) were examined by using PvuII restriction fragment length polymorphisms of rRNA genes followed by hybridization with Escherichia coli 16S and 23S rRNA (ribotyping). The AC strains belonged to Campylobacter cryaerophila (n = 13) and a newly defined species, "C. butzleri" (n = 64). Strains of C. cryaerophila belonged to two hybridization groups: DNA group 1A (including the type strain of C. cryaerophila) and DNA group 1B (J. A. Kiehlbauch, D. J. Brenner, M. A. Nicholson, C. N. Baker, C. M. Patton, A. G. Steigerwalt, and I. K. Wachsmuth, J. Clin. Microbiol. 29:376-385, 1991). Six AC strains not classified as C. cryaerophila or "C. butzleri" were also included. All 35 sporadic human and animal isolates of "C. butzleri" sent to the Centers for Disease Control for identification showed different ribotype patterns. However, most "C. butzleri" strains contained common bands at approximately 3.0, 6.2, 12.0, and 15.0 kb; the 3.0-kb band was present in all but four strains. An additional 23 strains of "C. butzleri," isolated as part of special studies, contained the 3.0-kb band. Thus, on the basis of visual identification of the 3.0-kb band, 94% of available strains were correctly identified as "C. butzleri." Ribotyping demonstrated that C. cryaerophila strains (DNA groups 1A and 1B) were different from C. butzleri strains. All C. cryaerophila strains demonstrated a common ribosomal DNA restriction fragment of 3.2 kb; DNA group 1B strains contained an additional common band at 2.6 kb. Ribotyping patterns of AC species were easily distinguished from patterns of other Campylobacter, Helicobacter, and Wolinella species.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of group 2 aerotolerant Campylobacter species from Thai children with diarrhea.

Campylobacter species were isolated from 93 (15%) of 631 Thai children with diarrhea using the membrane filter technique on nonselective blood agar incubated at 37 degrees C. Campylobacter jejuni was isolated from 62 (10%), Campylobacter coli from 14 (2%), and atypical campylobacters from 17 (3%). The 17 atypical strains were first characterized biochemically and by dot blot DNA hybridization. Catalase-negative strains also were characterized by DNA hybridization and ribotype pattern. One strain was a catalase-negative "Campylobacter upsaliensis" and another was a nitrate-negative Campylobacter jejuni doylei. Fifteen isolates were aerotolerant strains most closely resembling Campylobacter cryaerophila or "C. upsaliensis" by dot hybridization. These aerotolerant strains, designated group 2 ("Campylobacter butzleri"), had ribotypes distinct from C. cryaerophila and have previously been shown to be related by DNA hybridization at the species level to the group 2 aerotolerant Campylobacter type strain (D2686). Group 2 aerotolerant Campylobacter were the atypical Campylobacter species most frequently isolated from Thai children with diarrhea.

Evaluation of 10 methods to distinguish epidemic-associated Campylobacter strains.

We compared four phenotypic and six genotypic methods for distinguishing Campylobacter jejuni strains from animals and humans involved in four epidemics. Based on a comparison with epidemiologic data, the methods that correctly identified all strains in three milkborne outbreaks and one waterborne outbreak were heat-stable and heat-labile serotyping; multilocus enzyme electrophoresis (MEE); DNA restriction endonuclease analysis with BglII, XhoI, PvuII, or PstI; and Southern blot and hybridization of PvuII- and PstI-digested DNA with Escherichia coli 16S and 23S rRNA (ribotyping). Biotyping, phage typing, plasmid analysis, and probing of BglII and XhoI DNA digests with C. jejuni 16S rRNA genes failed to correctly separate one or more strains. MEE, restriction endonuclease analysis, and ribotyping were the most sensitive methods and identified nine types among the 22 strains. These methods were also capable of further distinguishing strains within the same serotype. Data from MEE were also analyzed to calculate genetic relatedness among strains. Serotyping was the most discriminating phenotypic method, with eight and seven types distinguished by the heat-stable and heat-labile methods, respectively. MEE and ribotyping had several advantages over the other methods because they measure relatively stable and significant chromosomal differences and are applicable to other species and genera. These methods, however, are complex and not easily quantified; they are currently limited to specialized laboratories. When antisera are available, serotyping appears to be an effective and more practical approach to the identification of epidemic-related strains.

Molecular epidemiologic techniques in analysis of epidemic and endemic Shigella dysenteriae type 1 strains.

During 1988 the number of Shigella dysenteriae type 1 infections reported in the United States increased fivefold. To determine if recent isolates from Mexico were related to those that caused epidemics of dysentery worldwide, Southern hybridization analysis was done with Shiga toxin and ribosomal RNA gene probes. Western hemisphere and Eastern Hemisphere strains differed by the size of a single EcoRI fragment carrying the Shiga toxin genes. Three ribosomal DNA (rDNA) patterns were observed, which correlated with the strain's continental origin for 81 of 83 isolates tested. Together the Shiga toxin and rDNA probe results indicated that recent Mexican isolates were chromosomally similar to earlier Central American isolates and distinct from Asian and African strains. This suggests there has been no significant exchange of organisms between continents in recent decades and that the 1988 outbreak in Mexico was caused by strains present in Central America since at least 1962.

Campylobacter butzleri sp. nov. isolated from humans and animals with diarrheal illness.

Seventy-eight aerotolerant Campylobacter isolates were characterized phenotypically and by DNA hybridization (hydroxyapatite method at 50 and 65 degrees C). Two DNA relatedness groups were found. (i) Sixty-four strains belonged to aerotolerant Campylobacter DNA hybridization group 2. These organisms were isolated from humans, primarily with diarrheal illness, and animals on several continents. Strains were aerotolerant at 30 and 36 degrees C and catalase negative or weakly catalase positive, grew in media containing glycine and on MacConkey agar, were susceptible to nalidixic acid, and were resistant to cephalothin. The name Campylobacter butzleri sp. nov. is proposed for this group. (ii) DNA hybridization group 1 consisted of the type strain of Campylobacter cryaerophila and 13 additional strains isolated from 10 animals outside the United States and from three humans within the United States. This group was genetically diverse; five strains were closely related to the type strain of C. cryaerophila (DNA hybridization group 1A), and eight strains were more closely related to one another (DNA hybridization group 1B). Strains in DNA hybridization group 1B were phenotypically diverse, with two of eight strains resembling C. cryaerophila. The seven strains from DNA hybridization groups 1A and 1B which resembled C. cryaerophila and the C. cryaerophila type strain were aerotolerant only at 30 degrees C and catalase positive, did not grow in glycine or on MacConkey agar, were generally susceptible to nalidixic acid, and were resistant to cephalothin. The remaining six strains of DNA hybridization group 1B phenotypically resembled C. butzleri; however, they were generally catalase positive and susceptible to nalidixic acid and cephalothin. DNA hybridization group 1B is not designated as a separate species at this time since it cannot, with certainty, be separated genetically from C. cryaerophila or phenotypically from C. butzleri.