I. Kaye Wachsmuth

Aeromonas Intestinal Infections in the United States

To evaluate the clinical and epidemiologic aspects of aeromonas enteritis, we studied the cases of 34 persons nationwide from whom Aeromonas hydrophila had been isolated in large numbers from stool in 1984. Compared with 68 control subjects, these patients were more likely to have drunk untreated water, usually from private wells (odds ratio = 20.9; p less than 0.01). Eighteen of the isolates belonged to a single DNA-relatedness group of the eight described for Aeromonas species, but no clear correlation between illnesses in patients and any tested genotypic or phenotypic characteristic of recovered organisms was found. Gastrointestinal complaints tended to be chronic in infected adults and acute and severe in children. Nine patients had become ill after taking antimicrobial agents to which recovered Aeromonas species were resistant; 5 persons took antimicrobials to which their Aeromonas strains were susceptible and had alleviation or resolution of their gastrointestinal symptoms. These findings indicate that at least some Aeromonas strains are enteropathogenic for the normal host and that these organisms are acquired by drinking untreated water.

Helicobacter cinaedi-associated bacteremia and cellulitis in immunocompromised patients.

Although initially associated with gastroenteritis in homosexual men [1-4], Helicobacter cinaedi was also isolated from asymptomatic [1, 3, 4] and bacteremic [5-7] homosexual men. These organisms are also associated with illness outside the homosexual population; Vandamme and colleagues [8] described three bacteremic patients and two children with fecal isolates. A retrospective epidemiologic study was done to define the clinical spectrum of illness and epidemiologic risk factors associated with H. cinaedi infection in the United States. We also looked at laboratory methods used to recover H. cinaedi. Patients were identified from H. cinaedi isolates received at the Centers for Disease Control and Prevention (CDC) between January 1982 and August 1990. Case Report A 32-year-old man developed red-copper-colored blotches on his left ankle 6 weeks before admission; these spread to his right ankle, up the legs, to the arms, chest, and face. At the time of onset, the patient reported fever but no gastrointestinal symptoms. He was given cephalexin, 500 mg four times a day, for sinusitis; he noted that the rash worsened. Three weeks before he was hospitalized, the patient received oral ciprofloxacin for 2 weeks; the rash resolved. The rash reappeared, and the patient presented with chills and fever (a temperature of 39.4 C), nausea, arthralgias, and the maculopapular skin eruption. At admission, blood cultures were done, and he was treated empirically with cefotaxime and tobramycin. His leukocyte count at admission was 7.8 109/L, with a differential of 73 segmented neutrophils, 18 lymphocytes, and 8 monocytes. Platelets were noted as adequate. His medical history included seropositivity to human immunodeficiency virus (HIV) and transient immune thrombocytopenia (platelet count, 35 109/L); a platelet count of 192 109/L was noted 4 months before admission. The patient stated that the rash first appeared approximately 24 hours after using a whirlpool spa. He did not recall eating raw dairy products, eggs, seafood, or other meats. The patient reported recreational exposure to sea and lake water but did not recall drinking untreated surface water. He traveled within the United States and Europe and reported having homosexual contact in the month before onset of illness. After positive blood cultures were identified, the patient was given empiric ciprofloxacin, 250 mg twice a day for 14 days. The cellulitis cleared, and the patient was discharged. The cellulitis recurred 11 weeks later; the patient was rehospitalized and treated with cefotaxime and ciprofloxacin. Two blood cultures obtained at the time of the second admission again yielded H. cinaedi. The patients leukocyte count was now 6.8 109/L. The rash again cleared. The patient reported three additional recurrences. After zidovudine therapy was initiated, no further recurrence of cellulitis was noted. Results Patients with H. cinaedi infection ranged in age from 24 to 84 years (mean, 44 years); 83% were men. Patients resided in 14 different states (1, Arizona; 1, Colorado; 6, California; 1, Georgia; 1, Illinois; 1, Kansas; 1, Michigan; 2, Missouri; 2, Nebraska; 1, New Mexico; 2, Ohio; 1, Tennessee; 3, Texas; and 1, Wisconsin). Isolation of the organism occurred from 1982 to 1990 (2 in 1982, 2 in 1984, 3 in 1985, 2 in 1986, 3 in 1987, 5 in 1988, 2 in 1989, and 4 in 1990) without seasonal clustering. No one died of this infection. Appendix Table 2 shows the clinical features of 21 patients (information on 5 patients was provided after a review of medical records by the local health department). Most patients had a sudden onset of fever (range, 37.8 to 40.0 C; mean, 38.9 C). Nine bacteremic patients (41%) had both fever and a distinctive cellulitis that was described as atypical, appearing red-brown or copper without noticeable warmth. Underlying immunosuppressive illness was reported for 14 of 21 patients; other underlying conditions, previously associated with systemic Campylobacter infections, were reported infrequently. Appendix Table 1. Characteristics of Patients with Helicobacter cinaedi Infection Information regarding potential exposures in the 4 weeks before onset was available for 15 patients. The most frequent exposures of interest were contact with or consumption of untreated surface water (three patients) and contact with animals (nine patients). Four patients reported out-of-state travel in the 4 weeks before onset: one to Mexico, one to Europe, one to Hawaii, and one to Colorado on a camping trip. All blood isolates of H. cinaedi were recovered after detection by an automated blood culture instrument; 21 of 22 isolates were recovered from the aerobic bottle; 1 isolate was also detected in the anaerobic bottle, and 1 isolate was detected solely in the anaerobic bottle. Most isolates were detected after 5 or more days of incubation by slightly elevated growth indexes (generally between 40 and 80; mean, 57). In general, organisms were not seen on initial Gram staining of the blood culture material but were detected by dark-field or acridine orange staining. Only 9 (41%) of 22 blood isolates were recovered by the primary hospital laboratory; all other isolates were cultured by reference laboratories. In contrast to Campylobacter jejuni, H. cinaedi is not susceptible to erythromycin in vitro (Table 1). In general, tetracyclines and aminoglycosides seem most effective in vitro. Table 1. Antimicrobial Susceptibility of 22 Strains of Helicobacter cinaedi Associated with Human Clinical Illness* Discussion Our findings indicate that H. cinaedi is associated with a new syndrome, consisting of fever, bacteremia, and recurrent cellulitis. Most patients had signs of systemic infection, including leukocytosis, and were often thrombocytopenic. Although H. cinaedi isolates were recovered primarily from immunocompromised patients and from those with chronic alcoholism, we also documented infections in three nonimmunocompromised men and in women (both with and without HIV infection). Thus, the patient group affected by H. cinaedi is larger than originally thought. We did not find distinctive risk factors for acquisition of H. cinaedi by interviewing a subset of patients; however, our review may have been hampered by the time between illness and interview. Our data suggest that contact with animals or exposure to untreated surface water are possible sources of infection. Currently, H. cinaedi has been isolated only from humans and gerbils [9], but no patients reported having contact with gerbils. Many antimicrobial therapies were used to treat patients with H. cinaedi infection. From our series, it appears that treatment with a penicillin, tetracycline, or aminoglycoside may be more effective than treatment with cephalosporins, erythromycin, or ciprofloxacin. In addition, prolonged therapies (2 to 6 weeks) may be more effective than short-term therapies ( 10 days; data not shown). The apparent effectiveness of tetracycline or aminoglycosides agrees with in vitro antimicrobial susceptibility data. Although two reports suggest treating H. cinaedi with ciprofloxacin [10, 11], infection reappeared in two patients treated with this agent, and our in vitro data indicate that their isolates and two additional isolates were resistant (minimal inhibitory concentration > 8 g/mL). This finding suggests that ciprofloxacin should be used with caution. However, we were unable to obtain isolates before and after treatment, so we cannot determine whether resistance to ciprofloxacin developed as a result of therapy or existed before therapy was begun. Our susceptibility data agree with previously published data [12], with one exception: Fifty percent of our strains were resistant to cephalothin. Laboratory diagnosis of H. cinaedi infection is unlikely using blood culture procedures that rely on visual detection because it grows slowly and the growth is difficult to see; all blood isolates were recovered using an automated system. We therefore suggest examining blood cultures that develop slightly elevated growth indexes in an automated system using acridine orange staining, Giemsa staining, or dark-field examination before discarding a specimen as negative. In general, specialized culture techniques and prolonged incubation (7 days) must be used to isolate these organisms: Growth is enhanced by the presence of hydrogen gas in a microaerobic atmosphere and incubation on rich, nonselective media (blood or chocolate agar) at 37 C. Techniques that would probably isolate H. cinaedi from stool specimens include filtration onto nonselective media or inoculation of appropriate selective media and incubation at 37 C in a hydrogen-containing atmosphere for 3 to 4 days. A retrospective review of patients with H. cinaedi infection suggests a syndrome of recurrent febrile bacteremia, which may be accompanied by cellulitis in immunocompromised patients. Helicobacter cinaedi infection should be considered in an immunocompromised or thrombocytopenic patient with fever and cellulitis. Specific antimicrobial therapy may be needed to prevent recurrence. The slow growth and fastidious culture requirements of this organism indicate that it may be currently under-recognized.

Non-O Group 1 Vibrio cholerae Gastroenteritis in the United States: Clinical, Epidemiologic, and Laboratory Characteristics of Sporadic Cases

Fourteen sporadic cases of non-O group 1 Vibrio cholerae gastroenteritis were identified through isolates submitted to the Centers for Disease Control in 1979. All the ill persons had diarrhea, 13 had abdominal cramps, 10 had fever, and three had vomiting; in four cases the patients had bloody diarrhea. Five patients had traveled outside the United States before they became ill. All nine domestically acquired cases were in patients who had eaten raw oysters within 72 hours of onset of illness; in a matched case-control study, illness in these patients was strongly associated with eating raw seafood (p less than 0.0001). Only one isolate produced heat-labile toxin by a Y-1 adrenal cell assay. All isolates were susceptible to tetracycline, chloramphenicol, kanamycin, and cephalothin.

Enzyme-linked immunosorbent assays for detecting antibodies to Shiga-like toxin I, Shiga-like toxin II, andEscherichia coli O157:H7 lipopolysaccharide in human serum

Shiga-like toxin-producingEscherichia coli O157:H7 are important causes of bloody diarrhea and hemolytic uremic syndrome. To facilitate the epidemiologic study of these organisms, we developed enzyme-linked immunosorbent assays (ELISAs) for antibodies to Shiga-like toxin I (SLT I), Shiga-like toxin II (SLT II), andE. coli O157 lipopolysaccharide (LPS). We tested serum samples from 83 patients in two outbreaks ofE. coli O157:H7 diarrhea and from 66 well persons. Forty-three patients (52%) had at least one serum sample positive for anti-O157 LPS antibodies; among 26 culture-confirmed patients, 24 (92%) had at least one positive serum sample. Two (3%) of 66 control sera had positive anti-O157 LPS titers. ELISA results for SLT I and II were compared with those of HeLa cell cytotoxicity neutralization assays on both patient and control sera. Neutralization assays detected anti-SLT I antibodies in at least one serum sample from each of 17 (20%) patients and 7 (10.6%) controls, while 16 (19%) patients and 7 controls had positive titers by anti-SLT I ELISA. Although all serum samples, including control sera, showed nonspecific neutralization of SLT II, no antibody titers to SLT II were detected by either neutralization or ELISA. These results indicate that ELISAs for SLT I and SLT II antibodies are comparable to HeLa cell cytotoxicity neutralization assays. Both the ELISAs and neutralization assays are insensitive in detecting infected patients. However, the ELISA for antibodies toE. coli O157 LPS is both sensitive and specific, and may be more useful than assays for antitoxic antibodies in detecting persons withE. coli O157:H7 infection.

PSEUDOMONAS AERUGINOSA PERITONITIS ASSOCIATED WITH CONTAMINATED POLOXAMER-IODINE SOLUTION

Pseudomonas aeruginosa was responsible for four cases of peritonitis and one of wound infection at the catheter site in outpatients on chronic peritoneal dialysis. All organisms had the same antimicrobial susceptibilities and serotype. Culture surveys showed that a strain of Ps. aeruginosa of identical susceptibility pattern, plasmid profile, and serotype was present in bottles of a poloxamer-iodine solution unopened until the time of culture. Both poloxamer-iodine and povidone-iodine solutions have now been shown to be vulnerable to bacterial contamination. Guidelines for their production and use must be reassessed to take this possibility into account.

Genetic diversity and relationships of Campylobacter species and subspecies.

The existence of tremendous genetic diversity within Campylobacter species has been well documented. To analyse the population structure of Campylobacter and determine whether or not a clonal population structure could be detected, genetic diversity was assessed within the genus Campylobacter by multilocus enzyme electrophoresis of 156 isolates representing 11 species and subspecies from disparate sources. Analyses of electrophoretic mobility of 11 enzymes revealed 109 electrophoretic types (ETs) and 118 ETs when nulls were counted as an allele. Cluster analysis placed most ETs into groups that correlated with species. With nulls counted as alleles, 19 ETs were identified among 33 isolates of Campylobacter lari, 31 ETs among 34 isolates of Campylobacter coli and 43 ETs among 59 isolates of Campylobacter jejuni subsp. jejuni. Nine C. jejuni subsp. jejuni isolates, confirmed as this species by DNA-DNA hybridization, were hippuricase-negative. Reported linkage analyses were done with nulls ignored. Scores for mean genetic diversity (H) were high for the total population (mean H = 0.802). Allelic mismatch-frequency distributions and allelic tracing pointed to possible genetic exchange between subpopulations. C. lari appears to be a panmictic species. Some pairs of species shared multiple alleles of certain loci, possibly indicating genetic exchange between species. Of the species tested, C. jejuni appeared to be the most active in sharing alleles. However, there was evidence of variable involvement in recombination by the different loci. Linkage analysis of loci in C. jejuni and C. coli revealed a clonal framework, with some loci tightly linked to each other. The loci appeared to occur in linkage groups or islands. Campylobacter may have a clonal framework with other portions of the genome involved in frequent recombination. Population genetic structure among Campylobacter is inconclusive and it remains to be seen if pathogenic types can be identified.

Two new Escherichia coli O groups: O172 from »Shiga‐like» toxin II‐producing strains (EHEC) and O173 from enteroinvasive E. coli (EIEC)

Two Escherichia coli strains were established as antigenic test strains for two new O groups, O172 and O173. The O172 strain (EHEC) which produces »Shiga‐like« toxin II (verocytotoxin 2) was isolated from a case of haemorrhagic colitis while the enteroinvasive O173 strain (EIEC) originated from a child with diarrhoea.

DNA probe analysis of diarrhoeagenic Escherichia coli: detection of EAF-positive isolates of traditional enteropathogenic E. coli serotypes among Bangladeshi paediatric diarrhoea patients.

Escherichia coli isolates from all surveillance patients less than or equal to 20 months of age seen for diarrhoea at the Dhaka Clinical Treatment Facility of the International Centre for Diarrhoeal Disease Research, Bangladesh between March 1 and August 31, 1988, were collected and hybridized with DNA probes to assess the potential importance of diarrhoeagenic E. coli among paediatric patients in Bangladesh. Of 396 patients evaluated, 18% were infected with enteropathogenic E. coli (EPEC) adherence factor (EAF)-positive E. coli, 23% were infected with enterotoxigenic E. coli (ETEC), 9% were infected with Shiga-like toxin-positive E. coli, and 13% were infected with diffuse adhesiveness-positive E. coli. None were infected with enteroinvasive E. coli. Ten percent of patients were colonized with more than one type of potential diarrhoeagenic E. coli. The majority of EAF-positive isolates were of traditional EPEC O:H serotypes. Although this was not a case-control study, the large number of EPEC and ETEC, which are recognized enteric pathogens, suggests these organisms are important causes of diarrhoeal diseases in this pediatric population.

Escherichia Coli O157: H7, a Cause of Hemorrhagic Colitis and Hemolytic Uremic Syndrome

During the investigation of two outbreaks of bloody diarrhea in Oregon and Michigan in 1982. Escherirhia c d i 0 157 : H7 was epidemiologically implicated as the etiologic agent of the newly described disease, hemorrhagic colitis [50]. The then rare serotype was present in stool cultures of ill but not well individuals, and no other pathogens were detected during an extensive search for bacterial, viral, and parasitic agents [66]. Although it was clearly implicated as the cause of the two outbreaks. E. c d i 0157: H7 did not possess any of the known E. coli virulence traits and its

Heat-stable enterotoxigenic Escherichia coli and necrotizing enterocolitis: lack of an association.

During an outbreak of diarrhea in a special care nursery caused by heat-stable enterotoxigenic Escherichia coli (serotype 078:H11:K80), nine (4.3%) of the 205 infants in the nursery developed necrotizing enterocolitis. Cases of necrotizing enterocolitis were not significantly more common in infants colonized or infected with these organisms; heat-stable enterotoxigenic E. coli was isolated from 5(56%) of nine cases of necrotizing ecterocolitis and from 27(38%) of the 71 infants without necrotizing enterocolitis who were also cultured. Our findings suggest that caution should be taken in implicating enterotoxigenic E. coli as a cause of necrotizing enterocolitis.