Robert E. Weaver

Epidemic listeriosis associated with Mexican-style cheese.

In Los Angeles County, California, 142 cases of human listeriosis were reported from January 1 through August 15, 1985. Ninety-three cases (65.5 percent) occurred in pregnant women or their offspring, and 49 (34.5 percent) in nonpregnant adults. There were 48 deaths: 20 fetuses, 10 neonates, and 18 nonpregnant adults. Of the nonpregnant adults, 98 percent (48 of 49) had a known predisposing condition. Eighty-seven percent (81 of 93) of the maternal/neonatal cases were Hispanic. Of the Listeria monocytogenes isolates available for study, 82 percent (86 of 105) were serotype 4b, of which 63 of 86 (73 percent) were the same phage type. A case-control study implicated Mexican-style soft cheese (odds ratio, 5.5; 95 percent confidence interval, 1.2 to 24.8) as the vehicle of infection; a second case-control study showed an association with one brand (Brand A) of Mexican-style soft cheese (odds ratio, 8.5; 95 percent confidence interval, 2.4 to 26.2). Laboratory study confirmed the presence of L. monocytogenes serogroup 4b of the epidemic phage type in Brand A Mexican-style cheese. In mid-June, all Brand A cheese was recalled and the factory was closed. An investigation of the cheese plant suggested that the cheese was commonly contaminated with unpasteurized milk. We conclude that the epidemic of listeriosis was caused by ingestion of Brand A cheese contaminated by one phage type of L. monocytogenes serotype 4b.

Disease caused by a marine Vibrio. Clinical characteristics and epidemiology.

We studied the clinical characteristics and epidemiology of disease associated with a rare, unnamed halophilic lactose-fermenting Vibrio species in 39 persons from whom the organism had been isolated. Two distinct clinical presentations were seen. In the first, the illness began with septicemia, often within 24 hours after raw oysters had been eaten; 18 of 24 such patients had pre-existing hepatic disease, and 11 of the 24 died. In the second, there was a wound infection after exposure to seawater or an injury incurred during the handling of crabs; none of these persons had pre-existing hepatic disease, and one of 15 died. Most cases (85 per cent) occurred during relatively warm months (May to October) in men (90 per cent) 40 or more years of age (95 per cent). This Vibrio species is a pathogen and should be considered in the differential diagnosis of septicemia with secondary skin lesions and of wound infections after exposure to seawater.

Non-cholera vibrio infections in the United States. Clinical, epidemiologic, and laboratory features.

Non-cholera vibrios are organisms that are biochemically indistinguishable from Vibrio cholerae but do not agglutinate in vibrio 0 group 1 antiserum. Since 1972 there has been a dramatic increase in the number of these organisms referred to the Center for Disease Control for identification. Clinical, epidemiologic, and laboratory data were analyzed for 26 of 28 patients with isolates identified between January 1972 and March 1975. Thirteen (50%) of the isolates were obtained from feces of patients who had an acute diarrheal illness; no other pathogens were isolated from their feces, and all patients survived. Four (15%) patients had non-cholera vibrios isolated from other gastrointestinal or biliary tract sites; none of these patients had acute illness definitely attributable to non-cholera vibrios. Nine (35%) patients had non-cholera vibrios isolated from other tissues and body fluids; four deaths occurred in this group. Patients with acute diarrhea frequently had a history of recent shellfish ingestion or foreign travel, whereas some patients with systemic non-cholera vibrio infection had a history of recent occupational or recreational exposure to salt water.

Legionella longbeachae Species Nova, Another Etiologic Agent of Human Pneumonia

A new species of bacteria that is an etiologic agent of human pneumonia has been isolated and characterized. Clinical symptoms of infection with this organism are not readily distinguishable from those caused by Legionella pneumophila infection. The organism was isolated from respiratory tract specimens from four patients. Two cases of infection apparently originated in California and one in Georgia, and a fourth was of unknown geographic origin. The name Legionella longbeachae species nova is proposed for this organism. The type strain of L. longbeachae is Long Beach 4 (= American Type Culture Collection 33462).

Analysis of Listeria monocytogenes by multilocus enzyme electrophoresis and application of the method to epidemiologic investigations

We examined 310 strains of Listeria monocytogenes by multilocus enzyme electrophoresis. Fifty-six electrophoretic types (ETs) of the organism were defined: 10 for serovar 4b strains, 11 for serovar 1/2b strains, and 30 for serovar 1/2a strains. Strains of serovars 1/2c, 3a, and 3b, and a non-typable strain were distributed among the remaining five ETs. The mean genetic diversity of the species was 0.41. Principal coordinate analysis revealed a sharp division among ETs which divided the species into two major clusters. ETs containing serovar 1/2a strains were in one cluster while all ETs containing serovar 4b, 1/2b, and 3b strains were in the second cluster. Except for two ETs that contained strains from both serovar 1/2b and serovar 3b, no ET contained strains from more than one serovar. Multilocus enzyme electrophoresis facilitated the analysis of epidemiologic data. In three separate epidemiologic investigations electrophoretic typing confirmed a common source as a cause of an outbreak; in a fourth investigation a single common source as a cause of an outbreak was effectively ruled out. Electrophoretic typing was also useful in documenting potential links between Listeria contaminated foods and persons with listeriosis who consumed those foods.

Characterization of Yersinia enterocolitica and Yersinia pseudotuberculosis by Deoxyribonucleic Acid Hybridization and by Biochemical Reactions

Strains of Yersinia enterocolitica and Yersinia pseudotuberculosis were characterized by deoxyribonucleic acid (DNA) hybridization, and the extent of DNA relatedness between the strains was assessed by hydroxyapatite chromatography. DNAs from 24 strains of Y. pseudotuberculosis were highly related, but Y. pseudotuberculosis was only 40 to 60% related to Y. enterocolitica. Y. enterocolitica strains formed three DNA relatedness groups, and the data strongly suggest a fourth relatedness group. Each relatedness group can be defined biochemically. One DNA relatedness group corresponds to typical Y. enterocolitica; the second is rhamnose positive; the third is rhamnose positive, melibiose positive, α-methyl glucoside positive, and raffinose positive. The suggested fourth hybridization group is sucrose negative. Although all of these DNA relatedness groups should remain in the genus Yersinia, only the first group is Y. enterocolitica. All of the yersiniae tested are distantly, but significantly, related to other members of Enterobacteriaceae. Yersiniae were more related to members of Enterobacteriaceae than to Pasteurella multocida.

Unidentified Gram-Negative Rod Infection: A New Disease of Man

A Gram-negative bacillus that defies identification was isolated from blood cultures of 17 patients with fever. Fifteen patients were male adults, and 14 patients had underlying diseases, including previous splenectomy in five, which impair host defenses against infection. Illnesses occurred in the summer and autumn in 14 cases and had been recently preceded by dog bites in 10 cases. Clincal syndromes included cellulitis in seven cases, primary bacteremia without localization in four, purulent meningitis in four, and endocarditis in three. Three patients died. The organism grows slowly on blood or chocolate agar in 10% CO, is oxidase- and catalase-positive, and is negative for nitrate reduction, indole production, and urease. It produces acid from glucose, lactose, and maltose. These features distinguish it from all previously described and classified bacteria. Furthermore, the epidemiologic features of the patients suggest that this organism is an opportunistic invader and may have an animal reservoir in nature.

Infection caused by Francisella philomiragia (formerly Yersinia philomiragia). A newly recognized human pathogen

We evaluated the clinical characteristics of patients with Francisella philomiragia (formerly Yersinia philomiragia) isolated from normally sterile sites. Isolates from 14 patients were received by the Centers for Disease Control between 1975 and 1987: 9 were from blood; 2 from lung biopsies; and 1 each from pleural, peritoneal, and cerebrospinal fluid. Underlying problems included chronic granulomatous disease in 5 patients, near-drowning in 5, and a myeloproliferative disease in 2. All 13 patients for whom records were available had a febrile syndrome compatible with bacterial infection. Pneumonia and fever-bacteremia were the commonest clinical syndromes reported. In 7 cases, F. philomiragia was the only sterile-site isolate, and the clinical syndrome did not resolve without appropriate antibiotics. Familiarity with this organism is important because of its ability to cause serious disease in chronic granulomatous disease and near-drowning patients. Further study may yield new insights into pathogenic and host defense mechanisms.

Classification of the Legionnaires' disease bacterium: An interim report

Deoxyribonucleic acid (DNA) from strains of the Legionnaires disease bacterium (LDB) was characterized in order to aid in the proper classification of this organism. The genome size of LDB DNA was estimated at 2.5×109 daltons by reassociation kinetics; a guanine-plus-cytosine content of LDB of 39% was established by optical thermal denaturation and buoyant density ultracentrifugation measurements. DNA relatedness studies on 12 strains of the LDB indicated that they were all members of the same species. DNA relatedness studies have thus far failed to show that the LDB is significantly related to any other organism, including all members of Enterobacteriaceae,Pasteurella multocida, Francisella tularensis, Rochalimaea quintana, Vibrio species,Staphylococcus epidermidis, andFlavobacterium meningosepticum.

Chryseomonas luteola comb. nov. and Flavimonas oryzihabitans gen. nov., comb. nov., Pseudomonas-Like Species from Human Clinical Specimens and Formerly Known, Respectively, as Groups Ve-1 and Ve-2

Pseudomonas luteola Kodama et al. 1985 is a senior subjective synonym of Chryseomonas polytricha Holmes et al. 1986 (formerly group Ve-1). The type strain of P. luteola (JCM 3352) was 78% related to the type strain of C. polytricha (NCTC 11843). We propose the new combination Chryseomonas luteola for this organism. For Pseudomonas oryzihabitans Kodama et al. 1985 (formerly group Ve-2) we propose the new genus and new combination Flavimonas oryzihabitans. We were in the process of proposing a scientific name for group Ve-2 on the basis of an examination of 19 strains when the description of P. oryzihabitans was published. We have included the type strain of P. oryzihabitans for comparison and here present our results for all 20 strains. Each of the 20 strains was examined for 129 characteristics, including reactions in 58 enzyme tests (API ZYM system). These bacteria are rod shaped, aerobic, gram negative, yellow pigmented, motile by a single polar flagellum, and saccharolytic, but they do not produce cytochrome oxidase. The mean guanine-plus-cytosine content of the deoxyribonucleic acid of three representative strains was 63.6 ± 1.6 mol%. The deoxyribonucleic acid relatedness of 11 strains of group Ve-2 to the strain we would have proposed as the type strain, CL162/81 (= NCTC 11850), averaged 93% (hydroxyapatite method, 70°C). The type strain of P. oryzihabitans (JCM 2952) was 93% related to CL162/81. The relatedness of CL162/81 to the respective type strains of the five major ribosomal ribonucleic acid hybridization groups of the genus Pseudomonas and to the type strain of C. polytricha (formerly group Ve-1) was 5% or less. All strains, except the type strain, of F. oryzihabitans were isolated from human clinical specimens.