Tài liệu Streptococcus iniae infections in Asian Aquaculture ppt

Invasive Infection with Streptococcus iniae -- Ontario, 1995-1996 During December 1995-February 1996, four cases of a bacteremic illness three accompanied by cellulitis and the fourth w

Streptococcus iniae infections in Asian Aquaculture

10 October 2003

Streptococcal disease caused by Streptococcus iniae is without doubt one of the major

bacterial diseases in fish It has been reported to cause significant mortality in more than 12 different aquaculture species Its distribution is worldwide in both freshwater and marine environments The annual impact to aquaculture has been estimated to be over US$100 million However, in the past, very few reports have described its presence in Asia Over the last

3 years, Intervet Norbio Singapore has gathered a substantial amount of information on the

severity and frequency of Streptococcus outbreaks in cultured fish of the entire Asian-Pacific

region

Aetiology

Streptococci are Gram-positive bacteria Streptococcal disease in fish is mainly caused by three

bacteria: S iniae, S difficile and S agalactiae S iniae is the most common and pathogenic one

in the marine environment

Host range, geographic distribution

S iniae infection is a major problem of warmwater aquaculture, but has very few limitations in

regard to geographic boundaries or host ranges The affected species reported include rainbow

trout (Oncorhynchus mykiss), tilapia (Oreochromis spp.), yellowtail (Seriola quinqueradiata), European seabass (Dicentrarchus labrax), European seabream (Sparus aurata), red drum (Sciaenops ocellatus), bastard halibut (Paralichthys olivaceus) and Asian seabass (Lates

calcarifer)

The following map shows the countries of Asia where Intervet has isolated S iniae from cultured

fish to date

In these countries, S iniae has been isolated in a variety of species as illustrated in the following table

Asian seabass/Barramundi

(Lates calcarifer) Malaysia, Singapore, Taiwan, IndonesiaThailand

Four-finger threadfin

(Eleutheronema tetradactylum) Malaysia

Grouper

Pomfret

Seabream (Rhabdosargus spp.,

Sparus spp.: Plectorhynchus spp.) China

Snapper

Tiliapia

(Oreochromis spp.) Philippines, Indonesia, China

Yellow croaker

(Larimichthys polyactis)

China

Fish species Country of isolation Asian seabass/Barramundi (Lates calcarifer) Malaysia,

Singapore, Taiwan, Indonesia, Thailand Malaysia Malaysia, China Pomfret (Trachinotus spp.) Malaysia,

Epidemiology

The transmission is horizontal with infection coming from direct contact with infected fish,

contaminated fish food or a contaminated environment As Streptococci bacteria can survive for

several months in frozen fish, feeding trash fish considerably increases the chances of infection Transmission from wild fish to cultured fish has also been reported Both acute and chronic mortality occurs Acute outbreaks often occur during the warmer months of the year or when fish are subject to increased stress, with cumulative mortality reaching 80% within a 10-day-period In

a marine cage-farming situation, the peak mortality usually starts suddenly from one cage and spreads progressively to the neighbouring cages as illustrated in the following graph

After an acute outbreak, a low-level chronic mortality can carry on for weeks or months with a

small number of fish dying every day Any size of fish can be affected by S iniae But most

outbreaks will take place on fish of at least 10 g

Clinical signs and gross pathology

Usually, fish infected with S iniae become lethargic and refuse to feed As these bacteria target

the brain and nervous system, erratic swimming, disorientation and swirling behaviour are commonly observed Very often, fish show unilateral or bilateral exophthalmia with opacification

of the cornea Petechial haemorrhage can be present at the base of the fins, or around the mouth, operculum or anus Darkening of the skin is another common external sign Internally, the symptoms are typical of a systemic bacterial infection with presence of ascites, splenomegaly, enlarged kidney, pallor and haemorrhages of the liver

Affected black Seabream (Spondyliosoma

cantharus wiht opacification of the cornea)

Diagnosis

Clinical signs and impression smear The presence of typical clinical signs and demonstration of Gram-positive cocci from internal organs by Gram-stained impression smears constitute a presumptive diagnosis

Bacteriology Samples from brain, liver, spleen and kidney tissues plated on standard,

nonselective TSA or BHIA media supplemented with salt if appropriate, incubated at 26ºC for 24

to 48 hours show small (0.5-1.0 mm diameter), whitish, translucent, rounded and slightly raised

colonies Streptococci are Gram-positive, nonacid fast, non-motile, oxydase-positive, catalase negative, cocci S iniae are ß-haemolytic The identification to the species level is done on the

basis of biochemical and phenotypical profile

Histopathology Invasion of a large number of Gram-positive cocci can be observed in most organs Proliferative inflammation with infiltration of macrophages engulfing bacteria and

multifocal areas of necrosis are particularly notable in the central nervous system, eye, heart, spleen, kidney and ateral muscles No notable changes are observable in the gills

Control

Considering the acute nature of the development of the disease, most fish will not be treatable through antibiotic treatment Presently there is no real effective cure

Prevention

Avoidance Screening and quarantine of incoming fingerlings and avoiding the feeding of trash fish diet are the two major means of avoidance relevant to Asia

Good husbandry practices Reducing overfeeding, overcrowding and unnecessary stress (such

as handling or transportation) can reduce the risk of outbreak The collection and sanitary

disposal of moribund or dead fish should be observed on a daily basis These measures may prevent outbreaks or at least reduce their severity

Vaccination A safe and effective vaccine against S iniae outbreak in fish has been developed

by Intervet Norbio Singapore and will soon be available in South East Asia as a major means to control this disease

Invasive Infection with Streptococcus iniae Ontario, 1995-1996

During December 1995-February 1996, four cases of a bacteremic illness (three accompanied by

cellulitis and the fourth with infective endocarditis, meningitis, and probable septic arthritis) were identified among patients at a hospital in Ontario Streptococcus iniae, a fish

pathogen not previously reported as a cause of illness in humans (1-3), was isolated from all four patients All four patients were of Chinese descent and had a history of preparing fresh, whole fish; three patients for whom information was available had had an injury associated with preparation of fresh, whole fish purchased locally This report summarizes information about these cases and presents preliminary findings of an ongoing investigation by health officials in Canada (4), which suggests that S iniae may be an emerging pathogen associated with injury while preparing fresh aquacultured fish Case Reports

The first three cases occurred during December 15-20, 1995, among previously healthy women who ranged in age from 40-74 years Each had a history of injury to the hand while preparing fresh, whole, aquacultured fish The first case-patient reported a puncture wound to her hand with a fish bone while preparing a newly purchased tilapia (Oreochromis species) *, a freshwater fish marketed primarily as whole fish; the second lacerated the skin over her finger with a knife that had just been used to cut and clean a freshwater fish of unknown type; and the third punctured her finger with the dorsal fin while scaling a fresh tilapia

The period from injury to onset of symptoms for the three cases ranged from 16 hours to 2 days

At the time of hospitalization, physical examination findings included fever (range: 100.4 F {38.0 C} to 101.3 F {38.5 C}) and cellulitis with lymphangitic spread proximate to the site of injury Leukocyte counts ranged from 12,900/mm3 to 16,900/mm3 with an increased proportion of neutrophils Blood cultures from all three patients were positive for S iniae, and treatment with beta-lactam antibiotics or clindamycin resulted in complete resolution of all manifestations of illness

The fourth patient, a 77-year-old man, was admitted to the hospital on February 1, 1996, because of a 1-week history of increasing knee pain, intermittent sweats, fever, dyspnea, and confusion Past medical history included diabetes mellitus, hypertension, rheumatic heart disease, chronic renal failure, Paget's disease, and osteoarthritis Approximately 10 days before admission,

he had prepared a fresh tilapia, although it was unknown whether he incurred an injury while preparing the fish Findings on examination included temperature of 96.1 F (35.6 C) and a large effusion and warmth of the right knee without overlying cellulitis New murmurs of aortic insufficiency and mitral regurgitation were noted While in the emergency department, he had a respiratory arrest and was intubated; treatment included administration of a beta-lactam agent and erythromycin The leukocyte count on admission was 25,200/mm3 with 95% neutrophils Ten hours following admission, his knee was aspirated, and a lumbar puncture was performed Analysis of the joint fluid included a leukocyte count of 72,000/mm3 but no evidence of crystals Analysis of the cerebrospinal fluid (CSF) included a leukocyte count of 87/mm3 (54% neutrophils), a glucose of 14 mg/dL, and a protein of 320 mg/dL Cultures of samples of synovial fluid and CSF were negative, but blood cultures yielded S iniae Based on the clinical and laboratory findings, and a transesophageal echocardiogram that documented a mitral-valve vegetation, S iniae endocarditis and meningitis were diagnosed Treatment with beta-lactam antibiotics was continued, and he recovered Microbiology

Isolates from all patients grew on sheep-blood agar incubated in room air at 95.0 F (35 C), appeared as gram-positive cocci in short chains or pairs, and were catalase-negative During the first 18 hours of incubation, colonies were alpha-hemolytic and initially were identified as viridans streptococci Further testing conducted by reference laboratories identified them as S iniae Three strains were resistant to bacitracin, and the fourth was susceptible Pulsed-field gel electrophoresis patterns of chromosomal Sma1 digests of all four isolates were identical Microbroth-dilution testing for susceptibility indicated that all isolates were susceptible to beta-lactams, macrolides, trimethoprim-sulfamethoxazole, and tetracycline Follow-Up Investigation

All four patients had prepared fresh, whole fish, three of which were known to be tilapia, that had been purchased from different stores In two cases, the fish were taken live from holding tanks in different fish markets Surface cultures were obtained from four fresh tilapia purchased

at selected fish markets in the community during March 1996 Cultures from three of the four fish yielded S iniae; however, pulsed-field gel electrophoresis patterns were different for each, and none matched the outbreak strain None of the vendors at the markets where the fish were purchased reported that the fish appeared to be sick Fresh, whole tilapia sold in Ontario were imported from U.S fish farms

The ongoing epidemiologic and microbiologic investigation includes the establishment of surveillance for cases of upper-extremity cellulitis in patients visiting the emergency departments

of 10 Toronto-area hospitals and use of a standardized questionnaire for interviewing patients In addition, to better characterize the prevalence of S iniae in fish, samples from live, aquacultured fish imported into Canada are being collected and tested by Canadian health officials for S iniae

Reported by: M Weinstein, MD, DE Low, MD, A McGeer, MD, B Willey, Mount Sinai Hospital and Princess Margaret Hospital, Univ of Toronto, and Canadian Bacterial Diseases Network, Toronto;

D Rose, MD, M Coulter, P Wyper, Scarborough Grace Hospital, Scarborough; A Borczyk, MSc, Public Health Laboratory of Ontario, Toronto; M Lovgren, National Reference Center for Streptococcus, Laboratory Center for Disease Control, Edmonton, Alberta, Canada Childhood and Respiratory Diseases Br, Div of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, CDC

Editorial Note

Editorial Note: Because of recent increases in aquaculture, the occurrence of infections caused by

a variety of streptococcal species is increasing among some salt-water and freshwater fish S iniae was first recognized in 1972 as a cause of disease in an Amazon freshwater dolphin, Inia geoffrensis In 1986, S iniae (reported as S shiloi) was identified as a cause of meningoencephalitis among tilapia and trout in Israel; the organism was identified subsequently among tilapia in the United States and Taiwan Infections with S iniae may be asymptomatic or may cause disease associated with death rates of 30% to 50% in affected fishponds (2)

The first recognized case of S iniae infection in humans occurred in Texas in 1991, and a second case occurred in Ottawa, Canada, in 1994; however, potential sources for both cases were not determined The pulsed-field gel electrophoresis digest from the isolates causing both of these infections was identical to the isolates of the cases described in this report, except for a one-band shift

Whether the recent cases of S iniae infection represent the emergence of a new human pathogen or previously unrecognized disease is unclear S iniae infection may not be recognized because cultures rarely are obtained from patients with wound infections or cellulitis and, if cultured, viridans streptococcus isolates may be considered contaminants and not be further characterized In addition, it is unclear whether human infections may be caused by any S iniae strain or whether the strain implicated in all six of the cases is more virulent than other strains Finally, because all four persons described in this report were of Chinese descent, potential racial/ethnic associations with risk for this infection should be further considered Additional culture surveys and laboratory studies of tilapia should assist in characterizing the diversity and virulence among S iniae

To more clearly define the role of S iniae as a human pathogen, physicians are encouraged to obtain blood and wound cultures from persons with upper-extremity cellulitis and to seek a history of recently having prepared a fresh, whole fish Microbiology laboratories should be able

to make a preliminary identification of S iniae based on several distinguishing phenotypic characteristics ** Possible S iniae isolates can be confirmed at the CDC Streptococcal Reference Laboratory and tested to determine whether they are the same strain as identified from the six cases of human disease

References

1 Eldar A, Frelier P, Assenta L, et al Streptococcus shiloi, the name for an agent causing septicemic infection in fish is a junior synonym of Streptococcus iniae Int J Syst Bacteriol 1995;45:840-2

2 Eldar A, Bejerano Y, Bercovier H Streptococcus shiloi, and Streptococcus difficile: two new streptococcal species causing a meningoencephalitis in fish Curr Microbiol 1994;28:139-43

3 Perera R, Johnson S, Collins M, et al Streptococcus iniae associated with mortality of Tilapia nilotica and T aurea hybrids Journal of Aquatic Animal Health 1994;6:335-40

4 Weinstein M, Low D, McGeer A, et al Invasive infection due to Streptococcus iniae: a new or previously unrecognized disease Ontario, 1995-1996 Canada Communicable Disease Report 1996;22:129- 32

5 Pier GB, Madin SH Streptococcus iniae sp nov., a beta-hemolytic streptococcus isolated from an Amazon freshwater dolphin, Inia geoffrensis Int J Syst Bacteriol

1976;26:545-53

6 Pier GB, Madin SH, Al-Nakeeb S Isolation and characterization of a second isolate of Streptococcus iniae Int J Syst Bacteriol 1978;28:311-4

* Tilapia is one of the fastest growing aquaculture industries in the United States and the world

** S iniae is beta-hemolytic; however, some strains may appear to be alpha-hemolytic because

a narrow zone of beta-hemolysis is surrounded by a larger zone of alpha-hemolysis (5,6) Beta-hemolysis always is observed under anaerobic incubation and in the area of stabs in the agar S iniae is nongroupable with Lancefield group A through U antisera In addition, the pyrrolidonylarylaminase and leucine aminopeptidase tests are positive, the Voges-Proskauer test

is negative, and the organism may have variable susceptibility to bacitracin

Invasive Infections Due to a Fish Pathogen,

Streptococcus iniae

Mitchell R Weinstein, M.D., Margaret Litt, M.H.Sc., Daniel A Kertesz, M.D., Phyllis Wyper, R.N., David Rose, M.D., Mark Coulter, A.R.T., Allison McGeer, M.D., Richard Facklam, Ph.D., Carola Ostach, C.P.H.I.(C), Barbara M Willey, A.R.T., Al Borczyk, M.Sc., Donald E Low, M.D., for The S iniae Study

Group

ABSTRACT

Background Streptococcus iniae is a pathogen in fish, capable of causing invasive disease and outbreaks in aquaculture farms.During the winter of 1995–1996 in the greater Torontoarea there was a cluster of four cases of invasive S iniaeinfection in people who had recently handled fresh, whole fishfrom such farms

Methods We conducted a prospective and retrospective community-basedsurveillance for cases

of S iniae infection in humans To obtaina large sample of isolates, we studied cultures obtained fromthe surface of fish from aquaculture farms Additional isolateswere obtained from the brains

of infected tilapia (oreochromisspecies) All the isolates were characterized by pulsed-fieldgel electrophoresis (PFGE)

Results During one year, our surveillance identified a totalof nine patients with invasive S iniae infection (cellulitisof the hand in eight and endocarditis in one) All the patientshad handled live

or freshly killed fish, and eight had percutaneousinjuries Six of the nine fish were tilapia, which are commonlyused in Asian cooking Thirteen additional S iniae isolates(2 from humans and 11 from infected tilapia) were obtained from normally sterile sites The isolates from the nine patients were indistinguishable by PFGE and were highly related to the other clinical isolates There was substantial genetic diversity among the 42 surveillance isolates from the surface of fish,but in 10 isolates the PFGE patterns were identical to thosefrom the patients with S iniae infection

Conclusions S iniae can produce invasive infection after skininjuries during the handling of fresh fish grown by aquaculture.We identified a clone of S iniae that causes invasive diseasein both humans and fish

Streptococcus iniae was first reported in 1976 to cause subcutaneousabscesses in Amazon freshwater dolphins (Inia geoffrensis) ataquariums in San Francisco and New York.1 , 2 Since the early1980s, epizootic meningoencephalitis caused by streptococcihas been recognized as an important cause of morbidity and mortalityin cultured fishponds.3 , 4 , 5 , 6 , 7 , 8 Outbreaks in Japan,

Taiwan,Israel, and the United States have affected tilapia (oreochromisspecies), yellowtail (Seriola quinqueradiata), rainbow trout,and coho salmon.3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 Several bacteria, includingS iniae, S agalactiae,6 , 11 and Lactococcus garvieae,12 , 13have been shown to cause

meningoencephalitis in fish grown byaquaculture S iniae may colonize the surface of fish or causeinvasive disease associated with 30 to 50 percent mortalityin affected fishponds.6 Infected tilapia become lethargic, swimerratically, have dorsal rigidity, and die within several days

Pathological studies show extensive infection in the centralnervous system.7

During the winter of 1995–1996, four persons in the greater Toronto area had bacteremic illnesses due to S iniae infection.Three had cellulitis, and the fourth had sepsis with endocarditis, meningitis, and arthritis All the patients were of Asian descent and reported having recently prepared whole, fresh fish for cooking In three cases the fish was identified as tilapia (also known as St Peter's fish or Hawaiian sunfish) (Figure 1) Weconducted an investigation of the clinical features and epidemiologyof this illness

Figure 1 A Tilapia (Oreochromis Species), Also

Known as St Peter's Fish or Hawaiian Sunfish

In Cantonese the name is pronounced "laap yu," and in Mandarin "lee yu." In Asian cuisine, tilapia are typically bought live, steamed, and served simply, so that their mild flavor can be enjoyed When they are bought frozen or as fillets, they are usually poached, grilled, baked, microwaved, or fried

Methods

Patients

After the first four patients (Patients 1 to 4) were identified at a community hospital in the greater Toronto area (population,4.2 million) between December 1995 and February 1996,14 , 15

retrospectiveand prospective surveillance was carried out to identify additionalpatients Twelve hospitals in greater Toronto were invited toparticipate Infection-control practitioners were asked

to reviewtheir medical records according to the codes defined in theInternational Classification

of Diseases, 9th Revision (ICD-9)for all patients hospitalized with cellulitis in the upper limbfrom October 1, 1995, through March 31, 1996, when there was no predisposing cause for the cellulitis, such as an intravenous line in place, a burn, a chronic skin disease, or lymphedema Patients were excluded from the study if their blood culturesrevealed an etiologic agent other than S uberis, S iniae,or some other, unidentified streptococcal species Once identified, the patients were interviewed with a standardized questionnaireto obtain clinical and epidemiologic data Beginning on April 1, 1996, the emergency departments at the hospitals were asked to identify prospectively patients who presented with acuteupper-limb cellulitis

Patients in whom S iniae was isolated from any sterile body site were considered to have confirmed cases of invasive disease Patients with diagnosed upper-limb cellulitis who had handled fresh, whole fish within the 72 hours before the onset of signs and symptoms were considered to have suspected cases

Additional Patients and Isolates of S iniae

We reviewed the records of the Centers for Disease Control andPrevention (CDC), Atlanta; the Public Health Laboratory of Ontario, Toronto; and the National Centre for Streptococcus, Edmonton,Alberta, to determine whether S iniae had been identified previously.To determine whether workers whose jobs included processingwhole fish had had cellulitis, we reviewed injury claims madeto the Workers' Compensation Board of Ontario over the precedingfive years

All live tilapia imported to greater Toronto originate in fishpondsin the United States A sample of such fish was taken to identifythe extent to which the surface of the fish was colonized withS iniae In May and June 1996, officials of the Canadian Department of Fisheries and Oceans identified five shipments of tilapia that entered Canada from five of the seven U.S farms supplyingToronto At least three live tilapia were randomly selectedfrom each shipment, and a culture was taken from the surfaceof each fish

In addition, surface cultures were obtained from fish grown by aquaculture and purchased at retail in greater Toronto andin Vancouver (courtesy of Dr N Press and E.A Bryce, Vancouver Hospital Health Science Centre) Clinical isolates were alsoreceived from tilapia that had acquired meningoencephalitisduring epizootics in 1993 in Texas and Virginia (CDC and courtesyof Dr P Frelier, Texas A&M University) Strains of S iniae from the American Type Culture Collection (ATCC, Rockville,Md.; types 29177 and 29178) were used as controls

Epidemiologic Investigation

We attempted to identify the source of the live tilapia responsiblefor the infections in humans by tracing the origin of the tilapiasold by retailers to the first four patients We studied thepurchase orders from these retailers and their wholesale suppliersthat corresponded to a six-week period preceding the purchaseof the fish, because live tilapia may be stored that long beforebeing sold

at market We used importation records from the InspectionBranch of the Department of

Fisheries and Oceans to confirmthe origin of the live tilapia

Microbiologic Analysis

Isolates were identified as S iniae by standard microbiologic methods.1 , 2 , 16 The characteristics used to identify streptococcal species as S iniae were that they had a -hemolytic reaction on trypticase soy agar with 5 percent sheep's blood; that they were not groupable with Lancefield groups A through V antiserum; that they were susceptible to vancomycin, not gas-producing, nonmotile, and positive for pyrolidonyl arylamidase and leucineaminopeptidase; and that they produced negative results on bile–esculin, Voges–Proskauer, and hippurate tests Most strains grewat 10°C but not at 45°C, and most did not grow in 6.5percent sodium chloride We used a commercial system (Bio-MérieuxVitek, Hazelwood, Mo.) that identified the isolates as S uberisor reported them as "unidentified," since S iniae is not includedin the data base

Surface swabs obtained from fresh, whole fish were inoculatedonto colistin–nalidixic acid blood agar (Unipath, Basingstoke,United Kingdom) and incubated at 35°C in 5 percent carbondioxide for 18 to 24 hours In vitro susceptibility testingwas carried out by broth microdilution according

to the methodsof the National Committee for Clinical Laboratory Standards.17

Molecular Typing

Pulsed-field gel electrophoresis (PFGE) was performed on all isolates of S iniae obtained from humans and fish PFGE was performed with the CHEF DRII apparatus (Bio-Rad, Mississauga, Ont., Canada) and restriction endonucleases SmaI and ApaI (BoehringerMannheim, Mannheim, Germany), with use of a modified version of the method of Murray et al.18 The modifications

includedthe supplementation of the Enzyme Commission lysis buffer with 20 µg of mutanolysin per milliliter (Sigma Chemical, Mississauga), a reduction in lysis time from overnight to 2 to 5 hours, and the use of the following for electrophoresis: pulse times of 5 to 60 seconds, a temperature of 12°C, and 175 V for 20hours Standard interpretive criteria were used to assess thePFGE patterns.19

Results

Clinical Findings and Characteristics

Eleven of the 12 hospitals agreed to review their clinical recordsfor cases of cellulitis, and 10 of them completed the review Thirteen emergency departments from 3 tertiary care and 10 communityhospitals participated in the prospective case finding

From December 1995 through December 1996, nine patients withbacteremic S iniae infections were identified (Table 1) Theirmedian age was 69 years (mean, 67.0; range, 40 to 80), and the female:male ratio was 2:1 All the patients with confirmed infectionswere of Asian descent: eight Chinese and one Korean All thepatients reported preparing whole, raw fish, and eight patients recalled injuring their hands by puncturing the skin with the dorsal fin, a fish bone, or a knife used in the cleaning andscaling None had prior breaks in the skin Six patients were able to identify the fish they were preparing as tilapia; three were not certain of the species No fish remained for possible culture For all the clinical isolates tested, the minimal inhibitory concentrations of penicillin, cefazolin, ceftriaxone, erythromycin,clindamycin, and trimethoprim– sulfamethoxazole were 0.25µg per milliliter or less; that of ciprofloxacin was 0.5µg per milliliter; and that of gentamicin was 16 µgper milliliter

Table 1 Demographic Characteristics of Patients with Culture-Confirmed Cases of

Invasive S iniae Infection

Eight of the nine patients had cellulitis of the hand They all had similar clinical presentations, with fever and lymphangitisoriginating from the site of injury The cellulitis developedwithin 16

to 24 hours after the injuries No patient had evidence of skin necrosis or bulla formation The leukocyte counts were elevated (range, 12,900 to 33,400 cells per cubic millimeter), with neutrophil predominances and leftward shifts Patient 4,who did not have cellulitis, met the Duke criteria for infectiveendocarditis20 of the mitral valve He also had clinical andlaboratory evidence

of meningitis and arthritis in his right knee, but cerebrospinal and synovial fluid cultures performed12 hours after the start of treatment with appropriate antibioticswere negative All the patients were admitted to the hospital and given parenteral antibiotics; they responded to treatmentwithin two to four days (Table 1)

Twelve patients with suspected cases of S iniae infection wereidentified Their median age was

46 years (mean, 50.0; range,36 to 68), and the female:male ratio was 1:1 Eleven of thepatients with suspected infections were of Asian origin; one was white All reported having injured themselves while handlingwhole or partially prepared fresh fish Nine reported the fishas being tilapia, and one as bass; the remaining two did not know the type of fish they had been preparing One patient witha suspected infection purchased a tilapia from the same retailstore, and on the same day, as a patient with a confirmed infection(Patient 7) Microbiologic cultures were negative, except inthe one white patient, whose tissue culture was positive forAeromonas hydrophila That patient did not know the type offish he had been handling when he was injured