|Year : 2003 | Volume
| Issue : 3 | Page : 199-201
Vibrionaceae from cases of acute diarrhoea and their antimicrobial sensitivity pattern - A five year prospective study
M Mathur , A De , K Saraswathi , A Varaiya , S Athalye
Department of Microbiology, LTM Medical College and General Hospital, Sion, Mumbai - 400 022, India
Department of Microbiology, LTM Medical College and General Hospital, Sion, Mumbai - 400 022, India
Over a five year period, stool samples were screened for Vibrionaceae from cases of acute diarrhoea, to study their isolation rate and their antimicrobial sensitivity pattern. All the isolates were identified by standard laboratory techniques. A total of 323 species belonging to Vibrionaceae were isolated from 4492 stool samples tested over five year period (1996-2000), giving a positivity rate of 7.2%. Maximum isolation was during the months of May to August (62.5%). Out of 323 isolates, Vibrio spp. comprised 252 and 93.3% of them were Vibrio cholerae O1 biotype El Tor. Aeromonas spp. were isolated from 71 samples and 64.8% of them were A.hydrophila. V.cholerae showed 86.8% sensitivity to amikacin followed by 73.8% to cefotaxime. Tetracycline sensitivity was only 39.6%. Aeromonas spp. also showed maximum sensitivity to amikacin (70.4%). Isolation of Vibrio spp. have increased over the years, whereas Aeromonas spp. have decreased. Amikacin sensitivity has remained within 70-80% over the years, cefotaxime sensitivity has increased and tetracycline sensitivity has decreased.
|How to cite this article:|
Mathur M, De A, Saraswathi K, Varaiya A, Athalye S. Vibrionaceae from cases of acute diarrhoea and their antimicrobial sensitivity pattern - A five year prospective study. Indian J Med Microbiol 2003;21:199-201
|How to cite this URL:|
Mathur M, De A, Saraswathi K, Varaiya A, Athalye S. Vibrionaceae from cases of acute diarrhoea and their antimicrobial sensitivity pattern - A five year prospective study. Indian J Med Microbiol [serial online] 2003 [cited 2020 Feb 20];21:199-201. Available from: http://www.ijmm.org/text.asp?2003/21/3/199/8017
More than half of the world's population lives in cholera endemic areas. Cholera is endemic in different states of India. Although sporadic cases of cholera have been reported throughout the year, outbreaks usually occur during the monsoon and El Tor vibrios have almost completely replaced the classical biotype since its recognition in 1961., Outbreaks due to V.cholerae O139 are being reported from various parts of India from 1992-1993 onwards., Amongst the other Vibrionaceae, waterborne and foodborne outbreaks of diarrhoea due to Aeromonas spp. have been reported in the recent years. We present here our experience with the isolation of Vibrionaceae, to find out the prevalence of different Vibrionaceae from cases of acute diarrhoea over a five year period and the change in their antimicrobial sensitivity pattern.
| ~ Materials and methods|| |
A total of 4492 stool samples were collected over a five year period, i.e. from 1996 to 2000, from patients suffering with acute diarrhoea. Exclusion criteria included patients using antimicrobial agents within the previous two weeks, to avoid cases of antibiotic associated diarrhoea.
Samples received in the laboratory were stool or rectal swabs. Macroscopic features of the stool samples were noted. All the samples were inoculated in alkaline peptone water (APW) and incubated for 18-24 hours at 37oC. From APW after three hours enrichment, a hanging drop preparation was done and observed for darting motility of vibrios. Direct plating of the fecal samples was done on MacConkey agar (MA). From APW, after 18-24 hours incubation, plating was done on MA, thiosulphate citrate bile salt sucrose (TCBS) agar and ampicillin sheep blood agar (ASBA) and incubated at 37oC for 24 hours. Oxidase test was performed from the colonies and the organisms grown were identified using recommended procedures. For the final identification of vibrios, slide agglutination was performed with Vibrio polyvalent O1, monospecific Ogawa and Inaba, and Vibrio cholerae O139 antisera.
Antibiotic sensitivity was performed on Mueller Hinton agar plates by the disc diffusion method of Kirby and Bauer. Antibiotics used were gentamicin (G) 30µg, amikacin (AK) 30µg, ciprofloxacin (RC) 5µg, norfloxacin (NX) 30µg, tetracycline (T) 30µg, nalidixic acid (NA) 30µg and cefotaxime (CF) 30µg, commercially available from PBL (Pathoteq Biological Laboratories, Gujarat, India).
| ~ Results|| |
Out of 4,492 fecal specimens, 323 Vibrionaceae were isolated, giving a positivity rate of 7.2%. Vibrio spp. isolated were 252 and 71 were Aeromonas spp. [Table - 1] shows the total Vibrionaceae isolated.
Of the 323 patients from whose fecal samples Vibrionaceae were isolated, 60.1% were males and 39.9% were females. Adults comprised 62.2% and children 37.8%.
Rice water stools were encountered in 81.1% specimens, which included 94.4% amongst total vibrios isolated and 33.8% amongst aeromonads isolated. Darting motility was seen in 71.8%, all of which were Vibrio spp. Maximum cases were encountered during May to August (62.5%), upto a maximum of 88.3% in 1999. This was followed by 26.3% during September to December.
[Table - 2] shows the overall antibiotic sensitivity pattern of all the 323 isolates. Both V.cholerae El Tor and Aeromonas spp. showed maximum sensitivity to amikacin (86.8% and 70.4% respectively). Sensitivity of Vibrio spp. to amikacin has remained almost similar over the years. From 1996 to 2000, ciprofloxacin sensitivity of V.cholerae El Tor reduced from 75.9% to 50%. Gradually increasing sensitivity to cefotaxime was seen from 60.5% to 80% over the five year period, while decreased sensitivity to tetracycline was seen (from 41.4% to 20%) over the same period.
Sensitivity of Aeromonas to cefotaxime has increased over the years (from 48.6% to 100%). Overall sensitivity to tetracycline was only 14.1%.
Diarrhoea was moderate in 79.8% cases, mild in 13.1% and severe in 7.1% cases. Amongst 323 patients, 58.7% were transferred to Infectious Disease Hospital and the remaining 41.3% recovered after treatment and were discharged. None of the patients expired.
| ~ Discussion|| |
Our study clearly indicates the prevalence of Vibrio cholerae El Tor Ogawa in Mumbai, i.e. 93.3% of the total Vibrio spp. isolated during the five year period. During this period not a single strain of V.cholerae O139 was isolated, though there was a case of V.cholerae O139 reported by Joshi et al in 1999.
Age and sex distribution of the cases from whose fecal samples Vibrionaceae were isolated did not show any significant correlation with diarrhoea. Out of 235 El Tor vibrios, 33 were Voges Proskauer (VP) negative (14%). VP negative El Tor isolates in our study were less in comparison to that reported by Jayaram et al (36.3%).
Majority of the Aeromonas spp. isolated were A.hydrophila (64.8%), which is consistent with the findings of Kannan et al. This was followed by A.sobria (31%) and A.caviae (4.2%).
Isolation of Vibrio spp. have increased over the years, i.e. from 55.2% in 1996 to 83.3% in 2000. On the contrary, Aeromonas spp. have decreased over the same period, i.e. from 44.8% in 1996 to 16.7% in 2000 [Table - 1]. Throughout the years, maximum cases were encountered during the monsoon (62.5%). But in the year 2000 more cases were seen during January to April (41.7%) as compared to May to August (33.3%). This was because a small cholera outbreak occurred in the month of April 2000 due to leakage of sewage pipes in a locality and all the cases were from that area. Niyogi et al had also reported an outbreak due to V.cholerae O1 in Orissa, contaminating source being dug wells and river water.
Out of 71 Aeromonas isolates, 10 were sensitive to ampicillin and all these grew on MacConkey agar. The 61 isolates growing on ASBA were haemolytic. Though haemolytic colonies of Aeromonas spp. are well identified on ASBA, all strains of Aeromonas do not grow in this medium.
In our study, rice water stool which is a constant feature of cholera stool, was also seen in stools from where Aeromonas spp. were isolated (33.8%). Thus, diarrhoea due to Aeromonas can also produce rice water stools. Patients treated in our hospital (41.3%), mostly recovered with oral rehydration solution, except in some cases with severe diarrhoea where ciprofloxacin or cefotaxime were given.
Thus Vibrio cholerae is endemic in Mumbai, with increased incidence in the monsoons. Diarrhoea due to Aeromonas is on the decline. Localized outbreaks like the one in April 2000, can be prevented by regular checking of sewage pipes and improving the drainage facilities in the city.
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