|Year : 2015 | Volume
| Issue : 1 | Page : 54-57
A case of Aeromonas hydrophila meningitis in septic shock
Gaurav Salunke1, Viraj Namshikar2, Raghoba Gaonkar3, Tripti Gaonkar4
1 Department of Microbiology, District Hospital, Margao, Goa, India
2 Department of Anaesthesia, Goa Medical College, Bambolim, Goa, India
3 Department of Medicine, District Hospital, Margao, Goa, India
4 Microbiology Student, Goa Medical College, Bambolim, Goa, India
|Date of Web Publication||4-Mar-2015|
Department of Microbiology, District Hospital, Margao, Goa - 403 601
There are ever-increasing reports of extra-intestinal human infections caused by Aeromonas, in both immunocompromised and immunocompetent patients. We present a rare case of Aeromonas hydrophila meningitis in septic shock, secondary to suspected gastrointestinal focus, in an unknown elderly male. Despite prompt broad-spectrum antibiotic, fluid replacement, vasopressors and extensive resuscitation, the patient died within 6 hours following initial presentation. The case highlights the clinical significance of infections by A. hydrophila which could be fatal.
Keywords: Aeromonas hydrophila , meningitis, septic shock
|How to cite this article:|
Salunke G, Namshikar V, Gaonkar R, Gaonkar T. A case of Aeromonas hydrophila meningitis in septic shock. Trop J Med Res 2015;18:54-7
| Introduction|| |
Aeromonas is a Gram-negative bacillus of the Vibrionaceae family. The species name "hydrophila" (water loving) indicates the natural habitat is water. They also reside in sink traps, drain pipes, tap water faucets and distilled water supplies. The spectrum of Aeromonas infections in humans is quite vast. 
The species have been attributed with the acquisition of certain pathogenic determinants like outer membrane proteins, enzymes (proteases, lipases, DNases, elastase and gelatinase) and toxins (hemolysin, aerolysin, cytotoxin, enterotoxin, cytotonic enterotoxin, endotoxin and lipopolysaccharide) that confer it with greater invasive capabilities.  The increasing antibiotic resistance among them also causes health problems in human beings. 
These characteristics make it an emerging pathogen posing several threats to humans.
We present a rare case of Aeromonas hydrophila meningitis in septic shock, secondary to suspected gastrointestinal focus.
| Case Report|| |
An unknown elderly male was found lying by roadside and brought to the Emergency Department of our Hospital.
At admission the patient suffered an episode of watery diarrhea. He was drowsy and confused; no history could be obtained. Physical examination revealed temperature of 39.4°C, blood pressure of 78/46 mmHg, heart rate of 110 beats/min and respiratory rate of 30 breaths/min. The patient had nuchal rigidity, pupils were semi-dilated, plantar response was extensor and brisk.
A plain CT scan showed effacement of cortical sulci (cortical edema), suggestive of meningitis.
Hematological analysis is shown in [Table 1]. A lumbar puncture was performed. The CSF (cerebral spinal fluid) picture is shown in [Table 2]. Retrocheck HIV test on serum was found to be negative.
Blood, stool and spinal fluid were sent for microbiological analysis. As advised by the Hospital Antibiotic Policy, Ceftriaxone 2 gm every 12 hourly and Vancomycin 1 gm every 12 hourly were started intravenously. Inotropes and fluids were administered to manage the shock.
Despite extensive resuscitation, the patient's condition further deteriorated resulting in death within 6 hours of admission.
Two days after the patient's death, blood, stool and CSF culture confirmed the presence of A. hydrophila.
| Microbiological Study|| |
The CSF sample was subjected to Gram stain which revealed plenty of pus cells and Gram-negative bacilli. A wet preparation of stool sample also showed the presence of pus cells.
Cultures were done by standard techniques. 
CSF was inoculated onto sheep blood (5%), Chocolate agar and Mac-Conkey agar plates and incubated for 24 hours.
Blood (10 ml) was inoculated into 100-ml brain-heart infusion (BHI) broth, incubated for 24 hours, after which a loopful was sub-cultured on sheep blood (5%) and Mac-Conkey agar plates and incubated for isolation of the organism.
Stool was inoculated on to Mac-Conkey and XLD (Xylose lysine deoxycholate) agar plate. In addition, APW (alkaline peptone water) was inoculated and incubated for 24 hours, after which a loopful from the upper one-third of the tube was streaked on to blood agar (5%) plates for isolation of the organism.
Chocolate agar, blood agar, and BHI bottle, with loosened cap, were kept in a CO 2 incubator. Mac-Conkey and XLD agar plate was kept in a regular incubator. Incubation temperature during cultures as well as biochemical studies was 37°C.
All the media were positive for bacterial growth within 24 hours. The same organism was isolated from CSF, blood and stool samples.
The profile of the isolate was as follows:
On microscopy, the organism appeared as a gram-negative, non-sporulating, short to elongated bacillus occurring singly and in pairs.
Cultural characteristics are shown in [Table 3] and biochemical results are shown in [Table 4] and [Figure 1], [Figure 2], [Figure 3]. On the basis of these morphological, cultural, and biochemical characteristics, the isolate was identified as A. hydrophila.
|Figure 2: Triple sugar iron agar slant, mannitol motility medium, indole test and urease test|
Click here to view
Antimicrobial susceptibility was performed using the Kirby-Bauer Method.  The organism was resistant to Penicillin, Ampicillin, Ampicillin-Sulbactam, and first- and second-generation Cephalosporins, and susceptible to third-generation Cephalosporins, Aminoglycosides, Carbapenems, Tetracyclines, Trimethoprim-Sulfamethoxazole, Chloramphenicol and Fluoroquinolones.
| Discussion|| |
A. hydrophila is motile, Gram negative, catalase and oxidase-positive facultative anaerobic bacilli. 
In this case, clinical signs, symptoms, CSF findings and CT scan picture were suggestive of meningitis and septic shock.
Patient's blood and CSF cultures were positive for A. hydrophila, which established A. hydrophila as the causative agent of meningitis and bacteremia. These circulating bacteria and their products, directly stimulate inflammatory responses within the vasculature, resulting in severe sepsis and septic shock. 
Severe infection by A. hydrophila usually involves people with underlying disease. 
In this case, the patient appeared malnourished and debilitated. Considering the patient was elderly and his general condition poor, it was quite possible that patient had a depressed immune response and an impaired reticulo-endothelial system. Reticulo-endothelial dysfunction can lead to significant degeneration of intestinal mucosa.
Under these circumstances, intestinal bacteria can easily invade the blood stream and cause bacteremia. These bacteria then enter the CNS by interacting and subsequently breaking down the blood brain barrier at the level of micro vascular endothelium, subsequently leading to meningitis.
In our case, the patient did not have any open wounds or superficial lacerations; therefore, it was less likely that the pathogen was introduced from the environment. The stool culture showed growth of A. hydrophila, which is an invasive pathogen.
Vasaikar et al. have previously reported A. hydrophila from patients with acute gastroenteritis.  Aeromonas has also been reported as a contaminant, from seafood samples from the east coast and the west coastal regions of south India where sea-water fish farming is a major occupation of the local inhabitants. ,
Goa being a costal state along the west coast of India and fish being the staple diet, the possibility of the patient having consumed seafood or contaminated drinking water harboring the pathogen can be considered. Therefore, in the present patient, hematogeneous spread of A. hydrophila from the gastrointestinal tract may be suggested to be the possible source of bacteremia leading to meningitis and septic shock.
Aeromonas spp. produce a beta-lactamase, which makes them resistant to Ampicillin and first-generation Cephalosporins. The antimicrobial agents most active against Aeromonas are the third-generation Cephalosporins, Imipenem and Fluoroquinolones.  A similar antibiotic sensitivity pattern was noted in our case.
| Conclusion|| |
There is a necessity to conduct studies, to assess the microbiological quality of drinking water and food served in Beach Shacks along the Goa Coast with respect to Aeromonas hydrophila.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]
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