Background

Extended spectrum ß-lactamases (ESBLs) represent a major group of lactamases responsible for resistance, mostly produced by gram-negative bacteria, to newer generations of ß-lactam drugs currently being identified in large numbers worldwide. The present study was undertaken to see the frequency of ESBL producing Pseudomonas spp. isolated from six hundred clinical specimens (wound, pus, aural, urine, sputum, throat and other swabs) collected over a period of three years from two tertiary care hospitals in Bangladesh.

Findings

Aerobic bacterial culture was performed on aseptically collected swabs and only growth of Pseudomonas was considered for further species identification and ESBL production along with serotyping of Pseudomonas aeruginosa. Antimicrobial susceptibility testing was carried out using the Kirby-Bauer agar diffusion method and ESBL production was detected on Mueller Hinton agar by double-disk synergy technique using Amoxicillin-Clavulanic acid with Ceftazidime, Cefotaxime, Ceftriaxone and Aztreonam. Culture yielded 120 Pseudomonas spp. and 82 of them were biochemically characterized for species. Pseudomonas aeruginosa was found to be the predominant (90.2%) species. Of 82 isolates tested for ESBL, 31 (37.8%) were ESBL positive with 29 (93.5%) as Pseudomonas aeruginosa, the remaining 2 (6.5%) were Stenotrophomonas maltophilia and Ralstonia pickettii. Antibiogram revealed Imipenem as the most effective drug (93.3%) among all antimicrobials used against Pseudomonas spp. followed by Aminoglycosides (63.7%).

Conclusion

ESBL producing Pseudomonas spp. was found to be a frequent isolate from two tertiary care hospitals in Bangladesh, showing limited susceptibility to antimicrobials and decreased susceptibility to Imipenem in particular, which is a matter of great concern.

Background

Visceral leishmaniasis (VL) remains as one of the most neglected tropical diseases with over 60% of the world’s total VL cases occurring in the Indian subcontinent. Due to the invasive risky procedure and technical expertise required in the classical parasitological diagnosis, the goal of the VL experts has been to develop noninvasive procedure(s) applicable in the field settings. Several serological and molecular biological approaches have been developed over the last decades, but only a few are applicable in field settings that can be performed with relative ease. Recently, loop-mediated isothermal amplification (LAMP) has emerged as a novel nucleic acid amplification method for diagnosis of VL. In this study, we have evaluated the LAMP assay using buffy coat DNA samples from VL patients in Bangladesh and compared its performance with leishmania nested PCR (Ln-PCR), an established molecular method with very high diagnostic indices.

Methods

Seventy five (75) parasitologically confirmed VL patients by spleen smear microcopy and 101 controls (endemic healthy controls −25, non-endemic healthy control-26, Tuberculosis-25 and other diseases-25) were enrolled in this study. LAMP assay was carried out using a set of four primers targeting L. donovani kinetoplast minicircle DNA under isothermal (62 °C) conditions in a heat block. For Ln-PCR, we used primers targeting the parasite’s small-subunit rRNA region.

Results

LAMP assay was found to be positive in 68 of 75 confirmed VL cases, and revealed its diagnostic sensitivity of 90.7% (95.84-81.14, 95% CI), whereas all controls were negative by LAMP assay, indicating a specificity of 100% (100–95.43, 95% CI). The Ln-PCR yielded a sensitivity of 96% (98.96-87.97, 95% CI) and a specificity of 100% (100–95.43, 95% CI).

Conclusion

High diagnostic sensitivity and excellent specificity were observed in this first report of LAMP diagnostic evaluation from Bangladesh. Considering its many fold advantages over conventional PCR and potential to be used as a simple and rapid test in the VL endemic areas of the Indian subcontinent, our findings are encouraging, but further evaluation of LAMP is needed.

Background

Human cutaneous anthrax results from skin exposure to B. anthracis, primarily due to occupational exposure. Bangladesh has experienced a number of outbreaks of cutaneous anthrax in recent years. The last episode occurred from April to August, 2011 and created mass havoc due to its dreadful clinical outcome and socio-cultural consequences. We report here the clinico-demographic profile and treatment outcome of 15 cutaneous anthrax cases attended at the Dermatology Outpatient Department of Rajshahi Medical College Hospital, Bangladesh between April and August, 2011 with an aim to create awareness for early case detection and management.

Findings

Anthrax was suspected primarily based on cutaneous manifestations of typical non-tender ulcer with black eschar, with or without oedema, and a history of butchering, or dressing/washing of cattle/goat or their meat. Diagnosis was established by demonstration of large gram-positive rods, typically resembling B. anthracis under light microscope where possible and also by ascertaining therapeutic success. The mean age of cases was 21.4 years (ranging from 3 to 46 years), 7 (46.7%) being males and 8 (53.3%) females. The majority of cases were from lower middle socioeconomic status. Types of exposures included butchering (20%), contact with raw meat (46.7%), and live animals (33.3%). Malignant pustule was present in upper extremity, both extremities, face, and trunk at frequencies of 11 (73.3%), 2 (13.3%), 1 (6.7%) and 1 (6.7%) respectively. Eight (53.3%) patients presented with fever, 7 (46.7%) had localized oedema and 5 (33.3%) had regional lymphadenopathy. Anthrax was confirmed in 13 (86.7%) cases by demonstration of gram-positive rods. All cases were cured with 2 months oral ciprofloxacin combined with flucoxacillin for 2 weeks.

Conclusions

We present the findings from this series of cases to reinforce the criteria for clinical diagnosis and to urge prompt therapeutic measures to treat cutaneous anthrax successfully to eliminate the unnecessary panic of anthrax.

Two independent mol­ecules comprise the asymmetric unit in the title compound, [Sn(C4H9)(C14H19N4S)Cl2]. In each mol­ecule, the SnIV atom exists within a distorted octa­hedral geometry defined by the N,N′,S-tridentate mono-deprotonated Schiff base ligand, two mutually trans Cl atoms, and the α-C atom of the n-butyl group; the latter is trans to the azo-N atom. The greatest distortion from the ideal geometry is found in the nominally trans angle formed by the S and pyridyl-N atoms at Sn [151.72 (7) and 152.04 (7)°, respectively]. In the crystal, mol­ecules are consolidated into a three-dimensional architecture by a combination of N—H⋯Cl, C—H⋯π and π–π inter­actions [inter-centroid distances = 3.6718 (19) and 3.675 (2) Å].

The distorted octa­hedral geometry about the SnIV atom in the title compound, [Sn(C6H5)2(C14H19N4S)Cl], is defined by the N,N,S-tridentate Schiff base ligand, two mutually trans ipso-C atoms of the Sn-bound phenyl groups, and the Cl atom which is trans to the azo N atom. The two five-membered chelate rings and pyridyl ring are almost coplanar with the dihedral angle between the outer five-membered chelate and pyridine rings being 5.39 (8)°. Centrosymmetric dimers feature in the crystal packing mediated by N—H⋯S hydrogen bonds, leading to eight-membered {⋯HNCS}2 synthons. The dimeric aggregates are connected into a three-dimensional architecture by C—H⋯Cl and C—H⋯π inter­actions, as well as π–π inter­actions occurring between centrosymmetrically related pyridine rings [centroid–centroid distance = 3.6322 (13) Å].

In the title thio­urea derivative, C10H17N3O2S, the carboxyl group and the least-squares plane through the cyclo­hexyl ring are twisted out of the plane through the central CN3S residue; the respective dihedral angles are 7.18 (8) and 62.29 (4)°. The conformation about the azomethine bond [1.275 (2) Å] is E. The NH groups are anti, with one forming an intra­molecular N—H⋯N hydrogen bond. The main feature of the crystal structure is the formation of linear supra­molecular chains along [110] mediated by alternating pairs of O—H⋯O and pairs of N—H⋯S hydrogen bonds.

In the title thio­urea derivative, C16H17N3OS, the hy­droxy- and methyl-substituted benzene rings form dihedral angles of 9.62 (12) and 55.69 (6)°, respectively, with the central CN3S chromophore (r.m.s. deviation = 0.0117 Å). An intra­molecular O—H⋯N hydrogen bond ensures the coplanarity of the central atoms. The H atoms of the NH groups are syn and the conformation about the N=C double bond [1.295 (4) Å] is E. In the crystal, helical supra­molecular chains sustained primarily by N—H⋯S hydrogen bonds are found. Additional stabilization is provided by C—H⋯π and π–π [ring centroid(hy­droxy­benzene)⋯ring centroid(methyl­benzene) = 3.8524 (18) Å] inter­actions.

In the title thio­urea derivative, C14H20N4S, the non-ring non-H atoms are approximately planar, with an r.m.s. deviation of 0.0720 Å. The pyridine ring is twisted out of this plane and makes a dihedral angle of 16.85 (13)° with it. The mean plane passing through the cyclo­hexyl ring is almost normal to the central plane [dihedral angle = 69.23 (8)°]. An intra­molecular N—H⋯N(imine) hydrogen bond occurs. Centrosymmetric dimers are formed in the crystal structure via pairs of N—H⋯S hydrogen bonds, and these are connected into a supra­molecular chain along the a axis via C—H⋯π(pyrid­yl) inter­actions.

Corrigendum to Acta Cryst. (2010), E66, m570.

The address of one of the authors in the paper by Salam et al. [Acta Cryst. (2010), E66, m570] is corrected.

The SnIV atom in the title compound, [Sn(C6H5)(C14H19N4S)Cl2], exists within a distorted octa­hedral geometry defined by the N,N′,S-tridentate monodeprotonated Schiff base ligand, two mutually trans Cl atoms, and the ipso-C atom of the Sn-bound phenyl group; the latter is trans to the azo-N atom. The greatest distortion from the ideal geometry is found in the nominally trans angle formed by the S and pyridyl-N atoms at Sn [151.03 (4)°]. With the exception of the cyclo­hexyl group (chair form), the Schiff base ligand is almost planar (r.m.s. deviation of non-H and Sn atoms = 0.053 Å). The nearly orthogonal orientation of the Sn-bound phenyl group [N—Sn—C—C torsion angle = 70.8 (5)°] to the planar portion of the Schiff base allows for the formation of significant intra­molecular C—H⋯Cl inter­actions which preclude the Cl atoms from participating in N—H⋯Cl hydrogen bonds. Instead, C—H⋯π contacts, involving methyl­ene H and the Sn-bound phenyl group, lead to the formation of supra­molecular chains that pack in the bc plane. Connections between these layers are of the type C—H⋯Cl.

In the title organotin compound, [Sn(C6H5)(C10H15N3O2S)Cl(H2O)], the Sn atom is coordinated by the S, O, and imine N atoms of the dinegative tridentate ligand, a chloride ligand, the ipso-C atom of a phenyl ligand and by a water mol­ecule in a distorted octa­hedral coordination environment. Coordin­ated water mol­ecules link the organotin mol­ecules by forming O—H⋯O hydrogen bonds with both carbonyl and carboxyl­ate O atoms, leading to 12-membered {⋯OCO⋯HOH⋯}2 synthons. This results in the formation of supra­molecular chains along the c axis. The chains pack in the ac plane and stack along the b axis with links between layers afforded by N—H⋯Cl hydrogen bonds.

The monodeprotonated Schiff base ligand in the title compound, [Sn(CH3)(C14H19N4S)Cl2], N,N′,S-chelates to the Sn atom, which is six-coordinated in an octa­hedral environment. The three coordinating atoms along with the methyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol­ecule, the hydrogen bond giving rise to a helical chain extending parallel to [100].

The monodeprotonated Schiff base ligand in the title com­pound, [Sn(C4H9)(C19H21N4S)Cl2]·CHCl3, N,N′,S-chelates to the Sn atom, which is six-coordinated in an octa­hedral environment. The three coordinating atoms along with the butyl C atom comprise a square plane, above and below which are positioned the Cl atoms. The amino group is a hydrogen-bond donor to a Cl atom of an adjacent mol­ecule, the hydrogen bond giving rise to a helical chain propagating in [010]. The Cl and H atoms of the chloro­form mol­ecule are disordered over two positions in an 0.67:0.33 ratio.